Heredity and Evolution
- Number of variations tends to increase from one generation to the next generation.
- The passing of phenotypic traits from parents to offsprings is called heredity.
- Set of observable characters is called phenotype. For example; hair colour, eye colour, shape of nose, etc. are phenotypic traits.
- Genetic makeup of an organism is called genotype. Genotype is not observable rather it is at the molecular level in the cells.
- When one pair of contrasting characters is considered for cross, it is called monohybrid cross.
- When two pairs of contrasting characters are considered for cross, it is called dihybrid cross.
- During gamete formation, alleles from a pair separate and each gamete gets one allele. This law is called the Law of Segregation.
- During gamete formation, different traits separate independently of each other. This law is called the Law of Independent Assortment.
- The change in inheritable traits over successive generations is called evolution.
- Evolution can happen because of natural selection, and because of genetic drift.
- Traits which are acquired during someone’s lifetime but fail to change the genotype are called acquired traits.
- Traits which bring change in the genotype can be transferred to next generations. Such traits are called inherited traits.
- When a new species emerges from a given species then the germ cells from two species cannot fuse and hence cannot interbreed.
- When the organs show similarity in design but serve different functions, they are called homologous organs.
- When organs serve the same function but show difference in design, they are called analogous organs.
- The preserved remains of living beings from distant past are called fossils.
- The most accepted theory of human evolution is called ‘Out of Africa Theory’.
These main points are highly helpful for last minute preparation for examination. You can glance through them while going for examination. You can view them in the school bus, in car, in elevator, etc.