BIOLOGY PRACTICAL ACTIVITIES

1. Ecology is best studied outdoors.
2. Students identify a habitat within or near the school compound, e.g. a flower bed.
3. The quadrat method is used.
4. Observation and recording of the various animals as well as their feeding habits is done.
5. Birds that feed on the plants or arthropods in the area studied are noted through observation of habitat at various times of the day.
6. Food chains are constructed e.g green plants ~ caterpillar ~ lizard and many others involving all organisms in the area.
7. The numbers of animals in 1 m2 is counted directly or estimated e.g small arthropods like black ants.
8. The number of plants is easily counted and recorded and ratio of consumers to producers calculated.
9. It will be noted that in terms of numbers where invertebrates are involved, there are very many consumers of one plant.
10. Several other quadrats are established and studied and averages calculated.

 

Adaptions to Habitat

Hydrophytes

• Specimen of hydrophytes e.g water lily is observed.
• Students should note the poorly developed root systems and broad leaves.
• Stomata distribution on leaf surface is studied through microscopy or by emersing a leaf in hot water and counting number of bubbles evolved.

Mesophytes

• Ordinary plants e.g bean hibiscus and zebrina can be studied.
• Size of leaves is noted and stomata distribution studied.

Xerophytes

• Specimen include Euphorbia, cactus and sisal which are easily available.
• The root system e.g in sisal is noted as shallow but extensive.
• It will be noted that sisal has fleshy leaves and stem while cactus and Euphorbia have fleshy stem but leaves are reduced to small hair-like structures.

 

Comparison of Root nodules from fertile and poor soils

Root nodules

• Are swellings on roots of leguminous plants.
• Soil fertility determines number of root nodules per plant.
• Bean plants are best used in this study.
• One plot can be manured while the other is not.
• Similar seeds are planted in the two plots.
• The plants are uprooted when fully mature (vegetatively) i.e any time after flowering and before drying.
• The number of nodules per plant is counted.
• An average for each plot is calculated.
• It is noted that the beans from fertile soil have more and large nodules than those grown in poor soils.

 

Estimation of Population using Sampling Methods

• The number of organisms both producers and the various consumers is recorded in each area studied e.g. using a quadrat.
• The total area of the habitat studied is measured.
• The average number of organisms per quadrat (1 m2) is calculated after establishing as many quadrats as are necessary to cover the area adequately.
• Total population of organisms is calculated from the area.
• Abiotic environment is studied within the area sampled.
• Air temperature soil surface temperature are taken and recorded.
• This is best done at different times of day, i.e., morning afternoon and evening.
• Any variations are noted.
• pH of the soil is measured using pH distilled water to make a solution.
• Litmus papers can be used to indicate if soil is acidic or alkaline, but pH paper or meter gives more precise pH values.
• Humidity is measured using anhydrous blue cobalt chloride paper which gives a mere indication of level of humidity.
• A windsock is used to give an indication of direction of wind.
• As all the abiotic factors are recorded observations are made to find the relationships between behaviour of organism and the environmental factors for example:
• The temperature affects the behaviour of animals.
• The direction of wind will affect growth of plants.
• The level of humidity determines the type, number and distribution of organisms in an area.

 

See also

HUMAN DISEASES (PARASITIC DISEASES)

HUMAN DISEASES – BACTERIAL DISEASES

POLLUTION

HYDROPHYTES (WATER PLANTS)

POPULATION ESTIMATION METHODS