# Class 12 Biology MCQ – Ecosystem – Productivity – 1

This set of Class 12 Biology Chapter 14 Multiple Choice Questions & Answers (MCQs) focuses on “Ecosystem – Productivity – 1”.

1. What is the rate at which solar energy is converted and stored by the producers per unit area over a time period called?
a) Primary productivity
b) Tertiary productivity
c) Gross primary productivity
d) Net productivity

Explanation: The rate at which solar energy is converted and stored by the producers per unit area over a time period is called primary productivity. The solar energy is converted into usable form by plants with the help of photosynthesis.

2. What is the rate of biomass production called?
a) Productivity
b) Decomposition
c) Photosynthesis
d) Respiration

Explanation: Productivity is the rate of new biomass production by an individual, population, community within an ecosystem. The productivity of an ecosystem depends on several environmental factors such as light, water, temperature, precipitation, etc.

3. Which of the following is a unit of primary productivity?
a) g
b) g-2 or kcal m-2
c) kcal
d) m

Explanation: The unit of primary productivity is the weight (g-2) or weight (kcal m-2). The rate at which the solar energy is converted and stored by the producers per unit area over a time period is called primary productivity.

4. Which of the following is a unit of productivity?
a) g-2 or kcal m-2
b) kcal
c) g
d) g-2 yr-1 or kcal m-2 yr-1

Explanation: The unit of productivity is g-2 yr-1 or kcal m-2 yr-1. Productivity is the rate of new biomass production by an individual, population, community within an ecosystem.

5. What are the two types of primary productivity?
a) Gross primary productivity and secondary productivity
b) Net primary productivity and secondary productivity
c) Net and Gross primary productivity
d) Net primary productivity and tertiary productivity

Explanation: Gross primary productivity and net primary productivity are the two types of primary productivity. The rate of production of organic matter during photosynthesis is defined as the gross primary productivity, while the net primary productivity is the energy left after the respiration i.e. the gross primary productivity subtracted by respiration losses.

6. By what letter is the gross primary productivity designated?
a) GMP
b) GPP
c) GAP
d) GTP

Explanation: The gross primary productivity is designated by GPP. The rate of production of organic matter during photosynthesis is defined as the gross primary productivity.

7. By what letter is the net primary productivity designated?
a) NAM
b) NAG
c) NTP
d) NPP

Explanation: The net primary productivity is designated by NPP. The net primary productivity is the energy left after the respiration i.e. the gross primary productivity subtracted by respiration losses.

8. What is the available biomass for the consumption of heterotrophs?
a) GPP
b) GAP
c) NPP
d) NAG

Explanation: The available biomass for the consumption of heterotrophs is the net primary productivity (NPP). The heterotrophs are herbivores and decomposers. NPP is the gross primary productivity subtracted by respiration losses.

9. What is NPP equal to?
a) GPP
b) GPP + R
c) GPP / R
d) GPP – R

Explanation: NPP is the energy left after the respiration i.e. the gross primary productivity subtracted by respiration losses. NPP = GPP – R.

10. What is the rate of production of new organic matter by heterotrophic organisms (consumers) called?
a) Gross primary productivity
b) Net primary productivity
c) Secondary productivity
d) Primary productivity

Explanation: The rate of production of new organic matter by heterotrophic organisms (consumers) is called secondary productivity. The secondary producers feed on primary consumers to fulfill their energy requirements.

11. Which of the following contributes to the highest rate of primary productivity?
a) Deserts
b) Grasslands
c) Coral reef
d) Agricultural ecosystem

Explanation: The grasslands contribute to the highest rate of primary productivity. Grasslands or transitional landscapes are the open areas of land where the vegetation is dominated by grasses and other herbaceous (non-woody) plants.

12. What is a frog that feeds on insects example of?
a) Decomposer
b) Primary consumer
c) Secondary consumer
d) Tertiary consumer

Explanation: A frog that feeds on insects is an example of a secondary consumer. The secondary consumers feed on primary consumers to fulfill their energy requirements.

13. What is the balance between photosynthesis and respiration and other plant losses as death referred to?
a) Gross primary productivity
b) Net primary productivity
c) Primary productivity
d) Net productivity

Explanation: The balance between photosynthesis and respiration and other plant losses as death is referred to as the net primary productivity. The NPP is the energy left after the respiration i.e. the gross primary productivity subtracted by respiration losses.

14. What is the rate of storage of organic matter not used by consumers called?
a) Gross primary productivity
b) Net primary productivity
c) Secondary productivity
d) Net productivity

Explanation: The rate of storage of organic matter not used by consumers (heterotrophs) is called the net productivity. It is equal to the net primary production minus consumption by the heterotrophs in a unit time.

15. Which of the following is a unit of net productivity?
a) Production of C/g/m2/day
b) g-2 or kcal m-2
c) g-2 yr-1
d) kcal m-2 yr-1

Explanation: The unit of net productivity is the production of C/g/m2/day. The rate of storage of organic matter not used by consumers (heterotrophs) is called the net productivity.

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