NCERT Solution for Class 10 Science Chapter 9
Heredity and Evolution
NCERT Books for Session 2020-2021
CBSE Board and UP Board
Intext Questions
Page No-143
Questions No-2
How does the creation of variations in a species promote survival?
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Sometimes for a species, the environmental conditions change so drastically that their
survival becomes difficult. The variations ensure that the survival of the species as they allow the members of population to adapt to the changing environment and conditions. Thus continuity of the species is maintained.
Sometimes for a species, the environmental conditions change so drastically that their
survival becomes difficult. For example, if the temperature of water increases suddenly,
most of the bacteria living in that water would die. Only few variants resistant to heat
would be able to survive. If these variants were not there, then the entire species of
bacteria would have been destroyed. Thus, these variants help in the survival of the
species.
However, not all variations are useful. Therefore, these are not necessarily beneficial for
the individual organisms.
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All the variations in the species do not have equal chances of survival in the environment. The survival of the variations depends upon the nature of variation. Different individuals have different chances. Selection of variants by environmental factors forms the basis for evolutionary processes. These variations may lead to increased survival advantages of the individuals due to positive adoption of traits or may merely contribute to the genetic drift.
The variations ensure that the survival of the species as they allow the members of population to adapt to the changing environment and conditions. The species are more suitable to the changed environment . Thus continuity of the species is maintained.
The variations provide stability to the population of various species by preventing them from getting wiped out during adverse conditions.
The natural environment also changes, and variations in species which become suited to the environment help it to survive.
Variations take place in response to the changes in the environment. Such variations enable a species to cope with the new changes. Thus, variations help a species in survival.
Depending on the nature of variations different individuals would have different kinds of advantage e.g., Bacteria variants which can tolerate heat have a better survival chances in heat wave in comparison to non-variant bacteria having no capacity to tolerate heat wave.