Solution of How do organisms Reproduce (Page No - 1 71- Biology by Lakhmir Singh, Class 10 | Extra Documents, Videos & Tests for Class 10 PDF Download

Question 56:
(a) What changes are seen in boys at the time of puberty ?
(b) Name the organs which produce sperms in human males.
(c) Draw a labelled diagram of the human male reproductive system. With the help of this diagram, describe the working of human male reproductive system ?
(d) What is the role of seminal vesicles and prostrate gland in human male reproductive system ?
Solution :
(a) The changes observed in boys during puberty are: Hair grows under armpits, pubic region between the thighs, chest and face. Body becomes more muscular due to the development of muscles. The voice deepens. Chest and shoulder broaden. The penis and testes become larger. Feelings and sexual drives associated with adulthood begin to develop.
(b) Testes.
(c) Working of human male reproductive system: The human male reproductive system consists of:
(i) Testes – Are the primary reproductive organs in males which are in pair. These are oval shaped organs which lie outside the abdominal cavity. It makes the male sex cells called sperms and produces male sex hormones called testosterone.
(ii) Scrotum – Is a muscular pouch which houses the testes. It is present outside the abdominal cavity and maintains a lower temperature than the normal body temperature.
(iii) Epididymis – The sperms formed in the testes goes into a coiled tube called epididymis which stores the sperms temporarily.
(iv) Vas Deferens (sperm duct) – It is a long tube which carries the sperms from epididymis to another tube called urethra.
(v) Seminal vesicles and prostrate gland – Both these glands are present along the path of vas deferens and add their secretions to sperms which allows them to transport easily.
(vi) Penis – It is an organ which pass?s the sperms from the man’s body into the vagina in the women’s body during mating.
(d) The secretions of seminal vesicles and prostrate gland provide nutrition to the sperms and also make their transportation easier by secreting a thick liquid. 

Question 57:
(a) What changes are seen in girls at the time of puberty ?
(b) Name the organs which produce ova (or egg cells) in human females.
(c) Draw a labelled diagram of the human female reproductive system. With the help of this diagram, explain the working of human female reproductive system.
(d) Describe the process of fertilisation in humans and development of embryo briefly.
Solution :
(a) The changes observed in girls during puberty are: Hair grows under armpits and pubic region. Mammary glands develop and breasts become enlarged. The hips broaden and extra fat is deposited in various parts of the body like hips and thighs. Fallopian tubes, uterus and vagina enlarge. Ovaries start to release eggs and menstruation starts. Feelings and sexual drives associated with adulthood begin to develop.
(b) Ovaries.
(c) Working of human female reproductive system: The human female reproductive system consists of:
(i) Ovaries – These are the primary reproductive organs in women. They are oval shaped organs which are inside the abdominal cavity of a woman near the kidneys and produces mature female sex cells called ova or eggs. They also produce female sex hormones called Oestrogen and Progesterone. Each ovary is composed of several thousand follicles which mature to form ripe eggs at puberty.
(b) Oviduct – These are paired tubes which have funnel shaped openings that cover the ovaries. The ovum released by an ovary goes into the oviduct through its funnel shaped opening. The fertilisation of egg by a sperm takes place in it. It is also known as fallopian tube.
(c) Uterus – It is a bag like organ in which the fertilised egg develops into a baby. It is connected through a narrow opening called cervix to another tube called vagina. It is commonly called womb.
(d) Vagina – It is a tubular structure. It receives the penis for putting sperms into the women’s body. It is also called birth canal because it is the passage through which the baby is born. 

Question 58:
(a) What is ovulation ? How often does it happen in human females ?
(b) Where does fertilisation take place in human females ?
(c) Explain why, fertilisation is possible if mating takes place during the middle of menstrual cycle.
(d) What is meant by implantation ?
(e) What is placenta ? What is its function ?
(f) What joins embryo to placenta in mother’s body ?
Solution :
(a) The release of an ovum from an ovary is called ovulation. In human females, the ovaries start releasing ovum once every 28 days from the age of puberty.
(b) Oviducts.
(c) Fertilisation is possible if mating takes place during the middle of menstrual cycle because in a normal healthy girl the ovulation takes place on the 14th day of the beginning of menstrual cycle of 28 days.
(d) The embedding of embryo in the thick lining of the uterus is called implantation.
(e) Placenta – Placenta is a disc like special tissue which develops between the uterus wall and the embryo after implantation. Its function is the exchange of nutrients, oxygen and waste products between the embryo and the mother.
(f) Umbilical cord.