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IB Biology HL 2.1.3 Equal and unequal cytokinesis in reproduction Question Bank

Practise IB Biology HL 2.1.3 by analysing how unequal cytokinesis allocates cytoplasm and affects daughter-cell development.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Analyse why budding produces daughter cells with different cytoplasmic volumes.
  • Compare equal cytokinesis in mitosis with unequal division in asexual reproduction.
  • Evaluate how cytoplasmic allocation affects growth, survival and reproductive timing.

D2.1.3—Equal and unequal cytokinesis question 1

[Maximum number: 2]

Ultraviolet (UV) light can penetrate cells, causing DNA damage. This effect can be reduced by using sunscreens or covering skin with clothing.

In an experiment to look at the effect of different treatments to reduce UV damage to DNA, yeast fungus (Saccharomyces cerevisiae) was used as the test organism. Six Petri dishes with agar were inoculated with yeast in sucrose solution. The Petri dishes were labelled according to the treatment applied to the lid, with sunscreen (Sun Protection Factors SPF15 or SPF50), cloth (polyester or cotton) or control (no treatment). Control 1 was placed in the dark and all the other Petri dishes were placed in direct sunlight for 6 hours. The dishes were then incubated for three days. The image shows yeast colonies that grew on the agar in one of the Petri dishes. The bar graph shows the number of yeast colonies present per Petri dish.

Figure for Question D2.1.3—Equal and unequal cytokinesis question 1 — IB Biology HL
Figure for Question D2.1.3—Equal and unequal cytokinesis question 1 — IB Biology HL

Describe how yeast cells reproduce.

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