The Chamorro people of Guam eat flying foxes, a type of bat, as part of their diet. The photograph shows a flying fox. (Source: © H Lansdown/Alamy Stock Photo) Scientists in Guam suggested there was a link between the diet of these people and the high incidence of the neuro-degenerative disease amyotrophic lateral sclerosis (ALS) in their population. In a second investigation, the scientists looked at the flying fox population and the number of men diagnosed with ALS. The graph shows the results of this investigation. (i) Explain the results of this investigation. Use information from the question to support your answer. (4) ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ (ii) The diagnosis of ALS is made using positron emission tomography (PET) scans and computed tomography (CT) scans of the brain and nervous tissue. Compare and contrast these two techniques. (3) ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................

Biology

IGCSE&ALevel

EDEXCEL

Exam No：wbi15-01-que-20240608 Year：2024 Question No：5(b)

Answer:

An explanation that includes four of the following points:
- ALS developed due to high \{concentrations / doses / levels\} of BMAA (from eating flying foxes) (1)
- population of flying fox decreased (1)
- decrease in number of people with ALS (could be) due to \{eating fewer flying foxes / eating a different food source / men dying / fewer men\} (1)
- (delay in decrease in people with ALS could be due) time taken for ALS to develop (1)
- (initial) increase in number of people with ALS could be due to increased \{awareness / education / testing / medical diagnosis techniques\} (1)
An answer that includes three of the following points:
Similarity
- both can produce an image (of the brain and nervous tissue) (1)
- both are non-invasive procedures (1)

Difference (max 2)
- CT uses \{x-rays / electron beams\} whereas PET \{uses \{tracers / isotopes\} / detects production of gamma rays\} (1)
- CT is \{quicker / cheaper\} (than PET scan) (1)
- PET scan can show \{(metabolic) activity / biochemical changes\} (whereas CT scan does not) (1)

Answer:

Knowledge points:

Solution:

Answer:

Knowledge points:

Solution:

Related Question