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
Answer:
Explanation:
Aldosterone is a hormone which is produced by the adrenal glands which are present above the kidneys. The role of aldosterone is to regulate the blood pressure. It causes the reabsorption of water and salts into the bloodstream during the kidney filteration process. Hence, maintains the blood volume, restors blood pressure and salt level.
Renin is an enzyme. It facilitates chemical reactions which stimulates the synthesis of angiotension II, it directs the synthesis of aldosterone.
The Outer core is liquid and moving.
Earth's core is composed of Iron and Nickel.
Answer:
One Idea was the appreciation that the age of the Earth was much greater than had hitherto for been imagined.
