Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Gametes are haploid () cells produced by meiosis, containing 23 chromosomes. The fusion of a sperm and an egg produces a diploid () zygote with 46 chromosomes.
The male reproductive system includes the testes (site of testosterone and sperm production), the scrotum (maintains temperature at approx. ), and the sperm duct (vas deferens).
The female reproductive system includes the ovaries (produce eggs, estrogen, and progesterone), the oviducts (site of fertilization), and the uterus (site of implantation).
The Menstrual Cycle is regulated by negative and positive feedback loops involving (Follicle Stimulating Hormone), (Luteinizing Hormone), estrogen, and progesterone.
During the follicular phase, stimulates the growth of a follicle which secretes estrogen. A surge in at approximately day 14 triggers ovulation.
The placenta allows for the exchange of , glucose, and amino acids from maternal blood to fetal blood, and the removal of and urea via diffusion across a selectively permeable membrane.
Antenatal care involves monitoring the health of the mother and fetus, including ensuring adequate intake of for hemoglobin and for bone development.
📐Formulae
💡Examples
Problem 1:
If a human skin cell contains 46 chromosomes, calculate the number of chromosomes present in a secondary spermatocyte and a mature zygote.
Solution:
Secondary spermatocyte: chromosomes; Mature zygote: chromosomes.
Explanation:
The skin cell is diploid (). A secondary spermatocyte is formed after Meiosis I, making it haploid (). The zygote is formed by the fusion of two haploid gametes (), restoring the diploid state ().
Problem 2:
Describe the hormonal change that occurs if fertilization does not take place during the menstrual cycle.
Solution:
The corpus luteum degenerates, leading to a sharp decrease in the concentration of progesterone and estrogen.
Explanation:
Progesterone is required to maintain the endometrium (lining of the uterus). When the levels of progesterone drop below a certain threshold, the lining breaks down, resulting in menstruation. The decrease in estrogen and progesterone also removes the inhibition on the pituitary gland, allowing levels to rise again for the next cycle.
Problem 3:
Explain why the concentration of is higher in the umbilical artery than in the umbilical vein.
Solution:
The umbilical artery carries deoxygenated blood from the fetus to the placenta, containing metabolic waste such as .
Explanation:
Fetal metabolism produces as a byproduct of aerobic respiration: . This diffuses across the placenta into the maternal blood to be excreted by the mother's lungs.