Nursing Elites

1. Dizygotic (DZ) twins share _________ percent of their genes.

• A. 100
• B. 75
• C. 50
• D. 25

Correct answer: C

Rationale: Dizygotic (DZ) twins share approximately 50% of their genes. This is because dizygotic twins, also known as fraternal twins, originate from two separate fertilized eggs and share similar genetic similarity to regular siblings. Choice A (100%) is incorrect because if twins shared 100% of their genes, they would be identical twins (monozygotic). Choice B (75%) is incorrect as it is not the typical genetic similarity seen in dizygotic twins. Choice D (25%) is incorrect as it represents a significantly lower genetic similarity than what is observed in dizygotic twins.

2. Which field of biology studies heredity?

• A. Etiology.
• B. Ecology.
• C. Genetics.
• D. Eugenics.

Correct answer: C

Rationale: Genetics is the branch of biology that focuses on the study of heredity and variation in organisms. Etiology (choice A) deals with the causes of diseases, not heredity. Ecology (choice B) is concerned with the relationships between organisms and their environment, not specifically heredity. Eugenics (choice D) is a controversial field that involves improving the genetic quality of the human population through selective breeding, which is different from the study of heredity itself.

3. Monozygotic (MZ) twins are known as fraternal twins.

• A. TRUE
• B. FALSE
• C. Possibly
• D. Never

Correct answer: B

Rationale: The correct answer is B: 'FALSE.' Monozygotic (MZ) twins are identical twins, not fraternal. Fraternal twins are dizygotic (DZ). The statement in the question is incorrect as MZ twins are genetically identical, while fraternal twins actually refer to dizygotic twins who develop from two separate fertilized eggs. Therefore, monozygotic twins are not known as fraternal twins, making option B the correct choice. Options A, C, and D are incorrect as they do not accurately describe the relationship between monozygotic and fraternal twins.

4. An individual’s phenotype reflects both genetic and environmental influences.

• A. phenotype
• B. chromosome
• C. allele
• D. genotype

Correct answer: A

Rationale: The correct answer is A: phenotype. A phenotype is the observable characteristics of an individual, which result from the interaction of their genotype with the environment. This interaction between genetics and the environment determines how genes are expressed and how traits are manifested in an individual. Choices B, C, and D are incorrect because chromosomes, alleles, and genotypes are components of an individual's genetic makeup, but they do not directly reflect the observable traits influenced by both genetics and the environment.

5. Rh incompatibility occurs when an Rh-negative woman is carrying an Rh-positive fetus.

• A. TRUE
• B. FALSE
• C. Sometimes
• D. Never

Correct answer: B

Rationale: Rh incompatibility occurs when an Rh-negative woman is carrying an Rh-positive fetus, not the other way around. Therefore, the statement that an Rh-positive woman is carrying an Rh-negative fetus is incorrect. Rh incompatibility can lead to hemolytic disease of the newborn, where maternal antibodies attack the fetal red blood cells. Choice A is incorrect because the statement is false. Choice C is incorrect as Rh incompatibility has a clear cause and effect relationship. Choice D is incorrect as Rh incompatibility can occur, but it depends on the Rh status of the mother and fetus.

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