Problem 132 - Objective Biology for NEET

Question

Assertion: Meiotic division help in evolution process. Reason: Meiosis increases genetic variability in the population.

Step-by-Step Solution

Answer

Meiotic division aids evolution by increasing genetic variability. The cell division processes of meiosis generate varied offspring, promoting changes in populations over time. These genetic variations are instrumental for natural selection and genetic drift, thereby favoring evolutionary processes.

Step 1: Understanding Meiotic Division

Meiosis is a type of cell division. Unlike mitosis which results in two identical daughter cells, meiosis results in four genetically varied daughter cells. This happens because of two rounds of genetic separation and cellular division. These differences in genetic material arise from both the random assortment of homologous chromosomes, as well as recombination during Prophase I.

Step 2: Appreciating Genetic Variability

Genetic variability is the differences in genes among individuals, which can lead to differences in health, appearance and behavior. By generating genetically varied offspring, meiosis introduces variation into populations of organisms.

Step 3: Linking Meiosis to Evolution

The role of meiosis in evolution is critical. Evolution is essentially a process of change over time, often powered by genetic variations. By increasing genetic variability, meiosis ultimately encourages evolution as new combinations of traits can improve survival and reproduction; this is known as natural selection. The other important aspect is genetic drift, which is also enabled due to the genetic variation produced by meiosis. It causes random changes of allele frequencies within a population, leading to evolutionary changes.

Key Concepts

Genetic Variability

Genetic variability refers to the differences in the genetic makeup among individuals within a population. These differences arise due to various processes like mutation, recombination, and the independent assortment of chromosomes. Meiosis plays a significant role in boosting genetic variability.
During meiosis, homologous chromosomes are randomly assorted, and genetic recombination occurs, especially during Prophase I.
These processes contribute to creating unique combinations of alleles in the daughter cells.

• Genetic variability is vital for the adaptability and survival of a species.
• It provides the raw material for evolution and natural selection to act upon.

High genetic variability in a population increases its ability to withstand environmental changes and adapt to them over successive generations.

Evolution

Evolution is a complex process through which species undergo gradual changes over generations. These changes are driven by genetic variations within a population. Meiotic division is fundamental to evolution because it creates new allele combinations in offspring, leading to genetic diversity.
As genetic variability rises, the chances for advantageous traits to appear and be passed down to future generations increase. This results in the adaptation of species to environmental changes over the long term.

• Evolution depends on genetic differences, fueling processes such as migration, mutation, and genetic drift.
• It ensures that species evolve by preserving beneficial genetic combinations.

Therefore, evolution is an ongoing process vital for the development of new species and the survival of existing ones in changing habitats.

Natural Selection

Natural selection is a mechanism of evolution where individuals with advantageous traits have higher chances of survival and reproduction. This concept focuses on how organisms better adapted to their environment tend to leave more offspring, thereby transferring their beneficial genes to the next generation.
Genetic variability brought about by meiosis enables natural selection to take place because it offers a variety of traits for environmental pressures to act upon.

• Survival of the fittest is a term often associated with natural selection.
• Populations evolve as advantageous genetic variations become more common.

Natural selection constantly shapes the genetic makeup of populations, gradually leading to changes in species over time.

Genetic Drift

Genetic drift is a random process that can cause changes in allele frequencies within a population. Unlike natural selection, which is directional, genetic drift is more about chance events that can lead to significant changes, especially in small populations.
Meiotic division's role in generating genetic variability sets the stage for genetic drift by introducing various allele combinations.
These changes are not necessarily beneficial but are rather a product of random chance.

• Genetic drift can lead to increased genetic variation between different populations.
• Over time, it can result in significant evolutionary changes or even new species.

Overall, genetic drift works alongside natural selection as fundamental forces in the evolution of populations and species.