AIIMS 2003
- Exam
- AIIMS
- Year
- 2003
- Subject
- Zoology
- Chapter
- Human Reproduction
AIIMS 2003 · Zoology · Human Reproduction
Assertion : Holoblastic cleavage with almost equal-sized...
Assertion : Holoblastic cleavage with almost equal-sized blastomeres is a characteristic of placental animals.
Reason : Eggs of most mammals, including humans, are of centrolecithal type.
Options
- AIf both Assertion and Reason are true and the reason is the correct explanation of the assertion
- BIf both Assertion and Reason are true but the reason is not the correct explanation of the assertion
- CIf Assertion is true statement but Reason is false
- Dif both Assertion and Reason are false statements
Correct answer
C. If Assertion is true statement but Reason is false
Step-by-step solution
In holoblastic cleavage, the cleavage furrows bisect the entire egg, or in other words, entire egg divides by each cleavage furrow. In placental mammals having isolecithal or microlecithal egg, the holoblastic cleavage produces blastomeres of equal or approximately equal size.
Centrolecithal eggs are found in insects and in some hydrozoa. Here, yolk is concentrated at the centre of egg and the cytoplasm is present surrounding it. Meroblastic cleavage occurs in them.