Sample 1Easy
Which of the following ecological pyramids is generally inverted?
- A
Pyramid of energy in a forest
- B
Pyramid of biomass in the sea
- C
Pyramid of numbers in a grassland
- D
Pyramid of biomass in a grassland
Show the answer
The answer is B.The pyramid of biomass in the sea is generally inverted because the biomass of fishes far exceeds that of phytoplankton. The pyramid of energy is always upright and can never be inverted.
- A.
The pyramid of energy is always upright.
- C.
The pyramid of numbers in a grassland is upright.
- D.
The pyramid of biomass in a grassland is upright.
NCERT: Class 12 Biology, Chapter 12 (Ecosystem), Ecological Pyramids
Sample 2Medium
An upright pyramid of energy has four tiers: producers at the base, then primary, secondary and tertiary consumers. The producers fix 20,000 J of energy. If only 10 per cent of the energy passes from each trophic level to the next, how much energy reaches the tertiary consumers?
- A
2000 J
- B
200 J
- C
20 J
- D
2 J
Show the answer
The answer is C.By the 10 per cent law, 20,000 J at producers gives 2000 J to primary, 200 J to secondary and 20 J to tertiary consumers. The pyramid of energy is always upright.
- A.
This is the energy at the primary consumer level.
- B.
This is the energy at the secondary consumer level.
- D.
This takes one transfer too many; tertiary consumers are three transfers above producers.
NCERT: Class 12 Biology, Chapter 12, 12.5
Sample 3NEET level
In a food chain, the producers fix 10,000 J of energy. Following the 10 per cent law, how much energy is available to the tertiary consumers?
- A
100 J
- B
10 J
- C
1 J
- D
1000 J
Show the answer
The answer is B.Only about 10 per cent of the energy is transferred from one trophic level to the next. Producers 10,000 J give primary consumers 1000 J, secondary consumers 100 J and tertiary consumers 10 J.
- A.
This is the energy at the secondary consumer level.
- C.
This would be the level after the tertiary consumers.
- D.
This is the energy at the primary consumer level.
NCERT: Class 12 Biology, Chapter 12 (Ecosystem), Energy flow