Answer:
The correct answer will be option-B.
Explanation:
Sertoli cells are the large somatic cells present in the testis which helps in the formation of spermatozoa. The Sertoli cells create a suitable environment for the production and maturation of the sperms as they produce certain molecules which nourishes the sperms.
The Sertoli cells act as a barrier between the testis and blood and secrete enzymes like inhibin. They eliminate the apoptotic germ cells and also produce seminiferous fluid to nourish the sperm. They do not play any role in primary spermatocytes.
Thus, Option-B is the correct answer.
<h3><u>Answer and Explanation</u>;</h3>
- Purines: Heterocyclic rings are synthesized one atom at a time, first atom attached to ribose phosphate (source is PRPP) and then all the other atoms are added .
- Pyrimidines: Common intermediate, orotate, synthesized first, then orotate is attached to ribose phosphate (source is PRPP or 5-Phosphoribosyl-1-pyrophosphate).
Answer: Geologists and other Earth scientists use geologic time scales to describe when events happened in the history of Earth. The time scales can be used to show when both geologic events and events affecting plant and animal life occurred. The geologic time scale pictured below (Figure below) illustrates the timing of events like:
Earthquakes.
Volcanic eruptions.
Major erosion.
Meteorites hitting Earth.
The first signs of life forms.
Mass extinctions.
Explanation:
