Question

Which of the following could qualify as a top-down control on a grassland community?

(A) limitation of plant biomass by rainfall amount.

(B) influence of temperature on competition among plants.

(C) influence of soil nutrients on the abundance of grasses versus wildflowers.

(D) effect of grazing intensity by bison on plant species diversity.

Short answer

1. The statement “limitation of plant biomass by rainfall amount” isfalse.

2. The statement “influence of temperature on competition among plants” isfalse.

3. The statement “influence of soil nutrients on the abundance of grasses versus wildflowers” is false.

4. The statement “effect of grazing intensity by bison on plant species diversity” is true.

Step-by-step solution

Grassland

The ecosystem in which an area, such as temperate and tropical regions, whose vegetation is covered by grasses but does not support a forest is called grassland.

Explanation of option ‘(A)’

When water falls from the sky in the form of a drop and then falls onto the ground, it is called rainfall.

Thus, the rain does not consider at the trophic level.

Therefore, the given statement is false.

Explanation of option ‘(B)’

The effects of temperature on plants are shoot growth reduction, reduction in plant enzyme activity, and decrease in root growth.

Thus, the temperature is not the organisms that inhabit an ecosystem.

Therefore, the given statement is false.

Explanation of option ‘(C)’

The different nutrients found in the soil are magnesium, nitrogen, sulfur, potassium, and phosphorous.

Thus, the soil nutrients do not affect the population of organisms in an ecosystem.

Therefore, the given statement is false.

Explanation of option ‘(D)’

In agriculture, the feeding strategy in which animals search, select, and grasp the wild vegetation for consumption as food is called grazing.

Thus, the top-down control represents the higher organisms population like predators at the trophic level affecting population present at the lower trophic levels; population dynamics of plant species is influenced by higher trophic level.

Therefore, the given statement is true.