8. Heredity
Heredity explores the mechanisms through which variations in traits are created and inherited among sexually reproducing organisms. Notably, Mendel's experiments elucidate the principles of dominant and recessive traits, the independent inheritance of characteristics, and the genetic factors determining sex in humans. The chapter emphasizes the crucial role of genetic variation in promoting survival in changing environments.
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What we have learnt
- Variations arising during the process of reproduction can be inherited.
- These variations may lead to increased survival of the individuals.
- Sexually reproducing individuals have two copies of genes for the same trait. If the copies are not identical, the trait that gets expressed is called the dominant trait and the other is called the recessive trait.
- Traits in one individual may be inherited separately, giving rise to new combinations of traits in the offspring of sexual reproduction.
- Sex is determined by different factors in various species. In human beings, the sex of the child depends on whether the paternal chromosome is X (for girls) or Y (for boys).
Key Concepts
- -- Heredity
- The transmission of traits and characteristics from parents to offspring through genetic material.
- -- Dominant Trait
- A trait that is expressed in the phenotype even when only one copy of the gene is present.
- -- Recessive Trait
- A trait that is only expressed in the phenotype when two copies of the gene are present.
- -- Independent Assortment
- The principle that genes for different traits are inherited independently of each other.
- -- Sex Determination
- The biological mechanism that determines the development of sexual characteristics in an individual, often influenced by chromosomes.
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