which of the following statements is true of downs syndrome

HESI LPN

HESI Maternity 55 Questions

1. 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.

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. The nurse has received a report regarding a client in labor. The woman’s last vaginal examination was recorded as 3 cm, 30%, and –2. What is the nurse’s interpretation of this assessment?

A. Cervix is effaced 3 cm and dilated 30%; the presenting part is 2 cm above the ischial spines.
B. Cervix is dilated 3 cm and effaced 30%; the presenting part is 2 cm above the ischial spines.
C. Cervix is effaced 3 cm and dilated 30%; the presenting part is 2 cm below the ischial spines.
D. Cervix is dilated 3 cm and effaced 30%; the presenting part is 2 cm below the ischial spines.

Correct answer: B

Rationale: The correct interpretation of the assessment provided is that the cervix is dilated 3 cm and effaced 30%; the presenting part is 2 cm above the ischial spines. In the given assessment, the measurements are ordered as dilation, effacement, and station. Choice A is incorrect as it wrongly places the presenting part below the ischial spines. Choice C is incorrect because it places the presenting part below the ischial spines. Choice D is also incorrect as it incorrectly states that the presenting part is below the ischial spines, even though it correctly mentions the dilation and effacement of the cervix.

4. What is the primary role of meiosis in the production of sperm and ova?

A. To reduce the chromosome number by half
B. To increase the chromosome number
C. To create identical copies of chromosomes
D. To repair damaged chromosomes

Correct answer: A

Rationale: The correct answer is A. Meiosis is a type of cell division that reduces the chromosome number by half, resulting in the formation of sperm and ova. Choice B is incorrect because meiosis does not increase the chromosome number. Choice C is incorrect because meiosis creates genetically diverse gametes, not identical copies of chromosomes. Choice D is incorrect because meiosis does not primarily function to repair damaged chromosomes.

5. What is the structure of deoxyribonucleic acid (DNA)?

A. single spiral
B. double helix
C. sphere
D. cube

Correct answer: B

Rationale: The correct answer is B: double helix. DNA is structured as a double helix, resembling a twisted ladder made up of two strands of nucleotides. Choice A, single spiral, is incorrect as DNA is not a single spiral structure. Choice C, sphere, is incorrect as DNA does not form a spherical shape. Choice D, cube, is incorrect as DNA does not have a cubic structure. Understanding the double helix structure of DNA is essential as it allows for the storage and transmission of genetic information in living organisms.