Chapter 8 How do Organisms Reproduce Solutions
Question - 11 : - How does the embryo get nourishment inside the mother’s body?
Answer - 11 : - The lining of the uterus thickens after fertilization. The blood flow is good so as to nourish the growing embryo. Placenta is a special tissue which is embedded in the uterine wall and helps the embryo get the nourishment from the mother’s tissue. Placenta has villi on the embryo side and blood space on the mother’s side. This spacing provides a large area between the mother and the embryo and also for waste removal.
Question - 12 : - If a woman is using a Copper-T, will it help in protecting her from sexually transmitted diseases?
Answer - 12 : - No, because usage of copper-T cannot stop the contact of body fluids. Hence, it cannot protect her from getting sexually transmitted diseases.
Question - 13 : - Asexual reproduction takes place through budding in
Answer - 13 : -
(a) Amoeba (b) Yeast
(c) Plasmodium (d) Leishmania
Answer
(b) Yeast
Yeast is an example for asexual reproduction taking place through budding. A small protuberance is produced on the parent cell that grows in full size forming a bud. In the parent cell, the daughter nucleus splits and migrates to the daughter cell. By forming a constriction, the bud detaches from the mother’s body at the base. This process of budding continues to form a chain of bud cells. The mother cell is smaller than the daughter cell.
Question - 14 : - Which of the following is not a part of the female reproductive system in human beings?
Answer - 14 : -
(a) Ovary (b) Uterus
(c) Vas deferens (d) Fallopian tube
Answer
(c) Vas deferens
Vas deferens is a part of male reproductive system. It is a long, muscular tube travelling from the epididymis into the pelvic cavity. It is behind the bladder. Its function is to transport the mature sperm to the urethra. It also carries urine to the outside of the body.
Question - 15 : - The anther contains
Answer - 15 : -
(a) Sepals (b) Ovules
(c) Pistil (d) Pollen grains
Answer
(d) Pollen grains.
Pollen grains are the microscopic particles that occurs in the pollen giving rise to male gametophyte of a seed plant.
Question - 16 : - What are the advantages of sexual reproduction over asexual reproduction?
Answer - 16 : -
Following are the advantages of sexual reproduction:
• The offspring has the characters of both the parents.
• The survival of the species is ensured as there are more variations.
• The offspring can easily adapt to environmental changes.
• It also improves the health of humans.
Question - 17 : - What are the functions performed by the testis in human beings?
Answer - 17 : -
Following are the functions performed by the testis in human beings:
• Apart from the production of sperms, it also produces the male hormone known as androgens.
• They also produce hormone called testosterone, which is responsible for secondary sexual characters in boys.
Question - 18 : - Why does menstruation occurs?
Answer - 18 : -
Menstruation is the normal bleeding of the vaginal line which starts between puberty and lasts till menopause. During this period, the body prepares itself for pregnancy.
Every month an egg is released from one of the ovaries at the same time where the uterus prepares itself for fertilized egg. The inner lining of the uterus gets thickened and is supplied with sufficient amount of blood for the embryo. Since there is no interaction between the egg and the sperms, the fertilization of egg doesn’t takes place. So when the egg doesn’t get fertilized, the uterus lining breaks down slowly resulting in menstruation.
Question - 19 : - Draw a labelled diagram of the longitudinal section of a flower.
Answer - 19 : - 
Question - 20 : - What are the different methods of contraception?
Answer - 20 : -
Following are the different methods of contraception:
• Natural method: In this method, the main focus is to avoid the meeting of sperms and ovum. This can be achieved by avoiding the mating from 10th to 17th day of the menstrual cycle. During this period, there are high chances of fertilization as ovulation is expected.
• Barrier method: In this method, the meeting of sperms and ovum is avoided by using a barrier. These barriers are available for males as well as for females. Condoms for both male and female, diaphragms for female, cervical cap and contraceptive sponge for females.
• Oral contraceptives: In this methods, pills are taken orally. These pills contain small portion of hormones that block the eggs so that fertilization doesn’t takes place.
• Implants and surgical method: In this method, contraceptive devices like copper-T or a loop can be used to block the meeting of sperms and ovum. In surgical method, the fallopian tubes are blocked in females to stop flow of eggs and vas deference is blocked in men to stop the flow of sperms.