Correct option is B
Explanation-
Statement analysis -
Statement A: "17β-estradiol, estrone and estriol are naturally occurring estrogens" - CORRECT
These are the three main naturally occurring estrogens in females:
1. 17β-estradiol: Most biologically active; predominant in non-pregnant females.
2. Estrone (E1): Weaker estrogen; predominant after menopause.
3. Estriol (E3): Weakest; most significant during pregnancy.
These estrogens play vital roles in regulating the menstrual cycle, development of secondary sex characteristics, and pregnancy.
Statement B: "They are 18 C steroids which do not have methyl group at 10th positions" - CORRECT
Estrogens are C18 steroids, meaning they have 18 carbon atoms. In androgens (C19), a methyl group is present at carbon 10, but during estrogen synthesis, this group is lost via aromatization of the A ring. This structural difference is crucial - absence of the methyl group at C10 and the presence of an aromatic A-ring distinguishes estrogens from androgens.
Statement C: "They are 21 C steroids which have methyl group at 10th position" - INCORRECT
C21 steroids include hormones like progesterone and corticosteroids, not estrogens. Estrogens are not C21 steroids. They are C18 steroids as explained above. Also, estrogens lack a methyl group at C10.
Statement D: "They are primarily synthesized by granulosa cells of the ovarian follicles" - CORRECT
Granulosa cells, with help from aromatase enzyme, synthesize estrogens in the ovary. Theca cells produce androgens (like androstenedione). These androgens diffuse into granulosa cells, where aromatase converts them into estrogens. This process is particularly active during the follicular phase of the menstrual cycle.
Statement E: "Their biosynthesis does not depend on the enzyme aromatase" - INCORRECT
Estrogen biosynthesis requires the enzyme aromatase, which catalyzes the conversion of androgens → estrogens. Without aromatase, estrogen cannot be formed from precursors. Deficiency or inhibition of aromatase leads to estrogen deficiency.
Final Answer: Statements A, B, and D are correct
Thus, the correct combination is Option b
