Q. 233.9( 7 Votes )
In human females, each time during maturation and release of the egg the inner wall of the uterus thickens. Is this thickening permanent? Give reasons.
No, the thickening of uterus lining is not permanent. It gets thickened to receive the fertilized egg but if the egg is not fertilized the inner lining sheds off. Blood along with mucus, an unfertilized egg is released out through menstrual flow. But if the egg is fertilized the uterus receives the zygote and supplies nourishment through the blood vessels. Till the complete development of the foetus in the uterus it provides nutrients, oxygen to the growing fetus. After the baby is born it sheds off.
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Fill in the following blanks with suitable words:
(a) Sexual maturity is reached at……………
(b) The changes which occur in boys and girls at puberty are brought about by various………….
(c) Initially, girls grow…..than boys.
(d) The changes occurring in body and mind during adolescence are a natural part of……………….up.
(e) The features which help us to distinguish between a mature boy and a girl are called………sexual characteristics.
(f) The onset of puberty is controlled by…………..
(g) Menstrual cycle in women is controlled by…………….
(h) Each normal body cell in humans contains……………..pairs of chromosomes out of which……………..pair is of sex chromosomes.
(i) X and Y chromosomes are called……….chromosomes.
(j) Early marriage and motherhood cause health problems in the ……………and the……………….
(k) The protective foods are ………. And ……………….
(l) Thyroid and adrenals secrete their hormones when they receive instructions from……..gland through its hormones.
(m) Metamorphosis in amphibians is brought about by…….hormone.Lakhmir Singh & Manjit Kaur - Science
Which of the two has a shorter reproductive phase of life: men or women?Lakhmir Singh & Manjit Kaur - Science
When a human female reaches a certain age, then vaginal bleeding occurs for a few days after rehular intervals of time:
(a) what is this process known as (i) in scientific terms, and (ii) in everyday language?
(b) What is the human female said to have attained at this stage?
(c) What does the onset of this process in human female signify?
(d) At what particular event in the life of a human female this process stops temporarily but starts again?
(e) What name is given to the event when this process stops permanently?Lakhmir Singh & Manjit Kaur - Science
Which of the following can lead to menstruation in a 21 year old woman during ovulation?
A) Sperms available for fertilization
B) Oviducts blocked
C) Sperms not available for fertilization
D) Oviducts not blockedLakhmir Singh & Manjit Kaur - Science
Define (i) menarche, and (ii) menopause.Lakhmir Singh & Manjit Kaur - Science
What name is given to the onset of menstruation in human females (or girls)? At what age does this occur?Lakhmir Singh & Manjit Kaur - Science
State whether the following statements are true or false:
(a) The estrogen hormone develops deeper voice in males at puberty.
(b) Menstruation stops in men permanently around the age of 45 to 50 years.
(c) Man (father) is responsible for the sex of the body.
(d) The sex chromosomes in all the gametes (sperms) of a man are not identical.
(e) Half the female gametes contain X chromosomes and the other half contain Y chromosomes.
(f) It is the sperm which determines the sex of a child.
(g) Each normal cell in our body contains 23 chromosomes and the other half contain Y chromosomes.
(h) A girl should not be allowed to work in the kitchen during menstruation.
(i) A woman (mother) is responsible for the sex of her child.
(j) Metamorphosis in insects (like silk moth) is brought about by thyroxine hormone.Lakhmir Singh & Manjit Kaur - Science
State one situation (other than menopause) when ovulation and menstruation stop in a woman.Lakhmir Singh & Manjit Kaur - Science
Give a suitable word for each of the following statements.
(a) The site which response to a hormone.
(b) Name of a gland which transports secretions through ducts.
(c) Chemicals which control changes at adolescence stage.
(d) It marks the beginning of the reproductive period.NCERT - Science Exemplar
Describe menstrual cycle. What is the duration of menstruation cycle in women?Lakhmir Singh & Manjit Kaur - Science