The secondary sexual characters develop in females because of:
(1) estrogen
(2) androgens
(3) absence of androgens
(4) absence of estrogens
(1) Estrogen is responsible for the developement of female secondary sexual characters. Progesteron is the pregnancy harmone.
Difficulty Level:
The cleavage divisions in humans is:
1. holoblastic, equal and indeterminate
2. holoblastic, unequal and indeterminate
3. holoblastic, equal and determinate
4. holoblastic, unequal and determinate
Holoblastic cleavage is possible due to nearly alecithal egg. The resultant blastomeres are equal in size and fate determination is late.
Difficulty Level:
Extra embryonic membranes of mammalian embryo are derived from:
(a) Inner cell mass
(b) Formative cells
(c) Trophoblast cells
(d) Follicle cells
Two of the extra-embryonic membranes (chorion and allantois) will contribute to the formation of placenta. Inner cell mass forms the embryo proper.
Difficulty Level:
The testes are situated outside the abdominal cavity within a pouch called scrotum. This is necessary as:
1. The scrotum can contain lengthy ducts for the transfer of sperms
2. Scrotum helps in maintaining the low temperature of the testes necessary for spermatogenesis
3. Scrotum reduces the pressure around testes necessary for spermatogenesis
4. Scrotum can store huge amounts of sperms
2. Read page 43, XII NCERT
Difficulty Level:
Each seminiferous tubule is lined on its inside by:
1. Spermatogonia
2. Primary spermatocytes
3. Sertoli cells
4. Both 1 and 3
Ans. 4
Read page 43, XII NCERT
Difficulty Level:
Leydig cells:
(1) Are present in seminiferous tubules and secrete androgens
(2) Are present in seminiferous tubules and help in maturation of sperms
(3) Are present in interstitial space and secrete androgens
(4) Are present in interstitial space and help in maturation of sperms
(3) Read page 43, XII NCERT
Difficulty Level:
Seminal plasma is rich in:
1. Sucrose, calcium and certain enzyme
2. Glucose, sodium and certain enzymes
3. Fructose, calcium and certain enzymes
4. Fructose, sodium and certain enzymes
(3) Read page 44, XII NCERT
Difficulty Level:
Ovaries are the primary sex organs in human females because they:
I. Produce the female gamete
II. Produce the hormone that regulates the development of secondary sexual characters
1. Both I and lI
2. OnlyI
3. Only II
4. None
(1) Read page 44, XII NCERT
Difficulty Level:
Each Ovary is connected to the pelvic wall and the uterus by:
(a) Peritoneum
(b) Adipose tissue
(c) Ligaments
(d) Areolar tissue
Ans. 3
Read page 44, XII NCERT
Difficulty Level:
The spermatids are transformed into spermatozoa by the process called:
(1) Spermiation
(2) Spermatocytogenesis
(3) Spermiogenesis
(4) Spermatolysis
(3) read page 47, XII NCERT
Difficulty Level: