Write notes on—
1. Adam’s apple.
2. Secondary sexual characters.
3. Sex determination in the unborn baby.
1. Adam’s apple.
2. Secondary sexual characters.
3. Sex determination in the unborn baby.
Solution and Explanation
(a) Adam’s apple: The protruding part of the throat is called Adam’s apple. It is the enlarged voice box or larynx which gets enlarged and visible from outside in boys at the onset of puberty. This makes the voice of boys hoarse.
(b) Secondary sexual characters: Secondary Sexual Characters are those characters which distinguish a male from female. Some of the characters are as follows:
Boys:
- Facial hairs such as beard and moustaches develop.
- Hair develops under the armpit, under chest and in the pubic regions.
- Voice becomes deeper.
- Muscles develop, and shoulder becomes broad.
- Increase in weight.
Girls:
- Development and enlargement of breasts.
- Hair develops under the armpit and in the pubic regions.
- Hips broaden and pelvic region widens.
- Initiation of menstrual cycle.
- Deposition of fat around hips.
(c) Sex determination in the unborn baby: All human beings have 23 pairs of chromosomes in the nuclei of their cells. Out of these two chromosomes are the sex chromosomes, named X and Y. A female has two X chromosomes, while a male has one X and one Y chromosome. The gametes (egg and sperm) have only one set of chromosomes. The unfertilised egg always has one X chromosome but sperms may have X or Y. When a sperm containing X chromosome fertilises the egg, the zygote would have two X chromosomes and develop into a female child. If the sperm contributes a Y chromosome to the egg (ovum) at fertilisation, the zygote would develop into a male child. This concludes that the sex chromosomes of the father determine the sex of an unborn baby.
Questions Asked in CBSE Class VIII exam
Underline the verbs and arrange them in two columns, Past and Earlier past.
(a) My friends set out to see the caves in the next town, but I stayed at home, because I had seen them already.
(b) When they arrived at the station, their train had left. They came back home, but by that time I had gone out to see a movie!
(c) So they sat outside and ate the lunch I had packed for them.
(d) By the time I returned, they had fallen asleep!
Past Earlier Past - CBSE Class VIII
- The Best Christmas Present in the world
Fill in the blanks using the correct form of the verbs in brackets.
My little sister is very naughty. When she ____ (come) back from school yesterday, she had _____(tear) her dress. We _____(ask) her how it had _____(happen). She ______(say) she _____ _____ (have, quarrel) with a boy. She _____ _____ (have, beat) him in a race and he _____ ____ (have, try) to push her. She _____ ____ (have, tell) the teacher and so he _____ _____ (have, chase) her, and she _____ _____ (have, fall) down and _____ _____ (have, tear) her dress.
- CBSE Class VIII
- The Best Christmas Present in the world
Mention the following.
(i) Two examples of social practices prevailing then.
(ii) Two oppressive policies of the British.
(iii) Two ways in which common people suffered.
(iv) Four reasons for the discontent that led to the 1857 War of Independence.
- CBSE Class VIII
- Glimpses of the past
Say whether the following are true or false.
1. Ignesious lost his wife, two children, his father-in-law, and his brother-in-law in the tsunami.
2. Sanjeev made it to safety after the tsunami.
3. Meghna was saved by a relief helicopter.
4. Almas’s father realised that a tsunami was going to hit the island.
5. Her mother and aunts were washed away with the tree that they were holding on to.
- CBSE Class VIII
- The Tsunami
- Write a short paragraph on the harmful effects of microorganisms.
- CBSE Class VIII
- Harmful Microorganisms