FREE NEET Biology Practice MCQ Test: Cell Cycle And Cell Division Exercise 3 Questions Answers With Detailed Explanations [PDF]

Answer: (c)

Metaphase chromosome is made up of two sister chromatids which are held together by the centromere. Chromosomes are moved to spindle equator and gets aligned along metaphase plate through spindle fibres to both poles.

Answer: (c)

In S-phase (synthetic phase) of cell cycle, the chromosomes replicate. For this their DNA molecules function as templates and form carbon copies. The DNA content doubles i.e., 1C to 2C for haploid cells and 2C to 4C for diploid cells. As a result duplicate sets of genes are formed. Along with replication of DNA new chromatin fibres are formed which, however, remain attached in pairs and the number of chromosomes does not increase. As chromatin fibres are elongated chromosomes, each chromosome comes to have two chromatin threads or sister chromatids which remain attached at a common point called centromere.

Answer: (a)

Answer: (c)

In metaphase, chromosomes consisting of two sister chromatids get arranged at equator. Discontinuous fibres radiate out from two spindle poles and get connected to the disc shaped structure at the surface of the centromere called kinetochores. These are known as chromosome fibres or tractile fibrils. A kinetochore is a complex protein structure that is analogous to a ring for the microtubule hook; it is the point where microtubules attach themselves to the chromosome.

Answer: (c)

Answer: (b)

Answer: (a)

Answer: (c)

During Anaphase I, the homologous chromosomes separate, after breaking apart (the process is called disfunction) while sister chromatids remain associated at their centromeres.

Answer: (d)

In mitosis chromosomes move to the equator and get aligned along equatorial plate in metaphase.

Answer: (a)

Mitosis occurs both in somatic cells as well as in germ cells of the gonads. In plants mitosis occurs in the meristematic cells of root tip or shoot tip. These cells divide at a faster rate. So the root tip shows active cell division and are used in the laboratory to study mitosis. For studying meiosis young anthers are used.

Answer: (b)

Answer: (d)

Mitotic anaphase differs from metaphase in possessing same number of chromosomes and half number of chromatids. During anaphase of mitosis, chromosomes divide at the point of centromere or kinetochore and thus two sister chromatids are formed which are called as chromosomes. While during metaphase, chromosomes become maximally distinct due to further contraction and thus size of chromosomes is measured at mitotic metaphase.

Answer: (a)

Answer: (b)

Answer: (a)

Answer: (d)

Answer: (b)

Sister chromatids are the two identical strands of a duplicated chromosome. So, it carries the same genetic information.

Answer: (c)

Answer: (d)

The plane of alignment of the chromosomes at metaphase is referred to as the metaphase plate. The key features of metaphase are, (1) Spindle fibres attach to kinetochores of chromosomes (2) Chromosomes are moved to spindle equator and get aligned along metaphase plate through spindle fibres to both poles.

Answer: (a)