Correct Answer: C

Explanation: Population attributes include natality (birth rate), mortality (death rate), sex ratio, and age distribution. Species interaction is an attribute of a community, not a single population.

Correct Answer: C

Explanation: Mycorrhiza is a symbiotic association between fungi and the roots of higher plants. It is an example of mutualism where both organisms benefit.

Correct Answer: B

Explanation: Vertical distribution of different species occupying different levels is called stratification. For example, trees occupy top vertical strata or layer of a forest, shrubs the second and herbs and grasses occupy the bottom layers.

Correct Answer: D

Explanation: Forest ecosystems generally have the highest biomass due to the presence of large trees. Biomass refers to the total weight of all living organisms in a given area.

Correct Answer: A

Explanation: Primary productivity is the rate at which organic matter is produced by producers (plants) during photosynthesis. Secondary productivity is the rate of formation of new organic matter by consumers.

Correct Answer: A

Explanation: Primary consumers are herbivores that feed directly on producers (plants). In a maize field, grasshoppers feed on maize plants, making them primary consumers.

Correct Answer: C

Explanation: Alexander von Humboldt observed that within a region species richness increased with increasing explored area, but only up to a limit. This is known as the Species-Area relationship.

Correct Answer: C

Explanation: Ex-situ conservation involves protecting an endangered species outside its natural habitat. Examples include seed banks, botanical gardens, and zoological parks. In-situ conservation protects species in their natural habitats, e.g., National Parks, Sanctuaries, and Sacred Groves.

Correct Answer: A

Explanation: Ozone layer thickness is measured in Dobson Units (DU).

Correct Answer: D

Explanation: Greenhouse gases include CO2, methane, nitrous oxide (N2O), and CFCs. Nitrogen (N2) is not a greenhouse gas.