Ecology Practical Activities - KCSE Biology Notes

Ecology Practical Activities

• Ecology is best studied outdoors. Students identify a habitat within or near the school compound, e.g. a flower bed.
• The quadrat method is used.
• Observation and recording of the various animals as well as their feeding habits is done.
• Birds that feed on the plants or arthropods in the area studied are noted through observation of habitat at various times of the day.
• Food chains are constructed e.g. green plants ~ caterpillar ~ lizard and many others involving all organisms in the area. 

• The numbers of animals in 1M squared  is counted directly or estimated e.g. small arthropods like black ants.
• The number of plants is easily counted and recorded and ratio of consumers to producers calculated.
• It will be noted that in terms of numbers where invertebrates are involved, there are very many consumers of one plant.
• 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 immersing 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

• These 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. 

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