Question

33. Stages of embryonic development

-the heart begins to beat

-inner cell mass differentiates into three germ layers

-mitosis leads to a 100-cell mass

-implantion occurs in the endomentrium

the embryonic development listed above occur in the sequence_,_,_,and _

34.which of the following correctly identifies the stages in embryonic development between weeks 2 and 8?

a) gastrualation --> neurulation and placental formation --> organ formation

b)formation of placenta -->gastrualation --> organ formation --> neurulation

c) gastrualation-->organ formation-->neuralation-->formation of placenta

d)formation of placenta-->neuralation-->organ formation-->gastrualation

35.all of the following events occur by the end of the eighth week of gestation except

a)the heart begins to pump, and red blood cells are formed in the liver

b)the embryo is about the size of a fig or just over 3 inches and weighs about 1.5 teaspoon of water

c) the limb buds form distinct fingers and toes, and the face can be seen

d)cartilages are starting to be replaced with bones

e)the reproductive structures have formed, and the gender of the baby can be determined through ultrasound

36. match the following numbered functions above with the correct structures listed below

structure:

Chorion_

Allantois_

Yolk sac_

Amnion_

Functions:

-encloses and protects the embryo and fetus from temperature fluctuations and trauma

-will form the umbilical cord and become part of the urinary bladder

-provides nutrients and blood circulation for the first two weeks of gestation

-is developed from the trophoblast layer of the blastocyst and forms the fetal portion of the placenta

37. What is the source of energy for the embryo immediately following the fertilization?

a) mitochondria

b)placenta

c)cytoplasm of the egg

d)amniotic fluid

38. the development of a zygote into a baby pre-embryonic development for the first two weeks, followed by embryonic development for the next six weeks, and finally fetal development until the baby is born. When is the developing baby considered a fetus?

a)when all the major organ systems have formed

b)when most major organ systems have formed;the neural system forms during the fetal stage

c)after neural tube forms

d)once gastrulation is complete

39.when doctors discuss prenatal development, they often calculate the due date from the first day of menstruation. In fact, the babys gestational age is calculated from the first dat of menstruation. At a maternity clinic, an obstetrician mentions that when a women is 10 weeks pregnant, the baby is referred to as a fetus

Which of the following is the correct calculation of the babys age from moment of fertilization, assuming a 28-day ovarian cycle?

a)the baby is 10 weeks old as stated by the doctor

b)the baby is 12 weeks old and at the end of the first trimester

c)the baby is 8 weeks old. This is when organ formation has completed.

d)the baby is in its second trimester. This is when they are referred to as a fetus.

40. Some embryos share many similarities and are difficult to tell apart, while others are slightly easier. What can conclude about the similarities and differences between the embryos of different species?

a)the more distantly related species show differences in only the later stages

b)the more closely related species share similarities until the later stages

c)the more closely related species show differences from the earlier stages

d)the more distantly related species share similarities until later stages.