Theory question 101
Habitats and Biomes(a) What is a habitat? (b) Describe the energy flow in a freshwater habitat. (c) List
(i) three biotic factors; (ii) five abiotic factors which affect plants in freshwater habitat.
Show the model answer
(a) A habitat is the natural place or area where an organism or a community of organisms lives.
(b) The sun is the source of energy; green plants and algae (phytoplankton, water weeds) trap light energy in photosynthesis and store it as food; zooplankton, tadpoles and small fish (primary consumers) eat the plants and get some of this energy; larger fish and water birds (secondary/tertiary consumers) eat them; at each step much energy is lost as heat in respiration, so less passes on; when organisms die, decomposers (bacteria, fungi) break them down, using the remaining energy; energy flows in one direction and is not recycled.
(c)(i) Any three: herbivores (grazing animals); parasites; decomposers/micro-organisms; competition with other plants; predators of pollinators/consumers; human activities.
(ii) Any five: light intensity; temperature; dissolved oxygen; dissolved carbon dioxide; pH; turbidity; water currents; salinity/mineral salts (nutrients); depth of water.
Energy flow must start with the sun and producers and show loss of energy at each level.