Dav Class 8 Science Chapter 15 Question Answer Reaching the Age of Adolescence of The Living World Science Book is the best study material for those students who are finding difficulties in preparing for their dav exams. The DAV Solutions material contains answers to all the questions present in the DAV textbooks. Students can also prepare their notes and other class assignments for free.
These DAV Solutions for class 8 science present you with answers to the question on the reaching the age of adolescence, sexual development, the endocrine system and reproductive health in details.
While solving the DAV textbook questions, students often face several doubts and eventually get confused. To help the students clear all their doubts instantly, the DAV Class 8 Science Chapter 15 question answer Reaching the Age of Adolescence come as a great resource. Here, the detailed Solutions for Class 8 Science Chapter 15 of DAV Class 8 Science book are given below.
DAV Class 8 Science Chapter 15 Reaching the Age of Adolescence Solutions
DAV Class 8 Science chapter 15 question answer Reaching the Age of Adolescence is given below. Here DAV Class 8 Science Chapter 15 solutions is provided with great explanation. To score very good marks in the DAV Class 8 Science examination students should solve the questions provided at the end of each chapter in Class 8 DAV books.
- Fill in the blanks.
- Match the following.
- Tick the correct option.
- Answer the following questions in brief.
- Answer the following questions.
The DAV Solutions for Class 8 Science comprises precise explanations to all the questions included in the DAV Class 8 Science Textbook. These solutions are prepared by our subject professionals in a systematic manner, according to the latest DAV School syllabus and guidelines.
A. Fill in the blanks.
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.
Answer: (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-
2. The onset of menstruation, in a human female, is known as-
3. The hormone, which controls the body’s response to stress, is known as-
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-
D. Answer the following questions in brief.
1. State the meaning of the term ‘Adolescence’.
Answer: Adolescence is the stage of transition from childhood to adulthood.
2. Define puberty. State the various factors which influence it.
Answer: The initial phase of adolescence is marked by certain dramatic changes in the body. This period is called puberty. Proper diet, genes and environment influence this period.
3. Why are endocrine glands known as ductless glands?
Answer: Endocrine glands are also known as ductless glands as they do not have any ducts of their own; they pour their secretions directly into the blood stream.
4. Why do tadpoles growing in iodine deficient waters fail to grow into frogs?
Answer: Tadpoles growing in iodine deficient waters fail to grow into frogs because Iodine is needed for the production of thyroxine and the hormone ‘thyroxine, produced by the thyroid gland of the frog, is essential to carry out the process of metamorphosis.
5. How does the pituitary gland control the maturation of the gonads?
Answer: Pituitary gland in the brain secretes hormones which activate the ovaries and the testes to produce estrogen, progesterone and testosterone. These hormones help in maturation of the gonads.
6. Women, above the age of fifty, are (generally) unable to give birth to children. Explain the reason for the same.
Answer: The menstrual cycle stops when the woman reaches 45-50 years of age. This marks the end of reproductive phase. Hence, women above the age of fifty are generally unable to give birth to children.
E. Answer the following questions.
1. Enlist the changes which occur in males and females during puberty.
Answer: During puberty the following changes occur in males and females:
Increase in height: The onset of the puberty period usually results in a dramatic, sudden and visible increase in height and weight. This spurt in physical growth is more evident in girls between 11-13 years of age; it is between 13-15 years for boys.
Changes in the size of heart and lungs: There are changes in the size of heart and lungs; these are less apparent but equally important. There is an increase in the size and capacity of lungs too.
Change in body shape: Many changes take place in the shape and size of the body; these changes are different for boys and girls.
Change in voice: Voice becomes deep. Larynx is present in the throat which gives a characteristic pitch of voice to every individual.
Increased activity of sweat and sebaceous glands: The sweat glands of the body develop fully during puberty and there is an increased secretion of sweat. Acne and pimples are common among adolescents due to increased production of sebum from the sebaceous glands.
(a) Identify the disease Arunima was suffering from along with its cause.
Answer: Arunima is suffering from goiter which happens because of deficiency of iodine.
(b) Why do you think that no medication was prescribed for Arun?
Answer: Adam’s Apple has developed in Arun. It is a normal development in boys. Hence, Arun does not need medications.
3. Discuss how the sex of the unborn child gets determined in human beings.
Answer: Human beings have 46 chromosomes in the nuclei of their cells. Of these 44 are known as autosomes and the last pair is termed as the sex chromosomes. This last pair is different in males and females. In males, it is XY and in females it is XX. The egg will always have (22+ X) chromosomes while a sperm will have either (22+ X) or (22 + Y) chromosomes.
During fertilisation, if an egg fuses with a (22+ Y) sperm, the resultant zygote will develop into a male child; if an egg fuses with a (22+ X) sperm, the resultant zygote will develop into a female child.
4. Enlist the events that regularly occur in the female reproductive system, after the onset of puberty, until menopause.
5. Highlight the importance of exercise and good personal hygiene during adolescence.
Importance of exercise during adolescence
Just like food, exercise is a daily requirement during adolescence. Scientific evidence indicates that walking, jogging, running and playing games stimulate the growth process and keeps the individual fit. Exercise also helps in better digestion of food and more efficient elimination of toxins from the body. It improves blood circulation and increases the respiratory efficiency of lungs. Physical activity is also important to combat the stress and strain of adolescence.
Importance of good personal hygiene during adolescence
Adolescents need to know how to take care of their evolving and changing body. Bathing daily, use of a proper soap, maintaining dental and oral hygiene, care of the eyes and ears, and proper grooming, are some of the habits that adolescents need to follow regularly.