Cleavage - Advance

Cleavage - Advance

Dear Readers,

Cleavage is the division of cells in the early embryo. The process follows fertilisation, with the transfer being triggered by the activation of a cyclin-dependent kinase complex.The zygotes of many species undergo rapid cell cycles with no significant overall growth, producing a cluster of cells the same size as the original zygote. The different cells derived from cleavage are called blastomeres and form a compact mass called the morula. Cleavage ends with the formation of the blastula.

Q1. The rate of cleavage is inversely proportional to the duration of

•  Anaphase
•  Metaphase
•  Interphase
•  Telophase

Interphase

Q2. Which of the following structure is found in blastula

•  Segmentation cavity
•  Notochord
•  Gill
•  Tail

Segmentation cavity

Q3. In which of the following animal cleavage divisions are restricted to a small part of cytoplasm and nucleus in animal pole of egg

•  Cockroach
•  Frog
•  Chick
•  Rabbit

Chick

Q4. Select the correct statement

•  Cleavage follows gastrulation
•  Yolk content of egg has no role in cleavage
•  Cleavage is repeated mitotic division of zygote
•  Gastrulation and blastulation are followed by each other

Cleavage is repeated mitotic division of zygote

Q5. Cleavage is unique form of mitotic cell division in which

•  The nucleus does not participate
•  There is no growth of cells
•  No spindle develops to guide the cells
•  The plasma membranes of daughter cells do not separate

There is no growth of cells

Q6. Holoblastic cleavage may occur in eggs which are

•  Oligolecithal only
•  Mesolecithal only
•  Macrolecithal only
•  Oligolecithal and mesloecithal both

Oligolecithal and mesloecithal both

Q7. As a result of cleavages, if blastomeres are symetrically placed around the polar axis the type of cleavage is known as

•  Spiral
•  Discoidal
•  Biradial
•  Radial

Radial

Q8. Meroblastic cleavage refers to one of the following types of division of eggs

•  Total
•  Partial
•  Spiral
•  Horizontal

Partial

Q9. The ratio of the nucleus to cytoplasm at the beginning of cleavage is

•  Very low
•  Very high
•  Normal
•  A bit higher than the normal

Very low

Q10. A blastula which is solid, is known as

•  Stereoblastula
•  Coeloblastula
•  Superficial blastula
•  Discoblastula

Stereoblastula