DAV Class 8 Science Solution Chapter 15 Reaching the Age of Adolescence
DAV School Books Class 8 Science Solution Chapter 15 Reaching the Age of Adolescence all Question Answer. DAV Class 8 15th Chapter Reaching the Age of Adolescence full Chapter explanation by expert teacher.
DAV School Books Class 8 Science Solution Chapter 15 Reaching the Age of Adolescence
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.
1. Ovary | a. adrenaline |
2. Pancreas | B. testosterone |
3. adrenal | c. thyroxine |
4. Testes | d. insulin |
5. Thyroid | e progesterone |
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: The phase between childhood and young adulthood known as adolescence normally lasts from the ages of 12 to 18. It is a time of physical, psychological, and social transformation when people transition from being children to being young adults.
2.) Define puberty. State the various factors which influence it.
Answer: The period of development known as puberty is when a person’s body grows and develops the capacity for sexual reproduction. Physical development, hormone production, as well as sexual maturation all rise during this period. Genetics, family history, nutrition, weight, exercise, lifestyle, plus exposure to environmental variables such endocrine-disrupting chemicals are some of the factors that affect puberty.
3.) Why are endocrine glands known as ductless glands?
Answer: Since they release their hormones direct into the circulation or surrounding tissue rather than through a duct that connects to another organ, endocrine glands are also referred to as ductless glands.
4.) Why do tadpoles growing in iodine deficient waters fail to grow into frogs?
Answer: Iodine is necessary for tadpoles to fully develop into frogs. Tadpoles cannot effectively grow into frogs if they are not given adequate iodine. The generation of thyroid function, which aid in regulating the tadpole’s growth, depends on iodine. The tadpoles may not be able to develop into frogs if there is not enough iodine to support normal development.
5.) How does the pituitary gland control the maturation of the gonads?
Answer: Hormones produced by the pituitary gland promote gonad maturation. The gonads produce sex hormones in response to the hormones luteinizing hormone (LH) and follicle stimulating hormone (FSH). In males, LH and FSH respectively enhance the synthesis of testosterone and sperm. FSH and LH both enhance the development of eggs and oestrogen and progesterone in females. Both hormones are necessary for the gonads to mature and for the sex hormones to be produced.
6.) Women, above the age of fifty, are (generally) unable to give birth to children. Explain the reason for the same.
Answer: Women over fifty are typically unable to have children for a variety of reasons, but their lowered fertility is the main one. Women’s levels of hormonal changes decline with age, making it harder for them to become pregnant and deliver a baby to term. Additionally, genetic abnormalities, preterm birth, and miscarriage are risks that rise with age. A healthy pregnancy and successful conception are much less likely in the eggs of women above fifty because of their increased likelihood of having eggs with genetic abnormalities.
E.) Answer the following question she 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:
Physical, psychological, and emotional changes take place throughout the transitional stage of puberty. Boys and girls both go through a variety of physical changes throughout puberty, including an increase in height, weight, and muscle mass, the emergence of secondary sex traits including the development of facial and body hair, and changes in body form. The production of testosterone rises in boys, which results in the growth of facial and body hair, a deeper voice, and an increase in muscle mass and strength.
Girls’ bodies produce more oestrogen, which causes their breasts to expand, their hips to enlarge, and their pubic and underarm hair to grow. Along with physical changes, puberty also brings about psychological and emotional changes, such as a greater sense of independence, enhanced self-consciousness, and awareness of the opposite sex.
Question 2
Arun and his sister arunima are both teenagers . Arunima observes a swelling on her neeck, following which she visits a doctor. The doctor identifies it to be a deficiency disease and prescribes medicines accordingly, along with suggesting dietary modifications. A few months later, arun observes a small protrusion on his throat and visits the doctor. However, the doctor assures him that it is a normal feature in boys of his age.
(a) Identify the disease Arunima was suffering from along with its cause.
Answer: She has had goitre, which is brought on by a lack of iodine inside the body.
(b) Why do you think that no medication was prescribed for Arun?
Answer: Adam’s Apple is the name of the area of inflammation. Arun does not require medication because it is a typical occurrence in men.
3.) Discuss how the sex of the unborn child gets determined in human beings.
Answer: In humans, the presence of a Y chromosome from the father determines the sex of the unborn kid. The embryonic male will be determined by the presence of the Y chromosome. The unborn child will be female if the Y chromosome is absent. This is so that the father can contribute the 23rd chromosome, an X or a Y chromosome. The unborn child will be male if the father contributes a Y chromosome, and female if the father contributes an X chromosome.
4.) Enlist the events that regularly occur in the female reproductive system, after the onset of puberty, until menopause.
From puberty through menopause, the female reproductive system experiences a variety of alterations. The main thing that happens after puberty is ovulation. This occurs when an egg is discharged from the ovaries into the fallopian tube. The sperm fertilises the egg, which then descends into the uterus. The egg will be released throughout the menstrual cycle if fertilisation does not take place. The uterus’s lining sheds during the menstrual cycle and leaves the body as menstrual flow. Typically, this happens every 28 days.
The body makes hormones like oestrogen and progesterone during the menstrual cycle that regulate the reproductive system. The body’s hormone levels are at their peak during ovulation, giving fertilisation the best chance possible. The menstrual cycle ends after menopause because the reproductive system quits ovulating as well as hormone production stops.
5.) Highlight the importance of exercise and good personal hygiene during adolescence.
Answer: Teenagers must exercise often and maintain good personal cleanliness because they are undergoing both physical and psychological changes at this time in their life. Adolescents who engage in regular physical activity have stronger bones, muscles, and joints as they grow and develop. Additionally, exercise can help teens reduce stress, boost self-esteem, and maintain better general health. Adolescents who practise good personal hygiene can stay healthy and project a favourable image. Maintaining good cleanliness helps to keep skin clear, cut down on body odour, and avoid the transmission of disease.