CourseCourseConceptConceptDocumentDocument

IB Biology HL D2.1.12 Hl Cell Proliferation Questions

Repeated mitosis increases cell number. This supports plant growth in meristems, early development, skin replacement and wound healing.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Calculate mitotic index or the number of cells undergoing mitosis from cell counts and table data.
  • Interpret how changes in mitotic index reflect cell proliferation, including changes across extract concentrations.
  • Relate meristems and repeated mitosis to the continued production of plant roots, leaves and stems.

IB Biology HL D2.1.12 Hl Cell Proliferation Questions question 1

[Maximum number: 4]

Question (a)

(a)

The photomicrograph shows a section of onion (Allium cepa) root tip cells.

× 1000

× 1000

[ 2 ]

Question (i)

(i)

Describe how a mitotic index could be obtained from this image.

[ 2 ]

Question (b)

(b)

Cadmium is a heavy metal that can cause environmental problems. Cadmium ions are released from various human activities such as the release of sewage sludge, mining and industrial processes. Plants take up cadmium ions and they enter food chains.

A study was carried out to look at the effect of various concentrations of cadmium ions on the mitotic index of the apical meristem of root cells from 4-day-old wheat (Triticum aestivum) seedlings.

Figure for Question (b) — IB Biology HL
[ 2 ]

Question (i)

(i)

State the effect of cadmium ion concentration on the mitotic index of root cells from wheat seedlings.

[ 1 ]

Question (ii)

(ii)

Suggest the effect the change in mitotic index would have on the wheat plant.

[ 1 ]
All question bank results loaded