The two factors are: crossing-over and independent assortment. Crossing over: In Prophase I of Meiosis I, homologous chromosomes line up their chromatids and “cross-over”, or exchange corresponding segments of DNA with each other. This produces genetic variation by allowing more combinations of genes to be produced.
a. A shared ancestral character.
Explanation:
The condition of birds and mammals having four limbs is a shared ancestral character because the structure of the limbs are similar in both the cases.
The forelimbs of the bird are modified into wings to aid flying.The hind limbs are modified into feel and claws.
These are homologous structures to the hands and feet in mammals.
That means they have a common origin, and hence are shared ancestral character.
Overtillage can increase the rate of humus decomposition
Answer:
Species distribution is the manner in which a biological taxon is spatially arranged. ... Species distribution is not to be confused with dispersal, which is the movement of individuals away from their region of origin or from a population center of high density.
Blood groups are inherited from both parents. The ABO blood type is controlled by a single gene (the ABO gene) with three types of alleles inferred from classical genetics: i, IA, and IB. The I designation stands for isoagglutinogen, another term for antigen.
