Animals and plants defend themselves against infection - Edexcel - GCSE Biology - Question 3 - 2017 - Paper 1

The number of deaths from malaria is only an estimate because data collection methods may be incomplete or inconsistent across different regions. Additionally, many deaths can be misattributed to other illnesses, and access to healthcare may vary greatly, leading to underreporting in some areas.

The immunisation appears to be effective as evidenced by the trial data. Out of 400 children who were not immunised, 64 developed malaria, while only 32 out of 400 children who were immunised did. This indicates a significant reduction in cases among the immunised group, suggesting that the vaccine lowers the risk of developing malaria.

The correct answer is B an antigen. Antigens are substances that induce an immune response, including the production of antibodies.

1. Personal beliefs or cultural reasons that oppose vaccination.
2. Concerns about potential side effects or reactions to the vaccine.

Plants can defend themselves against infection through several mechanisms:

1. Physical barriers: The outer cell layers such as the epidermis act as a first line of defense against pathogens.

2. Chemical defenses: Plants may produce antimicrobial compounds like phytoalexins or pathogenesis-related proteins that inhibit the growth of pathogens.

3. Localized responses: When attacked, plants can initiate localized hypersensitive responses to seal off infected areas and prevent further spread.