Spread of disease

Pathogens are transmitted to animals and plants by a variety of methods.

A group of scientists collected and analysed data about climate change and the number of cases of diseases transmitted by animal vectors.

The scientists wanted to know whether the number of cases of each disease had increased as a result of climate change.

They found that the number of cases had increased for 103 different animal vector‑transmitted diseases.

The scientists concluded that climate change has increased the transmission of pathogens by animal vectors.

Suggest one additional piece of information that is needed to assess the validity of the scientists’ conclusion.

Suggest why climate change might result in more cases of diseases caused by animal vector‑transmitted pathogens.

Neutrophils are white blood cells that contribute to the immune response against infection.

Neutrophils produce oxidative bursts as part of their response to infection.

An oxidative burst is the rapid production of highly reactive particles, including hydrogen peroxide (H₂O₂), inside the cell.

State the location of the stem cells that differentiate into neutrophils.

The graph shows the change in hydrogen peroxide concentration in a neutrophil during an oxidative burst.

Use the graph to calculate the initial rate of increase of H₂O₂ concentration in the neutrophil during an oxidative burst.

Suggest how an oxidative burst helps neutrophils to perform their function.

Antibodies can bind to receptors on the cell surface membrane of a neutrophil.

The binding of an antibody to a receptor causes the neutrophil to engulf the pathogen that is bound to the antibody.

State the name given to antibodies that act in this way.

Plants lack immune cells, but they have other defences against pathogenic infection.

The sentences describe one form of plant defence against pathogens.

Complete the sentences using the most appropriate word or phrase.

When a pathogen is detected in plant tissue, a plant increases the production of a

polysaccharide called........ This polysaccharide is deposited

in channels called........, which pass through cell walls. This

deposition stops the pathogen moving between cells. The polysaccharide is also

deposited in the small gaps between sieve tube elements. These gaps are known as

........ This deposition stops the pathogen moving between

different regions of the plant.

Which of the following changes of lifestyle is/are likely to reduce the spread of a disease that is transmitted by droplets of moisture?

1 Clean drinking water 2 Fewer people living together in the same house 3 Housing with improved ventilation

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

Your answer

Ash trees are an important part of the British landscape.

In 2012, a fungal disease known as ash dieback arrived in the UK from mainland Europe.

Which of the following could explain how ash dieback could have reached the UK from mainland Europe?

1 Spores carried on the wind 2 Young diseased trees imported from Europe and planted in the UK 3 Contaminated soil from a previously infected crop

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

Your answer

Bacteria and fungi can be used to make food for human consumption. The use of microorganisms in food production creates fewer ethical issues than the use of animals.

On an industrial scale, microorganisms can be cultured using either batch fermentation or continuous fermentation.

The table below lists statements about industrial culturing of microorganisms.

Place ticks (✓) in the table to indicate whether each statement applies to batch or continuous fermentation.

A student carried out a different serial dilution to estimate the size of another bacterial population.

The serial dilution resulted in four colonies developing on an agar plate.

Explain why the student’s estimation of this bacterial population is likely to be inaccurate.

Some microorganisms can be used by humans in industry. Some microorganisms are pathogenic.

Pathogenic microorganisms are transmitted in various ways.

Complete the following passage about the transmission of pathogenic microorganisms using the most appropriate terms.

Some pathogens are carried between host organisms by animals, which are often insects.

These animals suffer no symptoms of the disease and are known as........

Other pathogens, such as P. infestans that causes potato blight, produce reproductive structures

called........, which can be carried on air currents to infect other hosts.

Three methods of pathogen transmission between animals or plants are listed below.

1 direct contact 2 vectors 3 droplets

Which of the methods of pathogen transmission does not apply to plants?

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

Your answer