POLLUTION

POLLUTION
By the end of the lesson, students should be able to:
Define pollution.
Name air pollutants and their sources.
Enumerate the harmful effects of pollutant.
State effects of detergents, insecticides, artificial fertilizers and herbicides on aquatic and terrestrial organisms.
Identify poor sewage system as a source of pollution.
Name domestic and industrial wastes that pollute land and water.
Identify the decay of organic matter (e.g. dead animals and plants) as a source of pollution.


Pollution is the release of impurities or toxic or harmful substances or chemicals or energy into the environment by the natural forces or man and other animals to an extent that causes biological damages to man, natural resources, and other organisms.

What brought about pollution? Or how does pollution occur?
Man's effort to sustain his life due to increased  population size, resulted in increase in agricultural activities to get food for the increased population, and increase in industrial activities to raise a standard of living; these activities brought about discharge of chemicals, wastes and energy which accumulate in the ecosystem and hence resulted in imbalance, threat to lives and destruction of natural resources.

POLLUTANT
A pollutant is any harmful substance introduced into the environment by natural forces, man and other animals that causes the destruction or impairment in the environment. Examples are carbon dioxide, smoke, noise, refuse and sewage etc.
Major sources of pollutants:
Industrial activities i.e. Wastes (e.g. Carbon dioxide, sulphur dioxide etc), and energy (e.g. heat, sound and radiation)
Agricultural activities i.e. fertilizer application, use of insecticides, pesticides, herbicides, and other farming methods.
Natural processes such as excretion and volcanic eruptions.

Note: pollutants can be grouped into two. These are:

Biodegradable pollutants: These are pollutants which can be broken down into simple harmless substances, which when present in large volume in the ecosystem tend to be poisonous due to inability of the ecological cycle to cope with. e.g. any products of living organisms e.g. decayed body, waste , such as faeces, urine etc are examples.

Non-biodegradable pollutants: These are pollutants that accumulate in the environment, which cannot be broken down into simple harmless substances e.g. glass, plastics, nylon etc

                  TYPES OF POLLUTION
There are three major types of pollution. These are:
1. Air or atmospheric pollution;
2. Water pollution;
3. Soil or land pollution.

1. Air or atmospheric pollution
This is the addition of air-borne substances such as dust, smoke, noise, soot, radioactive energy, carbon dioxide, hydrocarbons into the air, which alters the composition of the atmosphere, causing harm to both plants and animals and resulting in ecosystem imbalance.

              Control of Air/Atmospheric Pollution
Proper maintenance of machinery, automobiles, furnaces and chimneys, through efficient burning to reduce release of gases such as carbon monoxide and soot.
Removal of sulphur compounds from coal and low-grade fuel oils before use.
Industries should be sited far away from residential areas
Legislation should be made against indiscriminate burning that may bring about smoke.
Chimneys should be filtered to remove pollutants
Banning of all chemicals that react with ozone to decrease the ozone layer.
Furnaces and car engines that operate at lower temperatures should be built to reduce the production of the oxides of sulphur and nitrogen
Using unleaded petrol or petrol with low lead levels

                       Definitions of terms used

Fallout: this is the tiny radioactive particles/dust that fall to earth after a nuclear explosion.

Chlorofluorocarbons : the family of synthetic chemicals that are compounds of the elements chlorine, fluorine, and carbon.

Noise: an unpleasant and irritating sound. The loudness of sound is measured in decibels (dB)

Photochemical smog: a form of smog formed when sunlight causes the oxides of nitrogen and unburnt hydrocarbons to react chemically.

2. Water Pollution
This is the discharge into water of any substance which may become harmful to aquatic organisms and unfit for human use.

Sewage: this is a waste matter/faeces, urine, waste water from animals/industrial/domestic sources; that is dissolved/suspended in water.

Effects of releasing untreated sewage into a stagnant water body

Spread of water-borne diseases
May be toxic/poisonous to aquatic life/organisms
Makes water unfit for consumption/use
Increased decomposition
Increased concentration of nutrients
Rapid growth of algae/aquatic plants/algal bloom/eutrophication
Depletion of oxygen
Suffocation/death of aquatic animals
Generates offensive odor/air pollution
Nutrient/nitrate/phosphate enrichment/accumulation in a water body; as a result of breakdown by bacteria.

Refuse: This is a dry or wet waste from paper scraps to abandoned vehicles collected from homes, offices, hospitals, schools, factories, and markets.

Eutrophication: This is the excessive growth of plant life usually algae i.e. algal bloom in water body caused by an increase in organic nutrients and minerals leading to the death of aquatic organisms.

Causes of eutrophication

Overuse of fertilizers/plant nutrients which drain off into water bodies
Sewage discharge
Wastes from fish farming

Effects of eutrophication

It reduces oxygen level in water
The death of algae leads to anaerobic decomposition which may breed some pathogens causing diseases
Renders water useless for man's use and consumption
Death of aquatic animals due to suffocation
The death of aquatic animals and plants result in foul odor hence air pollution occurs.

Class work
How would you control eutrophication?
If you were Nigeria president, how would you solve  the problem of water pollution in the Niger Delta and Lagos metropolis?
Discuss biochemical oxygen demand (BOD) and use it to explain indication of water pollution.
Discuss the effect of pesticides such as DDT in a food chain.
How does the phosphates in the treated sewage cause pollution problem?

Control of water pollution

There should be efficient and proper sewage disposal system
Public enlightenment on waste disposals
Industrial effluents should be recycled rather than being discharged into water bodies
The use of fertilizers and other manure should be regulated to avoid washing or leaching into water bodies
Oil spills should be prevented by using latest techniques of handling crude oil or petrochemicals
Industries should be checked by government using Environmental Impact Assessment before being sited/located
Government should provide good centralized sewer to convey sewages and such should be recycled.

      Methods of purifying water
Boiling
Addition of chemicals such as alum, chlorine
Filtration
Distillation
Sedimentation and boiling
Sterilization such as using ultra violet light.

Note: all sewage are biodegradable but not all refuse are biodegradable.

3. Soil or land pollution
This is the discharge into the soil of rubbish and chemicals which may become harmful to plants and animals including man and make soil infertile.

Control of land/soil pollution

Refuse should be burnt in incinerators
Urban wastes should be properly burnt or buried
Sewage should be properly treated before disposal
Legislation should be made by government against dumping of harmful wastes
Pesticides, herbicides and fertilizers should be applied as instructed
Metal scraps, bottles, cans, and vehicles should be recycled
Oil pipelines should be maintained and checked regularly to prevent sabotage or natural oil spillage
Farming practices should be properly checked to avoid erosion
Overgrazing of pastures should be avoided
Restoration of land where mining took place to prevent indiscriminate mining activities

NUTRIENT CYCLING

NUTRIENT CYCLING

At the end of the lesson, students should be able to:
Describe how carbon circulates in nature.
Draw the carbon cycle in detail.
State why the carbon cycle is used necessary for life.
Recognize the delicate balance between carbon and oxygen.
Describe the role played by plants and animals in water cycle.
Draw the water cycle in detail.
Describe with the aid of diagram the role of nitrogen.
State that energy can be obtained by decomposing organic substances.
Identify one of the gases produced during decay.


Nutrient Cycling
Nutrient cycle or ecological cycle is the movement and exchange of organic and inorganic matter back into the production of living matter. It occurs within ecosystem, since energy flow is unidirectional hence, the movement of mineral nutrients should be cyclic. Mineral cycles include: nitrogen cycle, water cycle, oxygen cycle, sulphur cycle e.t.c.

Carbon Cycle
Carbon cycle involves the series of processes in which carbon is continuously being removed from and added to the carbon dioxide in the atmosphere and the ocean.
Process of carbon cycling

The processes of carbon cycling include:
Removal (or absorption) of carbon from the air and water;
Addition of carbon into the air.

Removal (or absorption) of carbon from the air and water:

Photosynthesis: carbon dioxide is removed from the air (atmosphere) by photosynthesis during which plants use it to manufacture their food.
Leaching and drainage: Carbon is lost in form of carbonates of calcium and magnesium through leaching and drainage.

2.   Addition (or returning) of carbon into the air (atmosphere) and water:

Combustion: burning of fossil fuel like coal and and other crude oil, and wood are sources of carbon into the air.
Respiration: The release of gas during exhalation and fermentation send carbon out in form of carbon dioxide.
Decomposition: The death of all organisms bring about decay, and this results in release of  locked up carbon as carbon dioxide.
Diffusion of carbon dioxide from seas and other bodies of water acting as reservoir of carbon dioxide.
The action of volcanoes (i.e. volcanic eruption)which releases carbon dioxide.

Importance of carbon cycle in nature
Plant uses carbon dioxide obtained from the air to produce their food.
It is the major block of all organic matter.
It helps to purify the atmosphere and maintain atmospheric level of carbon dioxide.
Organic matter which is made from carbon helps to replenish soil nutrient.

Oxygen Cycle
Oxygen cycle involves the circulation of oxygen between the living organism and the non living things.

Process of oxygen cycle

The process of oxygen cycling include:
Removal/ or absorption of oxygen from the air and water;
Addition of oxygen into the air.

1. Removal of oxygen from the air and water:

Respiration in both plant and animal;
Combustion of fuels;
Decay of dead organic matter.

2.    Addition of oxygen into the air and water:
Photosynthesis.
Note: Oxygen cycle is the carbon cycle in reverse!

Importance of oxygen cycle in nature

It brings about life sustenance.
It makes carbon dioxide readily available for photosynthesis.
It purifies the air by avoiding pollution.
Oxygen cycle, if not altered, ensures balance in nature.
Carbon-Oxygen Balance
Many human activities increase the level of carbon dioxide, while oxygen is left at a very low pace.

Such activities that deplete oxygen level in the atmosphere include:

Deforestation;
Combustion of fuel;
Overpopulation which increases respiration rate;
Decay of many dead animals through war, and other means;
Burning of bush indiscriminately.

 If the activities mentioned above are not checked, they result into the following:

Climate change which could affect the important food-growing areas of the world. Hence, this result in food shortage;
Death of many aquatic organisms e.g. fish.
Greenhouse effect (i.e. an increase in the retention of the sun's radiant energy)
Global warming (i.e. an average increase in the earth's temperature which in turn causes changes in climate) which may result in melting of the polar ice-caps with a related rise in sea level.

Suggested solution to maintain a balanced carbon-oxygen level.

Limiting the use of land fill sites to reduce production of greenhouse gases such as methane, carbon dioxide, sulphur dioxide etc;
Limiting deforestation and encourage afforestation;
Exhaust fumes of vehicles should be properly checked to ensure that carbon dioxide and other gases are emitted are reduced;
Education and enlightenment on the effect of man's activities that alter oxygen level;
Birth control measure should be adopted to discourage overpopulation;
Production of chlorofluorocarbons must be discouraged.



Water Cycle
Water cycle is the continuous movement of water from the atmosphere to the earth and from the earth to the atmosphere.

Process of Water Cycling in Nature

The process of water cycling include:

Removal/ or absorption of water from the air;
Addition of water into the air.

1. Removal of water from the air/atmosphere involves all forms of processes in which land receives water. These processes include:
Rainfall or precipitation.
Infiltration and percolation.

2.   Addition of water into the air/atmosphere include all processes in which the atmosphere receives water. These processes include:
Evaporation from oceans, seas, rivers and land (e.g. from decay, excretory wastes, run off water etc)
Transpiration from plants.
Breathing or respiration by plants and animals.

Importance of water (cycle) to living organisms.

Maintains osmotic content of body.
Medium of transport of nutrient for both plant and animal.
Required for seed germination.
Provides medium for absorption of mineral salts by plants.
Aids excretion of waste products.
Provides a natural habitat for aquatic organisms.
It is an essential raw material in the process of photosynthesis.
Regulates body temperature i.e. thermoregulation.
It acts as a solvent for soluble food substances in digestion of food.

EXPERIMENT 1
Aim: To show the absorption of carbon dioxide and release of oxygen during photosynthesis.
Materials required: three beakers, test tubes, funnels, water plants, glowing splint.


Method: set up three set of apparatus as shown above. Distilled water is put in A, B, and C and then filled with water saturated with carbon dioxide.
Place C in a dark cupboard and A in bright sunlight and B in dim light until some gas has collected in one of the test tubes.
Test the gas in the test tube with a glowing splint, to find out if it is oxygen.
Observation: (tabulate your observation as shown below)


From this table, using glowing splint to test the presence of oxygen, it is observed that flask  C did not produce oxygen while flasks A and B produced oxygen.
Conclusion: The experiment simply shows that carbon dioxide and sunlight are required by plants🌿 during photosynthesis and during the process, oxygen is released to the environment.

EXPERIMENT 2
Aim: To show that water is given off during transpiration.
Materials required: Two polythene bags, two bell jars, anhydrous white copper II tetraoxosulphate VI, two potted plants (with one having its stem cut) and crucible.

Method: Place the copper II tetraoxosulphate VI (CUSO4) in a crucible along with the potted plant, covering the soils with the polythene bag. Repeat same with the control. Cover the white anhydrous copper II tetraoxosulphate VI with bell jars.
Observation: The white anhydrous copper II tetraoxosulphate VI in the main experiment turns blue while the control did not change colour.
Conclusion: The change in colour is due to the water given off during transpiration through the leaves.
Class work.
Using experiment 2 above, explain why;
the pot is enclosed in a transparent polythene bag;
the stem above the soil is smeared with a layer of vaseline.

Nitrogen Cycle                            
The nitrogen cycle is the pathway along which nitrogen moves through living and non-living components of the ecosystem to continuous uses.

Process of Nitrogen Cycling in Nature

1. Removal of atmospheric nitrogen: This is conversion of gaseous nitrogen into nitrates. This occurs in the following ways:

Nitrogen fixation by some free bacteria: Some bacteria can convert free atmospheric nitrogen in the soil to produce nitrates. Examples are  Azotobacter, Clostridium and Rhodospirillum.
Nitrogen fixation by symbiotic bacteria: Some bacteria have symbiotic association with roots of some leguminous plants ( such as groundnuts, beans, Crotalaria). They form nodules in which atmospheric nitrogen is converted to nitrates and absorbed by by the plant to form proteins. Example is Rhizobium leguminosarium.
Note: The Rhizobium bacteria are not capable of fixing nitrogen if they are free from leguminous roots.
Action of blue green algae: The blue green algae are capable of converting/fixing atmospheric nitrogen into nitrate. Examples are Anabaena and Nostoc.
Electrical discharge: During thunderstorms, the lightening produced causes the atmospheric nitrogen to combine with oxygen to form nitrogen (II) oxide i.e. N2 + O2 →2NO. The nitrogen (II) oxide reacts with oxygen to form nitrogen (IV) oxide i.e. 2NO + O2→ 2NO2. The nitrogen (IV) oxide reacts with rain water to form a weak solution of trioxonitrate (V) acid and dioxonitrate (III) acid i.e. 2NO2  + H2O → HNO3 + HNO2 . When this weak acid reaches soil, it combines with mineral salts in the soil to form nitrates which the plants absorb.
Putrefaction: The death of plants and animals releases protein into the soil. These proteins are converted by bacteria into ammonium compounds. The ammonium is therefore converted into nitrite by the genus of Nitrosomonas bacteria, then by those of the genus Nitrobacter into nitrates. The nitrates are absorbed by plants through their roots.

Note:
The bacteria converting protein into ammonia are called putrefying bacteria and the process is known as ammonification, while those converting/oxidizing ammonia to nitrites and nitrates are collectively called nitrifying bacteria and the process is called nitrification.
Application of farmyard manure/organic fertilizers/green manure also add nitrogen into the soil, but at the same time ammonification and nitrification end the reaction.

2. Addition of nitrogen into the atmosphere: This involves conversion of soil nitrates to gaseous nitrogen. This occurs through:
Denitrification: Some bacteria convert ammonia, nitrites or nitrates into free nitrogen which escapes into the atmosphere. This process is called denitrification. Example of denitrifying bacteria include Pseudomonas denitrificans.
Note:
Nitrogen is lost from the soil through the following:
Action of denitrifying bacteria;
Absorption by plant roots;
Action of leaching.


Decomposition in Nature
A decomposer is an organism that breaks down dead organisms or wastes of plants and animals into simpler substances and obtaining energy in the processes. Such organism is a saprophyte and feeds saprophytically i.e. undergoes saprophytic nutrition. Examples include all the fungi (e.g mushroom, Mucor) and some bacteria, others are earthworm, termite.
Classes/types of decomposer:
Micro-decomposers: They are tiny, and cannot be seen with the naked eyes. Examples are certain bacteria and some fungi
Macro-decomposer: they can be easily seen with the naked eyes. Examples are mushrooms, toadstools, mould, termite, earthworms, snails.

Process of Decomposition
The decomposer come on the dead matter/organism; secrete a lytic enzyme which breaks down the complex organic (e.g. proteins and carbohydrates) components into simpler and soluble inorganic (e.g. ammonia gas, hydrogen sulphide gas, carbon dioxide, water vapor and salts like phosphates, sulphate, nitrates, and potassium ions) components/compounds. The salts released are leached into the soil for plants use, while the carbon dioxide released is used for food manufacturing. The decomposer also make use of the nutrients and the energy released in form of heat. When the plant dies, the nutrients absorbed are returned back into the soil and the decomposer re-use it. This use and re-use is called recycling. When the decomposer dies, another decomposer feeds on it and utilize its energy as well for itself and other living organisms e.g. plants.


Roles of Decomposers in Ecosystem
They enrich the soil with nutrients which is used by plants for anabolism.
They cause nuisance and pollute environment when they are present in large numbers.
They are useful in the production of some economic products such as cheese and yoghourt.
They purify the environment through their cleaning activities.
They prevent accumulation of wastes which may be dangerous to our lives.
They maintain a steady supply of useful materials to the producers and the consumers.
Production of fuel e.g. biogas (produced from methane and carbon dioxide formed during decomposition).

EXPERIMENT 3

Aim: To show that carbon dioxide is released during decomposition.
Materials required: two test tubes, delivery tube, decaying humus, lime water.
Method: set-up two experiments; test experiment and control experiment. Label the test experiment as set-up A, while the control experiment is labeled as set-up B. In set-up A, add humus in the test tube as shown below, while in set-up up B, do not add humus. The whole experiment is allowed to stand for about 4-6 hours.
Observation: It is observed that the lime water in set-up A turns milky, while that of set-up B remains the same.
Conclusion: Since the lime water turns milky, it shows that carbon dioxide is released during decomposition.
Note: Hydrogen sulphide (a product of decomposition) can be identified by smell. It smells like a rotten egg.
Assignment.
Describe an experiment to show that heat is released during decomposition.
Construct a detritus food chain.
Discuss the statement: "The movement of energy through an ecosystem is unidirectional but the movement of nutrients is cyclic.

ECOLOGICAL MANAGEMENT

ECOLOGICAL MANAGEMENT
By the end of the lesson, students should be able to:
I. ASSOCIATION:
Recognise some of the different types of association existing between different species.
Identify beneficial harmful and neutral forms of association among organisms.
Deduce the mode of life of a given organism from observed characteristics.
II. TOLERANCE:
Discuss why living things possess a range of tolerance to environmental factors.
 List the abiotic factors that impose tolerance on organisms.
Depict tolerance range with a graph.
III. ADAPTATION:
State that adaptation may be a modification in response to environmental factors.
Describe the availability of water as the principal factor for plant and animal distribution.
List examples of adaptation to environmental factors.
IV. POLLUTION:
Define pollution.
Name air pollutants and their sources.
Enumerate the harmful effects of pollutant.
State effects of detergents, insecticides, artificial fertilizers and herbicides on aquatic and terrestrial organisms.
Identify poor sewage system as a source of pollution.
Name domestic and industrial wastes that pollute land and water.
Identify the decay of organic matter (e.g. dead animals and plants) as a source of pollution.

Biological Association.
This is the food relationship interactions between organisms in an ecosystem, which may be beneficial, neutral or harmful.
Any close and prolonged living together or association of two or more organisms of the same or different species which may be temporary or permanent, harmful, beneficial, or neutral to one or more or all the partners is termed symbiosis.
Types of Symbiosis:
Mutualism;
Parasitism;
Commensalism;
Competition.

Mutualism: A type of relationship in which two different kinds of organisms live together to the benefit of each other. Examples are:
Lichens: This is an association between alga and fungus. The alga provides food for the fungus through its photosynthetic activity, while the fungus provides water through rain water which is
used by alga to photosynthesis its food, it (fungus) also provides for the alga protection against physical damage and drying up.

Mycorrhiza: This is an association between a fungus and the root of a higher plant. The fungi act as root hairs and helps in the transfer of inorganic nutrients from the soil into the plant, while the plant provides the fungus with organic nutrients.
Insect pollinated flowers and insect pollinator: The flower supplies the nectar which the insect feeds upon, while the insect brings about effective reproduction in the plant by pollinating it.

Herbivorous animals and cellulose digesting bacteria in its intestine: These bacteria digest the cellulose of leaves and convert the digested cellulose to sugar which is absorbed by the herbivore, while the herbivore provides shelter and nutrients for the bacteria in the rumens and colon.

Nitrogen fixing bacteria in the root nodules of leguminous plants: The bacteria enter the root of a leguminous plant, causing cell division due to nodules formation, more so, the Rhizobium (the bacterium) fixes nitrogen directly into then plant, and hence, increasing the nitrogen requirement of leguminous plants. While the plant through its root provides nutrients for the growth of the bacteria.

Cattle and tick birds: Tick birds remove blood-sucking flies and ticks from the hides of cattle, in this case, the birds get their food by eating the ticks, while the cattle benefit by having their parasitic infestation reduced.


2. Parasitism: A type of relationship in which two different kinds of organisms live together to the benefit of one (i.e. the parasite) and the detriment of the other (i.e. host). Examples are:

Man and the ascaris/or tapeworm: The ascaris (i.e. roundworm) or tapeworm lives in the small intestine of man where it derives its nutrients, protection and habitat. The man who is the host suffers because he loses to the parasite part of the food he has eaten and digested. This is an example of endoparasitism because the parasite lives inside the body of the host.

Dog and the tick: The tick lives on the surface of the dog where it derives its food (i.e. nutrients) through sucking of the dog blood. The dog who is the host suffers anaemia because he loses to the parasite its blood. This is an example of ectoparasitism because the parasite lives on the outer surface of the host body.

Mistletoe/ or dodder (Cuscuta)/ or witch weed (Striga) and the flowering plant: The mistletoe/or dodder/ or witch weed are parasitic plants that live on flowering plants. The parasite derives support, and also absorbs water and mineral salts  from the flowering plant, while the host loses and harmed by losing to the parasite part of the water and mineral salts that it has absorbed.  This is also an example of ectoparasitism.

Effects of parasite on the host:
It damages the host's tissues.
It kills the host due to damages done to the tissue and due to toxic substances secreted.
Poor growth of the host.
 Discomfort.
 Weakness of the body or structure.
Lack of resistance to diseases.

Parasitic fungi: Some fungi are parasitic to green plants. Examples are:
Ustilago on maize.
Puccinia on maize, wheat or barley.
Phytophthora palmivora on cocoa.
Phytophthora infestans on tomato/potato causing blight
Alternation on tomato.

How parasites (endoparasites) enter the hosts:
Wounds.
Natural openings such as mouth, anus, nostril, ear, eyes in animals and stomata or lenticel in plants.

General adaptation of parasite: A parasite must:

be able to secrete enzymes to dissolve tissues of the host for easy penetration. This is common to endoparasites;
be able to cling or attach to the host's body surfaces (either internally or externally);
have organs that can penetrate through the host's body surface and absorb nutrients. This is common to ectoparasites;
have boring organs which will enable it to enter the body of the host. This is common to endoparasites.

Adaptation of gut parasites e.g. tapeworm, ascaris:

Presence of attachment organs onto the walls of the host gut. Such attachments are hooks and suckers in tapeworm;
ability to respire aerobically or anaerobically;
production of anti-enzymes to neutralize the host's enzymes;
possession of hard cuticles which cannot be digested by host's digestive enzymes;
presence of large surface area to small volume ratio for easy absorption of host's digested food.

How parasitic plants such as Mistletoe and Dodder are adapted to their parasitic life:
They grow on the stem of their host; they penetrate into the host using their sucker; absorb the nutrients from the host; using their sucker called haustoria.

How ectoparasite animals are adapted to their parasitic life:

They have an attachment structures such as claws, suckers and hooks, that enable them to cling to their hosts. Once they attach to the host's body surface, they pierce the host's outer tissues with their modified mouthparts; they suck blood of animals and secrete anti-coagulants to prevent blood clotting or the sap of plants if it is a plant parasite.
Examples of animal ectoparasite that feed on animals are leech, tick, bedbug.
Example of animal ectoparasite that feeds on plants sap is aphids.

Other example of plant parasite is Cassytha.


Assignment:
1. Discuss the life cycle of tapeworms.
2. Differentiate between the following; Tania solium and Tania saginata. Draw and label fully their diagrams.
3. Differentiate in a tabular form, parasitism and saprophytism.

3.    Commensalism: A type of relationship between two organisms of different species in which one of the organisms benefited (i.e. commensal) while the other is neither benefited nor harmed (i.e. host). Examples are:

Remora fish (shark-sucker) and shark: The remora attaches itself to the underside of the shark. The remora feeds on the scraps/left over of shark food. It (remora) also gets protection, and shelter from the shark, whereas the shark is neither harmed nor benefited as a result of the presence of the remora fish.

Oyster and crab: The crab gets shelter/habitation in the oyster shell, whereas the oyster is not harmed.

Epiphyte and a tree: The epiphyte gets a site where it can get enough sunlight to cary out photosyntheses, whereas the tree is not affected.

Dispersal of the fruits of some plants by animals: The fruit of Triumfetta is dispersed by passing animals such as sheep. Triumfetta plant benefits by having its fruits dispersed to a new environment while the animal is not harmed.

Kite and trees: A kite builds its nest on the branches of big trees like Iroko. The tree provides the Kite shelter, whereas the tree does not gain anything from the Kite nor harmed.

Sea cucumber and Fierasfer: The fish called Fierasfer lives in the rectum of sea cucumber. The fish comes out frequently to feed and returns to the rectum by poking the anus of the sea cucumber and enters with its tail. The fish gains shelter and the sea cucumber does not gain nor harmed.

Assignment
Deduce that there is no mutualism neither commensalism that will not lead to parasitism.

4. Competition: This is a type of association between a number of organisms of the same or different species for resources in limited supply such as food, water, space, light, suitable temperature, and mates.

Types of Competition.
There are two types of competition namely:
Intraspecific competition; and
Interspecific competition.

Intraspecific competition: This type of competition involves organisms of the same species. Examples include: planting of flowers or any other plants or crops too close together in a flower bed or space or heap, the plants will compete for space, light, water,  gases, and soil nutrients.

Effect of intraspecific competition: stunted growth and poor flowering and death if not checked. In a nutshell, overcrowding results in intraspecific competition.


How plants and animals have been able to solve problem of intraspecific competition:

To avoid intraspecific competition, overcrowding is solved, hence, plants disperse their spores, seed and fruits by various dispersal mechanism, while animals emigrate, while in human, birth control methods are adopted.

Interspecific competition: This type of competition involves two or more organisms of different species using the same limited resources.
 Effects of interspecific competition:

The stronger competitor may drive the weaker ones into extinction;
One species may enjoy competitive superiority in some regions while the other may be competitively superior in other regions with different environmental conditions.

Examples of interspecific competition include: 1. Two species of duck weeds, Lemma gibba, and Lemma polyrrhiza which grow equally when alone, but L. gibba always replaces L. polyrrhiza when they are grown together. 2. Two species of Paramecium, namely P. caudatum and P. aurelia. 3. Flowering plants and grasses.

The term allelopathy: This is an interaction in which one organism releases a chemical substance(s) into an environment causing a harmful effect on other organisms. For example, the release of chemical substances from the male inflorescence of maize flower inhibits the growth of other grasses near that area while the seed germination of maize is not affected. The maize plant has shown superiority over other plants, hence it will eliminate other plants.

Tolerance.
Tolerance is the ability of a living thing to successfully cope (withstand) with the extreme variations (upper and lower) limits of an environment which affect their survival.
Tolerance Range
This is the range between upper/maximum and lower/minimum limits of abiotic factors affecting the survival of living organisms in a particular area or habitat. Any abiotic factors affecting the organisms below or beyond this limits result in death of the organisms. For example, in most animals, the minimum temperature (i.e. abiotic) limit is 0°C and the maximum limit is 42°C . Their tolerance range is 0°C to 42°C. Anything below 0°C (the lower lethal temperature) and above 42°C (the upper lethal temperature) results to death!

Physiological Stress
 This is a phenomenon which occurs as a result of subjecting an organism beyond its optimum range (the range within which the species' growth and reproduction are at their peaks) which results in a steady fall in its growth and reproductive rate.

Geographic Range
This is the presence of a particular species only in a particular area or geographical region which is within their minimum and maximum limits of their tolerance range.  For example some organisms are limited only to arctic temperate or tropical regions due to temperature factor.

Abiotic factors that impose tolerance on organisms.
Temperature
pH
Soil type
Water//rainfall
Topography/altitude
Pressure
Sunlight/light
Air
Wind
Relative humidity/atmospheric humidity.
Graph showing tolerance range, optimum range and population size.

Adaptation
Adaptation is the ability of an organism to survive and reproduce successfully in any given environment or habitat over a long period of time due to possession of structural, functional or behavioral features.
Plants and animals possess certain features which enable them to adapt to either aquatic or terrestrial habitats.

Adaptation of plants to aquatic environment
Plants that live successfully in water are called hydrophytes. They include Eichornia (water hyacinth), water lily (Nymphaea lotus), Nuphar, red mangrove (Rhizophora racemosa), white mangrove (Avicenna spp.), Raphia palm, Pistia stratiotes(water lettuce), Elodea, Potamogeton, Duckweed ((Lemna) etc.
Adaptation include:
Possession of waxy cuticles on leaves to prevent wetting, e.g. water lettuce.
Possession of long stem and flower stalk to expose the flowers and leaves, e.g. water lily
Possession of air floats in the leaves and stems for buoyancy e.g. water hyacinth
Possession of breathing roots for gaseous exchange e.g. white mangrove
Possession of air spaces in the tissues for buoyancy e.g. water lettuce
Presence of chloroplasts on the leaves and stems                   for photosynthesis/manufacturing of food
Variable leaf shapes to prevent a minimum resistance to water currents and increase the surface area for water and mineral absorption e.g. Potamogeton
Flowers are raised above water for the purpose of pollination

Adaptation of plants to terrestrial environment
Plants living on land can be grouped into two, based on their need for water. These groups include:
Mesophytes: These are plants that live in a moderate condition of water supply (i.e. neither too dry nor too wet), e.g. cashew tree, oil palm tree, maize, yam, cassava, cocoyam, sweet potato
Xerophytes: These are plants that need very small amount of water to live e.g. Desert plants such as Cactus, Euphorbia, Acacia, Aloe, Portulaca.

Adaptation of mesophytes to their environment
Possession of large and flattened leaves to increase gaseous exchange
Possession of waxy cuticle to minimize water loss
Presence of stomata on the leaves for gaseous exchange
Presence of chloroplasts for photosynthesis
Possession of numerous leaves to enhance better photosynthesis
Adaptation of xerophytes to their environment
Presence of succulent stems for water storage e.g. Cacti, Euphorbia, and Opuntia
Presence of succulent leaves to conserve water e.g. Bryophyllum
Possession of deep tap root with extensive lateral roots to source for water e.g. Acacia, Baobab
Leaves are reduced to spine (e.g. in Cactus), or thorns (e.g. in Acacia), or reduced to scale-like structure (e.g. in Casuarina i.e whistling pine) to reduce rate of water loss/transpiration
Possession of thick bark to prevent destruction of parts due to fire outbreak e.g. Baobab
Presence of sunken stomata or lower number of stomata to reduce water loss


Adaptation of animals to terrestrial environment
Possession of hairs, in mammals, feathers in birds and scales in reptiles to regulate body temperature
Presence of lungs for respiration
Presence of sweat glands for excretion and thermoregulation
Presence of skin (e.g. Mammals) and exoskeleton (cuticle) in insects for protection against injury and desiccation
Possession of pairs of limbs to escape predator
Adaptation of animals to aquatic environment
Presence of lateral line to detect vibrations in water, hence adaptation to escape predator
Presence of fins (e.g. Fish) and webbed digits (e.g. Toad) to facilitate swimming
Presence of gills (e.g. Fish) and siphon-like tubes (Mosquito larva) for breathing
Possession of streamlined body to offer minimum resistance to water flowing over them
Presence of suckers or hairs for attachment to vegetation to avoid being swept away by water current e.g. Leech
Possession of nicitating membrane over eye in fishes and presence of eyelids in toads and frogs
Ability to burrow and remain in moist habitats to escape predators e.g. Annelids, clams, and snails

Adaptation of some organisms

Adaptation of toad or frog for food, protection and movement

(A) for food
It possesses special olfactory organ in the head for smelling/perceiving the odometer of its food
It has the ability to draw eyes in so that they make bulges in the root of the mouth which help to prevent their prey from escaping and help in swallowing
The tongue is attached at the front of the mouth which can be rapidly extended to capture/trap prey
The tongue is long and sticky to help hold the prey.

(B) for protection
The skin is slimy with mucous gland which makes the animal difficult to be caught by predators
Slimy fluid keeps the skin moist and prevents the skin from drying up
Toad  has poison glands on the skin which is poisonous and distasteful to the predators
Cryptic coloration to prevent them from being noticed by enemies and predators
The colour can be altered to match the type of background.

(C) for movement
Presence of powerful muscular hind limb to hop/jump, hence escape predators
Absence of tail facilitates hopping or jumping movement
Webbed hind limb can be used as paddle for efficient swimming in water
The stout and short nature of fore limb absorbs shock on landing and for propping up the front end of the body on landing after a jump or hop
Presence of streamlined body for easy movement and swimming
Adaptation of chameleon/lizard
Possession of long, sticky tongue for capturing preys
Possession of claws on the feet for holding objects on which it walks
Possession of powerful eyes to see preys and predators easily
Possession of scales to prevent desiccation
In chameleon, there is ability to change the colour of the body in order to hide from its predators.

Assignment
Discuss the adaptation of the following organisms to their environment:
Endoparasite e.g. Tapeworm
Tilapia fish
Tadpole

EXCRETORY SYSTEM
At the end of this chapter, students should be able to:
Identify and describe different types of excretory systems in plants and animals;
Explain the mechanisms of some of the excretory organs and relate structure to functions.

Definition of excretion
Excretion is the removal of waste products of metabolism which are harmful or would in time interfere with normal functions of organisms.
Note: excretion is not the same as egestion and secretion. Egestion is the removal of solid undigested food substances which are not by-products of metabolism, e.g. The removal of faeces from anus. Secretion on the other hand is the production of useful substances in the body by some special cells, e.g. Production of enzymes and hormones.

Importance of Excretion
We need to eliminate waste metabolic substances because of the following reasons:
The excretory products are harmful/toxic to the body hence, they need to be removed;
Some metabolic substances are poisonous whenever they accumulate in the body;
Excretion maintains water balance in the body;
Excretion maintains salt balance in the body;
Waste products when not removed can interfere with normal metabolic activities of the body.




MECHANISM OF EXCRETION IN SOME ORGANISMS

FLATWORMS










The excretory system consists of two longitudinal canals with network of ducts (tubules). The ducts branch to all parts of the body and end up in flame like cells.
The waste products e.g. water, ammonia and Carbon dioxide diffuse from the surrounding cells into the flame cells. With the aid of the flagella/ or cilia, which suck the excretory products into the funnel, the fluid containing the waste products is propelled/driven into the tubules. And finally they are eventually removed at the exterior.
Note: another major function of the flame cells is the regulation of the water content of the animal i.e. Osmoregulation.

EARTHWORM










Nephridium is the excretory organ in earthworm. Each Nephridium consists of a flattened funnel-like structure with two lips called the nephrostome. The earthworm excretes urea and guanin. The beating of the cilia of the nephrostome draws coelomic fluid. During this process of drawing fluid, salts and other useful substances are reabsorbed through the walls of the tubes. The unabsorbed substances, including water, are collected in the muscular tubes as urine. The excretory pore relaxes to allow the urine to escape to the exterior. While Carbon dioxide are removed through the moist body surface during gaseous exchange.

CRUSTACEANS











The excretory organ in crustacean are the green glands. Each gland consists of five parts: a small end sac, the green gland, flattened disc called the labyrinth, the Nephridium canal, and the urinary bladder.
How green glands perform excretion in crustacean

The green gland extracts metabolic wastes from the blood. During this process of extraction, water and dissolved salts pass into the end sac by filtration. Nitrogenous waste materials pass into the labyrinth. Selective reabsorption of salts and glucose takes place at the nephridial canal according to the needs of the animal. Urine is formed. The urine formed is hypotonic to the blood, and is collected in the urinary bladder and removed by the muscular contraction of the walls of the bladder, and discharged to the outside through the pair of excretory pores located at the base of the antennae.

Note: some of the crustacean's waste Carbon dioxide is excreted through the gills and some, together with calcium, is known to be used by crayfish to strengthen its exoskeleton.

INSECTS












The excretory organs of insects are the Malpighian tubules. They are found between the midgut and the rectum; each tubule consists of two parts:  the distal end (free and closed end, floating in the haemocoel) and the proximal end (opens into the gut).

MECHANISM OF EXCRETION IN INSECTS.
When nitrogenous waste products and water are liberated into the haemocoel, they are absorbed at the distal end of the malpighian tubules. At the distal end, urates of potassium and sodium are extracted from the blood. The alkaline contents at the proximal end become acidic due to the addition of carbon dioxide, hence uric acid is precipitated and the potassium and sodium ions are re-absorbed as bicarbonate. The uric acid is passed into the ileum, from where it is passed out mixed with faeces. More water is re-absorbed at the rectum. The uric acid, mixed with faeces, is thus expelled as more or less dry material.
Note:
1. Excretion by storage: This is an uncommon form of excretion in insects, which involves storing up of uric acid in special fat bodies within the body of the insect from where it does no harm.
Why would insect use "excretion by storage"?
2. Insects do not drink!
How do they (insects) get their water?
They get all the water they need from the food they eat and from the chemical breakdown of carbohydrate in which water is a by-product.
3. Reasons why insects are very successful group of animals: they can conserve water, hence, they are found everywhere even in the hottest and driest places on earth.
What are those factors enabling insects to conserve water?
Presence of wax on the outer layer which makes their outer surface waterproof;
Presence of spiracles to prevent water loss from the gaseous exchange surface which is inside the body;
Possession of efficient excretory system.

MAMMALS
The excretory system of a mammal consists of:
the kidneys;
the ureters;
the bladder;
the urethra.













                                                                      Excretory system of man
The longitudinal section of mammalian kidney


Structure of the kidney

A kidney is a reddish organ. It is bean-shaped with fibrous capsule. It is located at the dorsal wall of the abdomen. It is made up of three regions; the cortex (outer region), the medulla (inner region) and the pelvis (the funnel-shaped space). It is highly vascularised with many capillaries which are all branches of renal artery and renal vein. At the top/apex of each kidney lies the adrenal gland.

Structure of a urinary tubule

The kidney is made up of functional units, each is called a kidney tubule or nephron. A human kidney contains over one million nephrons. At the anterior end, each nephron is made up of cup-shaped and hollow structure called bowman's capsule, and a long tube called convoluted tubule. In the hollow of the bowman's capsule, there is a mass of blood capillaries called glomerulus. These blood capillaries in the glomerulus are branches of the renal artery, which brings blood from the dorsal aorta to the kidney. The glomerulus and the bowman's capsule form the malpighian body/corpuscle.
The capsule (i.e. Bowman's capsule) opens into a short coiled tube, the proximal convoluted tubule, which lies in the cortex and joins the bowman's capsule anteriorly and the loop of Henle posteriorly. Then the tubule goes back, as the ascending tubule, from the medulla to the cortex region, where it is again coiled and is known as the distal convoluted tubule. The distal convoluted tubule joins a collecting tubule, which passes through the medulla region and opens at the pelvis.

The capillaries in the glomerulus rejoin to form a blood vessel leading out of the capsule. This vessel then branches into a capillary network around the urinary tubule before rejoining to form a branch of the renal vein. Through the renal vein, blood from the kidney flows to the posterior vena cava and thence back to the heart.

Note: the proximal convoluted (coiled) tubule forms the Henle loop in the medulla when it descends and form a U-shaped structure.


The kidney nephron

Mechanism of kidney excretion in mammals or how the kidney carries out its function of urine formation and discharge

The processes of urine formation include:
Ultrafiltration;
Selective reabsorption;
Tubular secretion
Blood from the heart flows to the glomerulus under high pressure, resulting in filtration of amino acids, glucose, mineral salts, water and urea out of the thin walled capillaries into the the Bowman's capsule. This process of filtering materials from the glomerulus into the Bowman's capsule is called ultra filtration or pressure filtration.

Note: the liquid that filters from the blood into the space inside the Bowman's capsule is called the glomerular filtrate. It is similar to blood plasma, but does not contain blood corpuscles or blood proteins.

The fluid that filters into the Bowman's capsule flows down the tubule, therefore bringing about selective reabsorption of useful substances back into the blood in the blood capillaries. Hence, at the proximal convoluted tubule, those useful substances such as glucose, amino acids, mineral salts and water are reabsorbed into the blood capillaries against concentration gradient or by active transport.
All the urea, small amounts of mineral salts and water are left in the tubule.

The fluid in the tubule becomes more concentrated as it flows through the distal tubule where more water is reabsorbed by the action of anti-diuretic hormone (ADH) and urine is finally formed.

Note: During ultrafiltration, bigger molecules like plasma proteins and the blood cells cannot pass through the wall of capillaries, hence, they are returned back into the blood.

Note: The filtered blood leaving the kidney by the renal vein contains:
less oxygen and glucose, and more carbon dioxide, as a result of cellular respiration; and
less nitrogenous wastes, salts and water as a result of excretion.

Reasons why blood flowing from the heart to the glomerulus is under high pressure.
The blood capillaries in the glomerulus have narrow diameter relative to the renal artery.
The blood capillaries that leave the glomerulus, are narrower in diameter than those that lead into it.
A large amount of blood flows through the kidney.
Note: It is estimated that about one quarter of the blood that leaves the heart with each beat flows through the kidney. When a large volume of blood flows through narrow capillaries, which offer a resistance to the flow of blood, a high pressure is built up.

How urine formed is expelled:
Urine passes through the ureter to the bladder where it is stored. The bladder has a muscle at its posterior end called a sphincter, which closes the outlet of the bladder. When one is ready to urinate; when the bladder is full, it contracts, while the sphincter relaxes and hence, the urine is discharged/expelled through the urethra.



Other functions of the kidney:
Osmoregulation
Maintenance of acid-base balance of the blood
Note: urinary tubule/kidney nephron is the functional unit of the kidney.

Class work
1. Relate the environment of three types of vertebrates of your choice to their;
type of excretory wastes, and
means of excretion.
2. Assess the reason why blood is not found in the urine, whereas mineral salts are present in it.
3. Suggest three factors that dictate the forms of nitrogenous waste excreted by an animal.
4. Compare excretion in insects and amphibians with respect to the:
structure of their organs of excretion;
mechanisms of excretion, and
forms of excreted wastes.
5. The liver cells make bile, which  is needed for the digestion of fats. Justify with explanatory reason(s) why the bile salt is considered excretory product.
6. Describe the process of excretion through the mammalian skin.
7. How would you explain the pungent odor of the expelled urine in man?


Excretion in Plants

Plants do not have special excretory organs. Gaseous wastes diffuse through the stomata, while insoluble excretory products are stored in some of the cells. Such non-gaseous wastes are excreted in the form of insoluble oil droplets, crystals and granules. The main excretory organs of flowering plants are the stomata in the leaves and lenticels in the stem. The main excretory products formed in plants are water, carbon dioxide and oxygen.
Mechanism of Excretion in Plants
Plants have their waste products eliminated through:
Transpiration;
Respiration;
Photosynthesis;
Guttation.
Note: These processes require diffusion.

Through transpiration, photosynthesis and respiration, excess water is lost in form of vapor i.e. through respiration and transpiration; likewise carbon dioxide i.e. respiration; oxygen i.e. photosynthesis and as droplets (e.g. In tomato, potato, grass) of water i.e. guttation. Other insoluble materials such as tannins, mucilage, gum, crystals, alkaloids and anthocyanin are stored in the bark of stems, leaves and petals, which are shed periodically.
Note: wastes stored in the bark of stem, leaves and petals can be removed from plants by the process of leaf-fall.

Assignment
Provide the economic importance of the following insoluble wastes in plants:
Tannins;
Gums;
Alkaloids

CELL REACTIONS TO ITS ENVIRONMENT
Responses
There are three types of responses. These are tactic, nastic, and  tropic movements.
The ability of a living organism to respond to stimulus is called irritability. A stimulus is an environmental change which induces or brings about a response in a cell or organism.

Taxis or Tactic Movements
Taxis is the directional movement of a whole organism or a free moving part of it, towards or away from a stimulus. This type of response is positive if the organism moves towards the stimulus, and negative if it moves away from it.
Examples of tactic responses:

Nastism or Nastic Movements
Nastism is a non-directional movement(response) of part of a plant to a non-directional stimuli.
Examples of nastic movements are:
closing of the morning glory flower when the light intensity is low;
the petals of sunflower which open in the light and close in the dark;
the folding of the leaflets of the Mimiosa plant when it is touched;
the closing of the leaflets of the flamboyant tree i.e. sleeping movements due to low light intensity.

Tropism or Tropic Movements
This is a directional movement of part of a plant to a directional stimuli; either towards or away the stimuli.  It is a very slow growth movements. It is a bending growth movement, by a plant organ, in response to a stimulus from one direction, by which the plant organ assumes from one direction, by which the plant organ assumes a particular posture or orientation, which bears a relationship to the direction from which the stimulus is received. This type of response is positive if the plant organ moves towards the stimulus, and negative if it moves away from it.
Examples of tropic response:

Class work
In a tabular form, give five differences between;
tropic movement and nastic movement;
tactic movement and tropic movement;
tactic movement and nastic movement.
2. Mention five organs of higher plants that respond to stimuli.

Experiment 1
Aim: To show that shoots are positively phototropic.
Materials required: two boxes, seedlings growing in pot, knife, aluminium foil.
Procedure: The two boxes are arranged as seen in the diagrams below. Some germinating bean seeds/or maize seeds are placed in two boxes with a hole cut at one end. Box A contains normal seedlings while box B contains seedlings with caps of aluminium foil over the tips of the shoots. The inside of each box is painted black to prevent light reflection. The entire experiment is put on the window and observed for a few days.



Observation: The shoot of the seedlings in box A will be observed to bend towards the source of light while those in box B grow straight.
Conclusion: Since the shoot of seedlings bend towards light, it shows that the shoot is positively phototropic.

Experiment 2
Aim: To show that the roots of plants are positively hydrotropic.
Materials required: Two large beakers, water, maize/beans seedlings.
Procedure: Two large beakers in which some bean seedlings are growing by the sides are used. Small holes are made at the center of the two beakers as shown below. A little water is poured at the center in one of the beakers (i.e. control experiment) while there is no water in the second beaker. The entire set-up is allowed to remain for few days.
A B
Observation: At the end of the experiment, the seedlings from both beakers are removed. The seedlings in which the beaker contains water bend their roots towards the source of water while the roots of the other beaker with no water remain straight.
Conclusion: The bending of the roots towards the source of water shows that the roots are positively hydrotropic.
Movement
Movement is the ability of living organisms to change position in response to stimulus (internal or external). It brings about a change of shape, form or position; effects of movement.
Protoplasmic streaming or cyclosis.
Cyclosis is the circulation of protoplasm in cells.
Importance of cyclosis: brings about circulation of materials within the cell. This results in bringing cell to life.
Causes of cyclosis.
Cyclosis is brought about by two actions. They are:
Ability of cytoplasm to change from plasma gel to plasma soil, progressively, from the anterior end to the posterior end of the stream;
Exertion of pressure at the posterior end of plasmasol by the cytoplasm causing the cell to move forward.
Examples of cyclosis.
Amoeboid movement by Amoeba and white blood cell.
Reproduction
Reproduction is the ability of living organisms to give rise to new individuals of the same species.
Forms or types of reproduction.
There are two main types of reproduction. These are asexual and sexual reproduction.
Asexual reproduction does not involve fusion of gametes, while sexual reproduction involves the fusion of sex cells or gametes.
Differences between Asexual and Sexual Reproduction

Asexual Reproduction.
It is common among simple organisms, as well as, flowering plants. It can be divided into two, namely:
Natural asexual reproduction;
Vegetative reproduction.
Note: In organisms which can reproduce both sexually and asexually, asexual reproduction occurs when food is plentiful and environmental conditions are favorable for growth.
Types of natural asexual reproduction in plants and animals:


Binary fission in Amoeba Budding in yeast





Spore formation in Rhizopus





Types of Vegetative Reproduction
There are two types of vegetative reproduction. These are:
Natural vegetative reproduction; and
Artificial vegetative reproduction.
Natural vegetative reproduction: This method involves the production of new individuals from the vegetative parts of the plants. Such vegetative parts include stems, roots and leaves.
Forms of natural vegetative reproduction are:
I.Use of modified underground stem:




II. Use of fleshy leaves to produce buds:







Bryophyllum leaf.                         Corm of Cocoyam.                            An onion bulb.
2. Artificial vegetative reproduction: This involves the use of intelligence by man to grow new plants from cut portion of the vegetative body of an older parent plants.



Cassava stem cutting Layering in cocoa Budding using Lemon (as a stock) and orange (as a scion)



Grafting using lemon (as a stock) and orange (as a scion)





Marcotting (stages a, b, c and d)in Mango
Importance of budding and grafting
They are used to propagate many fruit trees, especially citrus trees
Such trees propagated by budding and grafting bear fruits quickly
The trees possess resistance to diseases and other environmental resistance.
Advantages of vegetative propagation
Growth in young plant is rapid since there is no resting period.
Plants that do not produce seeds can only be propagated vegetatively.
Offspring are identical to the parent.
Young plant uses food reserves of the parent as it becomes easily established.
Only one parent is needed.
Desirable characters are retained.
Offspring mature more rapidly.
Plants are less susceptible to adverse weather condition.
It is independent of agents of pollination.
While becoming established, plants grown vegetatively require less care than seedlings.
Disadvantages of vegetative propagation
It may lead to overcrowding of plants.
No new variety of species are produced.
Disease of parents can easily be transmitted to offspring.
There is no mixing of characters.
It reduces resistance to disease.
Undesirable characters are easily transmitted to offspring.
It brings about competition among offspring and parents.
It reduces resistance to changes in climate.
Colonization of new localities is unlikely since offspring are always produced close to parent plant.


Sexual Reproduction.
In sexual reproduction, offsprings are produced by fusion of two different sex cells (gametes) which usually come from two different parents. When the two gametes come together, their nuclei fuse, and this is called fertilization. This fusion results in the formation of zygote, which later develops into an embryo.
Types of sexual reproduction
There are two major types of sexual reproduction. These are:
conjugation,
fusion of gametes.
Conjugation: This is the process by which nuclear material is passed from one cell to another. That is, the whole cell act as a gamete, and pair with another similar whole cell and exchange nuclei. It is common among lower organisms. Examples include Mucor, Rhizopus, Paramecium and Spirogyra.
Fusion of gametes: This is the union of the haploid male and female gametes to produce diploid organisms called zygote. The male gamete is the sperm in animal and the pollen grains in flowering plants, while the female gamete is the egg or ovum in animal and the ovule or egg in flowering plants. Examples of organisms using this methods include Moss, Ferns, all flowering plants, Hydra, Earthworm, Insects, and all vertebrates.
Advantages of sexual reproduction.
It enhances speciation or formation of new species or formation of new species and allows for the continuity of the species.
It provides the means for the maintenance of chromosome number from generation to generation.
It permits variability of individuals, i.e. new varieties are produced.
It enhances survival in new or changing environment.
It allows for the production of hybrids for some desirable traits.

EXCRETION
Excretion is the removal of waste metabolites from the body of a living organism. Examples of excretory products are sweat, urea, urine, carbon dioxide, oxygen (in plants), water (in plants), and uric acid.
TYPES OF EXCRETORY SYSTEM

GROWTH
Growth is an irreversible increase in size and or dry mass. Cell division by mitosis, cell enlargement and differentiation form the basis for growth.
Aspects of Growth
Increase in number of cells
Increase in number and size (height, length, breath, girth)
Increase in dry mass
Differentiation of cells into tissues and organs
Synthesis of new body material.
Process of Growth
Assimilation
Expansion of the cell
Cell division
Differences between Plants and Animals Growth

Similarities between growth in plants and animals
Both multicellular plants and animals grow by mitotic cell division of pre-existing cells to form new cells
Both achieve a certain amount of vegetative or body growth before reproductive growth sets in
Both show sigmoid growth curve in which the rate of growth is slow at first, becomes faster later until the maximum is reached, then growth rate starts to decline
Both plants and animals require food for growth
Both secrete growth hormones for growth
Growth is irreversible in both plants and animals.
Types of Cell Division
 Mitosis: This is a process of cell or nuclear division during which each chromosome in the nucleus duplicates itself and two new cells are formed with equal number of chromosomes i.e. the division of a somatic cell into two daughter cells. It takes place in the somatic cells i.e. body cells that are not involved in the production of gametes.
Mitosis consists of a division of the nucleus followed by a division of the cytoplasm.
Stages of Mitosis
Interphase: during this stage, cell is not dividing; no chromosomes is visible
Prophase: there are two prophase stages: (a) early prophase and (b) late prophase.
Early prophase:  during this stage, centriole pairs separate and move to opposite poles; aster rays form around centriole pairs; spindle fibres develop between the centriole pairs to form a spindle; chromosomes become visible in nucleus, then shorten and thicken. Each chromosome can be seen to be made up of two chromatids joined at the centromere.
Late prophase: during this stage, nuclear membrane disappears, and the chromosomes lie free in the cytoplasm.
Metaphase: during this stage, chromosomes come to lie around the equator of the cell.
Anaphase: during this stage, the two chromatids in each chromosome separate at the centromere, and are moved towards opposite poles, along the spindle fibres.
Telophase: this is the last stage of mitosis, during which chromatids arrive at the poles, spindle gradually disappears. A nuclear membrane forms around each set of chromatids. Chromatids gradually become invisible.
This is the end of nuclear division proper. It is followed by the division of the cytoplasm.
Importance or Role of Mitosis
It promotes cell growth
It helps in the replacement or repair of damaged tissues
It serves as basis of asexual or vegetative reproduction
It produces genetically or identical offspring which are identical to the parents
It maintains the diploid number of the chromosome of the cell
Life examples of mitotic process in animals
Formation of new cells in the malpighian layer of the skin
Production of red blood and white blood cells in the bone marrow
Cell division in the liver
Binary fission e.g. in Amoeba
Repair or healing of wound
Life examples of mitotic process in plants
Mitosis occurs in root tip or apex
It occurs in stem tip or apex
It occurs in cambium
It is found in meristems
(b) Meiosis:  A kind of cell division during spermatogenesis (sperm formation) and oogenesis (egg formation) in which there is a reduction of chromosomes to half of the original number of chromosomes.
Note: during gametogenesis (sperm and egg formation), in humans, the 46 chromosomes are reduced to 23. Therefore, each sperm or egg now has 23 chromosomes. The fusion of the sperm and egg gives 46 chromosomes which every human being has.
Importance or Roles of Meiosis
It results in the formation of sperms in animals
It results in the formation of eggs in animals
It results in the formation of pollen grains in anthers of flowering plants
It results in the formation of ovules in ovary of flowering plants.
Life examples or areas where meiosis occurs in plants
Ovaries
Anthers
Life examples or areas where meiosis occurs in animals
Ovaries
Testes
Differences between Mitosis and Meiosis

Similarities between mitosis and meiosis
Both result in the formation of new daughter cells
Both involves division of nucleus preceding division of cytoplasm
Both require hormones
Both take place in plants and animals cells
Both pass through prophase, metaphase, anaphase, and telophase.
Regions of Fastest Growth in Plants
The regions of fastest growth in plants are the roots and stem apices i.e. apical meristems. The apical meristems consist of meristematic cells i.e. cells capable of active division.
Note: the stem apices include the terminal buds and the lateral axillary buds.
Roles of apical meristems
Bring about growth in length (height) of the plant
Give rise to branches, leaves and flower in the shoot
They bring about primary growth (i.e. the first growth) of a plant.
Factors Affecting Growth in Plants
External factors:
Warm temperature
Adequate sunlight
Adequate water/humidity
Mineral salts/nutrients availability
Sufficient oxygen/air
Adequate carbon dioxide
pH level
accumulation of metabolic products
Internal factors:
Hormones i.e. the growth hormones e.g. auxins, gibberellings and cytokinins
Genetic constitution
   Factors Affecting Growth in Animals
Balanced diet
Oxygen/air
Warmth/suitable temperature
Heredity/genetic constitutions
Hormones
Growth curves
There is a pattern to which, by and large, is shared by both plants and animals.
Growth pattern in plants: in annual plants, a typical sigmoid growth curve is exhibited with limited growth, while in perennial plants; a series of sigmoid curve is exhibited with unlimited growth.

Growth pattern in animals: in most invertebrates, such as fishes, they show  S-shaped or sigmoid curve with unlimited growth. In arthropods, such as insects, they moult time to time, hence this growth is called intermittent growth and the growth curve is sigmoid. In birds and mammals e.g. human they show limited growth with sigmoid curve.

NUTRITION/FEEDING
Nutrition: This is the process by which living organisms obtain and utilize food materials from external environment in order to supply the nutrients required for metabolic activities.
Food: This is any substance which when absorbed into the body cells yields energy and materials for growth, repairs of damaged tissues and regulation of body processes without harming the living organism. Food is the source of nutrients.


Usefulness of food
Living cells or organisms require food for the following reasons:
To provide energy needed for various life activities;
To make essential substances such as hormones and enzymes;
To make new cells for growth and replacement of worn-out tissues;
To supply various substances required for healthy growth and development
Modes/Types of Nutrition
The following are the types of nutrition:
Autotrophic nutrition (self-feeders); and
Heterotrophic nutrition (dependent-feeders)
Autotrophic nutrition: A type of nutrition in which organisms are able to manufacture their own organic food (i.e. glucose) from simple carbon compound and simple inorganic nitrogen . Such organism is referred to as autotroph,
Types of autotrophic nutrition
Photosynthetic (holophytic) e.g. green plants;
Chemosynthetic nutrition i.e. some bacteria e.g. blue-green algae; nostoc, suphur bacteria, Nitrosomonas e.t.c.
      2.    Heterotrophic nutrition: A type of nutrition carried out by organisms that are not capable of manufacturing their own food from simple inorganic substances. Such organism is called heterotroph
Types of heterotrophic nutrition
Holozoic nutrition: This is a type of nutrition in which food is obtained as a solid organic material, eaten, digested and absorbed into the body. Nearly all animals are holozoic in nutrition.
Saprophytic nutrition: This is a type of nutrition in which non-green plants feed on dead and decaying organic matter.
Note: organisms which feed saprophytically are known as saprophytes. Examples are most fungi (e.g. Mucor, Mushroom, and Yeast) and bacteria.
Symbiotic nutrition: This is a type of nutrition in which two organisms of different species live together to take advantage of each other. Examples are the association between alga and a fungus to form lichens, where the fungus provides moisture (i.e. water), mineral salts and support for the alga which the alga used in manufacturing food by photosynthesis for the fungus and itself; other example is the relationship between herbivorous animals (e.g. goat, sheep) and cellulose-digesting bacteria that live in the caecum and colon of herbivores.
Parasitic nutrition: This is a type of nutrition in which one organism obtains food from another organism and during the feeding process one organism is harmed and does not benefit. The organism causing harm is called parasite, while the one been harmed is called host.
Note: the association between a host and a parasite is called parasitism. Examples of parasites are Plasmodium, Ascaris lumbricoides, ticks, bugs e.t.c.




ROLES OF ENZYMES IN DIGESTION
Enzymes are organic catalysts of protein origin produced by living cells which help to speed up or slow down the rate of chemical reactions but remain unchanged chemically at the end of the reaction.
We shall discuss this in detail next term!

MINERAL SALTS
Mineral salts are contained in important elements. They have to be taken in compound forms, for example sodium chloride (table salt) is a compound of sodium and chlorine.
Why do we have to take mineral elements in compound forms?
Because if they are taken like that i.e. as mineral elements, they could be fatal but when taken in a compound form, they become harmless and useful to the body.
The soil is the main source of mineral salts, while gaseous elements such as oxygen, hydrogen and carbon are mainly derived from the atmosphere.
Classes of elements or plant nutrients
Plant nutrients are grouped into two classes depending on the quantity that is required by plants. The classes are:
Macro-nutrient or major elements: They are required by plants in large quantities for healthy growth and development. Examples are nitrogen, phosphorus, potassium, magnesium, calcium, oxygen, hydrogen, carbon, sulphur and iron.
Micro-nutrients or trace elements: They are required by plants in small quantities for healthy growth and development. Examples are zinc, copper, boron, molybdenum, cobalt, chlorine, and manganese, fluorine and iodine.
METABOLISM
Metabolism is the physical and chemical processes by which simple molecules of food are built up into complex molecules (assimilation, anabolism)and complex molecules are broken down into simple molecules (respiration)with liberation of energy for work by the organism.
Types of metabolism
Anabolism: This is the building up of simple molecules of food into complex molecules by living things, with the use of energy leading to an increase in size and complexity. Anabolism, or constructive metabolism, is the process of synthesis required for the growth of new cells and the maintenance of all tissues.
 Examples of anabolic processes are:
formation of glycogen from glucose;
formation of starch from glucose;
formation of proteins from amino acids;
formation of fats and oil from fatty acids and glycerol;
photosynthesis in green plants
growth
Catabolism: This is the breakdown of complex food molecules by living things with liberation of energy for work. It is the production of energy through the conversion of complex molecules into simple ones. Catabolism, or destructive metabolism, is a continuous process concerned with the production of the energy required for all external and internal physical activity.
Examples of catabolic processes are:
Respiration;
Fermentation;
Digestion.
Note:
When anabolism exceeds catabolism, growth or weight gain occurs. When catabolism exceeds anabolism, such as during periods of starvation or disease, weight loss occurs. When the two metabolic processes are balanced, the organism is said to be in a state of dynamic equilibrium.

Usefulness of energy released during metabolism
Energy released during metabolic activities is the ATP, which is used for the following purposes:
Anabolic process: ATP provides the energy necessary to build up macro molecules, e.g. proteins from amino acids;
Active transport: Energy is needed to move materials against a concentration gradient, e.g. by the use of ion pumps;
Movement: Muscle contraction, ciliary movement and contraction of the spindle fibers during cell division all require energy from the hydrolysis of ATP;
Activating reactants: Chemicals often require the addition of phosphate groups from ATP to make them more reactive, e.g. phosphorylation of glucose at the beginning of glycolysis;
Secretion: ATP provides energy for the secretion of cell products.
Uses of glucose
Builds new plant materials;
Used by plant as energy source;
Eaten by animal and used as energy source;
Used in building new animal materials.
Uses of ATP (adenosine triphosphate)
For chemical work (e.g. enzyme synthesis)
For mechanical work (e.g. muscle contraction)
For osmotic work e.g. water regulation
For electrical work e.g. nerve impulse transmission
For cell division i.e. it provides energy required by cells to divide

CELLULAR/INTERNAL/TISSUE RESPIRATION
This is the process of breaking down glucose by a series of chemical reactions controlled by enzymes to release energy. It may also be defined as the oxidation of food substance in the cells (particularly in the mitochondria), to release energy for work. The energy released is stored in adenosine triphosphate (ATP).
Differences between glucose and ATP


Types of cellular respiration
Aerobic respiration: it requires oxygen to break down/oxidize glucose/simple sugar (substrates) in the cell to release carbon (IV) oxide and water.i.e.
C6H12O6 + 6O2 →6CO2 + 6H2O + 38ATP
Anaerobic respiration: it does not require oxygen to break down glucose in the cells to release alcohol, carbon dioxide and 2 ATP as the products. i.e.
C6H12O6 → C2H5OH + 2CO2 + 2ATP
Chemical processes of cellular respiration
The breaking down of glucose in the body passes through several pathways before it can produce energy. These pathways are Glycolysis and Kreb’s cycle
Glycolysis: This is a series of chemical reactions which involves the breaking down of glucose to a 3-carbon molecule called pyruvic acid.
Note: what happens to the pyruvic acid depends on the presence or absence of oxygen. For example in animals, the pyruvic acid is converted to lactic acid. But in plant, the pyruvic acid is converted to alcohol; this is known as alcoholic fermentation.
Examples of organism that undergoes fermentation is yeast
Kreb’s cycle/citric acid cycle/tricarboxylic acid(TAC): This is a series of cyclic reactions which begin with the pyruvic acid formed from glycolysis which combined with acetyl co-enzyme A to form citric acid.
Differences between Glycolysis and Kreb’s cycle

Similarities between aerobic and anaerobic respiration
Both lead to the release of energy
Both occur in plant and animal cells
Both require enzymes to speed up the reactions
Both lead to generation of heat
Both give off carbon dioxide as by-product.
Differences between aerobic and anaerobic respiration


E

NUTRITION/FEEDING
Nutrition: This is the process by which living organisms obtain and utilize food materials from external environment in order to supply the nutrients required for metabolic activities.
Food: This is any substance which when absorbed into the body cells yields energy and materials for growth, repairs of damaged tissues and regulation of body processes without harming the living organism. Food is the source of nutrients.


Usefulness of food
Living cells or organisms require food for the following reasons:
To provide energy needed for various life activities;
To make essential substances such as hormones and enzymes;
To make new cells for growth and replacement of worn-out tissues;
To supply various substances required for healthy growth and development
Modes/Types of Nutrition
The following are the types of nutrition:
Autotrophic nutrition (self-feeders); and
Heterotrophic nutrition (dependent-feeders)
Autotrophic nutrition: A type of nutrition in which organisms are able to manufacture their own organic food (i.e. glucose) from simple carbon compound and simple inorganic nitrogen . Such organism is referred to as autotroph,
Types of autotrophic nutrition
Photosynthetic (holophytic) e.g. green plants;
Chemosynthetic nutrition i.e. some bacteria e.g. blue-green algae; nostoc, suphur bacteria, Nitrosomonas e.t.c.
      2.    Heterotrophic nutrition: A type of nutrition carried out by organisms that are not capable of manufacturing their own food from simple inorganic substances. Such organism is called heterotroph
Types of heterotrophic nutrition
Holozoic nutrition: This is a type of nutrition in which food is obtained as a solid organic material, eaten, digested and absorbed into the body. Nearly all animals are holozoic in nutrition.
Saprophytic nutrition: This is a type of nutrition in which non-green plants feed on dead and decaying organic matter.
Note: organisms which feed saprophytically are known as saprophytes. Examples are most fungi (e.g. Mucor, Mushroom, and Yeast) and bacteria.
Symbiotic nutrition: This is a type of nutrition in which two organisms of different species live together to take advantage of each other. Examples are the association between alga and a fungus to form lichens, where the fungus provides moisture (i.e. water), mineral salts and support for the alga which the alga used in manufacturing food by photosynthesis for the fungus and itself; other example is the relationship between herbivorous animals (e.g. goat, sheep) and cellulose-digesting bacteria that live in the caecum and colon of herbivores.
Parasitic nutrition: This is a type of nutrition in which one organism obtains food from another organism and during the feeding process one organism is harmed and does not benefit. The organism causing harm is called parasite, while the one been harmed is called host.
Note: the association between a host and a parasite is called parasitism. Examples of parasites are Plasmodium, Ascaris lumbricoides, ticks, bugs e.t.c.




ROLES OF ENZYMES IN DIGESTION
Enzymes are organic catalysts of protein origin produced by living cells which help to speed up or slow down the rate of chemical reactions but remain unchanged chemically at the end of the reaction.
We shall discuss this in detail next term!

MINERAL SALTS
Mineral salts are contained in important elements. They have to be taken in compound forms, for example sodium chloride (table salt) is a compound of sodium and chlorine.
Why do we have to take mineral elements in compound forms?
Because if they are taken like that i.e. as mineral elements, they could be fatal but when taken in a compound form, they become harmless and useful to the body.
The soil is the main source of mineral salts, while gaseous elements such as oxygen, hydrogen and carbon are mainly derived from the atmosphere.
Classes of elements or plant nutrients
Plant nutrients are grouped into two classes depending on the quantity that is required by plants. The classes are:
Macro-nutrient or major elements: They are required by plants in large quantities for healthy growth and development. Examples are nitrogen, phosphorus, potassium, magnesium, calcium, oxygen, hydrogen, carbon, sulphur and iron.
Micro-nutrients or trace elements: They are required by plants in small quantities for healthy growth and development. Examples are zinc, copper, boron, molybdenum, cobalt, chlorine, and manganese, fluorine and iodine.
METABOLISM
Metabolism is the physical and chemical processes by which simple molecules of food are built up into complex molecules (assimilation, anabolism)and complex molecules are broken down into simple molecules (respiration)with liberation of energy for work by the organism.
Types of metabolism
Anabolism: This is the building up of simple molecules of food into complex molecules by living things, with the use of energy leading to an increase in size and complexity. Anabolism, or constructive metabolism, is the process of synthesis required for the growth of new cells and the maintenance of all tissues.
 Examples of anabolic processes are:
formation of glycogen from glucose;
formation of starch from glucose;
formation of proteins from amino acids;
formation of fats and oil from fatty acids and glycerol;
photosynthesis in green plants
growth
Catabolism: This is the breakdown of complex food molecules by living things with liberation of energy for work. It is the production of energy through the conversion of complex molecules into simple ones. Catabolism, or destructive metabolism, is a continuous process concerned with the production of the energy required for all external and internal physical activity.
Examples of catabolic processes are:
Respiration;
Fermentation;
Digestion.
Note:
When anabolism exceeds catabolism, growth or weight gain occurs. When catabolism exceeds anabolism, such as during periods of starvation or disease, weight loss occurs. When the two metabolic processes are balanced, the organism is said to be in a state of dynamic equilibrium.

Usefulness of energy released during metabolism
Energy released during metabolic activities is the ATP, which is used for the following purposes:
Anabolic process: ATP provides the energy necessary to build up macro molecules, e.g. proteins from amino acids;
Active transport: Energy is needed to move materials against a concentration gradient, e.g. by the use of ion pumps;
Movement: Muscle contraction, ciliary movement and contraction of the spindle fibers during cell division all require energy from the hydrolysis of ATP;
Activating reactants: Chemicals often require the addition of phosphate groups from ATP to make them more reactive, e.g. phosphorylation of glucose at the beginning of glycolysis;
Secretion: ATP provides energy for the secretion of cell products.
Uses of glucose
Builds new plant materials;
Used by plant as energy source;
Eaten by animal and used as energy source;
Used in building new animal materials.
Uses of ATP (adenosine triphosphate)
For chemical work (e.g. enzyme synthesis)
For mechanical work (e.g. muscle contraction)
For osmotic work e.g. water regulation
For electrical work e.g. nerve impulse transmission
For cell division i.e. it provides energy required by cells to divide

CELLULAR/INTERNAL/TISSUE RESPIRATION
This is the process of breaking down glucose by a series of chemical reactions controlled by enzymes to release energy. It may also be defined as the oxidation of food substance in the cells (particularly in the mitochondria), to release energy for work. The energy released is stored in adenosine triphosphate (ATP).
Differences between glucose and ATP


Types of cellular respiration
Aerobic respiration: it requires oxygen to break down/oxidize glucose/simple sugar (substrates) in the cell to release carbon (IV) oxide and water.i.e.
C6H12O6 + 6O2 →6CO2 + 6H2O + 38ATP
Anaerobic respiration: it does not require oxygen to break down glucose in the cells to release alcohol, carbon dioxide and 2 ATP as the products. i.e.
C6H12O6 → C2H5OH + 2CO2 + 2ATP
Chemical processes of cellular respiration
The breaking down of glucose in the body passes through several pathways before it can produce energy. These pathways are Glycolysis and Kreb’s cycle
Glycolysis: This is a series of chemical reactions which involves the breaking down of glucose to a 3-carbon molecule called pyruvic acid.
Note: what happens to the pyruvic acid depends on the presence or absence of oxygen. For example in animals, the pyruvic acid is converted to lactic acid. But in plant, the pyruvic acid is converted to alcohol; this is known as alcoholic fermentation.
Examples of organism that undergoes fermentation is yeast
Kreb’s cycle/citric acid cycle/tricarboxylic acid(TAC): This is a series of cyclic reactions which begin with the pyruvic acid formed from glycolysis which combined with acetyl co-enzyme A to form citric acid.
Differences between Glycolysis and Kreb’s cycle

Similarities between aerobic and anaerobic respiration
Both lead to the release of energy
Both occur in plant and animal cells
Both require enzymes to speed up the reactions
Both lead to generation of heat
Both give off carbon dioxide as by-product.
Differences between aerobic and anaerobic respiration