AP 8th Class Biology 5th Lesson Questions and Answers Reaching the Age of Adolescence

AP State Board new syllabus 8th Class Biology Guide 5th Lesson Reaching the Age of Adolescence Textbook Exercise Questions and Answers.

AP 8th Class Biology 5th Lesson Questions and Answers Reaching the Age of Adolescence

8th Class Biology 5th Lesson Reaching the Age of Adolescence Questions and Answers (Exercise)

Question 1.
What is the term used for chemical secretions of endocrine glands responsible for changes taking place in the body ?
Answer:
‘Hormones’ is the term used for chemical secretions of endocrine glands responsible for changes taking place in the body.

Question 2.
Define adolescence.
Answer:

• The period of life when the body undergoes changes leading to reproductive maturity is called adolescence.
• Adolescence begins around the age of 11 and lasts upto 18 or 19 years of age.

Question 3.
What is menstruation ? Explain.
Answer:

• The ova begin to mature with the on set of puberty.
• One ovum matures and is released by one of the ovaries once in about 28 to 30 days.
• During this period, the wall of the uterus becomes thick so as to receive the egg.
• In case, it is fertilised and begins to develop. This results in pregnancy.
• If fertilisation does not occur the released egg and the thickened lining of the uterus along with it’s blood vessels are shed off.
• This causes bleeding in women which is called menstruation.
•  Menstruation occurs once in about 28 to 30 days.

Question 4.
List changes in the body that take place at puberty.
Answer:

• Sudden increase in height.
• In boys, shoulders are broaden and in girls, the region below the waist becomes wider.
• The voice of boys becomes hoarse. It is because of the development of Adam’s apple in throat region.
• Boys develop hair on their chest. They also develop facial hair (beard and moustache)
• Development of breasts in girls.
• Hair starts growing in different parts of the body.
• Sex organs in boys and girls develop completely.
• Boys and girls attain mental, intellectual and emotional maturity.

Question 5.
Prepare a Table having two columns depicting names of endocrine glands and hormones secreted by them.
Answer:

Name of the endocrine gland	Hormones secreted
1) Pituitary gland	1) a) Growth hormone b) Hormones that stimulate the functioning of other endocrine glands
2) Thyroid	2) Thyroxine
3) Adrenal glands	3) Adrenalin
4) Pancreas	4) Insulin
5) Testes	5) Testosterone
6) Ovaries	6) Estrogen

Question 6.
What are sex hormones ? Why are they named so ? State their function.
Answer:

• The hormones which secrete from testes and ovaries are called “Sex hormones”.
• In males, testes release a hormone called “testosterone”. In females, ovaries release a hormone called ‘estrogen’.

Functions of testosterone:

• brings growth in height
• develop secondary sexual characters like growth of facial hair, development of sex organs, change in voice etc….

Functions of estrogen
Once puberty is reached in girls, ovaries produce estrogen. This brings.

• the development in breasts
• development of mammary glands inside the breasts
• growth of hair in different parts of the body like below arms and near pubic region.

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:
(ii) proper diet is needed for the rapid growth taking place in their body.

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) Adam’s apple :

• At puberty, the voice box or larynx begins to grow. Boys develop larger voice boxes.
• The growing voice box in boys can be seen as a protruding part of the throat, called Adam’s apple. Because of this boys have a deep voice.
• Sometimes, the muscles of the growing voice box go out of control and the voice becomes hoarse. After a few weeks, the voice becomes normal.

b) Secondary sexual characters :

• The features that help to distinguish the male from female are called secondary sexual characters.
• At the on set of the puberty, hormones called testosterone and estrogen are secreted by testes and ovaries in boys and girls respectively.
• These hormones bring secondary sexual characters in boys and girls.
• Development of breasts and mammary glands, hair growth under the arms and in the regions above the thighs or pubic regions are seen in girls.
• Boys develop secondary sexual characters like facial hair, change in voice, hair on chest, development in chest and shoulder muscles, growth of hair under the arms etc….

c) Sex determination in unborn baby:

• All human beings have 23 pairs of chromosomes in their 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 gametes (egg and sperm) have only one set of chromosomes.
• The unfertilised egg always has one X chromosome. But sperms are of two kinds. One kind has an X chromosome and the other kind has a Y chromosome.
• When a sperm containing X chromosome fertilises the egg, the zygote would have 2 X chromosomes. It results in the development of female child.
• If the sperm contributes a ‘ Y ‘ chromosome to the egg (ovum), at fertilisation, the zygote would develop into a male child.
• The sex chromosomes of the father determine the sex of an unborn baby.

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 blood stream.
6) Voice box.
7) Term for changes at adolescence.
Answer:

Question 10.
‘The table below shows the data on 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.

Answer:

• By observing the above graph, we can conclude that girls at the age of 12 are generally taller than boys. While at 16 years, the height of both is the same
• But after that, boys gain height and become taller than girls.

Question 11.
Many of my classmates have a hoarse voice. Now I know why?
Answer:

• In adolescent boys, sometimes, the muscles of the growing voice box go out of control and the voice becomes hoarse.
• This state may remain for a few days or weeks after which the voice becomes normal.

Question 12.
Paheli says that the reproductive life of a woman lasts from menarche to menopause.Is she right?
Answer:

• Yes, she is correct.
• The first menstrual flow begins at puberty and is termed menarche.
• At 45 to 50 years of age, the menstrual cycle stops, stoppage of menstruation is termed menopause.
• Hence, the reproductive life of a woman lasts from menarche to menopause.

Question 13.
Are there hormones in other animals also? Have they any role to play in reproduction?
Answer:

• Yes, other animals also have hormones.
• Yes, they play a vital role in carrying out reproduction.

Question 14.
If people do not have enough iodine in their diet, will they get goitre caused by lack of thyroxine?
Answer:

• Yes, iodine play a vital role in the functioning of thyroid gland.
• It helps in the sufficient production of a hormone called thyroxine.
• If people do not have enough iodine in their diet, it leads to a disease called goitre. Big and bulging throat is the symptom of goitre disease.

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:

• Early marriage is a social evil.
• So, in our country the legal age for marriage is 18 years for girls and 21 years for boys.
• This is because teenage mothers are not prepared mentally and physically for motherhood.
• Early marriage and motherhood cause health problems for the mother and the child.
• It also curtails the employment opportunities for the young woman and may cause mental agony as she is not ready for responsibilities of mother hood.

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 stands for human immuno deficiency virus.
• It weakens a person’s immune system by destroying immune system, by destroying important cells that fight disease and infection.
• There is currently no effective cure for HIV. But with proper medical care, HIV can be controlled.
• HIV can be transmitted via the exchange of a variety of body fluids from infected people, such as blood, breast milk, semen and vaginal secretions.
• HIV can also be transmitted from a mother to her child during pregnancy and delivery.

Question 3.
In our country, according to 2011 census, there are 940 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) In most of the states in our country, many people have a belief that only the son can carry their hierarchy. Dowry system, customs and traditions prevailing in the society lead to female foeticide in our country. This results in low sex ratio
b) Amniocentesis gives certain information regarding the sex of the baby. In India, Prebirth sex determination is banned to prevent female foeticide.

Question 4.
Put your ideas together and write a short note on the importance of knowing facts about reproduction.
Answer:
Importance of knowing facts about reproduction :

• We can aware of changes in puberty.
• We can know the functions of different hormones and their role in the development of sex organs in boys and girls.
• We can become aware about the increased activities of sweat and sebaceous glands and the importance of balanced diet in adolescence.
• We become aware about health and hygiene and also about myths, taboos.
• We become aware of results of addiction of drugs during adolescent period.

8th Class Biology 5th Lesson Questions and Answers (Lab Activities)

Activity-1

The following chart gives the average rate of growth in height of boys and girls with age. The figures in columns 2 and 3 , give the percentage of the height a person has reached at the age given in column 1. For example, by the age 11, a boy has reached 81% of his probable full height, while a girl has reached 88% of her full height. These figures are only representative and there may be individual variations. Use the Table for your friends and work out how tall they are likely to be. Find out who is likely to be the tallest and who might be the shortest in your class.

Age in	% of full height
years	Boys	Girls
8	72%	77%
9	75%	81%
10	78%	84%
11	81%	88%
12	84%	91%
13	88%	95%
14	92%	98%
15	95%	99%
16	98%	99.5%
17	99%	100%
18	100%	100%

Calculation for full height (cm) = \(\frac{\text { Present height }(\mathrm{cm})}{\text { %of full height at this age }}\) × 100

Example: A boy is 9 years old and 120 cm tall. At the end of the growth period he is likely to be
\(\frac{120}{75}\) × 100 cm=160 cm tall
Answer:

Name of the child student	Age	Present height in cms	Maximum height he will attain
1. Abhijith	14	150 cm	163 cm
2. Pranav shashank	12	143 cm	170 cm
3. Yasho	10	130 cm	167 cm
4. Shravya	10	135 cm	160 cm
5. Sunny	12	147 cm	162 cm
6. Rajani	14	150 cm	153 cm

• The tallest may be Pranav shashank with 170 cm height.
• The shortest among the above might be Rajani with 153cms in height.

Activity-2

Use the data given in Activity 1 to draw a graph. Take age on the X-axis and percent growth in height on the Y-axis. Highlight the point representing your age on the graph. Find out the percentage of height you have already reached. Calculate the height you might eventually reach. Tally your graph with the one given here.

Answer:
Graph showing percentage of height with age

• From the above graph we can observe the height of boys 4nd girls with age.
• My present age is 14 and my height is 150 cm. So, I achieved 92% of height. I will attain a height of 163 cm in future (at the age of 18 years)
• From the above graph, we can conclude that girls grow faster than boys but by about 18 years of age, both reach their maximum height.
• The rate of growth in height varies in different individuals.

Activity-3

Write the importance of iodised salt in our regular diet.
Answer:

• Thyroid gland needs iodine to produce thyroxine hormone, which regulates the metabolic activities of the body.
• Deficiency of thyroxine leads to a disease called “Goitre”.
• It also burns extra fat deposits that could lead to heart diseases.
• Iodised salt helps to regulate heart rate and blood pressure.

Activity-4

Make a group with your friends. Write down the items of food in your breakfast, lunch and dinner you had on the previous day. Identify the items responsible for proper growth. Also identified the junk food that you consumed the previous day.
Answer:

Name of the individual	Break fast	Lunch	Dinner
1. Pardha Saradhi	Idli, Sambar and milk	Rice, dal, curd	Fruits and milk
2. Rama Prasad	Dosa, chutney Tea	Rice, Vegetable Curry, butter milk	Pulka and Palak curry
3. Srinivas	Poori – Aloo curry	Chapathi	Pizza – Noodles Chips – Tinned snacks
4. Raja	Chapathi	Rice, dal, chicken curry	Burgers – ice creams
5. Ravi	Idly – Chutney	Rice – curd fruits	Pulka – Chana curry – Butter milk

From the above table we may conclude that the meal that contains, carbohydrates, proteins and fats is called a balanced diet. Srinivas consumed junk foods like Pizza – Noodles – Chips – Tinned snacks. They are harmful to our health. Raja also ate burgers and ice creams. Eating junk food regularly cause obesity. They should be consumed occasionally.

Activity – 5

Prepare a chart showing a balanced diet.
Answer:

Activity-6

Prepare a report on the advantages of regular exercises.
Answer:

• Conduct a survey to find out how many of your classmates exercise regularly and how many don’t.
• Observe them and note down the difference in their fitness levels

SI. No.	Name of the Student	Doing regular exercises	Not doing regular exercises
1.	B. Raju	✓
2.	K. Venkat		✓
3.	B. Chaitanya	✓
4.	Ch. Jyothsna	✓
5.	B. Agasthya	✓
6.	B. Srilakshmi	✓
7.	Lakshmana		✓

From the above observations, we can conclude that.

• The persons who are doing exercises regularly are energetic, more alert and have a better immune system.
  My classmates who do not exercise regularly are lazy, drowsy, not concentrating on studies and often unwell.

It is necessary to do physical exercises like playing outdoor games, running, walking and cycling, especially for adolescents. These can improve physical and mental health.