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Cells and Living Systems

Cells and Living Systems — Free MYP3 Sciences Practice Questions

1QuestionExamples in Humans and PlantsConcept Practice

2 marks~3 minCriterion A

The diagram of a plant leaf shows three labels:

Label A — a single cell
Label B — the leaf's mesophyll (a group of similar cells)
Label C — the entire leaf

Identify which label represents a tissue. [1]

Explain why the other two labels do not represent a tissue. [1]

Solutions

2QuestionAdaptations of Specialized CellsConcept Practice

2 marks~3 minCriterion A

The diagram below shows a sperm cell with three regions labeled X, Y, and Z.

Identify the part of the sperm cell that contains the genetic information. [1]

Explain why the region labeled Y, which contains many mitochondria, is important for the sperm cell to carry out its function. [1]

Solutions

3QuestionComparing Diagrams of Plant vs Animal CellsConcept Practice

2 marks~3 minCriterion A

State one structure found in plant cells but not in animal cells. [1]

Describe the function of that structure. [1]

Solutions

4QuestionAdvantages and Limitations of UnicellularityConcept Practice

2 marks~3 minCriterion A

The diagram shows an amoeba and a human.

Identify which organism is unicellular. [1]

State the number of cells that make up a unicellular organism. [1]

Solutions

5QuestionBasic Structure of Plant and Animal CellsConcept Practice

3 marks~5 minCriterion B

The table below shows the presence (Yes) or absence (No) of three structures in three unknown cell samples.

Structure	Sample X	Sample Y	Sample Z
Cell wall	Yes	No	Yes
Chloroplasts	Yes	No	No
Large vacuole	Yes	No	Yes

State one structure present in Sample X that is not found in animal cells. [1]

Explain why Sample Z is classified as a plant cell, even though it lacks chloroplasts. [1]

Using all three samples, describe the pattern in the data that allows you to distinguish plant cells from animal cells. [1]

Solutions

6QuestionBasic Structure of Plant and Animal CellsConcept Practice

3 marks~5 minCriterion A

The diagram shows two cells, labelled Cell A and Cell B.

Identify which cell is the plant cell. [1]

Explain how one visible structure in the diagram supports your identification in (a). [2]

Solutions

7QuestionMagnification and Field of ViewConcept Practice

2 marks~3 minCriterion A

A diagram of a plant cell includes a scale bar showing

1 \text{ cm} = 10 \, \mu\text{m}

. The nucleus is labelled in the diagram and measures

3 \text{ cm}

.

(a) Calculate the actual length of the nucleus in micrometres (

\mu\text{m}

). [2]

Solutions

8QuestionInterdependence of LevelsAssessment Practice

6 marks~9 minCriterion B

Students investigated the effect of removing mitochondria from liver cells in mice. Results are shown below.

Condition: Normal liver cells
Tissue energy output: 100 units
Bile production rate: 5 mL/h
Mouse activity level: High

Condition: Mitochondria removed from liver cells
Tissue energy output: 15 units
Bile production rate: 1 mL/h
Mouse activity level: Low

State what happens to tissue energy output when mitochondria are removed from liver cells. [1]

Explain how the drop in tissue energy output leads to reduced bile production by the liver. [2]

Using the data, analyse how disruption at the cellular level produces effects at the tissue, organ, and whole-organism levels. In your answer, refer to emergent properties. [3]

Solutions

9QuestionExamples in Humans and PlantsAssessment Practice

4 marks~6 minCriterion C

A student planted two bean seeds of the same variety. Seed A was grown in rich compost soil with adequate water and sunlight. Seed B was grown in poor, sandy soil with limited water and sunlight. After two weeks, Seed A had a taller stem and longer roots than Seed B.

Explain how the root system and shoot system of Seed A worked together to support greater growth than Seed B. [2]

The student concludes: "Rich compost soil always produces taller bean plants than poor soil." Identify one limitation of this conclusion and explain how it affects the reliability of the student's finding. [2]

Solutions

10QuestionExamples in Humans and PlantsAssessment Practice

2 marks~3 minCriterion D

A patient is diagnosed with a heart attack in which cardiac muscle cells die, weakening the heart's ability to pump blood.

Explain why a doctor's understanding of the levels of biological organization — cells, tissues, and organs — is important when diagnosing and treating this patient. [2]

Solutions

11QuestionAdaptations of Specialized CellsAssessment Practice

5 marks~8 minCriterion B

The table below shows the oxygen absorption rate for four cell types with different surface-area-to-volume (SA:V) ratios.

Cell Type	A	B	C	D
SA	V Ratio: 2:1	4:1	6:1	8:1
Oxygen Absorption Rate (mL O₂/g tissue/min)	0.5	1.0	1.5	2.0

Describe the pattern shown in the data. [2]

Predict the oxygen absorption rate for a cell with an SA:V ratio of 10:1. Explain your prediction using the relationship between SA:V ratio and diffusion. [3]

Solutions

12QuestionComparing Specialized vs Unspecialized CellsAssessment Practice

5 marks~8 minCriterion C

A study measured three features of four cell types.

Cell type: Root hair cell / Red blood cell / Nerve cell / Unspecialized cell
Surface area (arbitrary units): 500 / 140 / 300 / 200
Number of mitochondria: 50 / 0 / 100 / 20
Specialized organelles present: Yes / No / Yes / No

Identify the unspecialized cell from the table and state two pieces of data that support your answer. [2]

Explain how the structure of the red blood cell suits its function, using data from the table. [1]

A student claims: "Specialized cells are always more effective than unspecialized cells." Analyse this claim using evidence from the table and your own knowledge. [2]

Solutions

13QuestionComparing Specialized vs Unspecialized CellsAssessment Practice

8 marks~12 minCriterion D

A biotechnology company has developed a treatment using stem cells sourced from human embryos to repair damaged spinal cord tissue. The embryos are destroyed during this process. Early trials show some patients regaining movement.

Describe what makes stem cells unspecialized and explain why this property is necessary for repairing spinal cord tissue. [2]

Explain one benefit of this treatment for patients and one concern about the source of the stem cells. [2]

A patient advocacy group argues the treatment should be approved immediately, while a religious organization argues it must be banned. Analyse how society could respond to both perspectives when deciding whether to allow this treatment. [4]

Solutions

14QuestionComparing Diagrams of Plant vs Animal CellsAssessment Practice

6 marks~9 minCriterion B

A scientist compares three cell types using the data below.

Cell type	Surface area-to-volume ratio	Metabolic rate (arbitrary units)
Plant leaf cell	0.6	5
Animal liver cell	0.8	8
Bacterial cell	3.0	20

Describe the relationship between surface area-to-volume ratio and metabolic rate shown in the data. [1]

Explain how two structural differences between a plant cell and an animal cell affect the plant cell's ability to produce energy. [3]

The three cells are placed in conditions without oxygen. Using the data and your knowledge of cell structure, justify which cell type is most likely to survive the longest. [2]

Solutions

15QuestionFunctions Related to Structure in Both CellsAssessment Practice

5 marks~8 minCriterion C

Two sealed chambers are kept at

25^\circ\text{C}

. Sample X contains plant leaf cells; Sample Y contains human muscle cells. Both chambers are exposed to light for the first 15 minutes, then placed in darkness.

Oxygen concentration (arbitrary units):

Time (min): 0, 5, 10, 15, 20, 25, 30

Sample X: 100, 120, 140, 160, 150, 140, 130

Sample Y: 100, 95, 90, 85, 80, 75, 70

State one function of chloroplasts and one function of mitochondria in a cell. [1]

Explain why the oxygen concentration in Sample X increases between 0 and 15 minutes, then decreases between 15 and 30 minutes. [2]

A student claims: "Sample Y is from a plant leaf because its oxygen concentration decreases over time." Analyse the data for Sample Y and evaluate this claim, using your knowledge of chloroplasts and mitochondria. [2]

Solutions

16QuestionComparing Diagrams of Plant vs Animal CellsAssessment Practice

2 marks~3 minCriterion D

Some weedkillers work by breaking down cell walls. A farmer wants to use one of these weedkillers to remove weeds growing among their crops.

Explain why this type of weedkiller will harm plants but not animals. [1]

Identify one limitation of using diagrams of plant and animal cells to predict how a real weed will respond to this weedkiller. [1]

Solutions

17QuestionExamples of Bacteria Amoeba and ParameciumAssessment Practice

6 marks~9 minCriterion C

A scientist grows bacteria and Paramecium together in a culture for 24 hours. Bacteria reproduce by binary fission. Paramecium feed on bacteria. The graph shows how both populations change over this period. Bacteria reach a peak at hour 12, then decline. The Paramecium population rises steadily from hour 6 onward.

Describe the trend in the bacteria population from hour 0 to hour 12, and from hour 12 to hour 24. [2]

Explain why the Paramecium population begins to rise after hour 6, using evidence from the graph. [2]

At hour 12, an antibiotic is added that rapidly reduces the bacteria population to near zero. Analyse how this would affect the Paramecium population over the following 12 hours, and justify your reasoning. [2]

Solutions

18QuestionAdvantages and Limitations of UnicellularityAssessment Practice

5 marks~8 minCriterion D

A school swimming pool contains a rapidly multiplying unicellular alga. The population doubles every hour. Starting with 100 cells, an exponential model predicts the population will cover the entire pool surface in 48 hours.

Calculate the number of algal cells present after 3 hours. Show all working. [2]

Explain why the algal population is unlikely to keep doubling every hour throughout the full 48 hours. [1]

The table below shows two pools with different conditions.

Pool A — nutrient-rich, no filtration, warm temperature
Pool B — low nutrients, active filtration, cooler temperature

Analyse which pool is more likely to reach full surface coverage by the algae, and justify your answer using the data provided. [2]

Solutions

19QuestionAdvantages and Limitations of UnicellularityAssessment Practice

6 marks~9 minCriterion B

A scientist measured how long a blue dye takes to diffuse from the surface to the centre of three organisms.

Organism: Amoeba / Flatworm / Hypothetical giant amoeba
Diameter (mm): 2 / 5 / 10
Diffusion time (s): 4 / 25 / ?

Describe the relationship between organism diameter and diffusion time shown in the data. [1]

Calculate the predicted diffusion time for the hypothetical giant amoeba. Show your working. [2]

Explain why a unicellular organism cannot survive if it grows too large, using the concept of surface area to volume ratio in your answer. [3]

Solutions

20QuestionFunctions of Cell Organelles Nucleus Cytoplasm etcAssessment Practice

6 marks~9 minCriterion C

A doctor examines cell samples from a patient and observes two abnormalities: some cells contain small or misshapen mitochondria, while others have enlarged rough endoplasmic reticulum (rough ER).

Describe one way that abnormal mitochondria could affect the functions of these cells. [2]

Explain how enlarged rough ER could indicate a problem with protein production in these cells. [2]

A colleague suggests that any cell whose organelles look normal under the microscope must be functioning normally. Analyse two reasons why this conclusion may not be valid. [2]

Solutions

21QuestionBasic Structure of Plant and Animal CellsAssessment Practice

6 marks~9 minCriterion D

A research laboratory claims to have created a 'plantimal' cell by fusing a plant cell and an animal cell. Scientists hope this could lead to new medical treatments, but the innovation raises ethical and environmental questions.

Describe two structural features found in a plant cell but not in a typical animal cell. [2]

Explain how one of these structural features could create an ethical concern about producing 'plantimal' cells. [2]

A 'plantimal' cell is accidentally released into a local pond ecosystem. Analyse one way its combined plant and animal cell structures could affect the organisms already living there. [2]

Solutions

22QuestionMagnification and Field of ViewAssessment Practice

2 marks~3 minCriterion D

A forensic scientist uses a microscope to examine a hair sample found at a crime scene. The microscope has a magnification of ×400 and a field of view diameter of 0.5 mm.

Explain how knowing both the magnification and the field of view allows the forensic scientist to make useful measurements of the hair sample. [2]

Solutions

23QuestionUsing a Microscope to View Prepared SlidesAssessment Practice

6 marks~9 minCriterion B

A student uses a microscope to observe prepared slides. The eyepiece magnification is

10\times

. The table below shows the field of view diameter at four objective magnifications.

Objective magnification ( $\times$ )	4	10	40	100
Field of view diameter (mm)	5.0	2.0	0.5	0.2

Describe the relationship between objective magnification and field of view diameter. [2]

Explain what happens to the field of view diameter when the objective magnification is doubled. Use one example from the data to support your answer. [2]

A student switches to a

20\times

objective lens. Calculate the expected field of view diameter and justify your answer using the pattern in the data. [2]

Solutions

24QuestionParts and Functions of a Light MicroscopeAssessment Practice

3 marks~5 minCriterion C

A student uses a light microscope at three different magnifications. The table below shows what becomes visible at each setting.

Magnification ( $\times$ )	4	10	40
Structure visible	cell outline	nucleus	mitochondria

State the trend shown in the data. [1]

Explain why increasing magnification allows smaller cell structures to be seen. [1]

A classmate claims that magnification alone is enough to observe mitochondria clearly. Using the data and your knowledge, analyse whether this claim is fully correct. [1]

Solutions