The 'corpus luteum' in the ovary secretes large amounts of progesterone primarily to:
A. Stimulate the growth of ovarian follicles
B. Maintain the uterine endometrium for potential implantation of a fertilized egg
C. Initiate menstruation
D. Trigger the LH surge for ovulation
Answer: Option B
Solution (By JKExamLibrary)
After ovulation, the ruptured Graafian follicle transforms into a temporary endocrine structure called the corpus luteum. Its primary function is to secrete large amounts of progesterone (and some estrogen). Progesterone is crucial for maintaining the thickened, highly vascularized uterine endometrium (secretory phase), making it receptive for the implantation of a blastocyst. If fertilization does not occur, the corpus luteum degenerates, progesterone levels drop, and menstruation begins.
Explanation:
Mycoplasma is a genus of bacteria that naturally lack a cell wall; they are the smallest known free-living organisms. Their membrane contains sterols providing some rigidity. Other bacteria typically have peptidoglycan cell walls. Fungi have chitinous walls, plant cells have cellulose walls. The absence of cell wall makes Mycoplasma pleomorphic and resistant to antibiotics targeting cell wall synthesis like penicillin.
Consider the following statements about vitamins:
1. Vitamin B₁ is thiamine.
2. Vitamin B₂ is riboflavin.
3. Vitamin B₆ is pyridoxine.
Which of the above is/are correct?
Explanation:
Commensalism (+/0) involves one species benefiting and the other neither harmed nor helped. Example: barnacles on a whale, or cattle egrets eating insects stirred by cattle. Mutualism benefits both (+/+), parasitism benefits one at expense of other (+/-), predation (+/-) involves killing. The distinction is based on the net effect.
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