A-level paper 1 mistakes Flashcards
Why might a patient have an unusually high proportion of eosinophils?
The patient will produce more of these cells due to an allergy
Explain why heart cells are damaged as a result of heart disease.
Plaque can lead to arteries becoming blocked
This deprives heart cells of oxygen
So cells cannot respire
Compare and contrast the properties and uses of embryonic stem cells and pluripotent stem cells (IPS cells)
Similarities:
Both are able to divide indefinitely
Both are able to differentiate into a number of different cells
Differences:
IPS cells were adult cells, embryonic cells taken from inner cell mass
IPS have a gene, embryonic stem cells don’t.
Less ethical issues surrounding IPS cells
IPS cells form adult cells whereas embryonic stem cells form younger cells
Explain how a mutation can result in a shortened protein being produced.
The mutation may produce a stop codon
Therefore translation will stop sooner
Some people have mutations that affect proteins involved in the electron transport chain.
Explain why these mutations lead to a build up of lactate.
Electron carriers can’t transport electrons
Reduced NAD will not be oxidised
So pyruvate will produce lactate
State the role of platelets in the blood clotting process.
They form a scab to seal the blood vessel.
What happens to oxygen availability in water as temperature increases?
It decreases
Describe the structure of a globular protein.
They have a 3 dimensional structure/ quaternary structure.
Held together by peptide bonds
Explain the role of the Krebs cycle.
Completely oxidises acetyl coA
To release energy
And generates ATP
Reduced NAD formed
Which can be used in the ETC
What substances are transported by xylem and phloem tissues?
xylem = water and mineral ions
Sucrose = water and sucrose
Describe the differences between the structure of the xylem and that of the phloem.
xylem cell walls contain lignin but phloem cell walls contain only cellulose.
Xylem is hollow but phloem has cell contents
Xylem doesn’t have companion cells but phloem does.
Do salmonella produce endo or exotoxins?
Endotoxins
A scientist wanted to grow some salmonella.
Explain why the use of streak plating on a selective media is a good method for isolating salmonella.
Media allows only salmonella to grow
Colonies will be spread out on agar
Separates individual bacteria
So colonies are individual and can be picked up.
Explain how stem rust fungus causes a reduction in a grain plant’s yield.
Stem rust fungus uses up nutrients.
Less glucose to form starch and for plant respiration.
Stem rust fungus also interferes with vascular tissue.
This can cause weakened stems.
State the meaning of DNA methylation.
The addition of a methyl group to a cytosine base.
