Both men and women have sex chromosomes. Men usually have one X and one Y chromosome, while women have two X's.
When an egg or sperm is made, it only gets one of the sex chromosomes from the parent. This means that women can only make eggs with an X chromosome. But men can make either X or Y sperm.
During fertilization, the sperm cells race toward the mother-to-be's egg cell. If a sperm with a Y beats all others, then the fetus will be XY. The pregnancy will result in a boy.
However, if a sperm with an X wins the race to the egg, then the fetus will be XX. The parents will have a baby girl.
Nearly everyone's chances are around 50% for having a boy and 50% for having a girl. And yet, we all know families that are all boys or all girls.
Telomerase activity is controlled during development and is extremely low in somatic (body) cells, virtually undetectable. These somatic cells age because they do not frequently use telomerase.
- Telomeres are repetitive sections at the very ends of chromosomes that are present in a variety of eukaryotic species, including humans and unicellular protists.
- Each round of DNA replication wears down a little portion of the telomeres, which serve as caps to safeguard the interior chromosomal regions.
- Most somatic (body) cells do not typically have telomerase activity, but certain adult stem cells and germ cells—the cells that produce sperm and eggs—have.
- Adult germ cells, tumor cells, and fetal tissues all contain telomerase. Telomerase activity is controlled during development and is extremely low in somatic (body) cells, virtually undetectable. These somatic cells age because they do not frequently use telomerase.
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Answer ; A.) Aquatic Animals .
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