IB Biology SL D2.1 Cell and Nuclear Division Questions
Practise IB Biology SL D2.1 by identifying mitosis stages, explaining cytokinesis and interpreting cell-division evidence.
- Syllabus
- First assessment 2025
- Course
- Biology SL
- Level
- SL
Exam points
- identify mitosis stages in micrographs and explain how sister chromatids separate
- compare cytokinesis examples, including equal division and unequal budding in yeast
- calculate or interpret mitotic index and chromosome-number changes from cell-division evidence
Covered syllabus points
D2.1.1—Generation of new cellsD2.1.2—CytokinesisD2.1.3—Equal and unequal cytokinesisD2.1.4—Roles of mitosis and meiosisD2.1.5—DNA replication prerequisiteD2.1.6—Shared featuresD2.1.7—Phases of mitosisD2.1.8—Identification of mitosis phasesD2.1.9—Meiosis as reduction divisionD2.1.10—Down syndromeD2.1.11—Meiosis generates variation
Question 1
Which process contributes to growth of a multicellular body?
A
Exocytosis
B
Meiosis
C
Mitosis
D
Osmosis
Question 2
Both the genome and the environment of an organism affect its growth and development. Variation between individuals of a species can be continuous or discrete (discontinuous). Mitosis produces identical cells for growth and meiosis allows for variation.
The micrographs show onion and whitefish cells in mitosis.
Question (a)
(a)
Identify the phase of mitosis labelled X .
[ 1 ]
Question (b)
(b)
The process of cytokinesis is occurring in the whitefish embryo cells. Explain how cytokinesis occurs in this animal cell.
[ 2 ]
Question 3
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.
Describe how yeast cells reproduce.
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