Year 11 · 2025 syllabus · 30 marks · Suggested 45 min

Biology: cells and evidence

A focused assessment of cell structures, membranes, cell size and exchange, microscopy and experimental evidence. The 2025 syllabus starts Year 11 teaching in 2027; these questions match the site's published 2025 lessons. This is not a whole-course paper.

Focus outcomes: BI-11-01, BI-11-02; BI-11WS-02,04,05,07. Original HSCScience questions; not an official NESA paper.

Return to student paper →

Check your own evidence

Tick only criteria supported by your response. This is a self-assessment, not a teacher-awarded result or predicted HSC mark. Use the linked lessons to repair missing evidence.

0 of 30 evidence points checked

Question 1 (1 mark)

Which feature is shared by a typical bacterium and a plant cell?

Answer and explanation

Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.

B: Ribosomes. Both have ribosomes for protein synthesis. Bacteria lack the membrane-bound organelles listed in the other options.

Repair this skill in the lesson →

Question 2 (1 mark)

Water moves into a cell through a selectively permeable membrane. Which description best identifies osmosis?

Answer and explanation

Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.

A: Net water movement down a water concentration gradient. Osmosis is the net movement of water across a selectively permeable membrane. A more rigorous account uses water potential.

Repair this skill in the lesson →

Question 3 (1 mark)

A 40× objective is combined with a 10× eyepiece. What is the total magnification?

Answer and explanation

Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.

C: 400×. Multiply objective and eyepiece magnifications: 40 × 10 = 400.

Repair this skill in the lesson →

Question 4 (1 mark)

A membrane protein transports ions against their concentration gradient using ATP. Which process is occurring?

Answer and explanation

Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.

D: Active transport. Moving ions against the gradient requires an energy input. Facilitated diffusion is down the gradient.

Repair this skill in the lesson →

Question 5 (3 marks)

Explain how the nucleus, ribosomes and rough endoplasmic reticulum contribute to producing a protein that will be secreted.

Marking criteria

Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.

The nucleus contains DNA; genetic information is transcribed into RNA instructions.
Ribosomes translate the instructions into a polypeptide.
Rough ER supports synthesis and processing of proteins destined for secretion; link the structures as a coordinated pathway.

One possible response

DNA information in the nucleus is transcribed into messenger RNA. Ribosomes associated with rough ER translate the RNA into a polypeptide. The rough ER processes and transports the protein towards further modification and secretion.

Repair this skill in the lesson →

Question 6 (3 marks)

A cell image is 24 mm wide at a stated magnification of 600×. Calculate the actual width in micrometres and explain one reason why magnification alone does not guarantee a clear image.

Marking criteria

Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.

Use actual size = image size ÷ magnification: 24 ÷ 600 = 0.040 mm.
Convert 0.040 mm to 40 µm, with the unit.
Resolution determines whether close features can be distinguished; increasing magnification cannot recover detail beyond the resolving limit.

One possible response

Actual width = 24 mm ÷ 600 = 0.040 mm = 40 µm. A highly magnified image may still be blurry because resolution, rather than magnification alone, limits the detail that can be distinguished.

Repair this skill in the lesson →

Question 7 (3 marks)

Distinguish a plant cell wall from its plasma membrane, relating each structure to a function.

Marking criteria

Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.

The cell wall is outside the plasma membrane and contains cellulose in typical plant cells.
The wall provides structural support and helps resist excessive expansion.
The plasma membrane is selectively permeable and regulates transport between the cell and its surroundings.

One possible response

The cellulose wall outside the membrane supports the cell and resists excessive expansion. The plasma membrane is a selectively permeable boundary that regulates the passage of substances. The wall does not replace membrane transport control.

Repair this skill in the lesson →

Question 8 (3 marks)

Potato cylinders were left in solutions for 30 minutes. Calculate the mean percentage mass change in solution B. Use the data to infer which solution is closest to having no net mass change. State a limit to that inference.

Synthetic classroom data: percentage mass change after 30 min
Solution	Trial 1 (%)	Trial 2 (%)	Trial 3 (%)
A	5	6	4
B	1	0	-1
C	-6	-4	-5

Marking criteria

Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.

Mean for B = (1 + 0 − 1) ÷ 3 = 0%.
B is closest to no net mass change, supported by the mean and the values around zero.
This does not prove every cell had zero water movement or establish an exact concentration; acknowledge duration, measurement uncertainty or mass change as an indirect measure.

One possible response

B has a mean change of 0%, compared with +5% for A and −5% for C. B is therefore closest to the tested condition producing no net mass change. Individual water molecules can still move both ways, and a zero cylinder mass change is only an indirect, time-limited estimate.

Repair this skill in the lesson →

Question 9 (3 marks)

Explain why a small cell generally has a higher surface-area-to-volume ratio than a geometrically similar large cell, and why this matters for exchange.

Marking criteria

Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.

For similar shapes, surface area scales with length squared and volume with length cubed.
The smaller cell has more surface area relative to the volume requiring supply and waste removal.
Relate the ratio and shorter diffusion distances to exchange demands, without claiming size is the only factor.

One possible response

As a similar-shaped cell grows, volume increases faster than surface area. A small cell therefore has more membrane area per unit volume and shorter diffusion distances. These features help substances reach the cell interior and wastes leave, although membrane properties and transport mechanisms also matter.

Repair this skill in the lesson →

Question 10 (3 marks)

A student reports: ‘There was no net mass change, so osmosis stopped.’ Evaluate the claim.

Marking criteria

Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.

No net change can mean equal water movement in opposite directions.
Distinguish net movement from continuing molecular motion.
Mass data alone do not prove equilibrium in every cell; identify a measurement or sampling limitation.

One possible response

The claim is too strong. Water can continue crossing the membrane in both directions at equal rates, producing no net change. Cylinder mass is an aggregate measurement and can hide cell-level differences or changes smaller than the balance can resolve.

Repair this skill in the lesson →

Question 11 (4 marks)

Design a valid and reliable investigation of how solution concentration affects potato cylinder mass. Explain four design choices.

Marking criteria

Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.

Vary only solution concentration across a suitable range and measure percentage mass change.
Control cylinder dimensions, potato source and immersion time or temperature, with a reason.
Use multiple independent cylinders per concentration and calculate summary values to assess variation.
Standardise blotting and weighing, record units and acknowledge instrument resolution.

One possible response

Use equal-sized cylinders from the same potato source in a concentration series for the same time and temperature. Measure initial and final mass after a consistent blotting procedure, then calculate percentage change. Use several separate cylinders at each concentration to estimate variation. Record balance resolution because water left on a cylinder and limited resolution can affect the result.

Repair this skill in the lesson →

Question 12 (4 marks)

Compare what light microscopy and electron microscopy can reveal about cells. Explain why a scientist may need evidence from both rather than simply choosing the higher magnification.

Marking criteria

Use these as evidence checkpoints. Award each point once; accept scientifically equivalent wording.

Light microscopy can examine suitably prepared living material and observe processes over time.
Electron microscopy can reveal finer ultrastructural detail owing to higher resolving power.
Preparation for conventional electron microscopy prevents observation of living cells and may introduce artefacts.
Match the method to the research question and explain why complementary evidence is useful.

One possible response

Light microscopy can show the behaviour of living cells under suitable conditions. Electron microscopy resolves much finer structures but conventional preparation requires fixed material and can introduce artefacts. A scientist studying movement and membrane ultrastructure needs different evidence for each question, so higher magnification alone is not a sufficient reason to choose a method.

Repair this skill in the lesson →