Answer:
Explanation:
Meiosis is a form of cell division that occurs in the sex cells of organisms. It ensures the reduction of a diploid cell to an haploid cell to allow for the formation of a diploid zygote after fertilization (contribution of both parents haploid sex cells to give a diploid zygote). Thus, this process is very essential and important.
The reduction is accomplished by 2 divisions after the duplication of chromosomes
- first division: separation of homologous pairs of chromosomes (this reduces the total in half)
- second division: separation of sister chromatids of a chromosome.
The rearrangement in meiosis occurs by crossing over/genetic recombination.
This is the exchange of genetic material between homologous pairs of chromosome bringing about a rearrangement and genetic variation
An example of a chromosomal abnormality that arises as a result of defects in this process is the Down Syndrome which is caused by a nondisjunction of the chromosomes 21 pair in a sex cell.
This condition produces offsprings that have some characteristic facial features, short stature etc
Explanation:
<em>Immunological memory</em> is the property of the immune system to store information about a stimulus so it can mount an effective response if it encounters the same stimulus again being this second response quicker and stronger even after years since the first encounter.
This kind of response is dependent on many subpopulations within T and B lymphocytes and NK cells. When encountering an antigen, B cells recognize it by membrane antibody specifically binding to the antigen and then being activated to expand rapidly with their progeny clones differentiating into plasma and memory B cells, these last ones have a long life span to remain in the body, ready when another encounter with the same stimulus occurs, this is how the basis for effective immunizations happens.
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Answer:
This similarity indicates that mice share a common ancestor with humans. Mice have a tail, while humans have a tailbone
Answer:
Organisms belonging to the plant kingdom are eukaryotic and multicellular organisms. They have a distinct cell wall made of cellulose. Cells are organised into true plant tissues
Explanation:
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Oxygen is extremely electronegative, making it very powerful in pulling electrons down the electron transport chain. Occurs in the cytosol. Glycolysis begins cellular respiration by breaking glucose into two molecules of a three-carbon compound called pyruvate. 2 ATP produced.
