Short Questions and Answers
One mark questions with answers
1. Gestation periods in human is
(a) 10 weeks
(b) 25 weeks
(c) 7 months
(d) 9 months
Answer: (d) 9 months
2. Clupein protein occurs in
(a) Human sperms
(b) Avian sperms
(c) Human ova
(d) Avian ova
Answer: (a) Human sperms
3. Amniotic fluid protects the foetus from
Answer: (a) shock
4. Human placenta is
(c) yolk sac
Answer: (a) haemochorial
5. Graafian follicles are found in
(a) testis of mammal
(b) ovary of frog
(c) ovary of cockroach
(d) ovary of mammal
Answer: (d) ovary of mammal
6. Clitoris in mammals is
(a) homologous to penis
(b) analogous to penis
(c) functional penis in female
(d) non functional
Answer: (a) homologous to penis
7. Amnion is helpful to embryo in
(b) protection from shock
Answer: (b) protection from shock
8. Human embryo is protected by
(b) Amniotic cavity
(c) Plural cavity
(d) Peritoneal cavity
Answer: (b) Amniotic cavity
9. Umbilical cord contains
(c) Discus proligerus
(d) Allantoic artery and vein
Answer: (d) Allantoic artery and vein
10. Site of fertilization in a mammal is
(d) fallopian tube
Answer: (d) fallopian tube
11. Gonads develop from embryonic
(d) both mesoderm and endoderm
Answer: (c) mesoderm
12. How many sperms are formed from a secondary spermatocyte?
Answer: (c) 2
13. Human eggs are
Answer: (a) alecithal
14. Location and secretion of leydig cells are
Answer: (c) testis-testosterone
15. Middle piece of mammalian sperm possesses
(a) mitochondria and centriole
(b) mitochondria only
(c) centriole only
(d) nucleus and mitochondria
Answer: (a) mitochondria and centriole
Two marks questions with answers
1. What is parturition? Which hormones are involved in parturition?
Answer: Parturition or childbirth is the process of delivery of fully formed foetus or baby at the end of pregnancy through vigorous contractions of uterus. The hormones which are involved in induction of parturition are oestrogen and oxytocin.
2. What is menstrual cycle? Which hormones regulate menstrual cycle?
Answer: Menstrual cycle is a series of cyclic changes found in the reproductive tract of human female during her reproductive life that recur at intervals of about 28 days and is characterized by menstruation in the first 3-4 days.
The hormones which regulate the menstrual cycle are gonadotropin-releasing hormone, follicle stimulating hormone, luteinizing hormone, oestrogen and progesterone.
3. Mention the functions of the following: Corpus luteum, endometrium, acrosome, sperm tail.
Answer: Corpus luteum: Secretion of mainly progesterone and small quantity of oestrogen some androgens are also formed by theca cells.
Endometrium: Nourishment and implantation of blastocyst and later foetus if fertilization has occurred. Otherwise cyclic changes of growth and degeneration.
Acrosome: Contain sperms lysins for separating cells of corona radiata and piercing through zona pellucida.
Sperm tail: Vibratile part that helps in swimming of sperm in the genital tract of the female reaching the ovum.
4. Mention two differences between spermatogenesis and oogenesis.
Answer: Spermatogenesis occurs inside testis whereas oogenesis occurs inside the ovary. In case of spermatogenesis the stages are completed inside the testis whereas the major part of oogenesis occurs inside ovary but last stages occur inside oviduct.
5. What is the difference between spermatogenesis and spermiogenesis?
Answer: Spermatogenesis is the process of formation of spermatozoa from germinal cells whereas spermiogenesis is the process of differentiation of spermatozoa from a spermatid. Spermatogenesis involves conversion of a diploid structure into haploid structure where as spermiogenesis changes the haploid structure into another haploid structure.
Three marks questions with answers
1. Describe the structure of a seminiferous tubule.
Answer: Seminiferous tubule is 70 to 80 cm long tubule that lies coiled inside a testicular lobule. At its free end it joins a network of channels called rete testis. The epithelium of seminiferous tubule functions as germinal epithelium. It is covered on the outside by basement membrane. Germinal epithelium has two types of cells primary germ cells and sertoli cells. Primary germ cells are cuboidal in outline sertoli cells are large pyramidal nurse cells. These cells are surrounded by 4 to 8 layers of spermatogonia and spermatocytes. The free ends of sertoli cells have a number of spermatids in various stages of maturation.
2. What is spermatogenesis? Briefly describe the process of spermatogenesis.
Answer: Spermatogenesis is the process of formation of haploid spermatozoa from diploid spermatogonia inside the testis of male. A fresh spermatogonium divide mitotically to form two types of spermatogonia, A and B. A type spermatogonia functions as mother spermatogonia. B type spermatogonia divide further and grow in size to function as primary spermatocytes. A primary spermatocyte undergoes meiosis to produce for haploid spermatids. The products of meiosis I are called secondary spermatocytes. Spermatids attach themselves to sertoli cells for obtaining nourishment and undergo differentiation to form spermatozoa. The process is called spermiogenesis.
3. Mention the name and fuctions of the hormones involved in regulation of spermatogenesis.
Answer: Gonadotropin releasing hormone- It is produced by hypothalamus. It stimulates anterior pituitary to produce two gonadotropins, FSH (follicle stimulating hormone) and LH or ICSH (luteinizing hormone or interstitial cell stimulating hormone). LH acts on Leydig cells for secreting testosterone and other androgens. Testosterone is required for spermatogenesis. Testosterone and FSH help in differentiation and function of Sertoli cells. Testosterone is under negative feedback. Sertoli cells produce inhibin that suppresses FSH synthesis by anterior pituitary and gonadotropin-releasing hormone synthesis by hypothalamus.
4. What are the major functions of male accessory ducts and glands?
Answer: Male accessory ducts-(a) intratesticular genital duct system. It consists of tubuli recti, rete testis and vasa efferentia. Cilia lining vasa efferentia help in passage of sperms. Endocytic cells present in their lining devour the debris accompanying sperms.
(b) extratesticular excretory genital duct system- It consists of epididymis, vasa deferentia, ejaculatory ducts and urinogenital duct (urethra).
Epididymis store sperms forms for a few weeks or till ejaculated. Older sperms are broken down. At the time of ejaculation each epididymis undergoes peristaltic and segmental movements. Vasa deferentia conducts sperms through muscular activity. Ejaculatory duct helps in quick conduction of sperms and secretion of seminal vesicles to muscular activity. Urinogenital duct transports semen through muscular activity.
Male accessory glands- Seminal vesicles- produce 60 to 70% of seminal plasma. Prostate glands forms 20 to 30% of seminal plasma. Cowper’s or Bulbourethral glands forms nearly 5% of seminal plasma.
5. What is oogenesis? Give a brief account of oogenesis.
Answer: It is a process of formation, development and maturation of haploid ovum or female gamete from diploid germinal cell of the ovary.
Cells of germinal epithelium of ovary undergo repeated mitotic divisions to form diploid oogonia or gamete mother cells. They are formed in the foetal ovary in large number, some 2 million. Oogonia form egg tubes that pass into cortex and produce egg nests. In each egg nest, one oogonium grows into primary oocyte while the rest give rise to follicular sheath around it. The whole complex is called primary follicle. Follicular cells surrounding a primary oocyte differentiate into few layers of granulose cells. They are covered by two layers of theca cells developed from cortex of ovary. The whole structure is now called secondary follicle. Granulosa cells secrete a fluid into interior around the primary oocyte. It produces a cavity termed as antrum. Antrum containing follicle is called tertiary follicle. Primary oocyte grows and completes meiosis 1 to produce haploid secondary oocyte and a small haploid polar body. The follicle grows further and is called Graafian follicle. A non cellular layer called zona pellucida developed around the secondary oocyte .