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 C3.2 Defence against disease Question Bank

[Maximum number: 1]

The growth of non-pathogenic Escherichia coli bacteria were studied in a microbiology laboratory at different temperatures with the antibiotic ampicillin. The number of bacterial colonies that grew were counted, and the mean and standard deviations calculated for five replicates per temperature.

At $25^{\circ} \mathrm{C}$ , the mean number of colonies counted was $70 \pm 8$ . The Petri dish shows the results obtained in one of the replicates at this temperature.

(a)

Suggest one reason for the presence of bacterial colonies despite the use of the antibiotic ampicillin.

[ 1 ]

[Maximum number: 3]

The photomicrograph shows a coronary artery and a cardiac vein.

(a)

(i)

The blood carried by arteries and veins contains antibodies. Explain antibody production by lymphocytes.

[ 3 ]

[Maximum number: 2]

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

(a)

(i)

Cells defend the body against pathogens. Outline how some of these cells ingest pathogens in the blood and in body tissues.

[ 2 ]

[Maximum number: 2]

The figure shows a transmission electron micrograph of rotavirus particles. Each rotavirus is about 70 nanometres in diameter.

(a)

Rotavirus causes diarrhea and vomiting. Explain why viral diseases cannot be treated using antibiotics.

[ 2 ]

[Maximum number: 2]

The image shows a castor bean tick (Ixodes ricinus) which is commonly found in woodlands or forest areas. This tick can carry bacteria that cause Lyme disease in humans.

(a)

A vaccine has been developed to protect people against the symptoms of Lyme disease.
The graph shows the relative number of antibodies specific to these bacteria in the blood of a person before vaccination.

[ 2 ]

(i)

Suggest what can be concluded from the graph about the person before they were vaccinated.

[ 1 ]

(ii)

Sketch a line on the graph to show how the number of antibodies would change over time after vaccination.

[ 1 ]

[Maximum number: 1]

The diagrams show a virus and a bacterium.

(a)

Outline the effectiveness of antibiotics against viruses and bacteria.

[ 1 ]

(a)

Outline the role of lymphocytes in defence against disease.

[ 2 ]

(a)

Explain how cuts in the skin are sealed by blood clotting.

[ 2 ]

[Maximum number: 1]

Azithromycin is an antibiotic commonly used to treat pneumonia, an infection of the lungs caused by Streptococcus pneumoniae. A patient was diagnosed for the second time with pneumonia, but the same antibiotic was ineffective this time. What biological explanation might there be for this?

S. pneumoniae had mutated.

S. pneumoniae had developed antibodies for the antibiotic.

The patient was immune to the antibiotic.

The patient had antibiotic remaining from the first treatment.

[Maximum number: 1]

Which function is primarily associated with helper T-cells in the immune system?

Phagocytosis of pathogens

Activation of other cells in the immune system

Antibody production

Retention as memory cells

0 selected

Question 2

Question 2(c)

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Question 3

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Question 17

Question 17