Download A-Level Biology Specimen Paper 3: Carbon Dioxide Release, Mutations, and Tree Biomass and more Exams Cell Biology in PDF only on Docsity!
A-Level Specimen Set 2 Paper 3
Complete Table 1 and plot a graph of your calculated values against temperature on the graph paper. Express your calculated rates with the appropriate number of
decimal places. -
Line graph with rate on y axis and temperature on x axis and linear scales;
Values calculated to 2 decimal places;
Rates correctly calculated and plotted, with ruled line connecting points and no extrapolation;
Calculate the change in the rate per hour of opening of the spindles between 10 °C and 20 °C. -
8 or 9
Explain how you could determine the total amount o f carbon dioxide secreted at 30 °C during the period of recording. -
Determine the area under the curve;
Suggest an explanation for the effect of temperature on the rate of carbon dioxide release. -
Enzymes/metabolism faster;
Higher rate of respiration and carbon dioxide production/release;
Spiracles open more often/remain open to excrete/get rid of carbon dioxide/get more oxygen;
What is a substitution mutation? -
Replacement of a base by a different base (in DNA);
Suggest how gel electrophoresis separated the proteins obtained from the synapses. -
(Depends on) size/mass (of protein);
(Depends on) charge (of protein);
Each type of labelled antibody binds specifically to one of the proteins. Explain why. -
Each protein has a different tertiary structure;
(Each) antibody has a specific antigen/binding/variable region/site;
So, (each antibody) forms different antigen- antibody complex
OR
(each antibody) only binds to complementary (protein);
What do these data show about the effects of the mutation on the proteins? -
Less NL3;
More NR2A and NR2B;
Using all of the information, suggest how the mutation affecting the NL3 protein may affect a mouse -
Higher ratio NR2B to NR2A with mutation;
(Perhaps) better memory in mice with mutation;
Use the data in Table 2 to calculate the percentage of water in the
freshly cut wood sample. Show your working. -
35.22 or 35.23% = 2 marks;
Award 1 mark if only fresh and dry masses correct, 1335.59 and 865.13 g;
The ecologists dried the samples in an oven at 103 °C for 24 hours. Describe how the ecologists could have determined whether or not this drying removed all the water from a sample of wood. -
(After 24 hours)
Record mass and reheat;
Until constant mass recorded;
What does Figure 3 show about the relationship between the diameter of the
trunk of the trees and their biomass? -
Positive correlation (between diameter and biomass);
Not linear/geometric/exponential/gradient gets steeper;
Set up grid system with coordinates;
Place large number of quadrats (at coordinates) selected at random;
Count number of/estimate percentage cover of native plant in quadrats;
Repeat at same time each year (for many years);
Effect size is calculated in the following way.
Divide the species richness in the last year of an investigation (SR2) by species richness in the first year of the investigation (SR1).
Find the natural log (loge) of the result.
Divide this by the time (T) between the first and last year in decades (1 decade =
10 years).
In one community:
species richness in year 2 (SR2) was 15.
species richness in year 1 (SR1) was 18. and the investigation lasted for 29 years.
Use loge, SR2, SR1 and T to write an equation for 'effect size' and calculate its value
for this investigation. On a calculator, the key for log e is shown as ln, or loge. -
Correct answer two marks - 0.0599;
Suggest one other way that putting ESCs into a person's heart might lead to more harm to the person. -
(ESCs) can replace any type of (heart) cell;
Group A was a control group. Explain two ways in which Group A acts as a control. -
Shows the effects of surgery;
Allows effects of transplants/treatment to be seen;
What can you conclude from these data about the stimulation by cardiomyocytes on growth of new blood vessels into damaged heart tissues? -
Other cell types cause some increase but most of increase due to cardiomyocytes;
Large SD, so some not much increase/no better than control;
Overlap of SDs indicates/suggests no significant difference;
Suggest how the growth of new blood vessels into damaged heart tissues could increase the rate of repair of tissues. -
Greater blood supply (to damaged areas);
Bringing more oxygen/glucose for respiration;
Brings more amino acids for protein synthesis;
For cell repair/mitosis/division;
The scientists used an optical microscope to measure the number of capillaries in thin sections cut from samples of heart muscle.
Describe the method they would have used to find the mean number of capillaries per mm2 -
Measure diameter of field of view and calculate area;
Using micrometer slide and eyepiece graticule;
Count number of capillaries in large number of fields of view and calculate mean;
Select fields of view randomly
