(Original post by R.P.Everything.)
An unofficial mark scheme. If I have missed out any answers, please say so in the thread below.
Q1a) What process produces oxygen (1)
Q1b) Name three variables that had to be controlled in the Pondweed experiment (3).
-Mass of Pondweed used.
-Intensity/distance of light.
-Temperature of the Water
-Same concentration of CO2
-pH of water used.
-Size of test tube?
-Volume of water used?
Q1c) What other factor might a pond owner also need to take into account before buying pondweed (all pondweed costs the same) (1)?
- Survivability/resistance to cold
- Whether or not the pondweed is poisonous to fish.
Q1d) The mineral ion that stops yellow leaves (1).
Q2a)What hormone controls blood glucose levels (1)?
Q2b)Where is this hormone secreted from (1)?
Q2c)Work out the change in person A's blood glucose levels after drinking the glucose solution.
-11 (99-88 = 11).
Q2d)Why might the glucose level have dropped? (1)
-Insulin converts glucose into glycogen.
-Glucose used up in respiration to release energy.
Q2e)How can you tell person B has diabetes. Use evidence from the graph (2)?
-High blood glucose levels to begin with.
-Takes three hours for blood sugar to return to normal.
-Blood glucose rose more sharply than person A.
Q3a)What might make people think Euglena is a plant (2)?
-Has a vacuole
Q3b)What might make people think Euglena is an animal (1)?
-No cell wall
Q3c) When put in salt water, the Euglena shrinks. Why? (3)
-Salt solution more concentrated than cytoplasm.
-Water moves out from Euglana into the solution...
-Through a semi permeable membrane...
-In a process called osmosis.
Q4a) Name two other enzymes secreted by the pancreas (2):
- Amylase/Carbohydrase (can have one or the other, but not both).
Q4b) How do the enzymes in the pill get released in the small intestine (2):
- No lipase in the stomach or mouth - only amylase and protease, so the lipid coating doesn't dissolve.
- Once in the small intestine, the duodenum secretes lipase, which digests the coating, releasing the enzymes into the small intestine.
Q4c) Why didn't the lipase in the shell digest the coating? (1)
-It was in the form of dry beads.
Q5a) Evaluate Superfarms (4) (any three points below for 1 mark each)
-Provide electricity for 2000 homes.
-Produces more milk per cow.
-Cheaper milk for customers.
-Less space for cows to move around in, so more biomass used to create milk.
-Animals are likely to spread disease.
-Animals only have 6 square meters of land to live on - poor conditions.
Argued conclusion for the last mark.
Q5b) Explain how the carbon compounds in the waste can be used to aid the grass in the fields (3).
-Decomposers eat the waste.
-Use it in respiration, releasing CO2.
-CO2 absorbed by plants in the field via photosynthesis.
Q6a) Explain the core body temperatures of the scientists (2).
-Scientist in the desert loses more heat, due to the higher wind speed
and lower humidity
-The air in the desert is hotter, so the scientists sweat more, thereby cooling them down?
Q6b) Explain how blood vessels respond to an increase in core body temperature. (2)
-Arterioles supplying the capillaries dilate.
-More blood in contact with the air, losing energy to the environment.
Q7a) What time does the rate of respiration equal the rate of photosynthesis? (1)
- 7:30am and 7:30pm.
Q7b) How many arbitrary units of CO2 given out in respiration per hour? (1)
Q7c) How many arbitrary units of CO2 taken in by photosynthesis at 3:00pm? (1)
- 22+11 = 33 units.
Q7d) Why is it important that a plant takes in more CO2 than it gives out? (2)
- takes in CO2 in photosynthesis to create glucose.
- gives out CO2 during respiration.
- Must create more glucose than it consumes in respiration, therefore, must take in more CO2 than it gives out.
Q8a) What alleles do the parents have? (4)
-Parent A is Hh, Parent B is Hh too.
-Marks for correct answers, drawing of a punnet square, and possibly for annotations as well.
Q8b) What combination of alleles might cat D have? (1)
-Cat D is either HH or Hh.
Q8c) Why can't you tell which combination it has? (1)
-The polydactyly gene is dominant, so it would be expressed in both cases.
ESTIMATED GRADE BOUNDARIES
A* - 28
A - 25
B - 20
C - 15
June 2011 grade boundaries were the same, but 2 lower in every grade. I've estimated conservatively, and don't expect the grade boundaries to exceed this.