Which is the purpose of the ovum's zona pellucida? a. Prevents ...

[nautica902]

Which is the purpose of the ovum's zona pellucida?
 
  a. Prevents multiple sperm from fertilizing the ovum
  b. Stimulates the ovum to begin mitotic cell division
  c. Allows the 46 chromosomes from each gamete to merge
  d. Makes a pathway for more than one sperm to reach the ovum

Question 2

One of the assessments performed in the birth room is checking the umbilical cord for blood vessels. Which finding is considered to be within normal limits?
 
  a. One artery and one vein
  b. Two veins and one artery
  c. Two arteries and one vein
  d. Two arteries and two veins

[jessicaduplan]

Answer to Question 1

ANS: A
Fertilization causes the zona pellucida to change its chemical composition so that multiple sperm cannot fertilize the ovum. Miotic cell division begins when the nuclei of the sperm and ovum unite. Each gamete (sperm and ovum) has only 23 chromosomes; there will be 46 chromosomes when they merge. Once sperm has entered the ovum, the zona pellucida changes to prevent other sperm from entering.

Answer to Question 2

ANS: C
The umbilical cord contains two arteries and one vein to transport blood between the fetus and the placenta. Any option other than two arteries and one vein is considered abnormal and requires further assessment. Two veins and one artery is abnormal and may indicate an anomaly. Two arteries instead of one is considered normal; this infant would require further assessment for other anomalies.

[nautica902]

TYSM

[xiaomengxian]

Gracias!