DAV Class 8 Science Chapter 15 Question Answers Today we will check the question answers with their explanation from DAV Class 8 science book, Chapter 15 Reaching the age of Adolescence.
DAV Class 8 Science chapter 15, Reaching the Age of Adolescence talks about the issues faced by children during puberty, the changes in their body, the body developments, different reproductive hormones, and the endocrine system.
Let us look at the solutions to question answers from DAV class Chapter 15
1. Endocrine glands release ___________ into the blood stream.
2. ___________ is also known as the voice box.
3. Acne and pimples are common in adolescence due to increased production of ___________ by the ___________ glands.
4. Deficiency of ___________ reduces the absorption of calcium by the body.
5. ___________ hormone is essential for metamorphosis to happen in a frog.
6. ___________ are chromosomes other than the sex chromosomes.
answers
(1) hormones (2) Larynx (3) sebum, sebaceous (4) vitamin D (5) Thyroxin (6) Autosomes
B. Match the following.
Answer: (1) E, (2) D, (3) A, (4) B, (5) C
C. Tick the correct option.
1. The period of life, marked by rapid changes leading towards sexual maturity, is known as-
Answer: puberty
2. The onset of menstruation, in a human female, is known as-
Answer: menarche
3. The hormone, which controls the body’s response to stress, is known as-
Answer: adrenaline
4. Out of following, the one that does not produce hormones, is the-
Answer: sebaceous glands
5. The mineral, whose presence is essential for a tadpole to grow into a frog, is-
Answer: Iodine
D. Answer the following questions in brief.
1. State the meaning of the term ‘Adolescence’.
Answer: Adolescence is the phase in which a person transit from his or her childhood to adulthood there are many changes which can be noticed during the adolescence period..
2. Define puberty. State the various factors that influence it.
Answer: As a child transits from childhood to adulthood many changes are visible in the body of a boy and a girl. This period is known as puberty. The factors that affect poverty are proper diet, genes and the influence from the outer environment.
3. Why are endocrine glands known as ductless glands?
Answer: Endocrine glands are called ductless gland because there is an absence of ducts in the case of endocrine glands. The secretions directly enter into the bloodstream.
4. Why do tadpoles growing in iodine deficient waters fail to grow into frogs?
Answer: Iodine-deficient water does not provide the essential iodine for the transition of tadpoles into frogs. Iodine is essential for the production of thyroxine hormone produced by the thyroid gland. This hormone is essential for the process of metamorphosis.
5. How does the pituitary gland control the maturation of the gonads?
The pituitary gland is also known as the master gland. Its function is quite crucial in the human body it activates the testes and the ovaries that are responsible for the production of testosterone, progesterone, and estrogen. All these hormones are responsible for the maturation of the gonads.
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6. Women, above the age of fifty, are (generally) unable to give birth to children. Explain the reason for the same.
Once the woman reaches an age of 45-50, the menstrual stops functioning. They are no longer under the reproduction phase. This is the reason, women above 45 or 50 are unable to give birth to young ones.
DAV Class 8 Science Chapter 15 Question Answers
E. Answer the following questions.
1. Enlist the changes which occur in males and females during puberty.
Various changes occur during the puberty period. These changes are visible in both boys and girls.
Increase in height: One can see a sudden change in the height. you must have seen that children attain a sudden increase in their height and weight.
Changes in the size of heart and lungs: The size of the heart and lungs also change.
Change in body shape: Body shape changes are quite common during the puberty period. In boys the chest may become wider.
Change in voice: During the puberty age, the voice of both boys and girls change.
Increased sweat: There is an increase in the amount of sweat released from the body as they are under the puberty period. Sebaceous glands become more active.
Question 2: Arun and his sister arunima are both teenagers. Arunima observe a swelling on her neck following which she visit s a doctor. the doctor identifies it to be a deficiency diseases and prescribes medicine accordingly along a suggesting dietary modifications. A few month later Arun observed a small protrusion on his throat abd visit a doctor. However, the doctor assures him that it is a normal features in boys of his age.
(a) Identify the disease Arunima was suffering from along with its cause.
Answer: Arunima is suffering from the Goitre disease which is caused by the lack of iodine in the diet. Earlier this disease was quite common in village areas.
(b) Why do you think that no medication was prescribed for Arun?
Answer: In boys, the neck grow bit outwards. This is known as Adam’s apple which is common among boys. This is the reason the doctor did not prescribe any medicine for Arun.
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3. Discuss how the sex of the unborn child gets determined in human beings.
Humans beings have 23 pairs of chromosomes. Out of these 22 pairs are known as the autosome while the last left pair of chromosomes decides the sex of the child. It is known as the sex chromosome. In total there are 46 chromosomes.
In males the chromosome pair is XY, in females it is XY. The Egg has (22+X) chromosome. Now, it depends on the other sperm, if the pair is 22+X, a boy will be born else if the other pair is 22 + Y, a girl child will be born.
4. Enlist the events that regularly occur in the female reproductive system, after the onset of puberty, until menopause.
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