Which one of the following statements about human sperm is correct?

  • Acrosome has a conical pointed structure used for piercing and penetrating the egg, resulting in fertilisation

  • The sperm lysis in the acrosome dissolve the egg envelope facilitating fertilization

  • Acrosome serves as a sensory structure leading the sperm towards the ovum

  • Acrosome serves as a sensory structure leading the sperm towards the ovum


B.

The sperm lysis in the acrosome dissolve the egg envelope facilitating fertilization

Penetration of human sperm is a chemical mechanism. In this, acrosome of sperm udergoes acrosomal reaction and release certain sperm lysins, which dissolves the egg envelope locally and makes the path for the penetration of sperm. Sperm lysins are acidic proteins. These sperm lysins contain a lytic enzyme hyaluronidase that dissolves the hyaluronic acid polymers in the intercellular spaces, which holds the granulosa cells of corona radiate together corona penetrating enzyme and acrosin.

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The first movements of the foetus and appearance of hair on its head are usually observed during which month of pregnancy?

  • Fourth month

  • Fifth month

  • Sixth month

  • Sixth month


B.

Fifth month

During development of the foetus in human by week 20, hair begins to grow including eyebrows and eyelashes, fingerprints develop. Fingernails and toe nails grow. Firm hand grip Between 16 and 20 weeks baby usually felt moving the for first time.

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The second maturation division of the mammalian ovum occurs

  • shortly after ovulation before the ovum makes entry into the fallopian tube

  • until after the ovum has penetrated by a sperm

  • until the nucleus of the sperm has fused with that of the ovum

  • until the nucleus of the sperm has fused with that of the ovum


B.

until after the ovum has penetrated by a sperm

In mammalian ovum during maturation phase, meiosis occurs, nucleus shifts towards the animal pole and undergoes meiosis-I. After fertilisation (penetration of sperm), the second meiotic division is completed with unequal cytoplasmic cleavage. This forms a large cell the ootid with the essentially whole of the cytoplasm and a very small cell, the second polar body.

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The part of fallopian tube closest to the ovary is 

  • isthmus

  • infundibulum

  • cervix

  • cervix


B.

infundibulum

The fallopian tubes, uterus and vagina constitute the female accessory ducts. Each Fallopian tube extends from the periphery of each ovary to the uterus, the part closer to the ovary is funnel -shaped infundibulum, which helps in the collection of the ovum after ovulation.

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The signals for parturition originate from

  • placenta only

  • placenta as well as the fully developed foetus

  • oxytocin released from the maternal pituitary

  • oxytocin released from the maternal pituitary


B.

placenta as well as the fully developed foetus

The process of giving birth to a baby is called parturition. Parturition is induced by a complex neuroendocrine mechanism. The signal for parturition originates from the fully developed foetus and the placenta, which induce mild uterine contractions called foetal ejection reflex.

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