Ecosystem Test - 78

 Correct option is (D)

 Explanation for the correct option.

 

1.       Lithosere is the community where it has to be established from a primary succession over a rock.

2.       Lichen is a pioneer species in the Lithosere, seral stage.

3.       Whenever it rains lichen has an exceptional property to absorb the maximum amount of water and germinate.

4.       Lichen spores germinate and are scattered very easily that makes it feasible to become a pioneer species even in the case of rock.

 

 

Correct option: C

The interaction + and + means both get benefit from this relationship.  But the female Sacculina larva finds shelter on a crab and injects its body into the crab. Further, the crab is now unable to perform the normal function due to loss of nutrition and impairs its overall growth. Thus, the interaction between Sacculina and crab is + and - respectively. Hence, the correct answer is option A.

If a keystone species is removed from an ecosystem there will not be any more increase in the rate of growth of one or more populations.

Plant species, through time undergo non-seasonally and directional cumulative change in a given area. This process includes colonization, development, and termination of the plant species which participate in this process. A disturbance in a given area is the primary reason of a place getting devoid of vegetation, resulting in start of succession. The cause of disturbance might be wind storms, fires, volcanic eruptions, severe flooding, pest infestation, etc. Succession completes when the species don’t change in the given area at that particular time. The community at that time is called as climax community.

Since one of the extreme phenotypes is being favored, the population would shift towards one of the extremes. Selection, when one of the extreme phenotypes is being favored, is termed as directional selection. In disruptive selection, both extremes are favored. 

Biomass can be called as the energy or fuel developed from organic matter. When the energy production is more than the consumption, the excess energy stored in the plants body leads to increase in its biomass. So in this case, the biomass of the plant community goes on increasing in terrestrial plants.

The process of change in ecological community of an area over time which in turn results in the formation of climax community is termed as succession. The direction and predictable change in the community lead to alteration of the environment. Now the changing environment leads to altered species composition and structure. Hence, conversion of the pond into a terrestrial habitat by its community is the example of succession. Option A is the correct answer. 

During 1850 to 1900, mosses (21 -10), shrubs (7-5) and tree species (4-3) were reduced dramatically. Given data does not show reduction of species in any other period.