BIOLOGY 3 Marks Question

If the testes fail to descend to the scrotum, gametogenesis could be inhibited. The process of spermatogenesis requires a marginally lesser ambient temperature than that in the abdominal cavity.

Trophoblast is the outer layer of blastocyst which helps in the attachment of blastocyst to the endometrium of the uterus.

Chorionic villi appear after implantation on the trophoblast. It becomes interdigitated with uterine tissue to form the placenta and increases the surface area for exchange of materials between the mother and the embryo.

First cleavage division of zygote occurs in the ampullary-isthmic junction in the female reproductive tract.

During the production of secondary oocyte and ovum.

These are mild uterine contraction induced by the signals for parturition originated from fully developed foetus and placenta.

The primary oocyte within the tertiary follicle grows in size and completes its first meiotic division to form secondary oocyte and first polar body.

Yes. For example, the external reproductive organ penis in males and clitoris in females.

Endometrium.

During pregnancy, placenta produces hormones like human chorionic gonadotropin and human placental lactogen and ovary produces relaxin.

Sertoli cells. They are found on the inner lining of seminiferous tubule.

Because eggs are non-motile (stationary) and sperms have to travel up to eggs.

1. Isthmus.
2. Ampulla.

Leydig cells are present in the regions called interstitial spaces outside the seminiferous tubules. They synthesise and secrete androgens (testosterone).

Sperms swim by vibrating their tail in the fluid while eggs do not require it.

The follicle cells that envelope the egg outside zona pellucida are called corona radiata.

Luteal phase/ Secretory phase.

Blastocyst stage.

It is the innermost glandular layer of uterus which lines the uterine cavity. Here, implantation of blastocyst takes place. It undergoes cyclical changes during menstrual cycle.

Spermiogenesis: It is the transformation of spermatids into spermatozoa or sperms.
Spermiation: It is the release of sperms from seminiferous tubules.

The secretions of the bulbourethral glands help in the lubrication of the penis.

400 sperms and 100 ova.

Ovulation.

60,000-80,000 primary follicles are left in each ovary.

Labia minora.

Amniotic fluid.

Testosterone.

Endometrium.

Luteinizing hormone.

S. No.	Column I	S. No.	Column II
A.	Cleavage	2.	Mitotic divisions of the zygote in quick succession.
B.	Implantation	3.	Embedding of the blastocyst in the endometrium of uterus.
C.	Inner cell mass	5.	Group of cells attached to one end of trophoblast that differentiate into embryo proper.
D.	Trophoblast	1.	Outer layer of the blastocyst that attaches to the endometrium during implantation.

200 sperms.

The correct order is Mammary tubules → Mammary duct Mammary ampulla Lactiferous duct.

Oogenesis in human females initiate at the foetal/ embryonic stage.
Spermatogenesis in human males starts at puberty.

It is the remaining part of Graafian follicle after ovulation in the luteal phase which acts as an endocrine gland.

Spermiation.

Ampulla.

Epididymis.

Colostrum contains necessary antibodies (IgA and IgG) that provide protection against diseases to newborn infants.

Inner cell mass.

1. Mesoderm.
2. Endoderm.

Cervix can hold about 7kg of foetus and fluid in the uterus against the pull of gravity for several days during pregnancy. Thus, it contains the largest and strongest sphincter.

High level of progesterone and estrogens during pregnancy suppress the gonadotropins which is required for the development of new follicles. Therefore, a new cycle cannot be initiated.

It is a mature ovarian follicle in the ovary.

23.

The acrosome of the sperm contains sperm lysin (hyaluronidase) which dissolve the mucopolysaccharide, hyaluronic acid by which the cells of corona radiata glued together.

Seminiferous tubule.

The signals for parturition arise from the fully-developed foetus and the placenta.

Lactation is the process of feeding the new born baby with the milk secreted by the mammary glands.
Endometrium is the inner most glandular layer of the uterine wall that undergoes cyclical changes during menstrual cycle, where implantation occurs; it also forms a part of the placenta.

Cervix helps in regulating the passage of sperms into the uterus and forms the birth canal to facilitate parturition.