MP Board Class 8th Science Solutions Chapter 10 Reaching the Age of Adolescence
MP Board Class 8th Science Reaching the Age of Adolescence NCERT Textbook Exercises
Question 1.
What is the term used for secretions of endocrine glands responsible for changes taking place in the body?
Answer:
Hormones.
Question 2.
Define adolescence.
Answer:
Adolescence is defined as the period of life (11 to 18 or 19 years of age) when the body undergoes changes leading to reproductive maturity.
Question 3.
What is menstruation? Explain.
Answer:
Menstruation. In females, the ova begin to mature with the onset of puberty. One ovum matures and is released by the ovaries once in 28 to 30 days. In case, the fertilization does not take place, the released egg and the thickened lining of the uterus along with its blood vessels are shed off. This causes bleeding in woman and is called, menstruation: It occurs once in about 28 to 30 days.
Question 4.
List changes in the body that take place at puberty.
Answer:
The following changes take place in the body at puberty.
- Sudden increase in height. The bones of the arms and legs elongate and make a person tall.
- Change in the body shape. In boys, the shoulders become broader and the chests become wider. In girls, the region below the waist becomes wider.
- Voice change. In boys, the voice becomes deep or hoarse. Generally the girls have high pitched voice.
- Increased activity of sweat and sebaceous glands glands. Pimples may develop on the face.
- Development of sex organs. In boys, testes begin to produce sperms. In girls, ovaries enlarge and start releasing matured eggs.
- Reaching mental, intellectual and emotional maturity. These changes are natural part of growing up.
Question 5.
Prepare a table having two columns depicting names of endocrine glands and hormones secreted by them.
Answer:
Hormones secreted by Endocrine organs.
Question 6.
What are sex hormones? Why are they named so? State their function.
Answer:
The hormones which are secreted by the testes and ovaries are called sex hormones. They are so called because they are secreted by the two human sexes of male and female.
Testosterone which is a male hormone causes changes like growth of facial hair in boys.
Oestrogen which is a female hormone makes the breasts develop in girls.
Question 7.
Choose the correct option:
(a) Adolescents should be careful about what they eat, because
(i) proper diet develops their brains.
(ii) proper diet is needed for the rapid growth taking place in their body.
(iii) adolescents feel hungry all the time.
(iv) taste buds are well developed in teenagers.
Answer:
(iii) adolescents feel hungry all the time.
(b) Reproductive age in women starts when their
(i) menstruation starts.
(ii) breasts start developing
(iii) body weight increases.
(iv) height increases.
Answer:
(i) menstruation starts.
(c) The right meal for adolescents consists of
(i) Chips, noodles, coke.
(ii) Chapati, dal, vegetables.
(iii) Rice, noodles and burger
(iv) Vegetable cutlets, chips and lemon drink.
Answer:
(ii) Chapati, dal, vegetables.
Question 8.
Write notes on:
(a) Adam’s apple.
(b) Secondary sexual characters.
(c) Sex determination in the unborn baby.
Answer:
(a) At puberty, the voice box or the larynx begins to grow. The growing voice box in boys can be seen as a protruding part of the throat called Adam’s apple.
(b) In girls, breasts begin to develop at puberty and boys begin to grow facial hair, that is mustaches and beard. As these features help to distinguish the male from the female, they are called secondary sexual characters.
(c) All human beings have 23 pairs of chromosomes (fertilized egg) in the nuclei of their cells. Two chromosomes out of these 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 unfertilized egg always has one X chromosome. But, testes produce two kinds of sperms. One kind has an X chromosome and the other kind has a Y chromosome. When a sperm containing X chromosome fertilizes 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 fertilization, the zygote would develop into a male child.
This is how sex determination in the unborn baby occurs.
Question 9.
Word game: Use the clues to work out the words.
Across
3. Protruding voice box in boys
4. Glands without ducts
7. Endocrine gland attached to brain
8. Secretion of endocrine glands
9. Pancreatic hormone
10. Female hormone
Down
1. Male hormone
2. Secretes thyroxine
3. Another term for teenage
5. Hormone reaches here through bloodstream
6. Voice box
7. Term for change at adolescence
Answer:
Question 10.
The table given shows the data on the likely heights of boys and girls as they grow in age. Draw graphs showing height and age for both boys and girls on the same graph paper. What conclusions can be drawn from these graphs?
Answer:
We conclude that girls are taller than boys at the age of 12 years generally and their height is same at the age of 16 years but some boys gain height and generally become taller than girls.
Reaching the Age of Adolescence NCERT Extended Learning – Activities and Projects
Question 1.
Find out from your elder relatives about their awareness of the legal status of early marriage. You yourself may get information on it from your teacher, parents, a doctor or the Internet. Write a two-minute speech explaining why early marriage is not good for the couple.
Answer:
The legal marriageable age for girls is 18 years and for boys it is 21 years. Before this age marriage is considered illegal. Early marriage is not good for couples because they are not prepared physically and mentally for the responsibilities of married life. A girl attains sexual maturity at age of about eighteen years. Before that her reproductive system is not fully prepared to bear a baby. Similarly boys are not capable of running the household as most of the boys at this age are pursuing their studies. So, the boys and girls should attain physical and mental maturity before getting married.
Question 2.
Collect newspaper cuttings and information in magazines about HIV/AIDS. Write a one page article of 15 to 20 sentences on HIV/AIDS.
Answer:
HIV/AIDS is a sexually transmitted diseased (STD) that means this diseases mostly spreads by sexual contacts with an HIV/AIDS infected persons. AIDS stands for Acquired Immune Deficiency Syndrome. It is created by HIV virus. This disease is a fatal disease for which no permanent treatment has been deviced by The scientists. AJDS is actually a disease, which destroys the patients immune’ system slowly. The damage is most of the Permanent and beyond repair. Due to weak immunity the patient easily falls prey to many diseases which eventually kill the person. Prevention is the only cure for HIV/ AIDS. It is advised that one should maintain sexual hygiene and practice safe sexual relationship with a single partner.
Question 3.
In our country, according to a census, there are 882 adolescent females for every 1000 males. Find out:
(a) The concerns of the community regarding this low ratio. Remember that the chance of having a boy or a girl is equal.
(b) What amniocentesis is and how useful this technique is. Why is its use for identification of sex of the unborn child banned in India?
Answer:
(a) The society is quite concerned about this issue. This is going to create a problem for them in future as it will become difficult for the boys to find girls for marriage.
(b) It is used to see, if all the organs of a foetus are developing well. It is, banned in India to use this technique to determine the sex of the unborn child because they kill the female foetus to have baby boys in future. This is called female foeticide. The female foeticide has disturbed the ratio of boys and girls in India.
Question 4.
Put your ideas together and write a short note on the importance of knowing facts about reproduction.
Answer:
Do yourself.
MP Board Class 8th Science Reaching the Age of Adolescence NCERT Intext Activities and Projects
Activity 10.3
Colled information from magazines or from doctors and prepare a note on the importance of consuming iodised salt. You can also look for this information on the internet.
Answer:
Iodine in the diet prevents the humans from getting goitre. This is due to the fact that the production of thyroxine requires the presence of iodine in water or any food. Thyroxine is produced by thyroid. The lack of iodine in the food can cause goitre.
Activity 10.4
Make a group with your friends. Write down the items of food in your breakfast, launch and dinner you had on the previous day. Identify the items responsible for proper growth. Also identified the junk food items that you consumed the previous day.
Answer:
I have three friends, Shyam Chatterjee a Bengali, Maninder Singh a Punjabi Sikh, and Kunju Ratnam a South Indian, This is the group I am in. I give below the items of food in our breakfast, lunch and dinner.
(i) Myself
Breakfast: Bread (chapati), vegetable and a glass of milk.
Lunch: Chapati, rice, vegetable, dal, curd, an orange or an apple.
Dinner: Chapati, dal, vegetable, kheer, a fruit and a glass of milk.
There is a little change in the food items of my friends. Over and above, my meal is a balanced food and I think this will give me proper growth.
(ii) Shyam Banerjee
Breakfast: Bread, butter and tea.
Lunch: Rice, fish curry and vegetable (fried).
Dinner: Chapati, rice, dal, vegetable and curd.
Up to some extent, the diet is balanced. So, proper growth of the body and mind is possible up to an extent.
(iii) Maninder Singh
Breakfast: Chhole-bhature or puri-vegetable with tea.
Lunch: Chapati, dal, breakfast or meat/fish etc. + curd
Dinner: Chapati, fish/meat/egg curry + curd.
To some extent this meal is a balanced one. Proper growth is possible.
(iv) Kunju Ratnam
Breakfast: Sambhar, bada/idli and tea
Lunch: Rice, sambhar, chatni and curd.
Dinner: Same as Lunch + chapati.
This meal is not balanced one. So, proper growth may not be possible.
Activity 10.6
Collect data on the number of children in your class who exercise regularly and who do not exercise regularly. Did you notice any difference in their fitness and health? Prepare a report on the benefits of regular exercise.
Answer:
Exercise of various kinds keeps our body and mind fit, alert and strong. As it is said that healthy mind live in a healthy body, so exercise is a boon for human life. The children who do regular exercise remain very healthy and fit not only by body but also by mind. And those who do not do any exercise remain sickly and lack in studies also.
Reaching the Age of Adolescence NCERT Additional important Questions
A. Short Answer Type Questions
Question 1.
What is adolescence?
Answer:
The period of life, when the body undergoes changes, leading to reproductive maturity is called adolescence.
Question 2.
Why can humans reproduce only after a certain age?
Answer:
Human reproduce only when they get reproductive maturity. The period of life when the body undergoes changes, leading to reproductive maturity is called adolescence. Adolescence begins around the age of 11 and last up to 18 or 19 years of age.
Question 3.
Which hormone is responsible for the worried. maturity of ova or sperms?
Answer:
Follicle stimulating hormone is responsible for the maturity of ova or sperms.
Question 4.
What is the function of adrenalin
Answer:
It helps the body to adjust to stress age. when one is very angry, embarrased or worried.
Question 5.
What is a balanced diet?
Answer:
A balanced diet means that the meals responsible for the maturity of ova or include proteins, carbohydrates, fats and sperms. vitamins in requisite proportions.
Question 6.
Which virus causes AIDS? hormone?
Answer:
Virus named HIV causes AIDS.
B. Long Answer Type Questions
Question 7.
Explain the reproductive health 30 days. It is the time when egg is matured
Answer:
The physical and mental well being and released by ovaries. If fertilisation does of an individual is regarded as an not occur, the released egg and the thickened individual s health. To keep the body lining of uterus along with its blood vessels healthy/every human being, at any age, are shed off This causes bieeding in women needs to have a balanced diet. The person which is called menstruation. must also observe personal hygiene and Q10 Write a short note on personal undertake adequate physical exercise. hygiene. During adolescence, however, these, become Answer: Everyone should have a bath at least even more essential as the body is growing.
Question 8.
Why some young boys and girls get teenagers because the increased activity of acnes and pimples on their face? sweat glands sometimes makes the body
Ans:
During adolescence the sweat glands smeUy An parts Gf the body should be and oil glands become more active. The Washed and cleaned everyday. If cleanliness sebaceous glands secrete more oil which is not maintained there are chances of blocks the skin and more secretions from catching bacterial infection. Girls should take sweat glands cause infections. Thus over special care of cleanliness during the time secretions from these glands cause acnes and 0f menstrual flow. They should keep track pimples on the faces of young boys and girls. of their menstrual cycle and be prepared
Question 9.
What is menstruation? for onset of menstruation.
Answer:
Monthly bleeding in women is called menstruation. It occurs once in about 28 to
Question 10.
Write a short note on personal hygiene.
Answer:
Everyone should have a bath at least once everyday. It is more necessary for teenagers because the increased activity of sweat glands sometimes makes the body smelly. All parts of the body should be washed and cleaned everyday. If cleanliness is not maintained there are chances of catching bacterial infection. Girls should take special care of cleanliness during the time of menstrual flow. They should keep track of their menstrual cycle and be prepared for the onset of menstruation.