CBSE Class 10 Science Human Reproduction and Reproductive Health Worksheet Set 16

Answer: (c) (iii) and (iv). Development of the placenta and oestrogen secretion are not functions of the testes.

Teacher's Note:
1. Placenta develops in the uterus during pregnancy.
2. Oestrogen is a female hormone.

Answer: (a) testis - vas deferens - urethra. Sperms pass from the testis through the vas deferens into the urethra.

Teacher's Note:
1. Sperms made in the testis pass through the vas deferens.
2. The urethra is the common passage for sperms and urine.

Answer: (a) The thick lining of the uterus breaks down and is shed with blood and the unfertilised egg as menstruation, lasting about 4 to 5 days.
(b) The lining is maintained and a special tissue, the placenta, develops to nourish the embryo.

Teacher's Note:
1. The uterine lining is prepared every month.
2. Menstruation is the sign that no pregnancy has occurred.

Answer: Puberty is the stage when sex hormones start being produced and a person becomes able to reproduce. Girls generally reach it earlier. Testes make sperms and testosterone, ovaries make eggs and the hormones oestrogen and progesterone.

Teacher's Note:
1. Puberty begins at about 10 to 12 years in girls and a little later in boys.
2. Hormones cause the body changes at puberty.

Answer: 1. Barrier methods keep sperm and egg apart, for example condoms.
2. Chemical methods change the body's hormones, for example oral contraceptive pills.
3. Surgical methods block the gamete passage, for example vasectomy or tubectomy.
Intrauterine devices such as Copper-T also prevent implantation.

Teacher's Note:
1. Contraception also reduces the risk of unwanted pregnancy.
2. Condoms also protect against infections.

Answer: (a) Vasectomy.
(b) Tubectomy (tubal ligation).
(c) Intrauterine contraceptive device (Copper-T).

Teacher's Note:
1. The vas deferens is blocked in vasectomy.
2. The fallopian tubes are blocked in tubectomy.

Answer: They are diseases spread by sexual contact with an infected person. Examples are gonorrhoea, syphilis and AIDS. Using condoms and avoiding multiple partners reduce the risk.

Teacher's Note:
1. Some are caused by bacteria and can be treated.
2. AIDS is caused by a virus.

Answer: (a) Ovaries.
(b) Oviducts (fallopian tubes).
(c) Vagina.

Teacher's Note:
1. Ovaries and testes both make gametes.
2. Oviducts and vas deferens both carry gametes.

Answer: (a) Voice deepens and facial hair grows.
(b) A sperm is a male gamete, while semen is the fluid containing sperms and secretions of glands.
(c) Their secretions nourish the sperms and help them move.

Teacher's Note:
1. Hormone testosterone brings on these changes.
2. Semen helps sperms to be transported.

Answer: (a) Ovulation is the release of an egg from the ovary.
(b) Pregnancy occurs only if sperms are present when an egg is available, which is around the middle of the menstrual cycle.
(c) The umbilical cord.

Teacher's Note:
1. In a 28-day cycle ovulation happens near the 14th day.
2. The egg survives only about a day.

Answer: The placenta is a disc-shaped tissue in the uterine wall with villi that is in contact with the mother's blood. It supplies oxygen and nutrients to the embryo and carries away its waste to the mother's blood.

Teacher's Note:
1. The placenta links the embryo to the mother through the umbilical cord.
2. Blood of mother and baby do not mix directly.

Answer: A is the vas deferens, B is sperms, C is the testes, D is the egg (ovum), and the procedure is vasectomy.

Teacher's Note:
1. Sperms are made in the testes but cannot reach the urethra.
2. The procedure does not stop hormone production.

Answer: A and C may be syphilis and gonorrhoea, and B is AIDS caused by HIV. AIDS has no definite cure yet.

Teacher's Note:
1. HIV attacks the immune system.
2. Bacterial diseases can usually be cured with antibiotics.

Answer: A is the egg (ovum), B is the sperm, C is the zygote, D is the uterus, E is the embryo and F is the foetus.

Teacher's Note:
1. The person producing the round germ cell is female.
2. The person producing the tailed germ cell is male.

Answer: T is the placenta and S is the umbilical cord. Oxygen and nutrients pass from the mother to the embryo, and wastes pass back to the mother. At birth the cord is tied and cut.

Teacher's Note:
1. The placenta is attached to the uterus wall.
2. The scar left on the baby's abdomen is the navel.

Answer: Menstruation is the monthly bleeding of a woman when the uterine lining is shed because no fertilisation occurred. Menarche is the first menstruation, which shows that the girl has reached puberty.

Teacher's Note:
1. The cycle repeats about every 28 days.
2. Menstruation stops during pregnancy.