GCSE B3 OFFICIAL UNOFFICIAL MARK SCHEME 9th June 2017

hi guys. here's the MS for B3, i believe there's already B2 out so may not be making one for that. will see how it goes though.

1a) how does deforestation increase global warming? [1]
reduces amount of CO2 taken in by photosynthesis, thus more in atmosphere

1b) decay question, graph given. forest A has temp of 10 degrees, what is decay rate? [1]
0.8 arbitrary units

1c) Forest B has temp of 30 degrees. what is decay rate? [1]
3.2/3.3

1d) how does decay increase global warming? [2]
microorganisms respire to decay, respiration releases CO2. leads to global warming


2a) what does sulphur dioxide contribute to? [1]
acid rain

2b) calculate % decrease of SO2 from UK sources[2]
1400 - 480 = 920, 920/1400 x 100 = 65.7%

2c) describe the trend shown by the graph uk transport SO2 production [2]
increased at one point up to (2005) and then decreased. After that it decreased at slower rate and the overall change was (cant remember)

3) 6 marker on removal of waste [6]
urea made in liver from excess amino acids. this is carried in the blood plasma and carried to the kidney, where it's filtered in the tubule. ALL urea is removed and blood passes back out. The filtered urea is mixed with excess ions and water to form urine, which is transported to the bladder, and then released later.
cells respire to release CO2 which is a waste product. this is also carried in the plasma and RBC's and diffuses into the lungs where it's exhaled out. water from respiration may also follow this path.

4a) heart question. label X and Y. [2]
X was left ventricle. Y was aorta

4b) heart contains valves. what is the function of valves? [1]
to prevent back flow of blood

4c) compare pros and cons mechanical valve [4]
no deaths from mechanical valve, 3 times less chance of death from second operation. however, almost double chance of death from bleeding, and need to consider whether the material (plastic) is durable and can withstand the pressure of the blood in the heart.

5ai) two tissues and what they transport [2]
xylem - water
phloem - sugars/minerals

5aii) describe the process of active transport [3]
substances move against concentration gradient, from low to high concentration, requiring energy from respiration.

5b) student said that D was clover plant, use figure to suggest and explain why [3]
showed fastest rate of mass loss (4.4g) in the 30 mins, due to largest number of stomata per mmsquared. (337.3) this means more water loss, so more transpiration

5c) clear box around plant A, how does this affect rate of transpiration [3]
box means water lost from some water vapour does not escape and so higher concentration around plant, makes it humid. this cools it, so rate slows and less water is lost. there's also no wind to increase the rate and so rate is slower

6a) Name substance X [1]
glucose

6b) scientist says a load of crap. work out the ratio of potassium to sodium ions[1]
112:38, 56:19, 2.9:1 or 3:1

6c) the scientist says P was the best sports drink, suggest why [2]
high glucose and ion content, while maintaining 2:1 ratio of ions

6d) the concentration inside blood cells is 280. T has a concentration of 493. explain what happens to the cell when put in the drink. [3]
the cell loses water by osmosis due to the concentration gradient formed as the sports drink T has higher concentration, the cell shrinks.

7ai) describe how the brain detect change in body temperature [2]
receptors in skin detect change and sends impulse to thermoregulatory centre in brain.

7aii) the man falls of the mountain. begins to shiver in cold water. He's injured and can't move. Explain how shivering raises his core body temperature. [3]
shivering is rapid contraction and relaxation of muscles. to contract these muscles need energy from respiration. as respiration occurs the energy warms the body.

7b) other than shivering, explain other ways in which the body is kept warm. [3]
can be the following:
hair rises, traps warm layer of air to insulate, reducing heat loss,
sweat glands stop producing sweat, thus no evaporation of it to remove energy
vasoconstriction, less heat lost by radiation.

8) 5 marker on villi, adaptation coeliac. Explain why someone with this disease would lose weight feel and have a vit and min deficiency. [5]
lower surface area means less absorption of soluble foods and vits and mins. less capillaries mean slower rate of absorption, longer diffusion pack means takes longer and so less absorbed. overall, less absorbed so lose weight and lack mins and vits

9a) explain what happens when the pancreas detects rise in blood sugar levels [2]
produces more insulin, glucose enters cells, lower blood sugar concentration

9b) someone with glycogen storage disorder. after exercise, they feel tired and may be unconscious. explain why they may feel this way [4]
glycogen is insoluble and so isnt used up until needed. As this person cant convert it, it remains as glucose and ALL of it gets used up during exercise, this means that there's less energy provided later as there's lack of glucose, and they feel tired and unconscious.

FULL MARK SCHEME.

This is so confusing

tbh it's only 1 mark. also, the triple grade boundaries are always low. I reckon it would be 45 for A* or 44

The question was only 1 mark?

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1c) Forest B has temp of 30 degrees. what is decay rate? [1]
3.2/3.3

7ai) describe how the brain detect change in body temperature [2]
receptors in skin detect change and sends impulse to thermoregulatory centre in brain.
FULL MARK SCHEME.

9a) explain what happens when the pancreas detects rise in blood sugar levels [2]
produces more insulin, glucose enters cells, lower blood sugar concentration


I'm not sure this is correct. I'm pretty sure Insulin is produced and then the glucose is removed by the liver and insulin makes the liver turn glucose into glycogen.

i was saying u only lost 1 mark. The other marks would have been carried over.

Also, there wasn't a question on Active Transport...

So you're still persistent that I have lost a mark despite me showing that I am right? Or are you just making the point that a mark isn't worth arguing about?

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If I said to prevent blood flowing backwards instead of to prevent back flow of blood, will I still get the marks?

Yes, I am sure that will be given a mark. You are virtually saying the same thing. It's like a business can merge/ can be a merger...bad example lol.

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it's glucose and minerals. Xylem is just water. PH (FF) as in food.

http://www.diffen.com/difference/Phloem_vs_Xylem
http://www.bbc.co.uk/schools/gcsebitesize/science/triple_aqa/transport_systems/transport_in_plants/revision/1/

Phloem - Glucose and other substances like amino acids
Xylem - Water and Mineral Ions

I know I'm right.