Question

Determinate cleavage is found in
A. Coelenterates
B. Annelids
C. Nematodes
D. All the above

Answer 1

Hint: Cleavage is the division of cells in early embryos in developmental biology. The process is followed by fertilization, with a transformation triggered by the activation of the cyclin-dependent kinase complex.

Complete Answer:
- Cleavage is the division of the cells of the early embryo. The cleavage forms morula and ends with the formation of the blastula. There are two types-Determinate and Indeterminate.
- Determined cleavage (also called mosaic cleavage) occurs in most protostomes. As a result, the developmental fate of the cells is set early in the embryo's development. Each blastomere formed by early embryonic cleavage has no capacity to develop into a full embryo.
- Determined cleavage reveals the evolutionary fate of the early embryo development cells. Annelid Larvae, Flatworms, Cnidaria, Nematodes.
- An indeterminate cleavage is a type of cleavage which is based on the formation of blastomeres where blastomeres are formed because of developmental fate of the cleavage which is not decided at an early embryonic stage. This form of cleavage is characteristic of deuterostomes.

So the correct option is D.

Note: The mechanisms of karyokinesis (mitosis) and cytokinesis work together to contribute to cleavage. The mitotic apparatus consists of a central spindle and a polar aster consisting of tubulin protein polymers called microtubules. The asters are nucleated by the centrosomes and the centrosomes are organized by the centrioles carried into the egg by the sperm as a basal body.