A Unity and Diversity

A1.1 Water

A1.2 Nucleic acids

A2.1 Origins of cells

A2.2 Cell structure

A3.1 Diversity of organisms

A4.1 Evolution and speciation

A4.2 Conservation of biodiversity

B Form and Function

B1.1 Carbohydrates and lipids

B1.2 Proteins

B2.1 Membranes and membrane transport

B2.2 Organelles and compartmentalization

B2.3 Cell specialization

B3.1 Gas exchange

B3.2 Transport

B4.1 Adaptation to environment

B4.2 Ecological niches

C Interaction and Interdependence

C1.1 Enzymes and metabolism

C1.2 Cell respiration

C1.3 Photosynthesis

C2.2 Neural signalling

C3.1 Integration of body systems

C3.2 Defence against disease

C4.1 Populations and communities

C4.2 Transfers of energy and matter

D Continuity and Change

D1.1 DNA replication

D1.2 Protein synthesis

D1.3 Mutation and gene editing

D2.1 Cell and nuclear division

D2.3 Water potential

D3.1 Reproduction

D3.2 Inheritance

D3.3 Homeostasis

D4.1 Natural selection

D4.2 Stability and change

D4.3 Climate change

IB Biology SL B3.2 Transport Question Bank

[Maximum number: 2]

Consumption of dark chocolate has been shown to have health benefits. A study was undertaken to see the effects of epicatechin (Epi), a substance in dark chocolate, on the aerobic capacity of leg muscles of mice.

A group of adult mice was used to measure the effects of a low dose of Epi given over 15 days. The mice were divided into four groups and given either water or Epi and were either kept idle (no exercise) or made to exercise on a treadmill.

After 15 days, the results were analysed. The blood capillary density in leg muscle was measured under the light microscope.

(a)

Describe how increased capillary density could affect the aerobic capacity of muscle.

[ 2 ]

[Maximum number: 3]

In an investigation to compare the elasticity of arteries and veins, rings of the same diameter $(20 \mathrm{~mm})$ of artery and vein tissue were cut from blood vessels obtained from a mammal.

Each ring was attached to a clamp. Multiple masses of 10 g were added and removed. The vertical diameter of the artery and the vein was measured, both with the mass and once the mass had been removed.

The results are shown in the table.

	Diameter of vein / mm		Diameter of artery / mm
Mass / g	With mass	Mass removed	With mass	Mass removed
0	20	20	20	20
10	26	26	26	22
20	34	33	30	23
30	38	36	35	23
40	40	37	38	24

(a)

Explain the differences between the results shown for vein and artery.

[ 3 ]

[Maximum number: 2]

Hormones are used for cell-to-cell communication in the human body.

(a)

Hormones enter and leave the bloodstream through capillaries. Outline two adaptations of capillaries for efficient exchange of substances with surrounding tissues.

[ 2 ]

[Maximum number: 2]

The photomicrograph shows a coronary artery and a cardiac vein.

(a)

Label the artery and the vein.

[ 1 ]

(b)

Describe one characteristic of the artery and vein which helped you to identify them.

Artery:

Vein:

[ 1 ]

[Maximum number: 2]

The structure of part of the digestive system is shown in the diagram below.

(a)

(i)

Explain how the structure of veins is adapted to their function.

[ 2 ]

[Maximum number: 3]

The micrograph shows a transverse section through blood vessels of a mammal.

(a)

Identify the vein by labelling it with the letter V.

[ 1 ]

(b)

Distinguish between the vein and the artery with reference to structures visible in the micrograph.

[ 2 ]

[Maximum number: 2]

In 1628, the physician William Harvey described details of the circulation of blood for the first time. In one experiment, he tied a tight bandage around the upper arm of a volunteer to display the blood vessels in the lower arm more clearly. He pressed his finger on the blood vessel at H . At the same time, he pushed the blood in the vessel from H to O with a second finger, removing the blood as shown in the diagram. When the finger at H was released, the blood vessel refilled with blood.

(a)

Deduce what the experiment demonstrated about the circulation of blood.

[ 2 ]

[Maximum number: 1]

B1. Backflow is the return of blood to the heart. In legs, backflow is enhanced by the pumping action of leg muscles during movement. When this does not occur efficiently, serious health problems can arise. The backflow speed of 40 patients was measured during the application of different therapy methods. The lying position is the control.

(a)

(i)

State which activity reduces backflow speed in relation to the control.

[ 1 ]

(a)

Distinguish between the structure of arteries and the structure of veins.

[ 3 ]

(a)

Outline the causes and consequences of blood clot formation in coronary arteries.

[ 2 ]

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