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

The first sign of a growing foetus is the formation of the heart. In human development, this occurs relatively early during embryogenesis. Once fertilization has taken place and the zygote is formed, it begins a process of rapid cell division and differentiation. As the embryo develops, the heart is one of the first organs to form and start functioning. 

Biologically, the development process can be outlined as follows:

• The fertilized egg divides to create a multi-cellular structure through cleavage and forms the blastocyst. It implants into the uterine wall.
• The cells continue to divide and specialize, forming the early structures of the embryo.
• The heart begins to form during the third week of development. By week four, the heart begins to beat.

Thus, the formation and functioning of the heart are critical early milestones in embryonic development. As additional structures develop, such as limbs and digits, and later, movement is observed, but these occur after the initial formation of the heart.

Answer 2

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 3

In humans, the primary spermatocytes are cells that undergo meiosis during the process of spermatogenesis, which is the formation of sperm cells in the male reproductive system. A primary spermatocyte is derived from a spermatogonium, a stem cell located in the testes that undergoes mitotic divisions. When a spermatogonium differentiates into a primary spermatocyte, it retains the diploid chromosome number present in somatic cells.

Human somatic cells are diploid, meaning they contain two sets of chromosomes, one from each parent. This results in a total of 46 chromosomes (23 pairs). Similarly, primary spermatocytes are also diploid and thus have 46 chromosomes.

During meiosis I, a primary spermatocyte will divide to form two secondary spermatocytes, each with 23 chromosomes, which are haploid. However, prior to this division, the primary spermatocyte maintains the full diploid count of 46 chromosomes.

Therefore, the correct answer is: 46

Answer 4

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 5

The transformation of spermatids into spermatozoa is referred to as spermiogenesis. This process is a crucial phase in the development of sperm cells, occurring after the completion of spermatogenesis. Here is a brief overview of each term related to this process:

• Spermatogenesis: This is the overall process of sperm cell development, beginning with spermatogonia and culminating in the formation of spermatids. 
• Spermiogenesis: Specifically refers to the transformation of non-motile spermatids into mature, motile spermatozoa. During this process, spermatids undergo morphological changes such as condensation of chromatin, formation of the acrosome, development of the flagella for motility, and shedding of excess cytoplasm.
• Spermiation: This is the release of mature spermatozoa into the lumen of the seminiferous tubules, preceding their journey through the male reproductive tract.
• Spermatogoniasis: There is no biological process with this specific term related to sperm development, making it the incorrect choice.

Understanding these terms helps clarify the distinct stages of sperm development in the male reproductive system. In summary, the correct answer is spermiogenesis as it describes the transformation of spermatids into fully developed spermatozoa.

Answer 6

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 7

In the context of the female reproductive system and the menstrual cycle, the hormone that is crucial for maintaining the endometrium during the luteal phase is Progesterone. The menstrual cycle comprises several phases, including the follicular phase, ovulation, and the luteal phase. After ovulation, the remnants of the follicle transform into the corpus luteum, which secretes progesterone. 

Progesterone plays a key role in preparing the endometrium for potential implantation of a fertilized egg. This hormone thickens the uterine lining, making it more receptive to a fertilized egg and ensuring the endometrium provides the necessary nutrients and support for early pregnancy. If fertilization does not occur, progesterone levels drop, leading to menstruation as the endometrial lining is shed. Without sufficient progesterone during the luteal phase, the endometrium cannot be maintained, potentially preventing pregnancy from progressing.

Hormone	Function
Luteinising Hormone	Triggers ovulation and corpus luteum formation
Relaxin	Relaxes uterine muscles
Progesterone	Maintains endometrium during the luteal phase
Follicle Stimulating Hormone	Stimulates follicle growth in the ovaries

Thus, among the given options, Progesterone is the essential hormone during the luteal phase for maintaining the endometrial lining in preparation for possible implantation and pregnancy.

Answer 8

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 9

The nucleus is an essential part of a human sperm cell, and it is located in the head of the sperm. The sperm consists of three main parts: the head, the middle piece, and the tail. Here is a brief explanation of each part: 

• Head: This part contains the nucleus, which houses the genetic material (DNA) that will be contributed to the offspring. It is covered by an acrosome cap, which helps in penetrating the egg during fertilization.
• Middle Piece: This section contains numerous mitochondria that provide the energy needed for the sperm to move.
• Tail: Also known as the flagellum, it is responsible for the motility of the sperm, allowing it to swim towards the egg.

Based on the structure and function of the sperm's components, the correct answer to the question is that the nucleus is located in the head of the human sperm.

Answer 10

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.