HIV (Human Immunodeficiency Virus) is an infectious pathogen that can lead to AIDS. How is the HIV virus transmitted from one person to another? Select one option:

• Through airborne droplets expelled during coughing or sneezing
• By direct contact with contaminated drinking water
• Through direct exchange of bodily fluids, such as sharing needles

The table below shows the number of new HIV diagnoses in a specific city.

Describe what happened to the number of new HIV diagnoses from 2011 to 2019.

What could cause a significant decrease in the number of new HIV diagnoses in the future? Select one option:

• An increase in the sharing of unsterilised needles among drug users
• Wider availability of pre-exposure prophylaxis (PrEP) and barrier contraception
• A decrease in public health campaigns promoting safe sex practices

Vaccines can be developed to prevent viral infections. The statements below describe how a vaccine works to immunise an individual.

• W - Memory cells are produced and remain in the body to allow a rapid response to future infection.
• X - Specific white blood cells identify the foreign antigens and are activated.
• Y - A safe, inactive form of the pathogen is introduced into the body.
• Z - Activated plasma cells produce and secrete specific antibodies.

Write the stages W, X, Y, and Z in the correct sequence to show how vaccination works. The first stage has been completed for you:

$Y\to \underline{}\to \underline{}\to \underline{}$

Before a vaccine or drug is approved for public use, it must undergo rigorous testing. Once preclinical testing on laboratory cells, tissues, and live animals is complete, what is the immediate next stage in clinical trials? Select one option:

• Testing on a small group of healthy human volunteers
• Testing on a large group of patients suffering from the target disease
• Distributing the drug directly to community pharmacies for general use

Many modern medicines were originally discovered in or derived from plants and microorganisms. Match each medicine to the correct natural source it originally came from:

• Digitalis
• Penicillin

Sources:

• Foxglove plants
• Willow bark
• Penicillium mould
• Opium poppy plants