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IB Biology SL D2.1.3 Equal and Unequal Cytokinesis Questions

Analyse how equal and unequal cytokinesis distributes cytoplasm in yeast budding or oogenesis in IB Biology SL D2.1.3.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • Identify yeast budding as unequal cytokinesis in which daughter cells receive different amounts of cytoplasm.

IB Biology SL D2.1.3 Equal and Unequal Cytokinesis Questions 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 IB Biology SL D2.1.3 Equal and Unequal Cytokinesis Questions question 1 — IB Biology SL
Figure for Question IB Biology SL D2.1.3 Equal and Unequal Cytokinesis Questions question 1 — IB Biology SL

Describe how yeast cells reproduce.

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