Biology 1 Marks Question

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.

Stem cells.

One ova is produced by one fully grown primary oocyte.

1. A primary spermatocyte is diploid and has 46 chromosomes; it undergoes meiosis I and forms two secondary spermatocytes.
2. A secondary spermatocyte is haploid and has 23 chromosomes; it undergoes meiosis II and forms two spermatids.

Colostrum.

1. A - Pelvic wall.
2. B - Clitoris.
3. C - Ova.

The urethra originates from the urinary bladder and extends through penis to its external opening called urethral meatus.

Progesterone.

The sperm penetrates through zona pellucida with the help of secretions from acrosome.

Zona pellucida.

Trophoblast forms chorionic villi, which become part of the placenta.

It is a mammalian blastocyst.
A is trophoblast.

Spermiogenesis is the formation of haploid, microscopic and functional spermatozoa (male gametes) from the spermatids. It takes place in the testes (male reproductive organ).

Acrosome contains hydrolytic enzymes used to penetrate the egg during fertilisation.

Trophoblast.

Cleavage refers to the rapid mitotic divisions that occur in the zygote.

Spermatic cords.

The basal parts of endometrium remain intact as they form the source of new endometrial lining and glands for the next cycle.

Ootid.

The time period between implantation and parturition, when the embryo completes its growth and development, is called gestation period.

ICM (Inner Cell Mass).

Menopause, i.e. stoppage of menstrual cycles occurs around 50 years of age; since no ovulation occurs, the woman cannot conceive after this age.

Relaxin and human chorionic gonadotropin.

Placenta is connected to embryo through umbilical cord and helps in transport of substance to and from the embryo.

Trophoblast is cells forming the outer layer of a blastocyst, which provide nutrients to the embryo and develop into a large part of the placenta. They are formed during the first stage of pregnancy and are the first cells to differentiate from the fertilized egg.

Chorionic villi are the finger-like projections formed by the trophoblast immediately after implantation; they form the foetal part of the placenta.

Rete testis. It leads to vas deference.