Which of the following pairs of bases is present in the rungs of the ladder-like structure of deoxyribonucleic acid (DNA)?

Correct Answer: A

Rationale: The correct answer is A: Cytosine with guanine. In the DNA double helix, cytosine always pairs with guanine forming a base pair, and adenine pairs with thymine. These complementary base pairs form the rungs of the ladder-like structure of DNA. Choice B, Rhodamine with biotin, is incorrect as they are not base pairs found in DNA. Choice D, Serine with tyrosine, is incorrect as they are amino acids, not DNA bases. Choice C, Diaminopurine with ribozyme, is also incorrect as ribozyme is an enzyme, not a base, and diaminopurine is not one of the standard bases found in DNA.

Correct Answer: B

Rationale: The correct answer is B: Performing a newborn's initial bath. Gloves should be worn during this procedure to protect against exposure to body fluids, such as amniotic fluid or blood. Assisting a mother with breastfeeding (Choice A) does not typically require gloves unless there are specific reasons for infection control. Administering vaccines (Choice C) and performing umbilical cord care (Choice D) are procedures that may require hand hygiene but not necessarily gloves, unless there is active bleeding or potential exposure to body fluids. The initial bath involves direct contact with body fluids, making it crucial to wear gloves for protection.

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.

Correct Answer: B

Rationale: The correct answer is B. According to the study by Fellman in 2013, the chances of having twins actually increase with parental age. Choice A is incorrect as the study does not specify a younger age for conceiving to increase the chances of twins. Choice C is incorrect as the frequency of intercourse before conception is not a highlighted factor in the study. Choice D is also incorrect as the study does not discuss the impact of fertility drugs on the likelihood of having twins.

Correct Answer: A

Rationale: Jill is a carrier of the recessive gene for Von Willebrand disease. Being a carrier means that she has one copy of the gene but does not show symptoms of the disease. Carriers can pass on the gene to their offspring. Choice B is incorrect as being a carrier does not mean she is susceptible to developing the disease after adolescence. Choice C is incorrect as 'acceptor' is not a term used in genetics in this context. Choice D is incorrect as susceptibility to the disease is not related to late adulthood in carriers of a recessive gene.