p2 - 2017 Flashcards
Glycogen and cellulose are both carbohydrates.
Two differences between the structure of a cellulose molecule and a
glycogen molecule
Cellulose is made up of β-glucose + glycogen is made up of α-glucose
Cellulose molecule has straight chain + glycogen is branched
Starch is a carbohydrate often stored in plant cells
Describe and explain two features of starch that make it a good storage molecule
Insoluble in water, so doesn’t affect water potential
Large molecule, so can’t cross the cell membrane
Which test would be used to show the presence
of starch?
Iodine/potassium iodide
Multiple copies of the AMY1 gene is an adaptation to a high-starch diet.
Use your knowledge of protein synthesis and enzyme action to explain the
advantage of this adaptation.
- More mRNA / more transcription
- More translation / enzyme
- So reaction faster
Describe a method the student could have used to monitor the temperature of the
water in each tube
Taking readings using thermometer
Multiple copies of the AMY1 gene is an adaptation to a high-starch diet.
Suggest how this evolved through natural selection
- Mutations produce extra copies of AMY1 gene;
- Those with more copies survive better on high starch diet
- And pass on multiple copies to offspring
Describe how the scientists could obtain data to produce a calibration curve and how they would use the calibration curve to find the concentration of protein in a sample of blood plasma
(3)
- Produce known concentrations of protein
- Measure absorbance of each concentration
- Plot a graph of absorbance on y-axis against concentration on x-axis and draw curve
Older people are more likely to suffer from infectious diseases.
Suggest how this may be linked to the decrease in the mean concentration of
protein in the blood as people get older
Lower plasma protein concentration suggests fewer antibodies
ABA is a substance that some plant species produce when little water is available.
Explain why producing ABA may help these species survive in dry conditions
Causes less stomatal opening so less transpiration
(So more) water available for photosynthesis /
metabolism / support;
Many species of plants can be infected by powdery mildew which is spread by microscopic spores in the air.
Suggest how treatment with Lam13 might protect plants against powdery mildew
infection
Closes the stomata so fewer/no spores enter leaf
NMO is a disease that leads to damage to nerve cells in the spinal cord. A person with NMO produces anti-AQP4 antibody that attacks only these nerve cells.
Explain why the anti-AQP4 antibody only damages these cells. (4)
- Anti-AQP4 antibody has a specific tertiary structure
- Has binding site complementary to one antigen
- Antigen to this antibody only found on these nerve cells
- So, antibody forms antigen- antibody complex with these nerve cells causing damage
A new treatment for NMO involves using a monoclonal antibody. The structure of the variable region of this monoclonal antibody is identical to the variable region of an anti-AQP4 antibody, but the rest of its structure is different.
Use this information and your knowledge of antigen-antibody complexes to suggest how this monoclonal antibody prevents anti-AQP4 damaging nerve cells
The monoclonal antibody binds to nerve cell antigen so less / no anti-AQP4 can bind
When monoclonal antibody binds it doesn’t cause damage to nerve cell
What is the effect of Patau syndrome on the chromosomes of this female?
an extra chromosome 13
Describe how the change in chromosome number in Patau syndrome was produced
In meiosis, sister chromatids do not separate
Explain why all the cells of the body will have this Patau syndrome mutation
extra chromosome in gamete that formed zygote
All cells derived from a single cell by mitosis
