TOPIC FOUR – BIODIVERSITY AND NATURAL RESOURCES
SAQ 440
(a) A . granum/thylakoid; chlorophyll molecules to trap light / light absorbing pigments/
light dependent reaction / part of light dependent reaction; 2
B . stroma; (contains enzymes for) carbon dioxide fixation/light-independent reaction/
part of light-independent reaction; (allow ribosome role of protein in photosynthesis) 2
(b) (i) C . starch; 1
(ii) from glucose in a condensation/polymerization reaction / many glucose molecules joine
together; 1
Total 6 AQA/BYB4/JAN
SAQ 441
2. a) The drawing shows a section through a plant cell.
(i) Name the organelle X.
(1)
Nucleus
SAQ 442
4. The diagram shows part of plant cell as seen through an electron microscope.
a) Name organelles A, B and C.
(3)
A – ribosomes
B – sap vacuole
C – smooth endoplasmic reticulum
b) Give the function of structure X and Y.
(2)
X is the cellulose cell wall. It is freely permeable to water and solutes. It reduces expansion
of the cell due to entry of water. This is called as turgor pressure. prevents plant cells from
bursting when placed in distilled water or a solution with a higher water potential than the
cell sap.
The cell wall also helps to maintain the shape of some plant cells.
c) Calculate the width of the structure labeled X in μm.
Show your working.
(2)
Magnification = measured length / actual length
25000 = 4000 / X
[Note: 4mm = 4000 µm]
X = 4000 / 25000
= 0.16 µm
(Total 7 marks)
June 2003 BYB1, AQA
SAQ 443
6. The diagram shows the outer layer of a cell from each of three different organisms. One
of the cells is a prokaryotic cell, one is an animal cell and one is a plant cell.
a) Which of the three cells, A, B or C, is the prokaryotic cell? Give a reason for your answer.
(1)
Cell A is a prokaryotic cell because it has a slime layer or capsule around the cell wall.
b) Complete the table which shows some of the similarities and differences between the outer
layers of these cells. Use a tick if the statement is true or a cross if it is not true.
Statement
Cell A
Cell B
Cell C
One of the layers surrounding this
cell contains cellulose
X
√
X
One of the layers surrounding this
cell is partially permeable.
√
√
√
c) Penicillin is a substance which kills bacterial cells by damaging their cell walls. As a result,
they burst when they take water.
(i) The concentration of dissolved substances is higher in the cytoplasm of a bacterial cell than
it is in the surrounding solution. Explain why water enters the bacterial cell.
(2)
The water potential inside the bacterial cell is lower than the water potential of the solution.
So water enters the cell by osmosis, across the selectively permeable cell membrane.
(ii) Penicillin kills bacterial cells but has no effect on plant cells. Suggest why. (1)
The bacterial cell wall is made up of murein or peptidoglycan, where as the plant cell wall is
made up of cellulose. Penicillin affects only murein and has no effect on cellulose.
d) Explain why a plasma membrane can be seen with an electron microscope but not with an
optical microscope.
The limit of resolution of a light (optical microscope) is 200 nm. Objects which are smaller or
narrower than 200 nm cannot be seen with the light microscope. However, the limit of
resolution of an electron microscope is 0.5 nm. Thus, the cell membrane can be seen with an
electron microscope. The width of the cell membrane is about 10 nm. (2)
(Total 8 marks)
SAQ 444
8. a) Complete the following table. Use a tick if the feature is present or a cross is it is absent.
(3)
Feature
Cell
Plasma
membrane
Cell wall
Nucleus
Red blood cell
√
X
X
Lymphocyte
Photosynthesizing cell from
a leaf
√
√
X
√
√
√
Bacterium
√
X
√
b) Cells were scraped from the cut surface of a potato tuber. They were stained with iodine
solution and examined with an optical microscope. The drawing shows one of these cells.
i) Name two polysaccharides found in this cell which would not be found in a red blood cell.
Starch and cellulose.
(1)
(ii) The diameter of this cell, measured from A to B, is 40 μm. Calculate the magnification of
the drawing. Show your working.
(2)
Magnification = measured length / actual length
Magnification = 40000 / 40
= 1000 times
(iii) The focusing knob of the microscope was adjusted slightly. The drawing below show how
the cell then looked. Explain the difference in appearance of the cell contents.
(2)
The microscope is now focused at a different level or depth. So different parts of the cells
are in focus.
(Total 8 marks)
SAQ 445
30. The diagram below shows the structure of a chloroplast, as seen using the electron
microscope.
a) Name the parts labelled A, B and C.
(3)
A – Chloroplast envelope
B – Stroma
C – Granum
SAQ 446
The electron micrograph below shows a longitudinal section of a chloroplast in palisade cell
section.
a) Name the parts labeled A and B. A – Stroma B – Chloroplast envelope (2)
b) Describe the function of the part labeled C.
(3)
The granum is made up of thylakoid membranes, which contains the
chlorophyll pigments. It is the site of the light dependent reaction, during which
ATP and NADPH2 are produced. Photolysis also occurs during this process.
c) The magnification of this electron micrograph is x 30 000. Calculate the actual length of the
chloroplast giving your answer in suitable units. Show your working. Magnification =
measured length / actual length
30 000 = 78000 / X
30 000 = 78000 / X
= 2.6 µm
[78mm is same as 78000 µm]
(2) Total 7 marks
SAQ 447
32. Ultracentrifugation was used to separate the components of cells from lettuce leaves.
The flow chart summarizes the steps in the process
(a) Explain why the mixture was filtered before it was centrifuged. (1)
To remove cellulose and other large cell debris.
(b) (i) Name the organelle present in the largest numbers in pellet A.
Nuclei
(ii) Name an organelle likely to be present in supernatant D. (1)
Ribosomes
(1)
(c) The mitochondria from pellet C were observed with an electron microscope. They had all
burst and appeared as shown in the diagram.
What does this suggest about the water potential of the solution in which the chopped
leaves were put? Explain your answer.
(2)
The water potential of the solution was higher than the water potential of the cell cytoplasm.
Thus water entered the organelles by osmosis and caused the organelles to burst.
(Total 5 marks)
SAQ 448
(i) Box drawn round appropriate H and OH; 1
(ii) Condensation; 1 Accept close versions such as condensing reaction or condensing.
(b) An H atom is at the bottom/an OH is at the top in β glucose; At the right-hand side of the
molecule; 2 Note that this is the lowest acceptable answer. Better candidates might be expected to
refer to C1. Obviously such answers should gain credit. Reject polymerisation.
(c) Two marks for correct answer of 0.9/0.89 or expressed as fraction 8/9 /0.8 ;;
One mark for incorrect answer such as 1.12(5) or 0.8 derived from correct values;
One mark for 0.9 with no working; 2 max
(d) (i) Left hand side marked; 1
(ii) Separates amino acids/spots/B and C more; 1
(a)
Total 8 AQA/BYA1/JAN
SAQ 449
SAQ450
Alpha glucose
Beta glucose
Glycosidic
Insoluble
Carbohydrates/energy
hydrogen
SAQ451
SAQ 452
(a) (i) both are polymers/polysaccharides/built up from many sugar units/ both contain glycosidic
bonds/ contain (C)arbon, (H)ydrogen and (O)xygen; 1
(ii) hemicellulose shorter/smaller than cellulose/fewer carbons; hemicellulose from pentose/fivecarbon sugars and cellulose from hexose/glucose/six-carbon sugars; 2 (only credit answers which
compare like with like.)
(b) protein/nucleic acid/enzyme/RNA/DNA/starch/amylose/amylopectin/ polypeptide; 1
(c) (i) to make sure that all the water has been lost; 1
(ii) only water given off below 90oC; (above 90oC) other substances straw burnt/oxidised/broken
down; and lost as gas/produce loss in mass; 2 max
(d) enzymes are specific; shape of lignin molecules; will not fit active site (of enzyme);
OR shape of active site (of enzyme); will not fit molecule; 2 max
(e) 1. made from β-glucose;
2. joined by condensation/removing molecule of water/glycosidic bond;
3. 1 : 4 link specified or described;
4. "flipping over" of alternate molecules;
5. hydrogen bonds linking chains/long straight chains;
6. cellulose makes cell walls strong/cellulose fibres are strong;
7. can resist turgor pressure/osmotic pressure/pulling forces;
8. bond difficult to break;
9. resists digestion/action of microorganisms/enzymes; 6 max
(allow maximum of 4 marks for structural features)
Total 15 AQA/ BYA1/JUNE05
SAQ 453
(a) Benedict’s and heat; yellow/green/brown/orange/red; 2
reference to heat must imply this but exact temperature not required. Thus accept warm, heat etc
but not an unqualified reference to putting in a water bath.
(b) (i) correct representation of β-glucose as shown below;1
(ii) H at top right end (instead of OH) / OH at bottom in α; 1 this represents the lowest level of
acceptable answer. Must clearly indicate position of H and OH and which pair the candidate is
referring to.
(c) joins (polysaccharide) chains/molecules to each other / makes microfibrils gives tensile
strength; 1
(d) nitrogen/N; 1 ignore references to sulphur but mark phosphorus incorrect.
(e) (i) E; 1
(ii) A; 1
Total 8 AQA/BYA1/JUN06
SAQ 454
(a)
Cellulose / cell wall thickened in corners ;
Tightly packed, no air space
B
ACollenchyma ;
Sclerenchyma ;
Thick cell wall / reference to lignification ; Tapered ends overlap (with other
cells) ; Reference to elongated cells conferring mechanical strength ;
4
(b)
Petiole / midrib (region) ;
1
[5]
SAQ 455
SAQ456
SAQ457
SAQ 458
(a) glucose; 1 (reject alpha glucose)
(b) hydrolysis; 1 (accept catabolic)
(c) (long) straight/unbranched chains; (idea of more than 1) chains lie side by side / form
(micro)fibrils; idea of H bonds holding chains together; 3
Total 5 AQA/BYB1/JAN 06
SAQ 459
Long straight/unbranched molecule;
Bonded together by hydrogen bonds;
Forming microfibrils;
High strength (in correct context); 3 max
(b) Includes H (from OH) and OH; 1
(c) O and OH reversed on carbon 1 and rest of molecule correct; 1
(a)
Total 5 AQA / BYB1/ JUN07
SAQ 460
SAQ 461
(a) 1. Glucose ;
2. Hydrogen ;
3. Microfibrils / fibre ;
4. Strong(er) / thick(er) / stiff(er) / rigid ;
[Do not credit hard]
5. Waterproof / impermeable ;
[Allow marking point 4 and 5 either way round]
5 marks
SAQ462 (june 2003 snab)
(a) Chloroplast
Vacuole
Cell wall
Plasmadesma
(b) (i) dead/ no cell contents/no cytoplasm /lignified
Very thick.strong cell walls / water proof
(ii) sclerenchyma folds have cross walls, xylem don’t
Sclerenchyma fibers have thicker walls than xylem
Sclerenchyma have smaller lumen than xylem vessel
© (i) spring wood has lager vessicals than fiber
(ii)
(iii)
SAQ 463
EITHER
(A)1. amniocentesis ;
2. amniotic fluid removed (from amniotic sac of mother) / eq ;
3. {fetal / embryonic} cells present in amniotic fluid /{fetal / embryonic} cells needed ;
4. DNA can be analysed / eq ;
5. to detect {defective / eq} gene(s) (in sample) / eq ;
OR
1. chorionic villus sampling ;
2. placental tissue removed (from womb of mother) / eq ;
3. fetal cells present in {placenta / placental tissue / chorionic tissue} / fetal cells needed ;
4. DNA can be analysed / eq ;
5. to detect {defective / eq} gene(s) (in sample) /
(b) Benefit:
1. gives information about abnormalities (in fetus) / eq ;
2. {opportunity for choice / eq} / {consider termination / eq} / time for {preparation /
treatment / eq } / {peace of mind / eq} ;
Risk:
3. possibility of miscarriage (due to procedure) / eq ;
4. {potentially a healthy baby would be lost / eq} / {risk to mother / eq} ;
OR
3. idea of {false positive / false negative} result ;
4. wrong decision made / description of wrong decision ;
OR
3. {damage / harm} to fetus ;
4. subsequent health issues / miscarriages / eq ;
(c ) 1. idea that a fetus is living ;
2. abortion is {wrong / murder} / eq ;
OR
1. who has right to decide if tests should be performed / eq ;
2. implications of medical costs / disagreements over next step ;
OR
1. issues relating to confidentiality of {parents / child} / eq ;
2. idea that {some other abnormality may be found / paternal DNA does not match / other
family members have right to know results} ;
OR
1. that or some other abnormality may be found ;
2. comment on possible problems with {future employment / insurance / what constitutes a
serious condition} / eq ;
OR
1. not fully understanding possible risks of prenatal testing;
2. possibility of {miscarriage / harm to child} / eq;
OR
1. {who has the right to make the decision for the fetus / fetus has decision rights} (if the test
is positive) ;
2. {denying them the opportunity to live / fetus should be allowed to live / fetus has a right to
live} ;
(9 MARKS)
SAQ464
7(a)
1. some people with (new) drug and some without (new) drug / eq ;
2. use placebo / description (e.g. sugar-coated dummy pill) /old drug ;
3. {doctors / eq} and {subjects / eq} do not know who is on (new) drug or who is not /eq ;
4. to see if new drug works better than {placebo / old drug}/eq ;
5. reduces bias /eq ;
(b)(i) glycosidic ;
(b)(ii) { α / alpha} glucose ;
(b)(iii)1. {bioplastic / starch} comes from {plants / eq} ;2. {plants / starch} are renewable ;
3. oil-based plastic is from non-renewable resource / eq ;
(b)(iv) will not accumulate / not contribute to landfill / can decomposed / eq ;
(C )
SAQ 464
SAQ465 JAN 2010 UNIT 2 (7)
SAQ 466
An experiment was carried out to investigate the uptake of different mineral ions by
barley plants. A large number of barley seedlings was grown in a nutrient solution containing
a range of mineral ions including potassium (K+), calcium (Ca2+), magnesium (Mg2+) and
nitrate (NO3–).
The
experiment was setup as shown in the diagram below
The concentration of these ions in the solution were measured at the beginning and at
the end of the experiment. The results are shown in the table below.
Concentration of ions in nutrient solution / arbitrary units
Mineral ion
Nitrate
Potassium
Magnesium
Calcium
At start of experiment
At end of experiment
7.0
3.0
2.0
5.0
1.8
0.0
2.1
5.6
(a)Calculate the percentage difference between the concentration of nitrate ions at
the beginning and at the end of the experiment. Show your working.
7.0 – 1.8 = 5.2;
5.2
7.0
Answer
 100
;
74.29 / 74.3 (%);
(3 marks)
(b) What do the results suggest about the mechanism of absorption of potassium
ions?
Explain your answer.
involvement of active transport;
(since) all (potassium) ions absorbed;
absorption against concentration gradient has occurred;
energy / ATP / respiration needed;
(3 marks)
(c ) Suggest an explanation for the changes in concentrations of magnesium and
calcium ions during the experiment.
plant takes in water ref water loss / transpiration (from barley plants); (2
marks)
(d) State two precautions which should have been taken to ensure that results for all the
barley seedlings were comparable.
1
seedlings
all
kept
at
same
temperature;
same
light
intensity
/
same
amount
of
light;
duration
of
experiments
the
same:
same humidity;
2
ref to plants of same age / size / stage of development / same mass
/ same no. of leaves / same sized roots / same variety / eq;
exclusion of light from roots / wrapping black paper around tube;
(2 marks)
(e)Describe the pathway taken by mineral ions as they pass from the nutrient
solution to the xylem in the roots of the seedlings.
root hair / root hair region / epidermal / piliferous layer cell;
cortex; endodermis / pericycle; ref apoplast / symplast / vacuolar pathways; (3
marks)
[Total 13 marks]
SAQ 467
The apparatus shown below can be used to study mineral nutrition in flowering plants.
(a)
Suggest the function of each of the following.
(i)
The stream of air
provides oxygen / O2 / or aerobic conditions;
for respiration;
for active transport / uptake of ions / minerals;
(2 marks)
(ii)
The black paper cover
excludes / or limits light / or keeps it dark;
prevents growth of algae;
algae use up / complete for ions / minerals / nutrients;
(2 marks)
(b)The nutrient solution contains various mineral ions including magnesium and
phosphate. Give one reason why each of these ions is essential to the plant.
Magnesium chlorophyll / co-factor of enzyme / ATP-ase / named eq; Phosphate OR
membrane ref phospholipids / ATP / nucleotides / phosphorylation / nucleic acids /
named eg / OR an eg of a phosphorylated product (PGA) or of phosphorylation /
NADP;
(2 marks)
[Total 6 marks]
SAQ 468
(a)
For aerobic respiration ;
respiration) ;
To provide oxygen ;
Reference to requirement for ATP (produced by
max 2
(b)
= 5.2 ; [accept 5.23]
38.1 ÷ 7.29 ;
2
(c)
They are taken up, by active transport / active uptake /
actively ;
Because the concentration in cell sap is higher than
concentration in culture solution / ions are taken up
against a concentration gradient ;
2
(d)
ions increases as temperature
increases ; Credit any quantitative description ;
(i)Concentrations of
2
(ii)
(Increase in temperature) increases, kinetic energy /
movement (of ions);
Increases enzyme activity ; Increases, (rate of) respiration / production of
ATP ;
Increases (rate of) collisions of ions with transporter
protein / eq ;
max 2
[10]
SAQ469
a) (i) 1. weigh fixed / known amount plant ;
2. measured/known volume of ethanol / known
concentration of ethanol ;
3. shake / leave for known / stated time ;
4. standardised crushing method ;
5. separation / filtration /eq ;
6. use same part of plant / same strain / variety of
the plant ;
(a)(ii) 1. description of plate pouring / eq ;
2. description of bacteria spreading / or putting
bacteria into molten agar and swirl / mix / eq ;
3. description of how garlic extract added (well,
filter paper) / eq ;
4. incubate (at stated temperature, <35) / eq ;
5. (incubate) {for appropriate time 1-3 days / upside
down} / eq ;
6. credit description of aseptic precaution e.g.
flaming neck of bacteria bottle / swabbing bench
at beginning / sterilising {loop /spreader} / using
(lit) Bunsen (flame) at back/ eq ;
7. any reference to reducing biohazard described
e.g. pipette in disinfectant / autoclave used eqpt.
/ swabbing bench at end / appropriate taping of
lid (i.e. not all round)/ eq ;
(a)(iii) 1. graph paper tracing / {mean / average} diameter
/ eq ;
2. count squares / calculate area / eq ;
3. subtract area of {well / paper} / eq ;
(b)(i) 1. axes correct (x-garlic extract, y-diameter) ;
2. axes labelled with units ;
3. correct plotting with sensible scale ;
4. suitable line of best fit / line joining points
accurately ruled ;
(b)(ii) 1. increasing concentration increases antibacterial
effect / eq ;
2. no effect 25 and below /positive correlation 50
above / eq ;
(c)(i)25 ; 1. garlic better than both tetracycline and
streptomycin / converse / eq ;
2. {not quite as good as / similar to}
chloramphenicol / converse / eq ;
3. credit correct figure manipulation / eq ;
(d) 1. correct ref to clear zone size related to
judgement on validity ;
2. correct ref to relatedness of onion to garlic ;
SAQ470 FOUND QUESTION- (JAN 2010 UNIT 2)
SAQ471
(a)avoidance of / minimising contamination by other / unwanted organisms /eq ;
by using sterile instruments / materials / conditions /eq ;
2
(b)
use of sterile agar / plates / petri dishes ;
flaming/sterilising (inoculating) needle/loop ;
flaming neck / top / lid of (slope culture) bottle ;
ref. to angled lifting of lid of plate /eq ;
ref. to holding on to plug/cap / not putting plug/cap down ;
ref. to flame generating convection currents /eq ;
max 3
(c)
stored upside down ;
to prevent condensation dripping onto agar ;
OR
sealed (with tape) /eq ;
to prevent lids falling off during handling/eq / contamination / bacteria escaping ;
OR
cross taping / sealing /eq ;
maintenance of aerobic conditions /eq ;
max 2
[7]
SAQ472
(a)
To kill (all) bacteria / microorganisms ;
Reference heat-resistant bacterial spores / thermophilic species ;2
(b)
To prevent the cotton wool being soaked / getting wet ;
(c)
Flaming of inoculating loops / forceps /eq bottle neck ;
1
Kills microorganisms present on the surface ;
Introduce loops into flames slowly ;
To avoid microbial aerosol formation / spluttering /eq ;
Swabbing laboratory work surfaces with disinfectant /eq ;
Reduces number of contaminating organisms ;
Reference to covering / sealing / minimum opening of dishes / cultures ;
Reducing entry of / exposure to air ;
Avoid breathing over cultures /eq ;
Reference to human contamination ;
Max 4
[7]
SAQ473
SAQ474
SAQ475
SAQ476
SAQ477
(a) (ii) 1. more expensive / eq ;
2. large numbers / long time / animal testing / legal costs / equipment qualified ;
(iii) Similarity
1. discovery / testing on people/ small to start with/ scale up / careful recording of results,
publication/ finding effective dosage / similar response to safety issues / monitoring patients /
need for replication ;
2. appropriate comments for both protocols ;
Difference
3. animal tests / large scale synthesis / placebo, double blind trials / sample size ;
4. appropriate comments for both protocols ;
SAQ478
(a) supercoiling / transcription factors /repressor molecules / hormones ; 1 mark
(b) A suggestion to include two from:
1. (due to) uncontrolled mitosis / cell division ;
2. the rate of cell division greater than cell death / apopotosis ;
3. correct reference to mutation ; 2 marks
(c) (i) A description to include four from:
1. animals / cell culture tested for humans ;
2. reference to female subjects ;
3. (phase I) preliminary (small scale) tests on healthy volunteers ;
4. {independent / official} body of {scientists / medics} / (UK) Medicines Control Agency
decides whether work can progress (to phase 2} ;
5. (phase II) drug tested on small groups of (volunteer) {patients / people} who
already have the disease ;
6. (phase III) {larger / 1000 to 3000 group of} {patients / people} who already have the
disease ; [Accept if no reference to phase I and II]
7. placed randomly in two groups one to receive treatment the other not /
as control ;
8. one group given medical product the other a placebo / dummy treatment /
no active ingredient ;
9. (double blind test) neither patients nor doctors know who has the active compound ;
10. statistics used to analyse results / test for significance ; [Credit points 6-9 in context of
animal testing]
(ii)
d)
4 marks 8048/9048 Mark Schemes 19
SAQ479
SAQ480
SAQ 481
(a) suitable method of capture; mark individuals and release; count percentage recaptured/use
Lincoln index/equation; 2 max .
(b) 282 x 281 = 3.12; 2 25384 (accept 3.1/3.122)
(c) decrease in total numbers of butterflies; (reject population) change in proportion of
species/example(s); increase in diversity in logged forest/ calculation (4.01); 2 max
Total 6 AQA/ BYB6A/JUN06
SAQ 482
(a) cultivation of single species/variety of crop/named crop / one crop grown over a large area; 1
(b) (i) more space for crop;
easier to use machines/named machine;
removes habitat for pests;
lower labour costs in maintenance;
less competition with (crop) plants for named resource; 2 max
(ii) more habitats/niches/food sources/more animal/insect/mammal/
bird species present/more species diversity/larger food webs/
more food chains; 2
(c) food source killed by pesticide;
insufficient food (for survival)/lack of alternative sources/specialist feeder;
OR pesticide passed through food chain;
biomagnification/bioaccumulation/concentration higher in top carnivores;
OR stored in fat; released over time;
OR run off/leached into rivers; kills aquatic life; 2 (animals eat pests containing the
pesticide gains 1 mark)
Total 7 AQA /BYB5W/JUN06
SAQ 483
(a) Breed (among themselves); To produce fertile offspring; OR Have same niche; Not shared with
any other species; 2 max
(b) High stability with greater number of species / converse; When number of species is high
stability levels out; More species linked to more food chains / food web; If one species dies others
available as food / converse; 3 max
Total 5 AQA/BYB5W/ JAN 07
SAQ 484
(a) Shorter food chain;
Less energy lost (transferring) between (trophic) levels; 2
(b) Use coordinates/random numbers/permanent quadrats;
(reject transect)
Use a large number of Quadrats;
Count number of (each) species of plant/percentage cover;
Repeat at regular time intervals/stated time interval;
Use data/ statistics to make a comparison; 4 max
(Accept ref. to diversity index)
Total 6 AQA/BYB5W JAN 2008
SAQ 485
(a)(i)1. appropriate feature ;
2. linked to appropriate explanation ; e.g.
1. {streamlined / hydrodynamic / flattened /eq} {body / shape} 2. reduces {drag / eq}
1. {hooked feet / claws / eq} 2. to {cling / attach / hold / eq} onto {rocks / eq}
1. wide spread legs 2. {to spread over rock / grab rocks / eq}
(a)(ii) 1. (tube) {breaks water surface / reaches into the air / eq} ;
2. acts as a snorkel / description ; 3. (atmospheric) air / oxygen obtained ;
(b) 1. camouflaged in its environment ;
2. (more likely) to catch {prey / eq} / {selective advantage eq} ;
3. (therefore) survive to adulthood / eq ; 4. to breed / eq ;
5. pass on {coat colour allele /genetic information / eq} ; 6. to offspring / eq ;
7. change in allele frequency over generations ; 8. reference to disruptive selection ;
9. idea of genetic variation present in ancestral population ;
SAQ 486
SAQ 487
(a) Habitat – physical place occupied by an organism/population;
Population – all organisms of one species in an area/habitat/ecosystem/community at
one time;
Community – all organisms / all populations in an area/ecosystem at one time; 3
(b) (Unsuccessful) competition with other species / outside realised niche;
Because less well adapted/condition less favourable; 2
Total 5 AQA BYA5 JUN 8
SAQ 488
(a)
Samples collected at random; Method for choosing random sites . random
coordinates/position from tables/calculator/other suitable means; Same size of net/same
width of opening of net/use of one quadrat/ Quadrats of sma size/of stated size/same area
disturbed/collect each Sample for same time; 3
(b)
Caenidae in deep water . because highest standard deviation/ .S.D.= 7.92. 1
(c)
(i) An organism.s role/ in the ecosystem/ community; [ALLOW refs. To trophic
levels/named] (IGNORE refs. To habitat) 1
(ii) Caenidae found mainly in deep water AND Baetidae in shallow water / one family mainly in
deep water AND the other in shallow water; 1
(iii) Reduces competition; For named factor . e.g. food/shelter/O2 ;
To ensure both types survive/otherwise better adapted type displaces other type;
OR Ref. to .Competitive exclusion principle. = 2 marks max 2
Total 8 marks AQA/BYB5W/JUN04
SAQ 489
(a) large surface area; so increases heat loss (to the air); OR increased blood flow into ears; so
increases heat loss; 2 max
(b) more movement needs greater energy use/ muscle contraction; more heat generated through
respiration; OR in sun, more heat absorbed; harder to lose heat by sweating/vasodilation; 2 max
Total 4 AQA/BYB6A/JAN 05
SAQ 490
(a) Description; Explanation;
E.g. Increase in transpiration/evaporation/diffusion;1 Higher kinetic energy / faster movement
of molecules/ particles/steeper water potential gradient;1
OR Decreases in transpiration/evaporation/diffusion; Due to closing of stomata;
2 max
(b) Sunken stomata/description;1 Reduces water potential/diffusion/concentration gradient /
traps humidity/water molecules;1
(Reject traps water) Thick cuticle; Impermeable to water (Accept waterproof) / increases
diffusion pathway/distance; 1
TOTAL 4 AQA/BYB3W/JAN 08
SAQ 491
(a) Any five from:
(i) 1. Parents/insularia are CiCt (and CiCi); Accept as gametes in genetic diagram
2. Can have offspring CiCi / CiCt AND CtCt;
3. Both phenotypes correctly assigned to genotypes;
4. insularia cannot have CC allele;
(ii) 1. Parents/carbonaria are CCCt and CCCi (and CCCC) ;
2. Can have different offspring with CC AND CiCi / CiCt AND CtCt;
3. All 3 different phenotypes correctly assigned to genotypes; 5 max (Accept argument in words
/ symbols / genetic diagrams)
(b) 1. Variation (in colour) present originally; [must be explicit, not just implied]
2. (Variation) due to mutation; [CONTEXT . not caused by environment]
3. Appropriate colour " camouflage / inappropriate colour " visability;
4. Camouflaged / better adapted moths survive / not eaten (/ converse for visible)/ dark moths
survive / are better adapted in Birmingham (/converse re. Dorset) / have selective advantage;
5. Pass on (relevant) allele / gene to offspring;
6. Increasing frequency of appropriate allele; 5 max
(c) (i) Can interbreed/ can be mated/crossed; 2
Producing fertile offspring/ described; Ignore viable
(ii) Mutation occurs; Correct example of isolating mechanism / .sympatric. e.g. temporal .
different breeding seasons / feeding times
/ behavioural . different courtship displays / different niches / habitats / feeding
Areas / mechanical . mismatch of reproductive parts / gamete incompatibility . sperm killed in
female.s reproductive tract / hybrid inviability / hybrid infertility
/ Geographical isolation / suitable example .allopatric.; Allow barrier (Eventually) 2 groups can
no longer interbreed successfully; 3
Total 15 AQA/BYA5/JUN7
SAQ492
(a) Measure {growth / height / number of leaves / mass / dry mass} ;
Growth with copper and {without copper / control / range of copper concentrations ;
Reference to controlling variables; Reference to {repeats / means / calculation of percentage
growth]; 2 marks
(b) High tolerance plants grow on {site B / eq} ; Tolerance genes from {mine site / site BI;
Carried by {pollen / seeds}; To {downwind site / site C} ; Tolerance higher downwind than
upwind-; 3 marks
(c) Plants compete / eq ; For {ions / water / nutrients / nitrates / tight / space / eq)
Tolerant plants less well adapted / converse / eq ; So tolerant plants {smaller / less dry mass} /
converse / eq Idea: Results are due to competition only because trays 1 and 3 growing the
same ;
Manipulated figures ; 4 marks
(d) Decreases / more non-tolerant; No benefit ; Competes less well;
2 marks Total 11 marks
SAQ 493
(a) Smaller groups within big groups / hierarchical; Based on similarities / features in common /
named example; Evolutionary relationships / common ancestry / phylogentic ; 3
(b) (i) Class, Drosophila melanogaster ; 1
(ii) 1, 6, 7, 2, 3, 4, 5; 1
(c) 1 Geographical Isolation of fruit flies;
2 No interbreeding / gene flow;
3 Range of habitats / environmental conditions;
4 Different selection pressures in separate populations;
5 Mutation;
6 Variation amongst fruit flies;
7 Some more suited to environment than others /differential survival;
8 Beneficial allele /gene passed on;
9 (Populations) unable to produce fertile offspring / reproductively isolated; 6 max
(d) 1 Hawaiian islands isolated / Britain less isolated;
2 Few colonising species;
3 More environments / niches/habitats available / more suitable environments;
4 Less competition;
5 Adapted;
6 British % 0.15, Hawaiian % 7.70 / higher proportion of insects in Hawaii;
7 Rapid evolution of species of drosophila; 4 max
Total 15 AQA/BYB4/JUN07
SAQ 494
(a) Discontinuous; (Only) two /discrete classes; 1
(b) (i) 1. Mutation, unbanded/banded form/variation;
2. Different environments/selection pressures;
3. Camouflage/description; (Accept crypsis)
4. Selection by predation/description;
5. (Survive to) reproduce/pass on advantageous alleles;
6. Change in allele frequency (in the next generation);
7. No gene flow between populations; 4 max
(ii) Two suitable suggestions: e.g. (Back) mutation; Migration (of banded snakes from
mainland); Banded could be recessive so still get (occasional) homozygotes/
heterozygous advantage; Stabilising selection/description of; Selection pressure stays the
same; 2 max
Total 8 AQA/BB4/JAN07
SAQ 495
(a) variation present in (original population); (copper) tolerant individuals more likely to survive;
(these reproduce and) pass on genes (to next generation/offspring); more/increase (in frequency)
of copper tolerance alleles/genes; 4
(b) 1. reproductively isolated / no interbreeding (due to different flowering times);
2. conditions different for two populations / different selection pressures;
3. different features or plants are selected or survive /different adaptations;
4. populations become (genetically) different;
5. unable to produce fertile offspring; 4
Total 8 AQA/BYB4/JAN5
SAQ 496
(a) breed together; if fertile offspring, then same species; 2
(b) isolation of two populations; variation already present due to mutations; different
environmental conditions / selection pressures; selection of different features and hence different
alleles; different frequency of alleles; separate gene pools / no interbreeding; 4 max
(c) selection of mate dependent on colour pattern; prevents interbreeding / keeps gene pools
separate; 2
Total 8 AQA/BYB4/JAN06
SAQ497
SAQ498
Haemoglobin in mammals is made up of four polypeptide chains, two identical chains
and two identical chains. The sequence of amino acids in these chains has been
determined for a number of different mammals.
Table 1 below shows a sequence of fifteen amino acids in an chain from four different
primates: a chimpanzee, a human, a gorilla and an orang-utan.
Table 1
Primate
Amino acid sequence
Chimpanzee
KAAWGKVGAHAGEYG
Gorilla
KAAWGKVGAHAGDYG
Human
KAAWGKVGAHAGEYG
Orang-utan
KTAWGKVGAHAGDYG
Key:
histidine
A = alanine
D = asparagine
E = glutamic acidG = glucine
H=
K = lysine
T = threonine
V = valine
Y=
W = tryptophan
tryrosine
(a)
(i)What differences
are there between the amino acid sequence for the orang-utan and the
chimpanzee?
orang-utan has T / threonine instead of A / alanine and has D / asparagine
instead of E / glutamic acid / T and D / chimp has A and E;
(1 mark)
Name one other pair of primates in the table in which there is a difference in
the amino acid sequence.
chimpanzee and gorilla / gorilla and human / orang-utan and gorilla / orangutan and human;
(1 mark)
(b)Comparisons of amino acid sequences have been used to determine evolutionary
(phylogenetic) relationship in the primates.
(i)Using evidence given in Table 1, complete the evolutionary tree diagram
below to show the possible evolutionary relationship between chimpanzees,
gorillas, humans and orang-utans.
orang-utan;
Common
ancestor
Chimpanzee
human;
gorilla;
(3 marks)
(ii)Give two ways in which the data in Table 1 support your suggested
evolutionary relationship.
1. human and chimp have (exactly) same / eq. sequence (so must be
together);
gorilla differs by one amino acid so more closely related to humans;
2. orang-utan more differences / 2 amino acids so not as close as
gorilla / eq;
(2 marks)
(c)When human blood serum is injected into a rabbit, the rabbit produces antibodies
against human serum proteins. When blood serum from humans and other
mammals is mixed with rabbit serum containing these antibodies, precipitation
occurs.
Table 2 below shows the percentage precipitation when this rabbit serum was mixed
with serum from a human, a gibbon, a spider monkey and a hedgehog.
Table 2
Mammal
Percentage precipitation
Human
100
Gibbon
79
Spider monkey
58
Hedgehog
17
What do these data suggest about the phylogenetic relationship of the four
mammals in Table 2?
gibbon closest to human;
hedge hog distantly / eq. related (to human);
spider monkey more distant than gibbon (to human)
(2 marks)
(d)
(i)Describe how
fossils can be used to provide evidence for human evolution.
sequence of changes can be seen;
ref. to dating of fossils;
skeleton / eq. shows trend from quadripedal to bipedal locomotion / eq.;
changes in hands show evolution of dexterity;
changes in jaws / teeth show changes in diet;
changes in skull / eq. show evolution of brain;
(3 marks)
(ii)Give one disadvantage of the use of fossils in providing evidence for human
evolution.
incomplete record / eq. incomplete / eq. fossils / unreliable dating / fossil
displacement;
(1 mark)
[Total 13 marks]
SAQ499
(a) (i) prokaryotae/eq ;1 mark
(ii) Kingdom Feature
protoctista / protista single celled; fungi mycelium / hyphae / chitin cell wall /
heterotrophic nutrition ; plantae cellulose cell wall/{large/ permanent} vacuole
/photosynthesis / autotrophic/ chloroplasts; animalia no cell wall or large vacuoles /
heterotrophic; (1 mark per correct 2 boxes)
(rows must match) 4 marks
(b) (i) B Formica aquilonia D Formica exsecta
E Formica sanguine 2) marks for all three, lose one mark per error
(ii) Formica ; 1 mark
Total 8 marks
SAQ 500
(a)
(i) (Large) groups are divided into smaller groups; 1
(ii) Based on evolutionary history / linked to common ancestors; 1
(b)
(i) Pongo; 1
(ii) Primates / Primata; 1
(c) (i) In the old classification / Figure 2, humans are in the same family as the apes / all classed
as Hominidae OR In the new classification / Figure 1/ now, humans are in a different family /
only humans classed as Hominidae; 1 max
(ii) One suitable source of evidence; e.g. DNA hybridisation; DNA / base sequences; Amino
acid sequences (in proteins); Fossils; Immunology; Embryology; 1 max
Total 6 AQA/BYB4/JUN08
SAQ 501
(a)
(i) Taxon A . there is more than one level/taxon below it / genus only has species / only
has one level / taxon above it;
(ii) Taxon C . there is more than one level/taxon above it / phylum only has kingdom / only has
one level taxon above it; 2
(b) chitin cell wall; ignore non . cellulose mycelial habit / hyphae; coenocytic / eq.; ignore
references to being non-photosynthestic, eukaryotic. 2 max accept reproduce by spores.
Total 4 AQA/BYA5/JUN06
SAQ 502
(a) (i) Certhidea olivacea; 1
(ii) 5; 1
(iii) Camarhynchus and Cactospiza; 1
(b)
Anatomy/morphology/ecology/biochemistry/fossils/embryological/behaviour/
valid
examples;; (any two) 2 max
(c) 1 Variation in beak shape present in original population;
2 No gene flow between islands/geographical isolation;
3 Selection of individuals with beaks suitable for eating small seeds on one
island/selection of beak suitable for eating large seeds on another;
4 Those with the most suited beaks (survived) to reproduce/pass on their
alleles/genes for beak shape;
5 Allele frequency changed on each island / populations became genetically different;
6 So that individuals from different islands unable to reproduce to produce
fertile offspring; 4 max
Total 9 AQA/BYB4/JAN 08
SAQ 503
(a) Phylum class order family genus; 1
(b) (i) Prokaryotes; 1
(ii) Ribosomes/DNA/cytoplasm/cell membrane; (accept flagellum/cell wall/unicellular) 1
(iii) Eukaryotic/any named eukaryotic organelle; 1
(c) (Cell wall of) chitin/hyphae/ mycellium/heterotrophic feeding/multinucleate; (accept spores
released in asexual reproduction) 1
Total 5 AQA/BYB4/JAN07
SAQ 504
(a) phylum, class, order; Species, Acinonyx jubatus; 2
(b) larger groups containing smaller groups; 1
(c) (i) do not interbreed to produce fertile offspring / different DNA / different niches; 1 (ii)
fossil record; evolutionary history/phylogeny; biochemical differences e.g.
DNA/proteins/cytochromes; homologous features / named feature; karyotype / number and
form of chromosomes; 2 (discount any example credited in (i))
Total 6 AQA/BYB4/JUN06
SAQ 505
(a) cell walls with chitin / hyphae / mycelium; 1
TOTAL 4 /AQA/BYB4/JAN5
SQA 506 SNAB
SAQ 507
SAQ 508
(a) Any two from:
1. DNA does not change ;
2. DNA unique to individual ;
3. Test reliable / reference to probability ;
2 marks
(b) Tissue / eq ;
Intact DNA / contain DNA / nuclei ;
2 marks
(c) An explanation to include:
1. Sample from corpse ;
2. Match with family ;
3. Match with sample / previous test ;
4. Example of source of comparison (e.g. hairbrush, toothbrush) ;
3 marks
(d) Any two from:
1. Dental records ;
2. Face / recognition / eq ;
3. Normal fingerprints ;
4. Personal artefacts ;
2 marks
Total 9 marks
SAQ 509
(a) (i) (Fencing): Rhinos come into contact more often; Spread of infectious disease /
leading to infection / more likely to suffer injury; (Captive breeding):
(Inbreeding) may pass on harmful genes / reduces genetic variation (can die of the
same diseases); (Artificial environment means) young rhinos don’t learn survival
strategies; 4
(ii) More food available to support larger population / less spread of disease but
poaching / hunting is still problem; 1
(b) Variation in resistance (to disease); Individuals with resistance more likely to
survive; Pass on alleles / genes; Causes a change in allele(s) frequency / higher
frequency of allele(s) for resistance; 3 max
Total 8 AQA/BYB6A/JUN07
SAQ 510
(a)
(i) (Dugongs) large enough to be seen from the air/regularly come to the
surface to breathe/found over large areas/planes don’t disturb habitat; 1
(ii) Allows comparison between different areas/takes into account different sizes of
areas surveyed; 1
(iii) N has smallest population per km2; OR L smallest area/smallest population; 1
(b)
(i) Protection of habitat; Legal measures; Captive breeding program; (Captive
breeding involving) surrogacy/artificial insemination; 2 max
(ii) Maintaining genetic diversity (for future breeding programmes); Ethical/aesthetic
reasons for conservation/tourism; Avoid damage to food webs/control local species;
May provide useful genes/chemicals to treat diseases; 2 max
(c) (i) and (ii) both sections read together, then marks awarded to a max of 3
(i) Myoglobin has greater affinity for oxygen (than haemoglobin); So takes up oxygen
from (oxygenated) haemoglobin in the blood; 2 max
(ii) At lower partial pressures, small change causes the release of (a lot of) oxygen;
Allows unloading/storage of oxygen at lower partial pressures (of oxygen) during
dive; 1 max
Total 10 AQA/BYB6A/JUN07
SAQ 511
1. conserve genetic variety / prevent inbreeding / increase
gene pool ;
2. breeding programmes ;
3. research / eq ;
4. education ;
5. reference to attracting visitors / increasing revenue /
increasing publicity ;
6. ethics of killing healthy animals / would die if released
into wild ;
SAQ512
(a) (i) twice as much / double / by 15 000 000; 1 mark
(ii) 85% of 60 / 60 / 100 x 85;
51 (million);
[full marks for correct answer] 2 marks
(b) (i) smaller area;
more fragmented; 2 marks
(ii) A suggestion to include two from:
1. less variety / smaller gene pool;
2. lose communication / no corridors / isolation;
3. reference to genetic drift / random changes in gene frequency;
4. less interchange of genetic information;
5. reference to possible speciation; 2 marks
(iii) A discussion to include five from:
1. biofuel less polluting;
2. palm carbon sink;
3. renewable / sustainable resource;
4. economic benefits;
5. palms provide new habitat;
6. danger of extinction of apes / inbreeding / eq;
7. less biodiversity / loss of forest resources;
8. forest bigger carbon sink;
9. problems of monoculture;
10. any valid point e.g. habitat loss;
5 marks Total 12 marks
SAQ513