What name is given to microorganisms that cause disease? Tick (✓) one box - AQA - GCSE Biology - Question 2 - 2021 - Paper 1

Viruses cause symptoms of disease by reproducing inside cells, damaging them. This disrupts normal cellular functions and can lead to the death of infected cells.

One reason that viruses are not classed as cells is that they do not have a cellular structure; they lack components such as a cell membrane or organelles.

The graph that demonstrates the concentration of antibodies typically shows a biphasic response, with a peak after each vaccination and a gradual decline, indicating the immune response over time.

The part of the plant that exhibits discolouration caused by TMV is the leaf.

To complete Figure 5:

1. Label the y-axis as 'rate of photosynthesis in arbitrary units'.
2. Add the correct scale to the y-axis ensuring it accurately represents the data.
3. Plot the data from Table 1, ensuring each data point is accurately represented.
4. Label each bar clearly to indicate the corresponding values.

From the data in Table 1, we can conclude that as the level of TMV infection increases, the rate of photosynthesis decreases.

A high level of TMV infection reduces growth in a plant because:

• The virus interferes with the plant's ability to perform photosynthesis, leading to a decrease in energy production.
• Affected plants may have fewer chloroplasts, which results in less light absorbed and ultimately reduces the plant's overall growth and productivity.