Amount of yolk and its distribution are changed in the egg. Which one is affected?[1993]a)Pattern of cleavageb)Formation of zygotec)Number of blastomeresd)FertilizationCorrect answer is option 'A'. Can you explain this answer?

Question

Answer

Eggs are classified into 3 types namely microlecithal, alecithal and telolecithal depending on the amount and distribution of yolk which also determines the direction of cleavage

so ans A Pattern of cleavage

Answer

Pattern of cleavage becoz if distribution of yolk is changed means furrow for the purpose of cleavage will disturb

Answer

Pattern of cleavage is affected.

Explanation:
- Cleavage is the process of rapid cell division that occurs after fertilization of the egg.
- During cleavage, the fertilized egg or zygote undergoes multiple divisions to form a multicellular embryo.
- The pattern of cleavage determines the arrangement and distribution of cells in the developing embryo.
- The amount of yolk and its distribution in the egg directly affects the pattern of cleavage.
- Yolk is a nutrient-rich substance found in eggs that provides nourishment to the developing embryo.
- In eggs with a large amount of yolk, such as bird eggs, the yolk is concentrated in the vegetal pole, while the animal pole contains less yolk.
- The presence of yolk affects the movement and distribution of cytoplasm during cleavage.
- In eggs with a moderate amount of yolk, known as mesolecithal eggs, cleavage is holoblastic and equal, meaning that the entire egg is divided into smaller cells during each division.
- However, in eggs with a large amount of yolk, known as macrolecithal eggs, cleavage is meroblastic and unequal.
- In meroblastic cleavage, only a small portion of the egg, known as the blastodisc, undergoes cell division, while the rest of the yolk remains undivided.
- The unequal distribution of yolk affects the distribution of cytoplasmic components and influences the pattern of cleavage.
- In macrolecithal eggs, cleavage is typically discoidal, where the blastodisc forms a disc-shaped layer on top of the yolk.
- The blastodisc undergoes cleavage while the yolk remains undivided, resulting in an embryo that is layered on top of the yolk.
- Therefore, the amount of yolk and its distribution in the egg directly affect the pattern of cleavage during embryonic development.

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