Choose the correct statements from the following:
A. Identification and enumeration of plant and animal species of an ecosystem gives its species composition.
B. Horizontal distribution of different species occupying different levels is called stratification.
C. In a forest, trees occupy the top vertical stratum and shrubs occupy the second layer.
D. In a forest, herbs and grasses occupy the bottom layers.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A, C and D only
The structure of an ecosystem comes from the interaction of its biotic and abiotic parts. Two features describe it: the species present (species composition) and the way they are arranged in layers (stratification).
A. Identification and enumeration of plant and animal species of an ecosystem gives its species composition. — True. Listing and counting the species tells us the species composition.
B. Horizontal distribution of different species occupying different levels is called stratification. — False. Stratification is the vertical distribution of species at different levels, such as the layers of a forest from the treetops down to the ground.
C. In a forest, trees occupy the top vertical stratum and shrubs occupy the second layer. — True. Trees form the top layer and shrubs the second.
D. In a forest, herbs and grasses occupy the bottom layers. — True. Herbs and grasses grow close to the ground, in the bottom layers.
So A, C and D are correct.
NCERT Extract:
Ecosystem – Structure and Function – “… Interaction of biotic and abiotic components result in a physical structure that is characteristic for each type of ecosystem. Identification and enumeration of plant and animal species of an ecosystem gives its species composition. 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.”