OB. A man’s testicles have not properly descended, lowering sperm count
Answer:
recognizes a hormone’s chemical structure
Explanation:
In living systems, chemical messengers called hormones are secreted into the body via the bloodstream or ducts by certain glands called endocrine glands e.g pancreas, hypothalamus etc. These hormones are meant to effect a physiological change in certain cells called TARGET CELLS.
In biology, a target cell is any receiving cell that has the ability to respond to signals and messengers like hormones. This responding ability of hormones is due to the possession of specific receptor sites for the specific hormones. The receptor on a particular target cell recognizes that specific hormone's chemical structure, hence, will only respond to it.
For example, an insulin hormone secreted by the pancreas will only be responded to by a target cell that recognizes the chemical structure of the insulin protein using its receptor molecule.
Answer:
The preferable option will be - 1.
1. The fish using ventral fins as "feet" will be present in increasing numbers.
Explanation:
After many years, the fish who are using ventral fins as "feet" will be present in increasing numbers because -
We know that
- These pools are temporary pools made up of rainwater. These pools do not last for longer times.
- Some fish have developed their ability to use their ventral fin as feet and can travel from one temporary pool to others.
- So, after many years, more and more fish will develop that ability to survive.
- As we all know about "the survival of the fittest" theory so some of them won't be able to make it.
- To develop their ventral fin as their real feet will take thousands of years and some genetic modification. So, that won't happen in many years.
Answer:
Hope this helps :)
Explanation:
Mitosis is the process by which cells duplicate.
Meiosis is a similar process which is just used to make reproductive cells such as eggs or sperm.
In mitosis, the cell DNA arranges into 46 chromosomes, duplicates, and then divides into two new cells.
In meiosis, the same duplication occurrs except four cells are created, each with only 23 chromosomes. (You know how you get half of them from each parent? This is so that the offspring have genetic variation.)
Another thing to notice about meiosis is that the cells are not identical like in mitosis, which simply duplicates them. Furthermore, in males all four sex cells are used as sperm but in females only one of these cells develops into an egg whereas the rest, called polar bodies, are reabsorbed into the body.
