2021TrialShort answer

Q25 (b)

2 marks

Question

Some types of leukocytes can change this shape to engulf foreign particles, for example bacteria. This process also includes the foreign particle being destroyed inside the cell.
The process above is a non-specific response to an antigen. Outline ONE physical change that occurs in a host’s cell or tissue in response to a pathogen by the human immune system.

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Solution

Criteria	Marks
• Outline of a physical change	2
• Identifies a physical change	1

Sample answer:

The second line of defence includes inflammation, which involves skin redness due to increased blood circulation to the site of infection.
Comments:
Only mark ONE, first one that appears. O
utline – general terms, main features
*Must be a physical change not chemical
Cytokines are protein signalling involved in the process of inflammation, but they would be classified as chemical changes. Cytokines are chemical signalling molecules Histamine are chemical signalling molecules Possible:  Heat, either increased local temperature, such as a warm feeling around a localised infection, or a systemic fever  Swelling of affected tissues. Range 0-2 Avg. 1.5

Supplied marking guidance · human reviewed

Compare this with your working, not only your final sentence.

Syllabus alignment

Module 7 · Infectious Disease

ImmunityInvestigate and model human innate and adaptive immune systems.
Responses to PathogensAnalyse physical and chemical changes in animal cells and tissues responding to pathogens.

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