A cell called the ______ is a fertilized cell with 46 chromosomes.

Correct Answer: D

Rationale: The correct answer is D: zygote. A zygote is formed when a sperm cell fertilizes an egg cell, resulting in a single cell with a full set of 46 chromosomes. This process is called fertilization and marks the beginning of a new individual. The other choices (A: spermatozoon, B: polar body, C: ovum) are not correct because a spermatozoon is a mature sperm cell with 23 chromosomes, a polar body is a byproduct of meiosis in the female reproductive system and has only 23 chromosomes, and an ovum is an unfertilized egg cell also containing 23 chromosomes.

Correct Answer: A

Rationale: The correct sequence is A: FSH, as it initiates the menstrual cycle by stimulating the growth of follicles in the ovaries. LH then triggers ovulation. Estrogen is produced by the developing follicles and peaks before ovulation, while progesterone rises after ovulation. The other choices are incorrect as they do not follow the physiological sequence of hormonal actions in the menstrual cycle.

Correct Answer: B

Rationale: The correct answer is B (44 autosomes) because a human primary spermatocyte is a diploid cell containing a total of 44 autosomes. This is because humans have 22 pairs of autosomes in their somatic cells. During meiosis I, the primary spermatocyte undergoes replication and recombination, resulting in 22 pairs of autosomes (44 autosomes) that will be divided into two haploid secondary spermatocytes. Choices A, C, and D are incorrect because they do not reflect the correct number of autosomes present in a human primary spermatocyte.

Correct Answer: B

Rationale: The correct answer is B (50-100) because each lobule in the testis contains multiple seminiferous tubules where sperm production occurs. The average number of seminiferous tubules per lobule ranges from 50 to 100. This is supported by anatomical studies and research on testicular structure. Explanation: A: 1-3 - This is too low as each lobule contains more seminiferous tubules for efficient sperm production. C: 200-300 - This is too high as it overestimates the number of seminiferous tubules per lobule. D: 500 or more - This is excessive and not accurate based on scientific findings. In summary, choice B is correct because it accurately reflects the typical range of seminiferous tubules per lobule, while the other choices either underestimate or overestimate this number.

Correct Answer: B

Rationale: The correct answer is B: Cervix. The cervix is the lower part of the uterus that opens into the vagina. It acts as a barrier between the uterus and vagina, and allows for the passage of menstrual flow, sperm, and a baby during childbirth. The other choices are incorrect because the urethra is a tube that connects the bladder to the outside of the body, the uterine tubes are also known as fallopian tubes that connect the ovaries to the uterus, and the inguinal canal is a passage in the abdominal wall.