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CAIE A-Level Biology AS 5.2 Chromosome Behaviour in Mitosis Questions

Practise mitosis questions by identifying stages from micrographs, tracking spindle and centromere behaviour and explaining chromosome separation.

Syllabus
2028–2030
Course
Biology 9700
Level
AS

Exam points

  • identify prophase, metaphase, anaphase and telophase from diagrams or photomicrographs
  • track spindle microtubules, centromeres and sister chromatids during chromosome separation
  • describe nuclear-envelope breakdown or re-formation and chromosome condensation or uncoiling

Covered syllabus points

5.2.1—Chromosome behaviour in mitosis5.2.2—Cell structures in mitosis5.2.3—Main stages of mitosis5.2.4—Mitosis image interpretation

Question 1

[Maximum number: 1]

During interphase of the cell cycle, individual chromosomes cannot be seen within the nucleus. The genetic material is termed chromatin during this stage.

Changes occur to chromatin during mitosis so that chromosomes become visible.

State what happens to chromatin so that individual chromosomes can be seen during mitosis.

Question 2

[Maximum number: 3]

The root apical meristem is a region of undifferentiated cells in the root tips of plants. Mitosis occurs in this region.

Question (a)

(a)

Fig. 1.1 is an image of the root tip of Allium as observed using a microscope with a low-power objective lens.

Fig. 1.1

Fig. 1.1

State which region, B, C, or D, should be chosen in order to observe the highest proportion of cells in stages of mitosis.

[ 1 ]

Question (b)

(b)

Describe the behaviour of the nuclear envelope during mitosis.

[ 2 ]

Question 3

[Maximum number: 1]

Fig. 3.1 shows the nematode worm, Caenorhabditis elegans.

Fig. 3.1

Fig. 3.1

Stem cells of C. elegans have been studied.
Fig. 3.2 shows the change in mass of DNA per nucleus in a stem cell during one cell cycle.
1pg=1×10−12 g1 \mathrm{pg}=1 \times 10^{-12} \mathrm{~g}

Fig. 3.2

Fig. 3.2

State the stage of mitosis shown by D in Fig. 3.2.

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