OCR Biology B - B4 B5 B6 - Unofficial Mark Scheme

I put 10kg, would that still get me a mark?

Also guys, what do you think the grade boundaries would be like this year? Any estimates?

I don't know - it was only a one marker and normally they're not as lenient in the markschemes, but you could still get the mark



Last year, you needed 49/85 for an A*, and judging from people's reactions to this paper, it will probably be similar.

Ohhh okay ugh I feel like I've failed this paper! One last question, what do you suppose a B would be? Thanks so much

Does anyone know what the 6 markers required you to write?

I've finished every question on the mark scheme, including the six markers ^, but if you feel I have made a mistake, please feel free to correct me because I have probably made some errors somewhere

Thank you!!

I put 10kg, would that still get me a mark?

Also guys, what do you think the grade boundaries would be like this year? Any estimates?

[Just copying and pasting my previous post! ]
In the past years, the grade boundaries have been as follows;
2015- A*: 49, A: 41, B: 33, C: 25
2014- A*: 53, A: 43, B: 33, C: 24
2013- A*: 47, A: 39, B: 31, C: 23
In comparison to these past papers, I believe that this paper was marginally more difficult, so I think that the grade boundaries will look something like this; A*: 48, A: 38, B: 32, C: 24.
Hope that this helps some of you out! [Links: "]http://www.ocr.org.uk/i-want-to/conv...marks-to-ums/]

Thank you so much Honestly, I feel just a tad better I guess, I calculated 38/85 but like idk how lenient I'm being with myself haha. Thanks so much anyway! Will you be doing this with Chemistry and Physics too? It really helps a lot

Hopefully! I have predictions for the grade boundaries for the first biology exam too, if you'd like them. I'm sure you did brilliantly- 38 is usually a solid A

Ooh yes please! Thanks once again I'm sure you did super well too, what d'you think you got?

No problem

How did you find the exam?

Hard.. And I made some really stupid mistakes so I've lost quite a lot of marks from that! Plus the fact that revision for this exam began the night before... How did you find it?

OCR Gateway Biology B
B4 B5 B6 + Section D Exam
Friday 17th July 2016
Unofficial Mark Scheme - 85 Marks

MODULE B4: 25 MARKS
1. Apple tree
a) A tree is not watered for a month
a)i) Pick the picture of the cell after no watering for a month [1]
D (1)

a)ii) Describe cell after no watering for a month [1]
Plasmolysed (1)

b) How would active transport work for minerals? [2]
moving substances / minerals against the concentration gradient (1)
using energy from respiration (1)

2. Methuselah the tree
a) Explain how photosynthesis and transpiration are affected by: low temperature, dry soil, and strong wind [6]
Marking points
low temperature: limiting factor of photosynthesis (enzymes) and so photosynthesis will be slower; transpiration will decrease as the water molecules will have less energy to evaporate out of the stomata

dry soil: less water for photosynthesis (reactant) and so photosynthesis will be slower; transpiration will increase as the concentration gradient will be maintained, further slowing photosynthesis

strong wind: transpiration will increase as the concentration gradient will be maintained - water outside will be blown away, further slowing photosynthesis as there will be less water

b) These trees have a resin that causes little water and oxygen absorption. Why would this stop the tee from rotting? [2]
stops decomposers respiring (1)
so they reproduce less / die (1)

c) Name the cells that transport substances, and what they transport [4]
xylem made of dead cells (1)
transports water (1)
phloem made of living cells (1)
transports food / sugars (1)

d) Ring width
d)i) Using the graph, evaluate the the claim that ring width has increased [2]
overall increase (1)
but has been mostly decreasing and only recently quickly increased (1)

d)ii) Evaluate the the claim that the data proves global warming [2]
example
ring width increase may have had other factors, not just temperature (1)
cannot be proven as this is just one scenario (1)

two marks may be awarded if a correct evaluation is done

3. Pigments in plants
a) Explain why red seaweed can live at the bottom of the sea (given a graph where red penetrates the least deep) [3]
use of data (1)
red seaweed absorb all of the light except red (1)
so they can live as deep as the deepest pigment they absorb (green) (1)

b) Name the four elements in a protein [2]
all four (2)
three (1)
otherwise (0)

carbon, hydrogen, oxygen, nitrogen

MODULE B5: 25 MARKS
4. Bones
a) Draw lines to show where the cartilage and bone marrow are in the femur [2]
line connecting cartilage to dotted bit at top of bone (1)
line connecting bone marrow to filled bit in middle of bone (1)

b) Explain the two types of joint in the femur [2]
ball and socket: full rotational movement (1)
hinge: only in one direction (1)

c) How many kg does she need to gain to be in the low risk category? [1]
8kg (1)

d) Explain why people over 45 may get a fracture if they have a fall [2]
calcium is lost from bones (1)
making them softer / more brittle (1)

5. Blood/the heart
a) What surgery would he need for a blocked coronary artery (tick one)? [1]
by-pass surgery (1)

b) Graph, aspirin, warfarin - how do they do what happens in the graph, and explain why he should take one [6]
Marking points
how blood clots: platelets come in contact with damaged blood vessels,causing a series of chemical reactions leading tothe formation of a mesh of fibrin fibres (clot)

aspirin and warfarin are anti-coagulants and so control clotting, but increase the risk of bleeding

aspirin: stops platelet production and so reduces clotting (as seen in graph) as the platelets cannot collect at the damaged vessel, meaning that they are less likely to cause a blockage - however, as seen in the graph, this does lead to the issue that there is a higher incidence of dangerous bleeding

warfarin: reduces fibrin and so the platelets are less reinforced and are more likely to be swept away by the blood, leading to the lower amount of dangerous clotting, as seen in the graph - however , also as seen in the graph, this will lead to the issue of dangerous bleeding as the platelets may be swept away, causing bleeding

why he should take one of them: so that his risk of dangerous blood clots is reduced, do that he doesn't need more surgery

c) He has a blood type O. Tick one box to show which antibodies and antigens he has. [2]
antibodies: anti-A and anti-B (1)
antigens: none (1)

d) Explain what would happen if he was transfused with A type blood. [2]
anti-A antibodies would lock onto A antigens (1)
agglutination (1)

6. Running race
a) Calculate Sanchez's percentage change and suggest who would win [2]
(60 / 64 - 1) x 100 = -6.25%/-6.3% (1)
Leroy, as he only is thirsty, while Sanchez is so dehydrated that he has muscle cramps and spasms (1)

b) Explain how the small intestine is adapted for rapid absorption [2]
any two of
villi (and microvilli) having a large surface area and good blood supply (1)
long so that there is high chance for absorption (1)
excellent blood supply (1)
thin permeable wall (1)

c) Explain why Leroy will produce more urine even though they drink the same amount [3]
more water in blood stream as less dehydrated (1)
less ADH released (1)
kidneys tubules less permeable and less water absorbed into blood - instead goes into urine (1)

MODULE B6: 25 MARKS
7. Invertase and enzymes
a) Using the graph, what are the ideal conditions for immobilised invertase? [1]
pH of 5 and temperature of 50°C (1)

b) On the graph, for free invertase, the rate for pH 5 + 55°C is the same as pH 5 + 60°C. Explain why 55°C is used [2]
lower temperature and no effect on activity (1)
any change in pH has a lesser effect as curve is smoother (1)

c) Using the data and your knowledge, give one advantage of immobilised enzymes, and one disadvantage of free enzymes [2]
do not contaminate product / continuous flow processing / easier to remove from mixture (1)
free enzymes have a much higher activity rate (1)

d) Explain why sucrose when broken down (sweeter) is beneficial to the food industry [2]
foods can therefore be sweetened without adding so much sugar (1)
e.g. in low calorie foods (1)

8. Phytoplankton/zooplankton numbers : similarities/differences between two graphs in two different areas, suggesting reasons for these [6]
similarities: predator-prey relationship in both, with explanation why it is out of phase, to include phytoplankton being the prey/producers, and the zooplankton being the predators/consumers

differences: phytoplankton increased in numbers in an earlier time of the year in the first graph, in comparison to the second graph - indicating that, earlier in the year, the first graph's area is warmer and sunnier than the second graph's area, as the phytoplankton would thus be able to photosynthesise more and increase in numbers

9. Biogas
a) Give two advantages of biomethane, and one disadvantage [3]
advantages - any two of
more energy released than landfill gas (1)
high methane concentration - not explosive (1)
less CO₂ produced (1)
'cleaner' (1)

disadvantage - any one of
requires energy to make from landfill gas (remove CO₂) (1)
there may be other suitable examples

b) Explain why more biogas will be produced in water-logged soils [2]
less oxygen for the decomposers (1)
therefore more anaerobic respiration producing more biogas (1)

c) Explain why production rate may be affected outside of 35°C-50°C [2]
below - enzyme function is slow (1)
above - enzymes denatured (1)

d) Explain why even after decommission, the landfill sites are monitored [1]
about 10% is explosive (1)

10. Genetic engineering
a)i) The enzyme used to cut DNA [1]
restriction enzyme (1)

a)ii) The enzyme used to stick DNA [1]
(DNA) ligase (1)

b) Explain why the same enzyme should be used to cut the DNA [2]
(there would be) no complimentary base pairing (1)
(DNA) ligase would not be able to repair the cut surfaces / sticky ends (1)

SECTION D: 10 MARKS
11. Parakeets
a) Given two surveys - explain if a trend could be seen [2]
there is a change in number of sightings (1)
but there wasn't any breeding before (1)

b) "they like to live down south because of warm temperatures" [2]
we don't know if the temperatures are the reason (1)
they might just live there by chance / are moving up north (1)

c)i) Year with most confidence [1]
2005 (1)

c)ii) Suggest why [1]
more data collected / observations matching predictions (1)

d)i) "numbers have been decreasing" [2]
line for all species has actually gone up a tiny bit (1)
the lines that are decreasing do not constitute half of the species in total (1)

d)ii) Suggest why percentages are used rather than population sizes [2]
population sizes are different for each species (1)
percentage is standardised (1)

Question 9c was different to what you have put down. The question asked why the temperature is reduced below 50 degrees but above 35 degrees when 50 gives best rate of reaction. The answer is because a compromise between the need for high rate of fermentation and the cost incurred by maintaining a high temperature is made. I think.

Ok, thank you - I have update my markscheme