The diagram represents a section of human skin punctured by a splinter of wood - Scottish Highers Human Biology - Question 13 - 2019
Question 13
The diagram represents a section of human skin punctured by a splinter of wood.
a) (i) Describe one way in which these epithelial cells defend the body against path... show full transcript
Worked Solution & Example Answer:The diagram represents a section of human skin punctured by a splinter of wood - Scottish Highers Human Biology - Question 13 - 2019
Step 1
Describe one way in which these epithelial cells defend the body against pathogens.
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Answer
Epithelial cells provide a physical barrier to prevent pathogens from entering the body.
Step 2
Name structure X.
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Answer
Blood capillary.
Step 3
Name the cells that release histamine.
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Answer
Mast cells.
Step 4
Explain why the skin around a puncture wound often becomes red and swollen.
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Answer
The skin becomes red and swollen due to vasodilation and increased blood flow resulting from the release of histamine, which increases the permeability of blood capillaries.
Step 5
Explain how a lymphocyte is able to recognise a particular pathogen.
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A lymphocyte recognizes a pathogen by identifying its specific antigens, which are unique molecules presented on the pathogen's surface.
Step 6
Describe how T lymphocytes destroy infected body cells.
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T lymphocytes destroy infected body cells by inducing apoptosis, or programmed cell death, within the infected cells.
Step 7
Suggest a reason for the decrease in HIV concentration during the first year after infection.
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The decrease in HIV concentration during the first year is likely due to the immune response being activated, which involves the production of antibodies and the action of T lymphocytes targeting the virus.
Step 8
Explain why the T lymphocyte concentration is decreasing between 1 and 5 years after infection.
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The decrease in T lymphocyte concentration between 1 and 5 years occurs because the virus is attacking and destroying T lymphocytes, leading to a reduction in their numbers.
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