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Human Reproduction

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Biology

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Biology

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CBSE Gujarat Board Haryana Board

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Class 10 Class 12

Which one of the following is the most likely reason of not occurring regular menstruation cycle in females? 

  • Fertilisation of the ovum

  • maintenance of the hypertrophical endometrial lining

  • Maintenance of high concentration of sex hormones in the blood stream

  • Retention of well-developed corpus luteum


A.

Fertilisation of the ovum

If fertilisation occurs and the foetus is implanted in the endometrium the trophoblast cells of the developing placenta secrete a hormone human chorionic Gonadotrophic (hCG). This hormone-like LH maintains the corpus luteum and the secretion of progesterone and estradiol by it. These two hormones check the breakdown of the endometrium of the uterus. The absence of menstrual bleeding is the earilest sign of pregnancy.

If fertilisation occurs and the foetus is implanted in the endometrium the trophoblast cells of the developing placenta secrete a hormone human chorionic Gonadotrophic (hCG). This hormone-like LH maintains the corpus luteum and the secretion of progesterone and estradiol by it. These two hormones check the breakdown of the endometrium of the uterus. The absence of menstrual bleeding is the earilest sign of pregnancy.


Ovulation takes place :
  • 2 weeks before the start of next menstrual cycle
  • 14th day of 28 days cycle
  • 10 days after the cease of previous monthly cycle
  •  All the above are correct.

B.

14th day of 28 days cycle

Which of the following shows hermaphroditism and self fertilization ?
  • Earthworm
  • Tapeworm
  • Both A & B
  • Rotifers.

B.

Tapeworm

The chromosone in primary spermatocyte are :
  •  22 + X 
  • 22+Y
  • 44 + XX
  • 44 + XY

D.

44 + XY

Primary spermatocyte produces 4 spermatozoa, but primary oocyte produces :
  • 1 ovum
  • 2 ova
  • 3 ova
  • 4 ova

A.

1 ovum

The process of differentiation of spermatid into a spermatozoa is known as :
  • spermatogenesis
  • gametogenesis
  • spermiogenesis
  • oogenesis

C.

spermiogenesis