Question

:
Define the following
(a) Sequential evolution
(b) Theory of recapitulation
(c) Genetic drift
(d) Crossing over
(e) Agrobacterium​

Answer 1

Answer:

(a) Sequential evolution – Evolution at its simplest involves relatively minor changes in the gene pool of a population from one generation to the next with corresponding modification in genotypic frequencies and range of phenotypic variation.

(b). The theory of recapitulation, also called the biogenetic law or embryological parallelism—often expressed using Ernst Haeckel's phrase "ontogeny recapitulates phylogeny"—is a historical hypothesis that the development of the embryo of an animal, from fertilization to gestation or hatching (ontogeny), goes through

(c). variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce.

(d) Crossing over is the swapping of genetic material that occurs in the germ line. During the formation of egg and sperm cells, also known as meiosis, paired chromosomes from each parent align so that similar DNA sequences from the paired chromosomes cross over one another

(e). Agrobacterium is a genus of Gram-negative bacteria established by H. J. Conn that uses horizontal gene transfer to cause tumors in plants. ... Agrobacterium is well known for its ability to transfer DNA between itself and plants, and for this reason it has become an important tool for genetic engineering.

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Answer 2

DEFINITIONS:-

• (a) Sequential evolution:- Sequential evolution at its modest includes somewhat minor changes in the gene corner of a population from one generation to the following with resembling modification in genotypic regularities and range of phenotypic fluctuation.

• (b) Theory of recapitulation:- The recapitulation theory asserts that ontogeny, which is the advanced history of an organism from the zygote stage until it is prepared for hatching or gestation, enacts phylogeny which is the history of the ancestor's evolution.

• (c) Genetic drift:- Genetic drift is a modification in allele frequencies in a population from generation to generation that arises due to possible events. For being more precise, genetic drift is changed due to "sampling error" in choosing the alleles for the following generation from the gene pool of the existing generation.

• (d) Crossing over:- Crossing over is a cellular process that arises at the time of meiosis when chromosomes of the same type are lined up. When two chromosomes that is one from the mother and one from the father line up then the parts of the chromosome can be swapped. The two chromosomes comprise identical genes but may have varied forms of the genes.

• (e) Agrobacterium:- Agrobacterium is a genus belonging to Gram-negative bacteria. Agrobacterium is reasonably known for its potential of transferring DNA between itself and plants, and for this purpose, it has become a vital tool for genetic engineering.

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