(a) Construct a pyramid of biomass in sea with phytoplankton and fishes. Explain giving reasons about the characteristic of the constructed pyramid.
Show Hint
Solution and Explanation
In aquatic ecosystems, the pyramid of biomass is inverted. This means that the biomass of primary producers (phytoplankton) is smaller than the biomass of primary and secondary consumers (fishes). This happens because phytoplankton reproduce rapidly, compensating for their lower biomass with a high turnover rate.
Top Questions on Ecosystem
Consider the following food chain: Grass → Grasshopper → Frog → Snake → Eagle If the amount of energy available at third trophic level is 50 kJ, the available energy at the producer level was:
Assertion (A): Food web is a network of several food chains operating in an ecosystem.
Reason (R): Food web decreases the stability of an ecosystem.We do not clean natural ponds or lakes, whereas an aquarium or a swimming pool needs to be cleaned regularly. Why?
- Differentiate between Net primary productivity and Gross primary productivity in an ecosystem.
- (A) Analyse the following ecosystems and discuss, which will be more productive in terms of primary productivity:
A young forest, a natural old forest, a shallow polluted lake.
Questions Asked in CBSE CLASS XII exam
- A meeting will be held only if all three members A, B and C are present. The probability that member A does not turn up is 0.10, member B does not turn up is 0.20 and member C does not turn up is 0.05. The probability of the meeting being cancelled is:
- CBSE CLASS XII - 2025
- Probability
- Vishesh, Manik and Amit were partners in the ratio 5 : 4 : 1. Amit retired on 31st March, 2024. Vishesh and Manik decided to share Amit’s share in the ratio 2 : 3. What will be the new profit sharing ratio between Vishesh and Manik?
- CBSE CLASS XII - 2025
- Retirement and Death of a Partner
- The electric field in a region is given by \( \vec{E} = 40x \hat{i} \, \text{N/C}. \) Find the amount of work done in taking a unit positive charge from a point (0, 3m) to the point (5m, 0).
- CBSE CLASS XII - 2025
- Electrostatics
- Consider the Linear Programming Problem, where the objective function \[ Z = x + 4y \] needs to be minimized subject to the following constraints: \[ 2x + y \geq 1000, \] \[ x + 2y \geq 800, \] \[ x \geq 0, \quad y \geq 0. \] Draw a neat graph of the feasible region and find the minimum value of $Z$.
- CBSE CLASS XII - 2025
- Linear Programming Problem
- A rectangular glass slab ABCD (refractive index 1.5) is surrounded by a transparent liquid (refractive index 1.25) as shown in the figure. A ray of light is incident on face AB at an angle \(i\) such that it is refracted out grazing the face AD. Find the value of angle \(i\).
- CBSE CLASS XII - 2025
- Refraction