Nursing Elites

1. The _________ is the hollow organ within females in which the embryo and fetus develop.

• A. placenta
• B. ovum
• C. uterus
• D. amniotic sac

Correct answer: C

Rationale: The correct answer is C: uterus. The uterus is the organ where the embryo implants and the fetus develops during pregnancy. The placenta (choice A) is an organ that develops during pregnancy and provides nutrients and oxygen to the fetus, but it is not the organ where the embryo and fetus physically develop. The ovum (choice B) is the female reproductive cell or egg that is fertilized by the sperm to form an embryo, but it is not the organ where the embryo and fetus develop. The amniotic sac (choice D) is a membrane filled with amniotic fluid that surrounds and protects the fetus, but it is not the organ where the embryo and fetus physically develop.

2. Before meiosis, a sperm cell:

• A. contains 46 chromosomes.
• B. contains two X chromosomes.
• C. is significantly larger than an egg cell.
• D. contains both an X and a Y chromosome.

Correct answer: A

Rationale: Before meiosis, a sperm cell contains 46 chromosomes. This is because sperm cells, like other somatic cells, have a diploid number of chromosomes. During meiosis, the number of chromosomes is halved to 23 to combine with an egg cell during fertilization. Choice B is incorrect because a sperm cell carries either an X or a Y chromosome, not both (Choice D). Choice C is incorrect as sperm cells are generally smaller than egg cells, which is an adaptation that aids in motility and penetration of the egg during fertilization.

3. Which of the following statements is true of Down’s syndrome?

• A. Down’s syndrome is usually caused by an extra copy of chromosome 21 in an individual.
• B. The symptoms of Down’s syndrome are similar to those of sickle-cell anemia.
• C. Down’s syndrome is caused by a sexually transmitted infection (STI) during conception.
• D. The probability of having a child with Down’s syndrome increases with the age of the parents.

Correct answer: D

Rationale: The correct answer is D. The likelihood of having a child with Down’s syndrome increases as the age of the parents increases, particularly the mother's age. Choice A is incorrect because Down’s syndrome is caused by an extra copy of chromosome 21, not a defect in the sex chromosomes. Choice B is incorrect as the symptoms of Down’s syndrome and sickle-cell anemia are different. Choice C is also incorrect as Down’s syndrome is not caused by a sexually transmitted infection during conception.

4. What determines a child’s sex?

• A. Presence of teratogens at the time of conception.
• B. Sex chromosome received from the mother.
• C. Presence of teratogens at the time of ovulation.
• D. Sex chromosome received from the father.

Correct answer: D

Rationale: The correct answer is the sex chromosome received from the father. The father contributes either an X or Y chromosome, which determines the child's sex. This occurs at the moment of fertilization when the sperm carrying either an X (resulting in a female) or Y (resulting in a male) chromosome fertilizes the egg. Choices A, B, and C are incorrect because the presence of teratogens at the time of conception or ovulation does not determine the child's sex. While the sex chromosome received from the mother is important, it is the father's contribution that ultimately determines the child's sex.

5. Monozygotic (MZ) twins share _________ percent of their genes.

• A. 100
• B. 75
• C. 50
• D. 25

Correct answer: A

Rationale: Monozygotic (MZ) twins share 100% of their genes because they originate from the same fertilized egg that splits into two, resulting in identical genetic material for both twins. Choice B (75%) is incorrect as it implies a partial genetic similarity, which is not the case for MZ twins. Choice C (50%) is incorrect as it suggests half of the genes are shared, which is applicable to dizygotic (DZ) twins, not MZ. Choice D (25%) is incorrect as it indicates minimal genetic sharing, which is not true for MZ twins.

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