19) Which of the following does NOT occur during mitosis? A) condensation of the

Question

19) Which of the following does NOT occur during mitosis? A) condensation of the chromosomes C) spindle formation B) separation of the spindle poles Diseplication of the DNA 20) Once a cell completes mitosis, molecular division triggers must be turned off. What happens to molecular division triggers must be turned off What happens to MPF during mitosis? A) The cyclin component of MPF is degraded. B) The Cdk component of MPF is degraded and exported from the cell. C) It is completely degraded. D) It is exported from the cell. 21) The M-phase checkpoint ensures that all chromosomes are attached to the mitotic spindle. If this 21) does not happen, cells would most likely be arrested in A) prometaphase B) prophase C) telophase D) metaphase 22) Cyclin-dependent kinase (Cdk) is 22) A) an enzyme that attaches phosphate groups to other proteins B) present only during the S phase of the cell cycle C) the enzyme that catalyzes the attachment of chromosomes to microtubules D) inactive, or "turned off," in the presence of cyclin 23) Motor proteins require which of the following to function in the movement of chromosomes 23) toward the poles of the mitotic spindle? A) synthesis of cohesin C) intact centromeres B) a microtubule-organizing center D) ATP as an energy source 24) Some cells have several nuclei per cell. How could such multinucleated cells be explained? 24) A) The cell had multiple S phases before it entered mitosis B) The cell underwent repeated cytokinesis but no mitosis. C) The cell underwent repeated mitosis with simultaneous cytokinesis The cell underwent repeated mitosis, but cytokinesis did not occur. 25) In human and many other eukaryotic species' cells, the nuclear membrane has to disappear to 25) permit A) the attachment of microtubules to kinetochores the splitting of the centrosomes C) the disassembly of the nucleolus D) cytokinesis 26) 26) If a horticulturist breeding gardenias succeeds in having a single plant with a particularly desirable set of traits, which of the following would be her most probable and efficient route to establishing a line of such plants? A) Clone the plant. B) Backtrack through her previous experiments to obtain another plant with the same traits. C) Breed this plant with another plant with much weaker traits. D) Force the plant to self-pollinate to obtain an identical one.

Explanation / Answer

Question 19.

Ans-- D) Duplication of the DNA

Discussion: Mitosis is a process in which one mother cell is divided into two genetically identical daughter cells.

Different events during mitosis: i) Condensation of the chromosome started ii) Formation of mitotic spindle (by microtubule fiber) iii) Breaking down of nucleus as the nucleolus disappears iv) releasing of the chromosome and capturing of them by the spindle fiber v) Arrangement of the chromosome at metaphase plate with its centromere attached to the microtubules of opposite spindle pole. vi) two sets of chromosome reached at two poles and decodensed vii) Formation of two nucleus and nuclear membrane reappear followed by the cytokinesis.

Question 20.

Ans -- The cyclin component of MFP is degraded

MFP (M-Phase promoting factor) is basically responsible for transferring a phosphate group from ATP to the targeted protein. The action of MFP is broadly dependent on the combined action of two proteins i) CDK ii) cyclin.
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During the mitosis cyclin degrading enzyme activated and result in the reduced amount of cyclin. As a result, the activity of the MFP is also down-regulated.

Question 21.

Ans-- A) Prometaphase

Discussion: Prometaphase is the intermediate phase of prophase and metaphase. If the centromere of the condensed chromosomes are not properly attached with the spindle microtubule properly at the metaphase plate then the spindle checkpoint activated and stop the cell cycle at the prometaphase stage. The cell cycle will further revive when all the chromosomes attached properly and processed to the metaphase followed by anaphase.

Question 22

Ans-- A)an enzyme that attaches a phosphate group to the protein

Question 23.

Ans-- D) ATP as an energy source

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