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10

Q1. Identical twins are
  • 1) Dizygotic
  • 2) Homozygotic
  • 3) Heterozygotic
  • 4) Monozygotic

Solution

Identical twins are formed by the splitting up of a single zygote and hence are homozygotic.
Q2. Teenagers experience depression due to
  • 1) Hormonal changes
  • 2) Loss of grandparents
  • 3) Change in body structure
  • 4) Emotional instability

Solution

Teenagers undergo various hormonal changes due to which they may experience depression.
Q3. How many hormones are secreted by pituitary gland?
  • 1) Four
  • 2) Nine
  • 3) Two
  • 4) Twelve

Solution

The pituitary gland secretes nine hormones which regulate homoeostasis and the secretion of other hormones.
Q4. Pimples appear because of inflammation of oil glands in the skin and disappear after the age of 20.
  • 1) False
  • 2) True

Solution

Acne tends to disappear in the early twenties.
Q5. Release of the ovum is achieved by
  • 1) Fertilisation
  • 2) Hybridisation
  • 3) Fusion
  • 4) Ovulation

Solution

The release of the ovum from a mature follicle is known as ovulation.
Q6. The endocrine part of the pancreas is called
  • 1) Langerhans cells
  • 2) Medulla
  • 3) Islets of Langerhans
  • 4) Cortex

Solution

The endocrine part of the pancreas is called the islets of Langerhans.
Q7. Which of the following is an example of a drug?
  • 1) Cocaine
  • 2) Paracetamol
  • 3) Penicillin
  • 4) All of these

Solution

Heroin, cocaine, paracetamol and penicillin are common examples of drugs which teenagers tend to get addicted to.  
Q8. Girls attain puberty at the age of 12-14 years. 
  • 1) True
  • 2) False

Solution

Girls attain puberty at the age of 10-13 years, while boys reach puberty at the age of 12-14 years.
Q9. Give the functions of GH GSH ICSH 

Solution

Functions of GH (Growth hormone) - Promotes the growth of bones and tissues GSH (Gonadotropic-stimulating hormone) - Stimulates gonads, testes and ovaries to secrete sex hormones ICSH (Interstitial cell-stimulating hormone) - Stimulates the interstitial cells or Leydig cells of the testes to produce the male sex hormone testosterone 
Q10. The ovulatory phase lasts from the 15th to the 28th day of the menstrual cycle.
  • 1) True
  • 2) False

Solution

The ovulatory phase lasts from the 13th to the 14th day of the menstrual cycle.
Q11. (a) Which hormones control metamorphosis in insects and frogs?(b) Which glands are represented by A, B, C and D in the below figure?

Solution

(a) Metamorphosis in insects is controlled by insect hormones.     In a frog, it is controlled by thyroxine, the hormone produced by thyroid. (b)     A- Pituitary gland    B- Thyroid gland    C- Adrenal gland    D- Pancreas
Q12. ACTH stands for
  • 1) Adrenocranial hormone
  • 2) Adrenocorticotropic stimulating hormone
  • 3) Adrenal cortical stimulating hormone
  • 4) Adrenocortaxal stimulating hormone

Solution

ACTH stands for adrenocorticotropic-stimulating hormone. It controls the secretions of the adrenal cortex, aldosterone and cortisone. 
Q13. Why endocrine glands are called ductless glands?

Solution

Endocrine glands release hormones directly into the bloodstream. So, they are also termed ductless glands.
Q14. The shoulder girdle is also known as the
  • 1) Pelvic girdle
  • 2) Rotating girdle
  • 3) Pectoral girdle
  • 4) Parietal girdle

Solution

The shoulder girdle is also known as the pectoral girdle.
Q15. The ovulatory phase lasts from the 15th to the 28th day of the menstrual cycle.
  • 1) True
  • 2) False

Solution

The ovulatory phase lasts from the 13th to the 14th day of the menstrual cycle.
Q16. Once in every 28-30 days, a single ovum matures and is released by both the ovaries.
  • 1) True
  • 2) False

Solution

False. Once in every 28-30 days, a single ovum matures and is released by one of the two ovaries.
Q17. Where are the adrenal glands located? Name the hormone secreted by adrenal glands. Write its two important functions.

Solution

Adrenal glands are located on the top of the kidneys. Adrenaline hormone is secreted by adrenal glands. Functions: (i) Adrenaline hormone maintains the correct salt balance in the blood. (ii) It helps during stress or emergency situations by regulating heart beat, breathing rate, blood pressure etc.
Q18. State two changes which take place in boys at puberty.

Solution

Testes mature and start producing sperms Pectoral girdle (shoulder girdle) grows Hair growth in the pubic region Development of moustache and beard Development of deep voice (ANY TWO)
Q19. Teenagers prefer to talk to
  • 1) Their teachers
  • 2) Their parents
  • 3) Their grandparents
  • 4) Their peers

Solution

Teenagers prefer to talk to their peers who are of the same age.
Q20. Teenagers tend to think a lot due to
  • 1) Increase in hormonal activity
  • 2) Sudden body changes
  • 3) Increased brain activity
  • 4) Peer pressure

Solution

During puberty, the brain develops further, and hence, individuals tend to think a lot as the brain activity increases.
Q21. The egg gets implanted in the uterine walls prior to fertilisation.
  • 1) False
  • 2) True

Solution

Only a fertilised egg cell gets implanted in the uterine wall.
Q22. Name one hormone secreted by: (a) Adrenal gland (b) Pituitary gland (c) Pancreas (d) Thyroid gland

Solution

(a) Adrenaline(b) Growth hormone(c) Insulin(d) Thyroxine
Q23. Acne tends to disappear
  • 1) Acne is permanent
  • 2) In the late 20s
  • 3) In the early 20s
  • 4) Before puberty

Solution

Acne tends to disappear in the early twenties.
Q24. Girls have a low-pitched voice, and hence, they sound shrill.
  • 1) True
  • 2) False

Solution

Girls have a high-pitched voice.
Q25. When the ovum is not fertilised, the thick lining of the uterus is no longer required.
  • 1) False
  • 2) True

Solution

True
Q26. The pituitary gland secretes nine hormones.
  • 1) True
  • 2) False

Solution

True
Q27. What changes occur in the female body when the egg is fertilised by a sperm?

Solution

The thick lining of the uterine walls is maintained to receive the fertilised egg. The body continues to secrete sex hormones to sustain the pregnancy. The fertilised egg divides and enlarges and gets implanted in the uterine wall. 
Q28. Depression in adolescents is mainly caused by
  • 1) Hormonal changes
  • 2) Physical changes
  • 3) Mental development
  • 4) Environmental changes

Solution

Depression in adolescents is mainly caused by hormonal changes in the body.
Q29. Girls attain puberty at the age of 12-14 years. 
  • 1) False
  • 2) True

Solution

Girls attain puberty at the age of 10-13 years, while boys reach puberty at the age of 12-14 years.
Q30. Acne is caused by the inflammation of the
  • 1) Tear glands
  • 2) Oil glands
  • 3) Mucous membrane
  • 4) Sweat glands

Solution

Acne is caused by the inflammation of the oil glands.
Q31. Hormones which regulate the production of sperms are secreted by the thyroid gland.
  • 1) True
  • 2) False

Solution

Hormones which regulate the production of sperms are secreted by the pituitary gland.
Q32. The egg gets implanted in the uterine walls prior to fertilisation.
  • 1) False
  • 2) True

Solution

Only a fertilised egg cell gets implanted in the uterine wall.
Q33. The pituitary gland secretes nine hormones which regulate homeostasis and the secretion of other hormones. 
  • 1) False
  • 2) True

Solution

True
Q34. Diagrammatically explain the events of the menstrual cycle.

Solution

 
Q35. Aldosterone regulates the metabolism of
  • 1) Na+ ions
  • 2) K+ ions
  • 3) Both Na+ ions and K+ ions
  • 4) Cl− ions

Solution

Aldosterone regulates the metabolism of minerals, specifically sodium (Na+)and potassium (K+) ions.
Q36. Write any two ways how the HIV virus can be transmitted from an infected person to a healthy person.

Solution

(i)  HIV virus can pass on to a normal person from an infected person by sharing the syringes used for injecting drugs. (ii) It can also be transmitted to an infant from the infected mother through her milk. (iii) Another way of transmission is through sexual contact with a person infected with HIV. (Any 2)
Q37. Children between the ages of 11 and 19 years are known as adults.
  • 1) False
  • 2) True

Solution

Children between the ages of 11 and 19 years are known as adolescents. 
Q38. Adolescence begins at the age of
  • 1) 8-9 years
  • 2) 10-11 years
  • 3) 11-12 years
  • 4) 9-10 years

Solution

On average, girls begin puberty at ages 10–11; boys at ages 11–12.
Q39. Armpit hair develops only in males.
  • 1) True
  • 2) False

Solution

Armpit hair develops in both females and males.
Q40. During which days of the cycle, the luteal phase of the menstrual cycle can be encountered?
  • 1) 1st to 5th day
  • 2) 5th to 14th day
  • 3) 15th to 28th day
  • 4) 13th to 14th day

Solution

The luteal phase begins on the 15th day and lasts till the 28th day of the menstrual cycle.
Q41. AIDS can be transmitted from mother to child through
  • 1) All of these
  • 2) Breastfeeding
  • 3) Blood transfusion
  • 4) Mixing of blood

Solution

AIDS can be transmitted from mother to child through blood transfusion, mixing of blood as well as through breastfeeding.
Q42. Name the gland which is responsible for the secretion of calcitonin and state its function.

Solution

Calcitonin is secreted by the thyroid gland, and it regulates the levels of calcium and phosphate in the blood.
Q43. The reproductive phase in females lasts until the age of 55-60 years.
  • 1) True
  • 2) False

Solution

False. The reproductive phase in females lasts until the age of 45-50 years.
Q44. Girls have a low-pitched voice, and hence, they sound shrill.
  • 1) True
  • 2) False

Solution

Girls have a high-pitched voice.
Q45. Discuss how the process of menstruation occurs in females.

Solution

Once in about 28 to 30 days, one ovum matures and is released by one of the ovaries. During this period, the wall of the uterus becomes thick so as to receive the egg, in case it is fertilised. If fertilisation does not occur, the released egg, and the thickened lining of the uterus along with its blood vessels are shed off. This causes bleeding in women which is called menstruation.
Q46. Pimples appear because of inflammation of oil glands in the skin and disappear after the age of 20.
  • 1) True
  • 2) False

Solution

Acne tends to disappear in the early twenties.
Q47. At puberty, there is an increase in the secretion of
  • 1) Oil glands
  • 2) Endocrine glands
  • 3) Both sweat glands and oil glands
  • 4) Sweat glands

Solution

At puberty, there is an increase in the secretion of both sweat glands and oil glands.
Q48. Which disease is this child suffering from? Write its cause.

Solution

The child is suffering from goitre, an enlargement of the thyroid gland. It is caused due to deficiency in thyroxine hormone produced by the thyroid gland.
Q49. List the harmful effects of drug addiction.

Solution

Harmful effects of drugs: Drugs are addictive. If you take drugs once, you feel like taking them again and again. Drug addicts become irritable and lose interest in studies or jobs. Drugs cause physical harm to the body. They can damage the liver, brain, lungs and kidneys. Drugs may even cause accidents due to a confused state of mind. Sharing of syringes for injecting drugs spreads AIDS among drug addicts. 
Q50. List the benefits of exercise during adolescence.

Solution

Benefits of regular exercise: Keeps the body fit Improves mental health Protects the person from heart disease, high blood pressure, diabetes and obesity Builds and maintains healthy muscles, bones and joints Increases efficiency in studies, sports and work Improves the general sense of well-being and makes a person feel happy 
Q51. Which components in the blood regulate calcitonin?
  • 1) Calcium and phosphorus
  • 2) Phosphorus and phosphate
  • 3) Calcium and phosphate
  • 4) Potassium and phosphate

Solution

Calcitonin regulates calcium and phosphate levels in the blood.
Q52. The pituitary gland secretes nine hormones which regulate homeostasis and the secretion of other hormones. 
  • 1) False
  • 2) True

Solution

True
Q53. Hormones which regulate the production of sperms are secreted by the thyroid gland.
  • 1) False
  • 2) True

Solution

Hormones which regulate the production of sperms are secreted by the pituitary gland.
Q54. Why does the diet of adolescents need:(a) Iodine(b) Calcium(c) Iron

Solution

(a) Iodine helps to prevent thyroid gland related diseases. (b) Due to an increase in skeletal mass, the adolescent diet should include calcium. Calcium intake needs to be increased to prevent osteoporosis in later life. (c) To compensate for iron deficiency due to muscle spurt in boys and menstruation as well as muscle spurt in girls, the diet of adolescents need iron rich diet. Lack of iron in the diet results in anemia.
Q55. Give reasons:(a) It is highly essential for teenagers to take a bath everyday.(b) All teenagers should walk and play in fresh air.

Solution

(a) It is very essential for teenagers to bathe everyday because the increased activity of sweat glands sometimes makes the body smelly.(b) Walking and playing in fresh air keeps the body fit and healthy.
Q56. What is the fate of the reproductive cycle in females if the ovum is not fertilised by a sperm?

Solution

If a sperm is not available at the time of ovulation, then fertilisation does not occur. As the ovum is not fertilised, the thick lining of the uterus is no longer required. The unfertilised egg dies within a day and the lining of the uterus also breaks down. The egg, the thickened lining of the uterus along with blood vessels and other uterine tissues are shed off as blood and mucus. This results in bleeding from the vagina in women. This is called menstruation.
Q57. Why do boys get a characteristic voice after puberty?

Solution

With the onset of puberty, the hormonal changes in the body cause the larynx or the voice box to enlarge, which gives boys a characteristic deep or low-pitched voice.
Q58. Both the ovaries in females release an egg cell each month.
  • 1) True
  • 2) False

Solution

Only one ovary in the female releases an egg cell each month.
Q59. The gonadotropin-releasing hormone stimulates the testes in males and the ovaries in females to release testosterone and oestrogen, respectively.
  • 1) True
  • 2) False

Solution

True
Q60. How are acne and pimples caused?

Solution

With the onset of puberty, there is an increase in the secretion of oil and sweat glands. When there is excessive secretion of these body fluids, the oil and sweat along with cellular debris collect in the glands. The growth of bacteria in these blocked pores results in the formation of acne and pimples.
Q61. Answer the following: (i) Thread like structures present in the nucleus and carrying genetic information.(ii) Number of chromosomes in every human.(iii) Number of chromosomes in gametes.(iv) Number of sex chromosomes.(v) The sex chromosomes in male.(vi) The sex chromosomes in female.

Solution

(i) Chromosomes(ii) 46(iii) 23(iv) 2(v) XY(vi) XX
Q62. Both the ovaries in females release an egg cell each month.
  • 1) True
  • 2) False

Solution

Only one ovary in the female releases an egg cell each month.
Q63. State the disease caused by the deficiency of Growth hormone Thyroxine  Insulin 

Solution

Deficiency diseases: Growth hormone - Dwarfism Thyroxine - Goitre Insulin - Diabetes 
Q64. Vijaya is confused between the terms menarche and menopause. Help her understand the difference between them. What is the approximate age for menarche and menopause?

Solution

The first menstrual cycle which begins at puberty is known as menarche, whereas the end of the menstrual cycle or reproductive phase is known as menopause.   Menarche occurs at 13 years (approx.), and menopause occurs at 45-50 years.
Q65. Give reasons:(i) Adolescents are also called teenagers.(ii) During puberty, there is sudden increase in height.(iii) In some adolescent boys, the voice become hoarse.

Solution

(i) The period of adolescence covers the 'teens' i.e. 13 to 18 or 19 years of age. Hence adolescents are also called teenagers.(ii) During puberty, the long bones i.e. the bones of the arms and the legs elongate and make a person tall. This results in sudden increase in height.(iii) Sometimes in adolescent boys, the muscles of the growing voice box go out of control and the voice becomes hoarse.
Q66. What do you understand by the following:(a) Adam's apple(b) Hormones(c) Puberty

Solution

(a) The growing voice box in boys seen as a protruding part of the throat is called Adam's apple.(b) Hormones are chemical substances secreted by endocrine glands.(c) The period during which adolescents reach sexual maturity and become capable of reproduction.
Q67. Write the function of:(i) Insulin(ii) Growth hormone

Solution

(i) Insulin controls the metabolism of sugar in our body.(ii) Growth hormone is necessary for the normal growth of a person.
Q68. Why is the mother not to blame for the sex of a newborn?

Solution

The sex of a newborn is determined by the sex chromosomes present in the cells. If the sex chromosomes are in the pair of XX, then the child will be a female. If the sex chromosomes are XY, then the child will be a male. The gametes produced by the mother are always X, while those produced by the father is X and Y. If the sperm carrying the X chromosome fuses with the egg cell, the child will be a female and if the sperm carrying the Y chromosome fuses with the egg cell, the child will be a male. So, the father decides the sex of the newborn and not the mother.
Q69. Children between the ages of 11 and 19 years are known as adults.
  • 1) False
  • 2) True

Solution

Children between the ages of 11 and 19 years are known as adolescents. 
Q70. Armpit hair develops only in males.
  • 1) False
  • 2) True

Solution

Armpit hair develops in both females and males.
Q71. What are the different stages of life based on the age of an individual?

Solution

Life stages: Infant - Children between 1 month and 1 year of age Toddler - Children between the ages of 1 and 4 years Adolescent - Children between the ages of 11 and 19 years Adulthood - Begins from the age of 18 years onwards 
Q72. List the functions of sex hormones.

Solution

Regulate spermatogenesis or oogenesis Regulate the structural development, maintenance and functions of accessory sex organs Help to develop secondary sexual characters at the proper age  Responsible for changes in the face, body structure and appearance; development of mammary glands; pitch of the voice; vigilant behaviour and sentimental behaviour
Q73. Which sex organs are present in females since birth?

Solution

Ovaries Oviducts Uterus Vagina 
Q74. Why pituitary gland is called as master gland?

Solution

Pituitary gland is called as the master gland because it secretes hormones that control the functioning of other glands.
Q75. What do you understand by adolescence? When does it take place?

Solution

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

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