twins that derive from a single zygote that has split into two are called

HESI LPN

HESI Maternity 55 Questions

1. Twins that derive from a single zygote that has split into two are called:

A. monozygotic (MZ) twins.
B. fraternal twins.
C. non-identical twins.
D. dizygotic (DZ) twins.

Correct answer: A

Rationale: The correct answer is A: monozygotic (MZ) twins. Monozygotic twins, also known as identical twins, occur when a single zygote splits into two embryos, leading to two genetically identical individuals. Choice B, fraternal twins, are twins that develop from two separate eggs fertilized by two different sperm cells, resulting in non-identical siblings. Choice C, non-identical twins, is not a common term used to describe this type of twinning. Choice D, dizygotic (DZ) twins, refer to twins that develop from two separate eggs fertilized by two different sperm cells, leading to non-identical twins.

2. A multiparous woman has been in labor for 8 hours. Her membranes have just ruptured. What is the nurse’s highest priority in this situation?

A. Prepare the woman for imminent birth.
B. Notify the woman’s primary healthcare provider.
C. Document the characteristics of the fluid.
D. Assess the fetal heart rate (FHR) and pattern.

Correct answer: D

Rationale: The correct answer is to assess the fetal heart rate (FHR) and pattern (Choice D). When a multiparous woman's membranes rupture after 8 hours of labor, the nurse's priority is to assess the fetal well-being. Rupture of membranes can lead to potential complications such as umbilical cord prolapse. Monitoring the fetal heart rate and pattern immediately after the rupture of membranes is crucial to ensure the fetus is not in distress. This assessment helps in determining the need for immediate interventions to safeguard the fetus. Documenting the characteristics of the fluid (Choice C) may be necessary but is of lower priority compared to assessing fetal well-being. While preparing the woman for imminent birth (Choice A) is important, assessing the fetal heart rate takes precedence to ensure the fetus is not compromised. Notifying the woman's primary healthcare provider (Choice B) is also important but not the highest priority at this moment.

3. The client who is 40 weeks gestation seems upset and tells the nurse that the physician told her she needs to have a nonstress test. The client asks why she needs the test. The nurse’s best response would be:

A. This is a test to see if your stress level is affecting your baby’s growth and well-being.
B. This is a test to see if your baby will be able to withstand the stress of labor.
C. This is a test to assess your baby’s well-being now that you are due to deliver soon.
D. This is a test to let us know if your baby needs to be delivered to avoid a bad outcome.

Correct answer: C

Rationale: The correct response is C because the nonstress test is specifically used to assess the baby's well-being close to the due date. It helps determine if the baby is receiving enough oxygen and nutrients in the womb. Choice A is incorrect as the test does not assess the mother's stress level but focuses on fetal well-being. Choice B is incorrect as the test does not predict the baby's ability to withstand labor. Choice D is incorrect because the test does not solely indicate if the baby needs to be delivered to avoid a bad outcome; rather, it assesses the current well-being of the baby.

4. Once the testes have developed in the embryo, they begin to produce male sex hormones, or _____.

A. androgens
B. genotypes
C. blastocysts
D. teratogens

Correct answer: A

Rationale: Androgens are male sex hormones, such as testosterone, produced by the testes after they have developed in the embryo. Androgens are responsible for the development of male secondary sexual characteristics. Genotypes refer to an individual's genetic makeup, not hormones. Blastocysts are early stage embryos, not male sex hormones. Teratogens are substances that can interfere with fetal development, not male sex hormones produced by the testes.

5. 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.