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Food chains are very important for the survival of most species.
6.1 If 10,000 J solar energy falls on green plants in a terrestrial ecosystem, what percentage of solar energy will be converted into food energy?
a) 10,000 J
b) 100 J
c) 1000 J
d) It will depend on the type of the terrestrial plant.
Answer
6.1 b) 100 J
Only 1% of the energy of sunlight that falls on leaves is convert into food energy by plants
If 10,000J is the energy of sunlight;
(1/100) x 10000 = 100J
Common mistake : Only 1% of energy from sunlight is converted to food energy. On the other hand, 10% of the energy flows from one trophic level to another
6.2 If Ravi is consuming curd/yogurt for lunch , which trophic level in a food chain should he be considered as occupying ?
a) First trophic level
b) Second trophic level
c) Third trophic level
d) Fourth trophic level
Answer
6.2 c) Third Trophic leve l
Curd is made from milk which is obtained from cow
Cow is a primary consumer that feeds on producer (grass) and occupies the second trophic level
Consuming the produce obtained from an organism at second trophic level makes Ravi belong to the third trophic level
6.3 The decomposers are not included in the food chain.The correct reason for the same is because decomposers:
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Act at every trophic level of the food chain
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Do not breakdown organic compounds
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Convert organic material to inorganic forms
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Release enzymes outside their body to convert organic material to inorganic forms
Answer
6.3 a) Act at every trophic level of the food chain
Thus, they do not belong to any particular trophic level
6.4 Matter and energy are two fundamental inputs of an ecosystem. Movement of
a) Energy is bidirectional and matter is repeatedly circulating.
b) Energy is in repeated circulation and matter is unidirectional.
c) Energy is unidirectional and matter is repeatedly circulating.
d) Energy is multidirectional and matter is bidirectional.
Answer
6.4 c) Energy is unidirectional and matter is repeatedly circulating
6.5 Which of the following limits the number of trophic levels in a food chain?
a) Decrease in energy at higher trophic levels
b) Less availability of food
c) Polluted air
d) Water
Answer
6.5 a) Decrease in energy at higher trophic level
The energy keeps on decreasing in each trophic level
This decrease is due to the heat released
As a result, the number of trophic levels is limited
