Jun 2016 Paper 1 Flashcards
Describe the difference between the structure of a triglyceride molecule and the structure of a phospholipid molecule.
In phospholipid, one fatty acid replaced by a phosphate
Describe how you would test for the presence of a lipid in a sample of food.
Add ethanol, then add water
White (emulsion shows lipid);
Describe how a saturated fatty acid is different from an unsaturated fatty acid.
Saturated single/no double bonds
between carbons
This fat substitute cannot be digested in the gut by lipase.
Suggest why
(Fat substitute) is a different/wrong shape/not complementary
Unable to fit/bind to (active site of) lipase/no ES complex formed
Suggest why the fat substitute cannot cross cell-surface membranes.
It is hydrophilic
Describe how ATP is resynthesised in cells.
From ADP and phosphate
By ATP synthase;
During respiration/photosynthesis
Give two ways in which the hydrolysis of ATP is used in cells.
To provide energy for other reactions/named process
To add phosphate to other substances and make them more reactive/change their shape;
What is the evidence from Figure 2 that a scanning electron microscope was used to take this photograph?
because it’s a 3D image
Name the part of the mitochondrion labelled X in Figure 2.
Cristae
P – diffusion through the phospholipid bilayer Q – facilitated diffusion R – active transport S – co-transport T – osmosis
Transport through a channel protein
Transport of small, non-polar molecules
Transport of glucose with sodium ions
Transport through a channel protein : Q
Transport of small, non-polar molecules : P
Transport of glucose with sodium ions : S
Y is a protein. One function of Y is to transport cellulose molecules across the phospholipid bilayer.
Using information from Figure 3, describe the other function of Y.
Makes cellulose
From β glucose
What is the evidence in Figure 3 that the phospholipid bilayer shown is part of the cell-surface membrane?
because the cell-surface membrane has cellulose on it
Describe the type of bond that holds the cellulose
molecules together side by side.
Hydrogen
Name the products of the hydrolysis of sucrose
Glucose
Fructose
What can you conclude about the growth of the plant cells from these data?
Explain how you reached your conclusions.
Sucrose hydrolysis linked to some aspect of growth; Greater the rate of/faster hydrolysis/more SPS activity as plant grows/cells divide (up to 8/10 days); Growth/division remains the same/slows after 8/10 days (because SPS activity is levelling off);
Describe the induced-fit model of enzyme action.
active site not complementary to/does not fit substrate;
Shape of active site changes as substrate binds
distorting it
A scientist investigated the hydrolysis of starch.
He added amylase to a suspension of starch and measured the concentration of maltose in the reaction mixture at regular intervals.
Explain the results shown in Figure 4.
High initial rate as plenty of starch/substrate/more E-S complexes;
No increase after 25 minutes/at end/levels off because no substrate/starch left;
The scientist used quantitative Benedict’s tests to produce a calibration curve of colorimeter reading against concentration of maltose.
Describe how the scientist would have produced the calibration curve and used it to obtain the results in Figure 4.
Make/use maltose solutions of known/different concentrations (and carry out quantitative Benedict’s test on each);
(Use colorimeter to) measure colour/colorimeter value of each solution and plot calibration curve/graph described;
Find concentration of sample from calibration curve;
Human papilloma virus (HPV) is the main cause of cervical cancer. A vaccine
has been developed to protect girls and women from HPV.
Describe how giving this vaccine leads to production of antibody against HPV
Vaccine/it contains antigen (from HPV);
Specific helper T cell (detects antigen and) stimulates specific B cell;
B cell divides/goes through mitosis/forms clone to give plasma cells;
B cell/plasma cell produces antibody;
What do these results suggest about whether it is better to give two or three doses of the vaccine? Give reasons for your answer.
Two (doses) because got more
antibody;
Also three doses would be more expensive
The doctors carried out a statistical test to determine whether the antibody concentrations were significantly different in girls given two doses of the vaccine,
compared with those given three doses. They determined the mean concentrations of antibody 9 months after the first dose of vaccine.
What statistical test should the doctors have used? Give the reason for your choice.
t-test
because they are comparing two means
There is genetic diversity within HPV.
Give two ways doctors could use base sequences to compare different types of HPV.
Compare (base sequences of) DNA;
Look for mutations/named mutations (that change the base sequence);
Compare (base sequences of) (m)RNA;
Chromosomes line up on the equator of the mitotic spindle in…
metaphase
Suggest why the development of a monopolar mitotic spindle would prevent successful mitosis
No separation of chromatids/chromosomes/centromeres;
Chromatids/chromosomes all go to one pole/end/sides of cell/not pulled to opposite poles
