Development from Zygote to Blastocyst

Q. Which one of the following statements about morula in humans is correct?

1. It has almost equal quantity of cytoplasm as an uncleaved zygote but much more DNA
2. It has far less cytoplasm as well as less DNA than in an uncleaved zygote
3. It has more or less equal quantity of cytoplasm and DNA as in uncleaved zygote
4. It has more cytoplasm and more DNA than an uncleaved zygote

Q.

State whether true or false:
In non-mammalian species, there is no inner cell mass. Instead, the blastula consists of just one cell layer.

1. False

2. True

Q.

Cleavage in the fertilised egg of humans

1. Is discoidal

2. Starts in uterus

3. Is meroblastic

4. Starts when egg is in fallopian tube

Q.

Match the figures with the respective descriptions.

1. Daughter cells that are formed are known as blastomeres.
2. There is no growth phase between divisions during cleavage.
3. Mammalian blastula that contains two distinct cell lineages.
4. Inner cell mass becomes the embryo itself and trophoblast cells help implantation in the uterine wall.

1. i)➡ b, ii)➡ a, iii)➡ d, iv) ➡ c

2. i)➡ d, ii)➡ b, iii)➡ a, iv) ➡ c

3. i)➡ c, ii)➡ d, iii)➡ b, iv) ➡ a

4. i)➡ d , ii)➡ c, iii)➡ a, iv) ➡ b

Q.

Morula differs from the blastula in the

1. Absence of cavity

2. Presence of cavity

3. Absence of yolk

4. None of these

Q. After which cell-stage does the blastulation occur?

1. 4-8 cells
2. 8-16 cells
3. 24-30 cells
4. 60-72 cells

Q.

At the time of implantation, the human embryo is called:

1. embryo

2. zygote

3. blastocyst

4. foetus

Q.

The embryo at the 16-celled stage is known as

1. morula

2. gastrula

3. blastula

4. blastomere

Q. Select the correct explanation for the labels A, B, C and D.

1. A represents the fertilised zygote.
   

2. B represents the stage of morula formation.
   

3. C represents the blastocyst.
   

4. D represents the blastocyst implantation.

Q.

Morula is a developmental stage___________

1. between the zygote and blastocyst

2. between the blastocyst and gastrula

3. between implantation and parturition

4. after the implantation