downs syndrome is caused by

HESI LPN

HESI Maternal Newborn

1. What causes Down's syndrome?

A. Alcohol abuse by the mother at the time of conception.
B. Sex-linked chromosomal abnormalities.
C. An extra chromosome on the 21st pair.
D. Drug abuse by the mother during pregnancy.

Correct answer: C

Rationale: Down's syndrome, also known as trisomy 21, is caused by the presence of an extra chromosome on the 21st pair. Choice A is incorrect as alcohol abuse is not the cause of Down's syndrome. Choice B is incorrect because Down's syndrome is not related to sex-linked chromosomal abnormalities. Choice D is also incorrect as drug abuse by the mother during pregnancy is not the cause of Down's syndrome.

2. A client is 4 hours postpartum and is experiencing hypovolemic shock. Which of the following actions should the nurse take?

A. Administer indomethacin
B. Insert a second 22-gauge IV catheter.
C. Insert an indwelling urinary catheter.
D. Administer oxygen at 4L/min via nasal cannula.

Correct answer: D

Rationale: In hypovolemic shock, there is decreased oxygen delivery to tissues. Administering oxygen at 4L/min via nasal cannula can help improve oxygenation and support tissue perfusion. Indomethacin (Choice A) is a nonsteroidal anti-inflammatory drug and is not indicated in the management of hypovolemic shock. Inserting a second 22-gauge IV catheter (Choice B) may be necessary for fluid resuscitation, but oxygen administration takes precedence. Inserting an indwelling urinary catheter (Choice C) may be considered for monitoring urinary output, but it is not the priority action in managing hypovolemic shock.

3. Which of the following statements is true of menstruation?

A. During this time, the endometrium is shed.
B. During this time, an unfertilized egg is discharged.
C. During this time, a female can engage in sexual activity with her partner.
D. During this time, a fertilized egg implants in the uterine lining.

Correct answer: B

Rationale: The correct statement regarding menstruation is that during this time, an unfertilized egg is discharged along with the shedding of the uterine lining. Choice A is incorrect because the endometrium is shed during menstruation. Choice C is incorrect as menstruation does not prevent a female from engaging in sexual activity with her partner. Choice D is incorrect as a fertilized egg does not undergo mitosis during menstruation but rather implants in the uterine lining for further development.

4. After meiosis, each new cell nucleus contains _____ chromosomes.

A. 46
B. 35
C. 23
D. 12

Correct answer: C

Rationale: After meiosis, each resulting cell contains 23 chromosomes. Meiosis is a process that involves two sequential divisions resulting in four daughter cells, each with half the number of chromosomes as the parent cell. In humans, the parent cell has 46 chromosomes (diploid), and after meiosis, the resulting cells (sperm or ova) have 23 chromosomes (haploid). Choice A (46 chromosomes) is incorrect because this is the number of chromosomes in a human diploid cell before meiosis. Choices B (35 chromosomes) and D (12 chromosomes) are incorrect as they do not represent the correct number of chromosomes after meiosis in human cells.

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.