1 Skin flora provide a barrier, protecting the body from infection by bacteria.
(a) Which of the following also act as barriers, protecting the body from infection
by bacteria?
(1)
A antigens and stomach acid
B antigens and interferon
C interferon and skin
D skin and stomach acid
(b) The di...
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Pearson Edexcel International Advanced Level
Thursday 11 January 2024
Morning (Time: 1 hour 45 minutes) Paper
reference WBI14/01
Biology
International Advanced Subsidiary / Advanced Level
UNIT 4: Energy, Environment, Microbiology
and Immunity
You must have: Total Marks
Scientific calculator, ruler, HB pencil
Instructions
•• Use black ink or ball-point pen.
Fill in the boxes at the top of this page with your name,
centre number and candidate number.
•• Answer all questions.
Answer the questions in the spaces provided
– there may be more space than you need.
Information
•• The total mark for this paper is 90.
The marks for each question are shown in brackets
– use this as a guide as to how much time to spend on each question.
• structure
Questions labelled with an asterisk (*) marks will be awarded for your ability to
your answer logically, showing how the points that you make are related
or follow on from each other where appropriate.
Advice
•• Read each question carefully before you start to answer it.
Try to answer every question.
• Check your answers if you have time at the end.
Turn over
Answer ALL questions. Write your answers in the spaces provided.
Some questions must be answered with a cross in a box . If you change your mind about an
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
answer, put a line through the box and then mark your new answer with a cross .
1 Skin flora provide a barrier, protecting the body from infection by bacteria.
(a) Which of the following also act as barriers, protecting the body from infection
by bacteria?
(1)
A antigens and stomach acid
B antigens and interferon
C interferon and skin
D skin and stomach acid
(b) The diagrams show the effects of different methods of washing hands on
skin flora.
The dark areas show the presence of microorganisms and the light areas show
clean areas.
1. before washing 2. “rinse and shake” 3. six seconds, no soap
4. six seconds with soap 5. fifteen seconds with soap 6. thirty seconds with soap
2
*P73452A0228*
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(i) Describe two conclusions that can be made about the different methods of
washing hands.
(2)
DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA
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