Question

What is the first sign of a growing foetus?

• A. Development of limbs and digits
• B. Movement of foetus
• C. Formation of heart
• D. Development of head
• A. 46
• B. 23
• C. 92
• D. 12
• A. Spermiation
• B. Spermiogenesis
• C. Spermatogenesis
• D. Spermatogoniasis
• A. Luteinising Hormone
• B. Relaxin
• C. Progesterone
• D. Follicle Stimulating Hormone
• A. Middle piece
• B. Acrosome
• C. Head
• D. Tail

Answer 1

The Correct Option is C

In the process of human pregnancy and fetal development, the first sign of a growing fetus is the formation of the heart. During early embryonic development, the heart starts to form around the third week of pregnancy and begins to function soon after. This is the first functional organ to form, marking the beginning of the embryo's ability to circulate blood and oxygen.

Here’s why the other options are incorrect:

(1) Development of limbs and digits: This occurs later in embryonic development, typically during the 8th week.

(2) Movement of fetus: The fetus starts to move around 16 to 25 weeks into the pregnancy, which is much later than the formation of the heart.

(4) Development of head: The development of the head begins early, but it is not the first sign. The heart forms before the head becomes well-developed.

Thus, the correct answer is (3) Formation of heart, as it is the first sign of a growing fetus.

Answer 2

The formation of the heart is one of the earliest signs of fetal development. The heart begins to form and beat early, marking the start of fetal growth and enabling circulation, essential for developing other organs.

Answer 3

Human primary spermatocytes are diploid cells that undergo meiosis to form haploid sperm cells.

Humans have a total of 46 chromosomes (23 pairs). A primary spermatocyte is a diploid cell, meaning it has the full set of chromosomes, i.e., 46 chromosomes (23 pairs).

During meiosis I, the primary spermatocyte divides to form secondary spermatocytes, which are haploid (23 chromosomes).

Thus, the correct answer is (1) 46.

Answer 4

Human primary spermatocytes are diploid (2n) and contain 46 chromosomes. During meiosis, these cells divide to form haploid spermatids with 23 chromosomes each, ensuring genetic diversity.

Answer 5

The transformation of spermatids into spermatozoa is known as spermiogenesis. This process involves the maturation of spermatids into fully functional sperm cells by the development of a tail (flagellum), the condensation of the nucleus, and the formation of an acrosome.

Here’s an explanation of the other terms:

(1) Spermiation: This is the process where mature spermatozoa are released from the Sertoli cells into the lumen of the seminiferous tubules. It follows spermiogenesis.

(3) Spermatogenesis: This refers to the overall process of sperm cell production, starting from spermatogonia and culminating in the formation of spermatozoa, which includes both spermatogenesis and spermiogenesis.

(4) Spermatogoniasis: This is not a recognized term in human reproductive biology.

Thus, the correct answer is (2) Spermiogenesis, as it specifically refers to the transformation of spermatids into spermatozoa.

Answer 6

Spermiogenesis is the process by which spermatids mature into spermatozoa, developing tails and other structures necessary for motility and fertilization, completing the process of sperm cell maturation.

Answer 7

During the luteal phase of the menstrual cycle, progesterone is the hormone essential for the maintenance of the endometrium.

Progesterone is produced by the corpus luteum, which forms from the ruptured follicle after ovulation. This hormone prepares the endometrium for potential pregnancy by promoting its thickening and ensuring it remains suitable for implantation of a fertilized egg.

Here’s why the other hormones are incorrect:

(1) Luteinising Hormone (LH): LH is involved in triggering ovulation, not in the maintenance of the endometrium.

(2) Relaxin: Relaxin is involved in the relaxation of the uterus and the softening of the cervix during pregnancy, but it is not primarily responsible for maintaining the endometrium during the luteal phase.

(4) Follicle Stimulating Hormone (FSH): FSH is important for the development of follicles in the ovary but does not directly affect the maintenance of the endometrium during the luteal phase.

Thus, the correct answer is (3) Progesterone.

Answer 8

Progesterone is vital during the luteal phase to maintain the endometrial lining, preparing it for potential implantation of a fertilized egg. Progesterone also supports early pregnancy if fertilization occurs.

Answer 9

The nucleus is present in the head of the human sperm.

The head contains the genetic material (DNA) of the sperm, which is crucial for fertilization. The acrosome, which is a cap-like structure covering the head, contains enzymes that help the sperm penetrate the egg during fertilization.

Here’s the breakdown of the other parts of the sperm:

(1) Middle piece: The middle piece contains mitochondria, which provide energy for the sperm’s movement.

(2) Acrosome: The acrosome is part of the head and is not where the nucleus is located. It contains enzymes needed to penetrate the egg.

(4) Tail: The tail (or flagellum) is responsible for the movement of the sperm but does not contain the nucleus.

Thus, the correct answer is (3) Head, as this is where the nucleus of the sperm is located.

Answer 10

In human sperm, the nucleus is located in the head, containing the genetic material necessary for fertilization. The acrosome, also in the head, contains enzymes for egg penetration, while the nucleus holds the DNA.