Class 12 biology chapter 14 MCQs ( Ecosystems and Energy flow )



Multiple choice questions

1. Which one of the following has the largest population in a food chain?
    a. Producers
    b. Primary consumers
    c. Secondary consumers
    d. Decomposers

Answer : Decomposers
Explanation : Decomposers include micro-organisms such as bacteria and fungi. They form the largest population in a food chain and obtain nutrients by breaking down the remains of dead plants and animals.








2. The second trophic level in a lake is ________________
    a. Phytoplankton
    b. Zooplankton
    c. Benthos
    d. Fishes

Answer : zooplankton
Explanation : Zooplankton are primary consumers in aquatic food chains. They feed upon phytoplankton. They are present in the second trophic level. Hence, second most important trophic level in a lake is zooplankton.



3. Secondary consumers are __________
    a. Herbivores
    b. Producers
    c. Carnivores
    d. Autotrophs

Answer : Carnivores
Explanation : Secondary consumers are usually carnviores (meat eaters) but can also be omnivores. Omnivorous consumers eat everything.



4. What is the % of photosynthetically active radiation in the incident solar radiation?
    a. 100%
    b. 50 %
    c. 1-5%
    d. 2-10%

Answer : 50%
Explanation : Out of total incident solar radiation, about fifty percent of it forms photosynthetically active radiation or PAR.



5. Give the term used to express a community in its final stage of succession?
    a. End community
    b. Final community
    c. Climax community
    d. Dark community

Answer : Climax community
Explanation: The term climax community is used to express a community in its final stage of successionThe climax community may change if there are changed in climate or long term evolutionary changes in species.



6. After landslide which of the following type of succession occurs?
    a. Primary
    b. Secondary
    c. Tertiary
    d. Climax

Answer : Primary
Explanation: Succession is generally regarded as primary when it occurs on a landslide where rock and subsoil, virtually free of organic matter are exposed, despite the fact that landslide was formed the substratum just beneath a developed soil carrying vegetation.



7. Which of the following is most often a limiting factor of the primary productivity in any ecosystem.
    a. Carbon
    b. Nitrogen
    c. Phosphorus
    d. Sulphur

Answer : Carbon