The male gonads have both sperm-

Correct Answer: D

Rationale: Step-by-step rationale for why the correct answer is D: 1. Testes are the male gonads responsible for producing sperm. 2. The testes function as the primary reproductive organ in males. 3. Sperm production occurs in the seminiferous tubules within the testes. 4. The testes also produce testosterone, the primary male sex hormone. Summary of why other choices are incorrect: A: Producing - While testes do produce sperm, this choice lacks specificity regarding the male gonads. B: Estrogen functions and are called ________ - Estrogen is a female sex hormone, not produced by male gonads. C: Progesterone - Progesterone is a female sex hormone produced mainly by the ovaries, not by male gonads.

Correct Answer: D

Rationale: The correct answer is D: Sertoli cells. Seminiferous tubules are lined with Sertoli cells, which provide structural support and nourishment to developing sperm cells. These cells also help in the process of spermatogenesis. A: Oocytes are female germ cells found in the ovaries, not in the seminiferous tubules. B: Red blood cells are not found in the seminiferous tubules. They are responsible for carrying oxygen in the bloodstream. C: Leydig cells are found in the interstitial tissue of the testes and are responsible for producing testosterone, not lining the seminiferous tubules. Therefore, the correct choice is D as Sertoli cells play a crucial role in sperm production within the seminiferous tubules.

Correct Answer: A

Rationale: The correct answer is A because oestrogen actually has a negative feedback effect on the hypothalamus. When oestrogen levels rise, it signals the hypothalamus to stop producing gonadotropin-releasing hormone (GnRH), which in turn decreases follicle-stimulating hormone (FSH) and luteinizing hormone (LH) production. This negative feedback loop helps regulate the menstrual cycle. Choices B, C, and D are correct statements about oestrogen. Oestrogen does stimulate retention of fluid, growth of ovaries and follicles, and the development of female body characteristics.

Correct Answer: B

Rationale: The correct answer is B because oestrogen levels in females rise and fall every month in response to the menstrual cycle. This hormone is produced by the ovaries and plays a key role in regulating the menstrual cycle. During the menstrual cycle, oestrogen levels increase during the first half of the cycle (follicular phase), peak around ovulation, and then decrease in the second half of the cycle (luteal phase). This cyclical pattern is essential for preparing the uterus for potential pregnancy. Choices A, C, and D are incorrect because oestrogen levels do not follow a continuous decline throughout a female's life, peak during gestation, or reach their highest level just after birth.

Correct Answer: B

Rationale: The correct answer is B: fallopian tubes. Fertilization occurs in the fallopian tubes where the sperm meets the egg. The fallopian tubes are where the egg is released from the ovary and where fertilization takes place. The uterus (choice A) is where the fertilized egg implants and develops into a fetus. The labia (choice C) are external genital structures and do not play a role in fertilization. The vagina (choice D) is the birth canal and does not directly participate in fertilization. Therefore, the fallopian tubes are the correct choice for the site of fertilization in the female reproductive system.