A2.2 Cell structure questions for IB Biology
39 questions on Cell structure, written by Augment in the style of IB exam papers. Six of them are below in full, to answer on paper.
- IB Biology
- Part of A Unity and diversity
- SL and HL
Questions by paper and level
SL and HL questions are for students at either level. HL only questions cover what only HL students study.
| Paper | SL and HL | HL only | All |
|---|---|---|---|
| Paper 1A | 15 | 5 | 20 |
| Paper 1B | 4 | 1 | 5 |
| Paper 2 | 8 | 6 | 14 |
| Every paper | 27 | 12 | 39 |
Counted on
Questions to try
Written by Augment in the style of IB exams, not past papers. Answer them on paper, then check each one against its markscheme with a free account.
A previously unknown microorganism is collected from a deep-sea hydrothermal vent. Before examining it, biologists predict that it will consist of one or more cells. Which type of reasoning are they using?
Students compared the length of epidermal cells from two regions of the same fleshy leaf of an onion (Allium cepa) bulb: near its base and near its tip. A strip of inner epidermis from each region was mounted in a drop of iodine solution under a cover slip. Using a light microscope at ×100, they measured the length of eight cells from each region with an eyepiece graticule. At this magnification, 10 eyepiece units corresponded to 100 µm on a stage micrometer.
Region of leaf | Cell lengths / eyepiece units | Mean / eyepiece units | Standard deviation / eyepiece units |
|---|---|---|---|
Base | 18, 22, 20, 25, 19, 21, 23, 20 | 2.3 | |
Tip | 31, 28, 35, 30, 33, 27, 34, 30 | 31.0 | 2.8 |
- (a)
Outline how the eyepiece graticule was calibrated.
2 marks
- (b)
Calculate the mean length, in µm, of the cells from the base of the leaf.
2 marks
- (c)
Suggest why the cells were mounted in iodine solution.
1 mark
- (d)
A photograph taken through the microscope was printed. On the print, a cell that is 250 µm long measures 50 mm. Calculate the magnification of the print and state the length that a 100 µm scale bar would have on it.
2 marks
- (e)
Evaluate whether the data show a difference between the cells from the base and the tip of the leaf.
2 marks
- (f)
Suggest one improvement to the method that would increase confidence in the conclusion.
1 mark
Evolution has been occurring over an immense length of time.
- (a)
Discuss the evidence that the last universal common ancestor (LUCA) evolved in the vicinity of hydrothermal vents.
7 marks
- (b)
Outline approaches used to estimate the dates of the first living cells and of LUCA.
4 marks
- (c)
Describe the evidence that mitochondria originated by endosymbiosis.
4 marks
In an electron micrograph a mitochondrion is 36 mm long. The magnification of the micrograph is ×24 000. What is the actual length of the mitochondrion?
Paramecium caudatum is a unicellular organism that lives in fresh water. Students placed Paramecium in pond water to which sodium chloride had been added to give five concentrations. After 10 minutes, they placed a drop of each culture on a slide and used a stopwatch to measure the time between successive contractions of a contractile vacuole. Ten vacuoles in different cells were timed at each concentration.
Concentration of NaCl added / mmol dm-3 | Mean time between contractions / s | Standard deviation / s |
|---|---|---|
0 | 6.2 | 0.8 |
25 | 9.5 | 1.1 |
50 | 14.8 | 1.9 |
75 | 23.6 | 2.7 |
100 | 38.0 | 5.2 |
- (a)
State the dependent variable in this investigation.
1 mark
- (b)
Calculate the number of contractions per minute of a contractile vacuole in pond water with no added sodium chloride.
1 mark
- (c)
Describe the effect of sodium chloride concentration on the activity of the contractile vacuoles.
2 marks
- (d)
Explain the effect of sodium chloride concentration on the activity of the contractile vacuoles.
3 marks
- (e)
In some groups, students added a drop of methyl cellulose solution to slow the movement of the cells. Suggest why this could make their results invalid.
1 mark
- (f)
State the process of life in unicellular organisms that contractile vacuoles carry out.
1 mark
The boundary between living and non-living things is not always clear.
- (a)
Outline the processes of life carried out by unicellular organisms.
4 marks
- (b)
Outline the roles of mRNA, ribosomes and tRNA when a viral gene is translated inside a host cell.
4 marks
- (c)
Discuss whether viruses should be considered living organisms.
7 marks
Practice all 39 in Augment
Free with an account. Every question has its markscheme, and Augment keeps the ones you got wrong so you can come back to them.
More questions in Unity and diversity
- A1.1Water
- A1.2Nucleic acids
- A2.1Origins of cellsHL only
- A2.2Cell structureThis page
- A2.3VirusesHL only
- A3.1Diversity of organisms
- A3.2Classification and cladisticsHL only
- A4.1Evolution and speciation
- A4.2Conservation of biodiversity
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