Syllabus Edition

First teaching 2023

First exams 2025

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Transport (SL IB Biology)

Exam Questions

2 hours35 questions
1a
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2 marks

The following diagram compares the structure of two main blood vessels in the body.

6-2-easy-q2a

(i)

Identify blood vessel A.

[1]

(ii)

State a reason for your answer in part i).

[1]

1b
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2 marks

Blood vessel B has a very large lumen.

(i)

Identify blood vessel B.

[1]

(ii)

State one reason for the presence of a large lumen in blood vessel B.

[1]

1c
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2 marks

The flow of blood in veins is not assisted by the pressure generated by the beating of the heart.

List two structures that assist with the flow of blood in veins.

1d
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1 mark

Systolic pressure is one of the measurements taken by a doctor to determine the blood pressure of a patient.

Define the term 'systolic pressure'.

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2a
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2 marks

The following table shows the mean pressure (in mmHg) measured in different blood vessels of the body.

Blood vessel Mean blood pressure / mmHg
Aorta 94
Arteries 90
Arterioles 68
Capillaries 24
Venules 10
Veins 3
Vena Cava 2

Calculate the percentage difference between the mean blood pressure of the aorta and vena cava. Show your working and give your answer to three significant figures.

2b
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1 mark

Using the table provided, identify the blood vessels where the greatest decrease in mean blood pressure occurs.

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3a
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1 mark

The following diagram compares the structure of an artery of a healthy person with that of someone suffering from atherosclerosis.

6-2-easy-q4a

Identify structure X.

3b
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1 mark

Atherosclerosis can lead to the occlusion of arteries over time.

Define the term 'occlusion'.

3c
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2 marks

Occlusion of the arteries can have a serious impact on cardiovascular health.

List two consequences of an occlusion of the arteries.

3d
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1 mark

When blood flow to part of the heart muscle is restricted due to blockages in the coronary arteries, it will impair its ability to contract fully. This will reduce blood flow, and therefore oxygen flow, to the body tissues.

State one treatment option available to patients with blockages in their coronary arteries.

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4
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3 marks

Capillaries provide the exchange surface in the tissues of the body.

List three characteristics of capillaries.

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5a
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1 mark

The image shows the cross section of a leaf.

7-2-fig-2-1Identify the substance which is represented by the arrows in the diagram.

5b
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3 marks

Draw three lines to correctly identify the method of particle movement shown in the diagram from part a).

4~MdS3aW_transport-mechanism-sq
5c
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2 marks
(i)

Identify the letters from the diagram in part a) that represents the xylem.

[1]

(ii)

Describe one adaptation of the xylem which makes it suitable for its function.

[1]

5d
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1 mark

The diagram below represents a plant organ.

iiQrQbZs_xylem-in-the-root-sq

State the name of this organ.

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6a
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1 mark

The transpiration stream relies on cohesion to maintain a continuous column of water in the xylem.

Define the meaning of the term 'cohesion'.

6b
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1 mark

Capillarity is a term used to describe the movement of water through narrow diameter tubing, called capillary tubing, against the force of gravity. This phenomenon is represented by the image in the diagram.

capilarity-and-adhesion-sq

In combination with the cohesion described at part a), identify one other property of water which allows transport through the capillary tube.

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7
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4 marks

Draw a labelled diagram of the vascular system seen in the cross section of a plant stem.

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8a
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2 marks

A traditional practice used in forestry to manage tree growth is called girdling. This involves removing a complete ring of bark, as shown in the image below. The tree dies over a period of time, allowing forests to be thinned out as required. 

92cjzMKs_girdling---sq

State how girdling may kill a tree over time. 

8b
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2 marks

State the role of the parenchyma in phloem tissue. 

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1a3 marks

The graph below shows the data obtained by scientists investigating the effect of omega-3 fatty acid consumption on the relative risk of coronary heart disease in humans.

Figure 1

 q4c-2-2-carbohydrates-lipids-medium-ib-hl-biology-sq

Using the data in the graph, evaluate whether coronary heart disease can be prevented by increasing omega-3 intake.

1b
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2 marks

Using the graph in part (a), deduce the approximate daily mass of omega-3 required to reduce the risk of coronary heart disease by 40%

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2
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2 marks

Valves are important structures found in the heart and veins.

Explain how valves work.

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3a
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1 mark

The graph below shows the rate of blood flow in various blood vessels in the body. It also shows the total cross-sectional area of the vessels.

YPP-3p1w_screenshot-2023-07-13-at-6-21-47-am

Suggest why the rate of blood flow increases from the venules to the vena cava despite a large decrease in the total cross-sectional area.                                                               

3b
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2 marks

The relative thickness of layers in the wall of an artery and a vein are shown in the table below.

Layer in wall Thickness / µm
Artery Vein
Endothelium 25 25
Smooth muscle 495 245
Elastic tissue 375 245
Connective tissue 125 125

 

Explain the difference in the thickness of elastic tissue for the artery versus the vein.

3c
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2 marks

The external diameter of a vein was measured at 1.5 mm. 

Calculate the diameter of the lumen of the vein.

3d
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3 marks

Explain how the structure of capillaries enable them to function efficiently as exchange surfaces.

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4a
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2 marks

Plant sterols and plant stanols are found in a range of food, including vegetables,  cereals, seeds and nuts. Plant sterols and stanols have a similar structure to cholesterol and reduce the absorption of cholesterol in the small intestine, so more cholesterol is lost in the faeces. This helps to lower the levels of cholesterol in the blood and in turn, reduce the risk of coronary heart disease (CHD).

A group of scientists wanted to investigate the effects of eating plant sterols and stanols on the risk of CHD. The scientists randomly divided healthy volunteers into two groups. Every day for eight weeks, one group was given plant sterols and stanols to eat. The other group acted as a control.

Each week, the scientists measured the diameter of the lumen of the main artery in the arm of the volunteers.

State how the control group should have been treated.

4b
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3 marks

The results of the experiment in part (a) are shown in the table below.

  Mean maximum diameter of lumen of main artery in the arm (mm)

Experimental group

(± standard deviation)

Control group

(± standard deviation)

Before experiment 0.69 (± 0.02) 0.71 (± 0.02)
After 8 weeks 0.74 (± 0.03) 0.72 (± 0.05)

 

A student reading the results concluded that there was sufficient evidence to assume a causal relationship between plant sterols and stanols, and a reduced risk of CHD.

Evaluate the student’s conclusion.

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5
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4 marks

Describe how blood returns to the heart from the legs.

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6a
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2 marks

The diagram below shows a transverse section (TS) of a plant stem.

q3a_9-1_transport_in_the_xylem_of_plants_medium_ib_hl_biology_sq

Identify the structure found at J and state its function.

6b
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3 marks

In xylem vessels, hydrogen bonds form between polar water molecules.

Describe the role that hydrogen bonding plays in the cohesion-tension theory of water transport in the xylem of plants.

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7
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2 marks

Explain a property of water that allows it to flow as mass transport in the transpiration stream. 

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1a
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2 marks

Carnitine is a chemical that plays an essential role in energy metabolism by transporting long-chain fatty acids into mitochondria in cells where they are then oxidised. It is often used as a supplement by athletes to enhance their athletic performance and to aid in weight loss.

Recent studies have linked the prolonged use of carnitine supplements with increased levels of trimethylamine N-oxide (TMAO) in the bloodstream. TMAOs can trigger inflammatory and immune responses in the body, as well as elevated blood glucose levels.

Based on the information provided, explain why increased TMAO levels could increase the risk of suffering a heart attack.

1b
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1 mark

Scientists investigated the effect of carnitine in the diet on the plasma concentration of TMAO in mice. Four groups, consisting of ten mice each, were fed one of four possible diets.

  • Diet 1 - a normal mouse diet with natural carnitine levels 
  • Diet 2 - a normal mouse diet with added carnitine
  • Diet 3 - a low carnitine mouse diet
  • Diet 4 - a normal mouse diet with added carnitine and antibiotics

The TMAO levels in the bloodstream of the mice were measured over time and a mean for each group was calculated.

Suggest a possible hypothesis for this investigation.

1c
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1 mark

The results of the investigation described at part b) are shown in the following graph.

RkEvF74L_h-4c

Explain the results from the group that followed diet 4.

1d
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3 marks

The scientists concluded that a diet high in carnitine will increase levels of TMAO in the bloodstream in humans.

Evaluate this conclusion.

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2a
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4 marks

The effect of humidity on the transpiration stream within the xylem of an oak tree was investigated, the results are displayed in the graphs below.

7vWwP4N8_humidity-and-cohesion-tension-sq

Describe how the trends shown in graph A compare with the trends shown in graph B.

2b
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4 marks

Outline how the changes in humidity lead to the changes in water tension measured in the xylem at the top of the tree.

2c
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4 marks

During the investigation, the scientist also measured the diameter of the tree trunk, the results can be seen in the table below:

Time Circumference of the trunk (cm)
7:00 97.5
9:00 97.4
11:00 96.5
13:00 95.7
15:00 95.7
17:00 96.3
19:00 97.3
21:00 97.4
23:00 97.5

Explain how this data and the data in the graphs from part a) support the cohesion-tension theory.

2d
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5 marks

The scientist who carried out the investigation in part a) concluded from his data that water moves through the xylem through the cohesion tension mechanism.

Evaluate his conclusion based on the validity of the evidence provided by the results of this investigation.

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3
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2 marks

The microscope image below shows a cross section of part of a stem of a herbaceous (non-woody) plant.

Vascular bundle xylem phloem cambium stem micrograph

Image courtesy of Berkshire Community College Bioscience Image Library. Adapted and redistributed under a Creative Commons CC0 1.0 Universal Public Domain Dedication license under conditions found at https://creativecommons.org/publicdomain/zero/1.0/deed.en 

Identify tissue types X and Y in the image.

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