IB Biology HL B2.3 Cell Specialization Questions

Practise IB Biology HL B2.3 with evidence-led questions on stem-cell potency, differentiation, exchange surfaces and the structure–function adaptations of specialized cells.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • identify stem-cell potency and explain differentiation through gene expression and signalling gradients
  • relate surface-area-to-volume ratios and specialized structures to efficient exchange or absorption
  • deduce how pneumocytes, cardiac muscle and gametes use structure to perform specialized functions

Question 1

[Maximum number: 3]

Outline reasons for the therapeutic use of stem cells.

Question 2

[Maximum number: 3]

Stem cells in the bone marrow can be forced into blood vessels in a process called mobilization. Mobilization of stem cells from the bone marrow into the blood vessels represents the basis for modern bone marrow transplantation procedures.

To test the effect of light on the mobilization of stem cells, mice were subjected to a simulated "jet lag" by advancing the light-dark cycle by 12 hours. This was done by subjecting mice to a 24-hour light period before the results shown in the graph were recorded. The results were compared to the stem cells in control mice under normal conditions of 12 hours of light (□) and 12 hours of darkness (dark box).

Figure for Question 2 — IB Biology HL
Figure for Question 2 — IB Biology HL

Compare the effect of isoprenaline and clenbuterol with the normal release of stem cells and the production of mRNA for CXCL12.

Figure for Question 2 — IB Biology HL

Question 3

[Maximum number: 1]

Which is a description of stem cells?

A

Hair follicle stem cells are pluripotent.

B

Stem cells in bone marrow are multipotent.

C

Very early embryo stem cells are pluripotent.

D

Late embryo stem cells are totipotent.

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