RBSE Solutions for Class 12 Biology Chapter 34 Menstrual Cycle in Woman
RBSE Solutions for Class 12 Biology Chapter 34 Menstrual Cycle in Woman
Rajasthan Board RBSE Class 12 Biology Chapter 34 Menstrual Cycle in Woman
RBSE Class 12 Biology Chapter 34 Multiple Choice Questions
Question 1.
The reproductive cycle in a mammalian female is called –
(a) Oestrous cycle
(b) Menstrual cycle
(c) Both of the above
(d) None of these
Answer:
(c) Both of the above
Question 2.
How many days (average) are required to complete a menstrual cycle in women?
(a) 18 days
(b) 28 days
(c) 38 days
(d) 12 days
Answer:
(b) 28 days
Question 3.
During the menstrual cycle, how many days the menstruation occurs.
(a) 3 – 5 days
(b) 8 – 12 days
(c) 13 – 20 days
(d) 26 – 30 days
Answer:
(a) 3 – 5 days
Question 4.
The essential hormone for ovulation is –
(a) FSH
(b) LH
(c) Estrogen
(d) Oxytocin
Answer:
(b) LH
Question 5.
Essential hormone for milk ejection is –
(a) FSH
(b) LH
(c) Estrogen
(d) Oxytocin
Answer:
(d) Oxytocin
RBSE Class 12 Biology Chapter 34 Very Short Answer Type Questions
Question 1.
In how many days one menstrual cycle completes?
Answer:
28 to 30 days
Question 2.
Write names of reproductive cycles found in mammalian females.
Answer:
Menstrual cycle and Estrus cycle.
Question 3.
Which hormone secretes during parturition?
Answer:
Oxytocin and Relaxin.
Question 4.
Which hormones are secreted during the gestation period?
Answer:
Progesterone and LH.
RBSE Class 12 Biology Chapter 34 Short Answer Type Questions
Question 1.
What is Estrous cycle?
Answer:
Cycle:
- It is exhibited by all eutherian mammalian females except the order -primate.
- The mammalian females which exhibit one estrus cycle in one breeding season are called as monoestrous.
Example: Dogs, Fox, Bats, Deer etc. - The mammalian females which exhibit two or more oestrous cycles in one breeding season are called polyestrous.
Example: Rat, squirrel, cow, pig, horse, cat, sheep rabbit etc. - The oestrous cycle is studied with the help of vaginal smears.
- The duration of various phases of the oestrous cycle varies from species to species. In the rat, it is from 4 to 5 days and in the rabbit is 16 to 17 days.
The oestrous cycle has 4 phases –
1. Diestrus phase:
- It is also called as anestrus phase.
- It is the longest phase & its duration is of 60 to 70 hours.
- The ovary is without Graffian follicles.
- The uterine gland is thin, small & inactive.
- The vaginal smear shows leucocytes.
- During the non-breeding season, the female remains in the diestrus phase.
2. Proestrus phase:
- It is the smallest phase. Its duration is 1/2 to 5 hours.
- There is no growth of ovarian follicles.
- Vaginal smear exhibits epithelial cells.
- The uterine glands begin to increase in number & size.
- The thickness & contractability of the uterine wall begins to increase.
3. Oestrous phase:
- Its duration in the rat is 9 to 15 hours.
- It is also called a heat period.
- The basal temperature of the body is increased.
- Formation of Graffian follicles in the ovary.
- The vaginal smear shows the presence of cornified cells.
- The maximum level of estrogen in the blood.
- Ovulation takes place.
4. Post-Estrus or metestrus phase:
- Its duration is of 10 to 14 hours.
- The vaginal smear shows cornified cells & leucocytes.
- The maximum level of progesterone in the blood.
- Formation of Corpus luteum in the ovaries.
- If there is fertilization, the female remains in metestrus till the parturition.
- The oestrous cycle repeats if there is no fertilization and after parturition.
Question 2.
What is the Menstrual cycle?
Answer:
Menstrual cycle:
- It is found only in primate females.
- Its duration is 28 to 30 days in a woman and 35 days in the chimpanzee.
- In woman, the menstrual cycle begins at an age of 12 years which is called menarche.
- The menstrual cycle ceases naturally at an age of 45 to 50 years which is called menopause.
The menstrual phase has 4 phases of viz.
- Menstrual phase
- Follicular phase or Proliferative phase
- Ovulatory phase or recovery phase
- Luteal phase or secretory phase
Question 3.
Which is the Ovulation phase?
Answer:
- Oestrous phase:
- It is a phase of Menstrual cycle.
- Its duration in the rat is 9 to 15 hours.
- It is also called a heat period.
- The basal temperature of the body is increased.
- Formation of Graffian follicles in the ovary.
- The vaginal smear shows the presence of cornified cells.
- The maximum level of estrogen in the blood.
- Ovulation takes place.
RBSE Class 12 Biology Chapter 34 Essay Type Questions
Question 1.
Describe the Menstrual cycle in detail.
Answer:
Menstrual cycle:
- It is found only in primate females.
- Its duration is 28 to 30 days in the woman and 35 days in the chimpanzee.
- In woman, the menstrual cycle begins at an age of 12 years which is called menarche.
- The menstrual cycle ceases naturally at an age of 45 to 50 years which is called menopause.
The menstrual phase has 4 phases of viz.
1. Menstrual phase:
- Its duration is of 3 to 5 days in a woman.
- Term menstruation means bleeding.
- During this phase, the blood is released along with dead ovum & pieces of the uterine endometrium.
- The ovary has immature follicles & corpus Albicans.
- The body has less estrogen & the progesterone is almost absent.
2. Follicular phase or Proliferative phase:
- Its duration is of 8 to 10 days.
- Maximum estrogen in the blood.
- Formation of Graffian follicles up to the end of this phase.
- Increased thickness of the uterine wall and increased number of uterine B.Vs. & uterine glands.
- Blood FSH is increased but blood LH is reduced.
3. Ovulatory phase or recovery phase:
- There is ovulation which occurs 14th + 2 days in a woman.
- The ovary has burst Graffian follicle.
- FSH & Estrogen get lowered slightly.
4. Luteal phase or secretory phase:
- It is also called as the pre-menstrual phase.
- It is the longest phase. Its duration in a woman is 12 to 16 days.
- The ovary shows fully developed corpus luteum.
- Myomatrium & endomatrium are maximum developed.
- Maximum estrogen, progesterone & LH in the blood.
- Uterine glands are completely developed & corkscrew-shaped.
- The female remains in lateral phase till parturition.
- If there is no fertilization, the menstrual cycle is repeated.
- Increase in body temperature.
Question 2.
Write an essay on Parturition in Human.
Answer:
Parturition:
- In the rabbit, man & other eutherians embryonic development completes in the uterus which is followed by the birth of young ones. It is called parturition.
- The duration between the fertilization & the parturition is called gestation.
- The gestation is different in, the different species.
- In the rabbit, it is of 28 – 30 days and in man is 270 to 280 days. In the rabbit, the young ones are hairless, blind & deaf.
- They become normal in 5 to 7 days. Parturition is a hormonal process which involves many hormones.
- At the completion of the embryonic development, the pituitary increases the secretion of FSH, decreases the secretion of
- LH & begins the secretion of oxytocin & MH.
- Decreased LH, in turn, decreases the secretion of progesterone.
- As a result, the placenta gets dissolved and the foetus separates from the uterine wall.
- Increased FSH restarts oogenesis.
- Oxytocin is the main hormone of parturition.
- It causes labour pains by contracting the uterine muscles.
- The contractions in the uterus push the foetus into the vagina.
- Relaxin in man is secreted by the corpus luteum and.in rabbit by the placenta.
- This hormone provides broad passage for parturition by relaxing pubic symphysis of the pelvic girdle.
Question 3.
Write an essay on Lactation in Human.
Answer:
Lactation:
- Prolactin (PRL) hormone is secreted by the anterior pituitary gland during gestation period from 5th week up to parturition is responsible for the development of mammary glands.
- It also promotes the secretion of milk from the breasts after the birth of the child. Besides this placenta also secretes human chorionic somatotropin (HCST) which is also helpful in milk secretion.
- The secretion of prolactin from the anterior pituitary is stimulated by Oxytocin.
- Up to three days since. parturition, the secretion of breasts is yellow fluid which is rich in proteins and lactose.
- This fluid is called colostrum. It contains Immunoglobulins (IgA), which develops innate immunity in the newborn child.
- Milk Secretion – milk → alveoli → ductule → mammary duct → mammary sinus → lactiferous duct → breast nipple → child sucks milk.
- The neuroendocrine reflex is required for milk secretion.
- Oxytocin hormone secretion from the pituitary gland is responsible for milk secretion.
- When a newborn child sucks the milk of mother than somatic neural reflex reaches to the hypothalamus and it initiates oxytocin secretion from the posterior pituitary.
- It facilitates milk ejection by contracting epithelial muscular cells of mammary gland so milk flow in tubules and child receive milk from nipples.
- Prolactin secretion of the anterior pituitary is responsible for the synthesis of milk in the mammary glands.
- While oxytocin hormone is responsible for milk secretion from mammary glands.
- Milk secretion is a Conditional reflex in which milk secretion occurs by the combined action of Suckling reflex and Ejection reflex.
- Breastfeeding is essential for 6 months after parturition for proper development of the child.
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