Test: Gametogenesis (NCERT) - NEET MCQ

Secondary spermatocyte contains half the number of chromosomes i.e., 8. Each chromosome has 2 chromatids, therefore, 8 chromosomes will have 16 chromatids in all.

During oogenesis, primary oocyte grows and completes- meiosis I (first maturation division) producing a large secondary oocyte and a small polar body. The secondary oocyte proceeds with meiosis II (second maturation division) but the division gets arrested at metaphase stage. It is in this stage of oocyte that the ovum is shed during ovulation. It passes into oviduct, where the cell cycle resumes only after the entry of sperm.

During embryonic development the primordial germ cells migrate to the testis where they become spermatogonia. At puberty the spermatogonia proliferate rapidly by mitosis. Some undergo growth phase to become primary spermatocytes that further undergo through meiotic division I to become secondary spermatocytes. After completion of meiotic division II the secondary spermatocytes produce spermatids which differentiate to form spermatozoa.

The secondary oocyte is formed by the meiotic division of primary oocyte (2n), therefore, it is haploid. Primary spermatocyte is formed by the mitotic division of spermatogonium (2n), therefore it is diploid.

To solve this question, we need to match the correct terms for the given blanks in each statement. Let's analyze each statement and its options:
Statement (A):
- Seminiferous tubules produce ______ while Leydig's cells produce ______.
- The correct terms for these blanks are (i) spermatozoa and (ii) testosterone.
Statement (B):
- In females, urethra is small and conducts ______ while in males it conducts urine and ______.
- The correct terms for these blanks are (iii) urine and (iv) semen.
Statement (C):
- The process of formation of spermatozoa from spermatogonia is called ______ and the process of maturation of spermatids into spermatozoa is called ______.
- The correct terms for these blanks are (v) spermatogenesis and (vi) spermiogenesis.
Now let's match the correct terms with the blanks for each statement:
(A) - Option A:
- (i) spermatozoa, (ii) testosterone
(B) - Option B:
- (iii) urine, (iv) semen
(C) - Option C:
- (v) spermatogenesis, (vi) spermiogenesis
Since Option A matches all the correct terms for the blanks in each statement, the correct answer is A: (i) spermatozoa, (ii) testosterone, (v) spermatogenesis, (vi) spermiogenesis.

Hypothalamus releases Gonadotropin releasing hormone (GnRH) that stimulates anterior pituitary to release FSH (follicle stimulating hormone) and LH (leuteinsing hormone). These hormones induce ovary to release estrogen and progesterone.

• Mitochondria are present in the middle piece of the sperm.
• They are essential for producing energy required for movement of tail.
• This is essential for movement through the genital tract and oviduct before sperm encounters the egg.
• Rakesh might have less or poorly functional mitochondria, which prevent his normal count of sperms from moving along the genital tract.

 In the head of the epididymis, the sperms undergo physiological maturation, acquiring increased motility and fertilizing capacity.

Female gamete is released from the ovary in the secondary oocyte stage by rupturing the wall of the ovary.

Oogenesis is the process of formation of functional haploid ova from the diploid germinal cells in the ovary. Oogenesis begins during embryonic development but is completed only at puberty of the secondary oocyte with the sperm.

Spermatogenesis involves conversion of a diploid structure (spermatogonia) into haploid structures (spermatozoa). Spermiogenesis changes a haploid structure (spermatid) into another haploid structure (spermatozoon).

In human males, the primordial germ cells divide mitotically and produce spermatogonia. Some of the spermatogonia grow into large primary spermatocytes. Each primary spermatocyte undergoes first maturation division which is a reductional (meiotic) one. Thus, the primary spermatocyte divides into two haploid daughter cells called secondary spermatocytes. Each secondary spermatocyte now undergoes second maturation division which is a mitotic one. Thus, each secondary spermatocyte gives rise to two spermatids that undergo transformation to form two sperms. Overall, two secondary spermatocytes give rise to four sperms.

In human females, certain cells in the germinal epithelium divide by mitosis to produce a large number of oogonia (diploid). The oogonia multiply by mitotic divisions to form primary oocytes (diploid). Each primary oocyte undergoes two maturation divisions. In the first meiotic division the primary oocyte divides into two very unequal haploid daughter cells- a large secondary oocyte and a small first polar body. In the second maturation division (mitotic), the first polar body may divide to form two second polar bodies and the secondary oocyte divides to form two unequal daughter cells, a large ootid and a small polar body. The ootid grows into a haploid ovum. Thus, from one oogonium, one ovum and three polar bodies are formed.

So, the correct answer is 'One functional egg and three polar bodies'.

The middle piece of sperm contains mitochondria coiled around the axial filament. They provide energy for the movement of the sperm.

Immediately after ovulation, the layer that forms around the ovum is called corona radiata. It is formed by the granulosa cells of cumulus oophorus. Corona radiata probably increases the likelihood that the ovum will be picked up in the uterine tube.

• Sperm count is essential as it determines the probability of a sperm encountering the egg.
• Sperm motility is essential to ensure the passage of sperms through the genital tract, uterus and oviduct.
• Sperm production rate determines the number of healthy coitus a male can have.
• Sperm height is not a determining factor of fertility.

FSH acts on the Sertoli cells and stimulate secretion of some factors which help in the process of spermatogenesis.

One primary spermatocyte produces four spermatozoa, therefore, four primary spermatocytes will produce 16
spermatozoa.

Head of the sperm is anterior, broad, flattened and oval structure. It consists of two parts, posterior large nucleus and anterior small cap-like acrosome. The nucleus consists of condensed DNA and basic proteins.

Sperms are released out from seminiferous tubules facilitated by seminal plasma composed of secretions from epididymis, vas deferens, seminal vesicle, and prostate.