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Biology · 2024 · 4 marks
CBSE 2024 · Region 4 · Set 2 · Q30
Read the following passage: Populations evolve to maximise their reproductive fitness in the habitat in which they live. Ecologists suggest, the life…
Read the following passage : Populations evolve to maximise their reproductive fitness in the habitat in which they live. Ecologists suggest, the life history of organisms have evolved in relations to the constraints imposed by the biotic and abiotic components of the habitat in which they live. This gets reflected in the population growth pattern of all organisms including humans. Study the population growth curves shown in the given graph and answer the questions that follow :
(a)
Identify the growth curves 'A' and 'B'.
(b)
Mention what does the dotted line in the graph indicate and state its importance also.
OR
(b)
Growth curve 'B' shows a different pattern from that of growth curve 'A'. Justify giving one reason.
(c)(i)
Which one of the two curves is more "realistic" and why ?
(ii)
Which one of the two curves is relevant in present days with respect to human population in our country and why ?
Marking-scheme solution
(a)
•
A- exponential growth curve/ J-shaped curve
•
B- Logistic growth curve/ S- shaped curve/ sigmoid curve
(b)
•
It represents carrying capacity (K)
• Maximum possible number of individuals beyond which no growth
of population is observed.
OR
(b)
Growth curve B is formed when resources (food and space) in nature are
limited have environmental checks while growth curve A is formed when resources are unlimited with no environmental checks.
(c)(i)
•
‘B’/ Logistic growth curve
•
As resources are never infinite in nature.
(ii)
•
J-shaped curve/ exponential growth
It is a continuous growing population.
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CBSE Class 12 Biology past-paper question from the 2024 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.