(a) what is an ecosystem?
(b) Name twi abiotic factors each which affect plants and animals in a terrestrial habitat
(c) Describe the effect of three abiotic factors pn a named plants and an animal in the habitat mentioned in (b) above
Explanation
(a) An ecosystem; is a natural unit in which there is an interaction between all living organisms (biotic factors) and non-living organisms (abiotic factors) within an environment or habitat.
(b) Abiotic factors that affect plants and animals are: inorganic compounds or elements, e.g. O\(_2\), N\(_2\), salts, CO\(_2\) , H\(_2\)O etc; water/rainfall; temperature; light/ sunlight; wind; altitude; pressure; moisture/humidity; pH; wildfire/thunder and lightning
(c) Effects of abiotic factors include:
(i) Temperature:
(1) high temperature leads to high transpiration rate in plants/ aestivation and hibernation in animals
(2) High rate of metabolism in organisms
(3) a high rate of decay of organic matter
(4) a higher rate of growth and shorter length of life cycle in some organisms, e.g. housefly and toad
(5) at very low temperature plant roots absorb water at slower rates leading to reduction in the rate of transpiration and metabolism of organisms
(6) at low temperature, animals, e.g. snails may hibernate., birds migrate.
(ii) Rainfall:
(1) makes water available to organisms (plants and animals)
(2) quantity of rainfall determines type of vegetation in a habitat
(3) vegetation in turn influences types of animals that will live there
(4) rainfall, splash or floods may dislodge organisms
(5) rainfall increases relative humidity which may affect the rate of transpiration and perspiration in plants and animals respectively
(6) rainfall causes soil erosion which deprives plants of soil nutrients
(7) may form puddles or ponds thereby creating habitats or breeding ground for certain terrestrial organisms
(iii) Wind:
(1) steady wind increases rate of evaporation, transpiration and desiccation for animals
(2) strong wind causes soil erosion which affects living organisms
(3) strong wind breaks off branches of trees, fell trees or bend them, and force animals out of cover
(4) aids dispersal of organisms
(5) aids pollination
(iv) Light:
(1) intensity of sunlight affects plants by affecting rate of photosynthesis
(2) affects the rate of transpiration and stomata opening
(3) adequate sunlight promotes growth of many plant species
(4) low light leads to growth of shade tolerant species
(5) light affects the vision/movement of animals
(6) light affects the distribution of organisms in habitat.
(v) Pressure/Altitude:
(1) at high altitude, pressure decreases and animals have problems with respiration and blood pressure
(2) at high altitude, temperatures decrease while wind action increases, and this affects the distribution of organisms
(3) at high altitudes, only animals with special hemoglobin are found in the environment
(4) altitude may affect speciation
(5) altitude may affect the behavioral pattern of animals.
(vi) Inorganic Compounds:
(1) used by organisms (plants and animals) to maintain growth and sustain life
(2) 02 for respiration
(3) CO2 for photosynthesis
(4) N2/Nitrates promote plant growth
(5) H2O for growth and maintenance of body temperature
(6) PO for protein synthesis
(7) SO4\(_2\) for plant growth.
(vii) Humidity:
(1) affects rate of transpiration and perspiration
(2) affects the vision of animals through the formation of fog or mist
(3) affects the activities of poikilothermic animals
(4) affects the distribution of organisms, e.g. earthworms; bryophytes, e.g. liverworts etc.
(viii)Wildfire/Thunder and Lightning:
(1) destroys organisms, vegetation and animals
(2) displaces organisms (animals) from their habitat