(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 square loop MNPK of side \( l \) carrying a current \( I_2 \) is kept close to a long straight wire in the same plane and the wire carries a steady current \( I_1 \) as shown in the figure. Obtain the magnitude of magnetic force exerted by the wire on the loop.
- CBSE CLASS XII - 2025
- Magnetic Force
- Let the polished side of the mirror be along the line \[ \frac{x}{1} = \frac{1 - y}{2} = \frac{2z - 4}{6}. \] A point \( P(1, 6, 3) \), some distance away from the mirror, has its image formed behind the mirror. Find the coordinates of the image point and the distance between the point \( P \) and its image.
- CBSE CLASS XII - 2025
- 3D Geometry
A shop selling electronic items sells smartphones of only three reputed companies A, B, and C because chances of their manufacturing a defective smartphone are only 5%, 4%, and 2% respectively. In his inventory, he has 25% smartphones from company A, 35% smartphones from company B, and 40% smartphones from company C.
A person buys a smartphone from this shop(i) Find the probability that it was defective.
- CBSE CLASS XII - 2025
- Probability
- How is the necessary force provided to an electron to keep it moving in a circular orbit according to Bohr model of hydrogen atom? Derive an expression for the total energy of an electron moving in an orbit of radius \( r \) in hydrogen atom. Give the significance of the negative sign in this expression.
- CBSE CLASS XII - 2025
- Atomic Physics
- Define ‘Mass defect’ and ‘Binding energy’ of a nucleus. Describe ‘Fission process’ on the basis of binding energy per nucleon.
- CBSE CLASS XII - 2025
- Nuclear Physics