Food Chains & Energy Flow — Homi Bhabha Class 9 Biology MCQs with Solutions
Free Homi Bhabha Class 9 Biology Food Chains & Energy Flow MCQs with step-by-step solutions (10 questions). Part of Ecosystem & Environmental Management. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Food Chains & Energy Flow · medium · theory
In a food chain, green plants are called ______ because they make their own food:
A. producers ✓ Correct
B. predators
C. decomposers
D. consumers
Solution: Green plants are producers (autotrophs) and form the base of every food chain.
Q2 — Food Chains & Energy Flow · medium · theory
Animals that eat only plants (herbivores) occupy the level of ______ in a food chain:
A. producers
B. primary consumers ✓ Correct
C. decomposers
D. tertiary consumers
Solution: Herbivores feed directly on producers, so they are primary consumers.
Q3 — Food Chains & Energy Flow · hard · theory
The flow of energy in a food chain is:
A. circular
B. unidirectional (one-way) ✓ Correct
C. zero
D. in both directions
Solution: Energy flows one way — from the Sun to producers to consumers — and is lost as heat at each level.
Q4 — Food Chains & Energy Flow · hard · theory
According to the ten-percent law, the energy passed on to the next trophic level is about:
A. 100%
B. 50%
C. 10% of the energy at the previous level ✓ Correct
D. 90%
Solution: Only about 10% of the energy at one level is transferred to the next; the rest is used up or lost as heat.
Q5 — Food Chains & Energy Flow · medium · theory
Organisms such as bacteria and fungi that break down dead matter are called:
A. carnivores
B. decomposers ✓ Correct
C. producers
D. herbivores
Solution: Decomposers break down dead organisms, returning nutrients to the environment.
Q6 — Food Chains & Energy Flow · hard · theory
A network of many interconnected food chains in an ecosystem is called a:
A. food pyramid only
B. food web ✓ Correct
C. trophic level
D. biome
Solution: A food web is formed by the interlinking of several food chains.
Q7 — Food Chains & Energy Flow · easy · theory
In a food chain, green plants that trap sunlight and make their own food are called:
A. Primary consumers
B. Secondary consumers
C. Decomposers
D. Producers ✓ Correct
Solution: Green plants are producers (autotrophs). They capture solar energy and convert it into chemical energy through photosynthesis, forming the first trophic level of every food chain.
Q8 — Food Chains & Energy Flow · medium · numerical
A food chain is: Grass to Grasshopper to Frog. If the grass stores 10000 kJ of energy, how much energy is available to the frog, assuming only 10% passes to each next level?
A. 500 kJ
B. 100 kJ ✓ Correct
C. 1000 kJ
D. 10 kJ
Solution: Using the 10% law: grass 10000 kJ, then grasshopper gets 10% = 1000 kJ, then the frog gets 10% of 1000 = 100 kJ.
Q9 — Food Chains & Energy Flow · medium · theory
Food chains rarely have more than 4 or 5 trophic levels. The best reason is:
A. About 90% of energy is lost at each level, so too little remains to support more levels ✓ Correct
B. Producers are always fewer than consumers
C. Top predators are usually the largest animals
D. Decomposers destroy the animals at the top
Solution: Only about 10% of energy passes to the next trophic level; roughly 90% is lost as heat and in life processes. After a few levels, the remaining energy is too small to sustain another level.
Q10 — Food Chains & Energy Flow · hard · numerical
Producers in a grassland fix 20000 kJ of energy. Following the 10% law, how much energy is available at the 4th trophic level?
A. 2000 kJ
B. 2 kJ
C. 20 kJ ✓ Correct
D. 200 kJ
Solution: Each level retains 10% of the level below. Level 1 = 20000, Level 2 = 2000, Level 3 = 200, Level 4 = 20 kJ.