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Reproduction in Lower and Higher Animals Class 12 Biology Chapter 2 Questions And Answers Maharashtra Board

1. Multiple choice questions. 1. The number of nuclei present in a zygote is ……a. two b. one c. four d. eight Answer. b. one 2. Which of these is the male reproductive organ in human?a. sperm b. seminal fluid c. testes d. ovary Answer. (c) Testes 3. Attachment of embryo to the wall of the uterus is known as……..a. fertilization b. gestationc. cleavage d. implantation Answer. (d) implantation 4. Rupturing of follicles and discharge of ova is known as …………..a. capacitation b. gestationc. ovulation d. copulation Answer. (c) ovulation 5. In human female, the fertilized egg gets implanted in uterus ………………….a. After about 7 days of fertilizationb. After about 30 days of fertilizationc. After about two months of fertilizationd. After about 3 weeks of fertilization Answer. (a) after about 7 days of fertilization 6. Test tube baby technique is called………a. In vivo fertilizationb. In situ fertilizationc. In vitro fertilizationd. Artificial insemination Answer. (c) In Vitro Fertilization 7. The given figure shows a human sperm. Various parts of it are labelled as A, B, C, and D .Which labelled part represents acrosome ? a. B b. C c. D d. A Answer. (d) A 8. Presence of beard in boys is a …………a. primary sex organb. secondary sexual characterc. secondary sex organd. primary sexual character Answer. (b) secondary sexual character 2. Answer in one sentence. 1. What is the difference between a foetus and an embryo ? Answer. Embryo is a growing egg after fertilization until the main parts of the body and the internal organs have started to take shape while foetus is a stage which has the appearance of a fully developed offspring. 2. Outline the path of sperm upto the urethra. Answer. The path of sperm up to the urethra in male is as follows :Seminiferous tubules → Rete testis → Vasa efferentia → Epididymis → Vas deferens → Ejaculatory ducts Urethra. 3. Which glands contribute fluids to the semen? Answer. The glands which contribute fluids to the semen are seminal vesicles, prostate gland. 4. Name the endocrine glands involved in maintaining the sex characteristics of males. Answer. Interstitial cells of Leydig which lie in between the seminiferous tubules are involved in maintaining the sexual characteristics of male by secreting the male hormone androgen or testosterone. Adenohypophysis also regulates this secretion from the testis. 5. Where does fertilization and implantation occur? Answer. Fertilization of ovum takes place in the ampulla region of fallopian tube whereas implantation occur in the endometrium of uterus. 6. Enlist the external genital organs in female. Answer. The external genital organs in female include the following parts such as vestibule, labia minora, clitoris, labia majora and mons Veneris. 7. Give two differences between blastula and gastrula. Answer. 8. What is the difference between embryo and zygote? Answer. Zygote is the unicellular diploid structure formed as a result of fusion of sperm and ovum whereas embryo is a multicellular structure formed from zygote in the uterus 3 weeks after fertilization. 3. Fill in the blanks: 1. The primary sex organ in human male is ………. Answer. testis 2. The………. is also called the womb. Answer. uterus 3. Sperm fertilizes ovum in the ………….. of fallopian tube. Answer. ampulla 4. The disc like structure which helps in the transfer of substances to and from the foetus’s body is called………… Answer. placenta 5. Gonorrhoea is caused by …………… bacteria. Answer. Neisseria gonorrhoeae 6. The hormone produced by the testis is ……………….. Answer. testosterone 4. Short answer questions. 1. Write a note on budding in Hydra. Answer. 2. Explain the different methods of reproduction occuring in sponges. Answer. 3. Write a note on IVF Answer. 4. Comment on any two mechanical contraceptive methods. Answer. Two mechanical contraceptive methods are as follows:A. Condom or Nirodh: B. Diaphragm, cervical caps and vaults: 5. Write a note on tubectomy Answer. 6. Give the name of causal organism of syphilis and write on its symptoms. Answer. 1. Syphilis is a sexually transmitted veneral disease caused by a Spirochaete bacterium Treponema pallidum. 2. The site of infection is the mucous membrane in genital, rectal and oral region. 3. Symptoms of syphilis: 7. What is colostrum? Answer. 5. Answer the following questions. 1. Describe the phases of menstrual cycle and their hormonal control. Answer. Menstrual cycle (Ovarian cycle):i. Menstrual cycle involves a series of cyclic, changes in the ovary and uterus. The cyclic events are regulated by gonadotropins from pituitary and the hormones from ovary.ii. The cyclic events in woman are repeated within approximately 28 days.iii. Menstrual cycle is divided into following phases, viz. 1. Menstrual Phase: 2. Proliferative phase/Follicular phase/Post menstrual phase: (3) Ovulatory phase: (4) Luteal phase/Secretary phase :(i) Since the empty Graafian follicle converts itself into corpus luteum under the influence of LH, this phase is called luteal phase in ovary. At the same time, the uterine endometrium thickens and becomes more secretory and hence it is called secretory phase in uterus. (ii) Corpus luteum secretes progesterone, some amount of estrogens and inhibin. These hormones stimulate the growth of endometrial glands which later start uterine secretions. (iii) Endometrium becomes more vascularized becomes 8-10 mm. in thickness. These changes are the preparation for the implantation of the ovum if fertilization occurs. (iv) In absence of fertilization, corpus luteum can survive for only two weeks and then degenerate into a non-secretory white scar called corpus albicans. (v) If ovum is fertilized, woman becomes pregnant and hormone hCG (human Chorionic Gonadotropin) is secreted by chorionic membrane of embryo which keeps corpus luteum active till the formation of placenta. 2. Explain the steps of parturition. Answer. Parturition involves the following three steps:1. Dilation stage: 2. Expulsion stage: 3. After birth or placental stage : In the last stage of 10 to 45 minutes, once the baby is out then the placenta is also separated from uterine wall and is expelled out as “after birth”. This is accompanied by severe contractions of the uterus. 3. Explain the histological structure of testis. Answer. Histological structure