NCERT Solution for Class 10 Science Chapter 9
Heredity and Evolution
NCERT Books for Session 2022-2023
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 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.
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.
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.
The creation of variations in a species is a fundamental aspect of the process of evolution, and it plays a crucial role in promoting the survival and adaptability of a population. Here are several ways in which the generation of variations contributes to the survival of a species:
1. Adaptation to Changing Environments:
» Environments are dynamic and can change over time. Variations in traits provide a pool of options for a species to adapt to new or changing environmental conditions. Individuals with traits that are better suited to the current environment are more likely to survive and reproduce, passing those advantageous traits to future generations.
2. Response to Selective Pressures:
» Natural selection acts on variations within a population. If certain traits provide a selective advantage in a particular environment (e.g., better camouflage, improved foraging abilities, resistance to diseases), individuals carrying those traits are more likely to survive and pass on their genes, leading to an increase in the frequency of those advantageous traits in the population.
3. Genetic Diversity:
» Genetic diversity resulting from variations is essential for the overall health and resilience of a population. It reduces the risk of the entire population being wiped out by a single disease or environmental catastrophe. A diverse gene pool ensures that some individuals may have the genetic makeup needed to survive unforeseen challenges.
4. Speciation:
» Over time, accumulated variations can lead to the development of new species. Speciation occurs when populations diverge due to genetic differences, and these new species may occupy different ecological niches, reducing competition between them and promoting overall biodiversity.
5. Reproductive Success:
» Variations in traits can affect reproductive success. Some variations may enhance an individual’s ability to attract mates, compete for resources, or successfully reproduce. Traits that contribute to reproductive success are more likely to be passed on to future generations.
6. Evolutionary Innovation:
» New traits and variations can lead to evolutionary innovations that open up new ecological opportunities. For example, the development of flight in birds allowed them to exploit new habitats and food sources.
In summary, the creation of variations in a species through processes such as genetic mutation, recombination, and genetic drift provides the raw material for natural selection. This variation allows a species to adapt to changing conditions, respond to selective pressures, and increase its chances of survival and reproductive success in diverse environments.