2015 Flashcards
What is the function of the coronary arteries?
[2 marks]
(Carry) oxygen/glucose;
2. (To) heart
muscle/tissue/cells/myocytes;
The rise and fall in blood pressure in the aorta is greater than in the small arteries.
Suggest why. [3 marks]
(Aorta) 1. (is) close/directly linked to to the heart/ventricle / pressure is higher/is very high; 2. (Aorta has) elastic tissue; 3. (Aorta has) stretch/recoil;
Give two differences in the variation in body length of male and female thorny lizards.
[2 marks]
1. Females are (generally) longer/larger/bigger/up to 115(mm) / males are (generally) shorter/smaller/up to 100(mm); 2. Females show a greater range/variation / males show a narrower range/variation;
The ecologists also determined the index of diversity of lizards in an oil palm plantation
next to the woodland area. They found fewer species of plant in the oil palm plantation.
Lizards feed on plants and insects.
Explain why fewer species of plant would lead to fewer species of lizard in the oil palm
plantation.
[3 marks]
(Fewer plant species) – no mark 1. (So) few(er) habitats/niches; 2. (So) lower diversity of insects / fewer insect species/fewer insect types; 3. (So) fewer food sources / less variety of food;
Give two ways in which the structure of starch is similar to cellulose.
[2 marks]
1. Are polymers/polysaccharides/ are made of monomers/of monosaccharides; 2. Contain glucose/carbon, hydrogen and oxygen 3. Contain glycosidic bonds; 4. Have 1–4 links; 5. Hydrogen bonding (within structure);
Give two ways in which the structure of starch is different from cellulose.
[2 marks]
- Contains α/alpha glucose;
- Helical/coiled/compact/branched/not
straight; - 1,6 bonds/ 1,6 branching;
- Glucoses/monomers same way up;
- No H-bonds between molecules;
- No (micro/macro) fibres/fibrils;
suggest and explain one other way in which sieve cells are adapted for
mass transport.
[2 marks]
1. No/few organelles / very little cytoplasm / cytoplasm at edge / more room/hollow/large vacuole/large space/thick walls; 2. (So) easier/more flow/ (thick/strong walls) resist pressure;
suggest and explain one other way in which companion cells are
adapted for the transport of sugars between cells.
[2 marks]
1. Mitochondria release energy/ ATP/ site of respiration; 2. For active transport/uptake against concentration gradient; OR: 3. Ribosomes/roughendoplasmic reticulum produce(s) proteins; 4. (Proteins) linked to transport eg carrier proteins/enzymes;
Describe the role of DNA polymerase in DNA replication.
[1 mark]
Joins nucleotides (to form new strand);
Other than being smaller, give two ways in which prokaryotic DNA is different from
eukaryotic DNA.
[2 marks]
(Prokaryotic DNA) 1. Circular/non-linear (DNA); 2. Not (associated) with proteins/ histones; 3. No introns / no non-coding DNA;
Humans and grasshoppers have very similar percentages of each base in their DNA but
they are very different organisms.
Use your knowledge of DNA structure and function to explain how this is possible.
[2 marks]
- Have different genes;
- (Sobases/triplets) are in a different
sequence/order; - (So) different amino
acid(sequence/coded for) / different
protein/different polypeptide/different
enzyme;
The DNA of the virus is different from that of other organisms.
Use Table 2 and your knowledge of DNA to suggest what this difference is.
Explain your answer.
[2 marks]
(Virus DNA) 1. A does not equal T / G does not equal C; 2. (So) no base pairing; 3. (So) DNA is not double stranded/is single stranded;
Give three ways in which courtship behaviour increases the probability of successful
mating.
[3 marks]
1. Recognise/identify/attract same species; 2. Stimulates/synchronises mating/production/release of gametes; 3. Recognition/attraction of mate/opposite sex; 4. Indication of (sexual) maturity/fertility/receptivity/readiness to mate; 5. Formation of a pair bond/bond between two organisms (to have/raise young);
The scientists wanted to know if the recorded natural song was less effective than the
natural song in stimulating courtship behaviour.
Suggest how the scientists could determine if the recorded natural song (L) was less
effective than the natural song.
[2 marks]
- Use a (real) male (with intact
wings/no wing removed); - Determine (percentage) response
(of females compared withL)
A student concluded from Table 3 that the number of chirps and ticks is essential for
successfully stimulating courtship behaviour.
Do these data support this conclusion? Explain your answer.
[4 marks]
1. Lowest/only 30% courtship with no song/K/ (or) courtship still occurred when no song played/K; 2. Reducedcourtship when no ticks/M / there is some courtship when no ticks/M; 3. Reduced courtship when no chirps/N / there is some courtship when no chirps/N; 4. (So) courtship must involve a visual stimulus/other factor involved; 5. Chirps more important as lowest courtship when none/N / ticks less important as similar courtship when changed/M; 6. Data only show presence and absence of chirps/0 and 7 chirps;
The events that take place during interphase and mitosis lead to the production of two
genetically identical cells. Explain how.
[4 marks]
- DNA replicated;
- (Involving)
specific/accurate/complementary
base-pairing; - (Ref to) two identical/sister
chromatids; - Each chromatid/ moves/is separated
to(opposite) poles/ends of cell;
The student cut thin sections of tissue to view with an optical microscope.
Explain why it was important that the sections were thin.
[2 marks]
- To allow (more) light through;
- A single/few layer(s) of cells to be
viewed;
What does Figure 5 show about the growth of roots?
Use the data to explain your answer.
[2 marks]
1. More/faster mitosis/division near tip/at 0.2 mm; 2. (Almost) no mitosis/division at/ after 1.6 mm from tip; 3. (So) roots grow by mitosis/adding new cells to the tip
This classification system consists of a hierarchy as there are small groups within larger
groups.
Give one other feature of a hierarchy that is shown in Figure 6.
[1 mark]
No overlap;
Complete colour blindness occurs at a higher frequency on Pingelap than in the USA.
Use the information provided to explain why.
[3 marks]
- Genetic bottleneck;
- Less genetic diversity / small(er)
gene pool / less variety of alleles; - Individuals breed within group /
do not breed with outsiders; - High(er) chance of inheriting
allele/high(er) frequency of allele
in offspring;
A mutation can lead to the production of a non-functional enzyme. Explain how.
[6 marks]
1. Change/mutation in base/nucleotide sequence (of DNA/gene); 2. Change in amino acid sequence/primary structure (of enzyme); 3. Change in hydrogen/ionic/disulfide bonds; 4. Change in the tertiary structure/shape; 5. Change in active site; 6. Substrate not complementary/cannot bind (to enzyme/active site) / no enzyme-substrate complexes form;
One way in which the stringent response gives resistance to this antibiotic is by stopping
cell division.
The scientists concluded that stopping cell division is not the only way in which the
stringent response gives resistance to this antibiotic.
Explain how Figure 7 supports this conclusion.
[2 marks]
- Division stopped (of both strains by
scientist); - SR strain still more resistant/fewer
die/none die (at higher
concentrations of antibiotic);
The stringent response involves a number of enzyme-catalysed reactions.
Explain how scientists could use this knowledge to design drugs that make the treatment
of infections caused by the SR strain more successful.
[2 marks]
1. Make a competitive/non-competitive inhibitor; 2. Competitive competes with/blocks active site/non-competitive inhibitor affects/changes active site; OR 3. (Make a drug) that inhibits/denatures/destroys enzyme/stringent response; 4. Give at the same time as/before an antibiotic
Use the information provided and Figure 8 to suggest an explanation for the greater
resistance of the SR strain to this antibiotic.
[3 marks]
SR strain) 1. Fewer free radicals (than non-SR); 2. Produces more catalase (than nonSR); 3. Catalase (might be) linked to production of fewer free radicals / breaking down/removing free radicals;
The scientists removed the ovaries from the mice for the investigation. They also gave
the mice injections of the substrate of aromatase each day.
Explain why these steps were necessary.
[2 marks]
1. Removes (main/largest) source of oestrogen / (different) mice produce different amounts of oestrogen; 2. (Allows) oestrogen to be controlled/oestrogen to be made by aromatase only / only oestrogen made in lungs to be involved;
The scientists predicted that fulvestrant would be more effective when given with
anastrozole than when given alone.
Use the information provided to suggest why they predicted this.
[2 marks]
1. (Anastrozole) prevents/reduces oestrogen production; 2. (Fulvestrant) stops remaining oestrogen binding /less oestrogen binds to receptors;
The scientists concluded that both drugs should be used together to reduce the risk of
lung cancer in women exposed to tobacco products.
Do you agree? Explain your answer.
[5 marks]
(Yes for Group T) 1. Least tumours per animal (from fig. 9) 2. Lowest (mean) tumour area/size (from fig. 10); 3. Lowest top of range; (But) 4. Means (tumour area) are similar; 5. Ranges overlap/share values so differences may not be real/treatments may be just effective in reducing tumour; 6. Range affected by outliers/ SD’s would be better; 7. Done on mice / not done on women/humans; 8. Only 10 mice used per group/small sample size so may not be representative/reliable; 9. Might be side effects ; 10. Only did for 15 weeks somaximum effect of drugs may not have been seen
The scientists used tumour area as an indicator of tumour size.
Explain why tumour area may not be the best indicator of tumour size and suggest a
more reliable measurement.
1. Tumours may be different depths / area does not take depth into account / tumours are 3-D/are not 2- D; 2. (Measure) tumour volume/mass/ weight
The scientists repeated the investigation but this time they did not give the drugs until
week 9.
Suggest why they gave the drugs at week 9, rather than at week 5.
[2 marks]
1. Allows tumours to grow/develop/form; 2. (So) can investigate treatment rather than prevention (of tumours)/ when tumour/cancer is more advanced;
Another group of scientists is currently using these drugs in human trials. However, the
control group is not being given a placebo.
Suggest why a placebo is not being given and what is being given to this group instead.
[2 marks]
- Unethical (not to treat patients) /
may increase probability of patients
dying/getting more ill; - Use normal cancer drugs/treatment;
