Animals and plants defend themselves against infection - Edexcel - GCSE Biology - Question 3 - 2017 - Paper 1
Question 3
Animals and plants defend themselves against infection.
(a) Malaria is an infection caused by a parasite.
In 2013, there were approximately 198 million cases of ma... show full transcript
Worked Solution & Example Answer:Animals and plants defend themselves against infection - Edexcel - GCSE Biology - Question 3 - 2017 - Paper 1
Step 1
(i) Calculate the number of deaths from malaria in Africa in 2013.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
To find the number of deaths from malaria in Africa, we take 90% of the total deaths worldwide.
Total deaths worldwide = 584,000
Deaths in Africa = 0.90 × 584,000
Calculating that gives:
Deaths in Africa = 525,600.
Step 2
(ii) Suggest why the number of deaths from malaria is only an estimate.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The number of deaths from malaria is only an estimate because not all cases are reported or documented due to lack of healthcare access in some regions. Additionally, different organizations may use varying methods to estimate deaths, leading to discrepancies.
Step 3
(i) Describe the effectiveness of the immunisation.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The effectiveness of the immunisation can be analyzed by comparing the number of children developing malaria in both groups:
Children not immunised: 64 out of 400
Children immunised: 32 out of 400
This indicates a clear reduction in malaria cases among the immunised children compared to those who were not, suggesting that the immunisation significantly reduces the incidence of malaria.
Step 4
(ii) Complete the sentence by putting a cross (X) in the box next to your answer.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The correct choice is B: an antigen, as it is the part of an immunisation that triggers the immune response to produce antibodies.
Step 5
State two reasons why some people might choose not to be immunised.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Misinformation about vaccine safety may lead individuals to distrust immunisation.
Some may have health concerns or medical conditions that prevent them from receiving vaccines.
Step 6
Explain how plants defend themselves against infection.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Plants have several defense mechanisms against infection. They can produce chemicals such as phytoalexins and phenolics, which have antimicrobial properties. Additionally, plants can form physical barriers like thick cell walls and cuticles to prevent pathogen entry. When infections do occur, some plants can activate systemic acquired resistance, enhancing their overall immunity.
