OCR AS Biology F211 - Unofficial Mark Scheme

same here

... I thought that was what you were meant to do?!

Instead of homogenous pair of chromosomes I put alleles, is that still acceptable?

And also, for the question about how haemoglobin aids the transport of oxygen, could you write about how oxygen and haemoglobin bind reversibly in the erythrocytes, and travel to the resourcing tissues where they are needed, and then dissociate? Sorry /:


and for the question about what the structure was containing the xylem and phloem, was it okay if you wrote vein (vascular)?

Oh also I said Bohr effect not shift, the microtubules move the organelles; keep the shape of the cell; and i didn't say release it afterwards for the balloon question

-Bohr effect should be fine
-I'm not sure if you'll be given that, because they don't directly do so, but it's only part of the question and you might have gotten credit for the other things you'd written
-That's right
-I don't think that'll make much difference

I've not got the paper, I just sat it. The answers aren't exact, they just give people an idea of if they've written the right thing

CELL STRUCTURE QUESTION

1a)i) Present in plant cells but not animal cells:
Chloroplasts, cell wall
ii) Present in animal cells but not plant cells:
Centrioles
1b) Description of what the cytoskeleton does:
Determines shape of cell; changes shape of cell; vesicles move down microtubules; RNA/other
molecules move down microtubules
1c) Secretion of protease enzymes from pancreatic cells:
EXOCYTOSIS; mRNA moves out of nuclear pores to the ribosomes; ribosomes assemble the proteins;
vesicles move to Golgi body down microtubules; modified and repackaged; vesicles move to the cell surface membrane; fuse with membrane; deposit enzymes outside cell

VASCULAR TISSUES CROSS-SECTION LEAF QUESTION
-Xylem on top, phloem on bottom (DON'T label the middle, that's cambium)
-Vascular bundle

BALLOONS
The balloon expands because pulling the rubber sheet down increases the volume inside the bell jar, which decreases the pressure, so air is sucked into the balloons down the pressure gradient
Tidal volume: Volume of air moved in and out of the lungs from a 'normal' breath at rest
How to demonstrate it: Pull the rubber sheet down and release it (in tandem with a student's even
breaths at rest?)
Vital capacity: Maximum volume of air that can be inspired + maximum volume of air that can be
expired
How to demonstrate it: Pull the rubber sheet down as far as it can go without the balloons bursting

TISSUE FLUID/HAEMOGLOBIN/BOHR SHIFT
a) Why erythrocytes don't enter the tissue fluid:
They're too big, 7 micrometres, can't fit through the fenestrations of the capillary wall
b) Haemoglobin transporting oxygen:
High affinity for oxygen; 4 haem groups, each of which can bond to one oxygen molecule; transported
around body in blood; oxygen released to tissues where there is a low O2 partial pressure
c) How hydrogencarbonate ions are made:
Carbonic anhydrase; reaction of water and carbon dioxide to make H2CO3; dissociation into H+ ions
and hydrogencarbonate ions
d) Carbon dioxide reaction:
Bohr shift. The H+ ions produced due to the high partial pressures of carbon dioxide bind to haemoglobin and displace the oxygen atoms, so they diffuse out of the haemoglobin into the actively respiring tissue.

GREX
a) Mitosis (asexual reproduction)
b) 3 is where differentation starts
c) Cell signalling
d) There is cell signalling with the folic acid and bacteria; and the cAMP (specific complementary
receptors...molecules...trigger response...)
e) They can be adapted to this by having specific, complementary receptors in their plasma membranes
to the molecules folic acid and cAMP, e.g. glycoproteins

TRANSLOCATION
Observations:
2 and 3 means that charged particles (H+ ions) are transported out and then back into the companion
cells, due to the changes in pH; against concentration gradient
4 means that the process is an active process requiring ATP from aerobic respiration.
Gap fill:
Active transport, concentration, facilitated, diffusion, ARGH (amino acids is definitely correct; waiting for confirmation on glucose/fructose/maltose)

DEFINITIONS
-Homologous pair (of chromosomes)
-Organ system
-Open circulatory system
-Apoplast pathway
-Ultrastructure
-Meiosis
-Exocytosis

TRANSLOCATION
Observations:
2 and 3 means that charged particles (H+ ions) are transported out and then back into the companion
cells, due to the changes in pH; against concentration gradient
4 means that the process is an active process requiring ATP from aerobic respiration.
Gap fill:
Active transport, concentration, facilitated, diffusion, ARGH (amino acids is definitely correct; waiting for confirmation on glucose/fructose/maltose)

CELL STRUCTURE QUESTION

1a)i) Present in plant cells but not animal cells:
Chloroplasts, cell wall
ii) Present in animal cells but not plant cells:
Centrioles
1b) Description of what the cytoskeleton does:
Determines shape of cell; changes shape of cell; vesicles move down microtubules; RNA/other
molecules move down microtubules
1c) Secretion of protease enzymes from pancreatic cells:
EXOCYTOSIS; mRNA moves out of nuclear pores to the ribosomes; ribosomes assemble the proteins;
vesicles move to Golgi body down microtubules; modified and repackaged; vesicles move to the cell surface membrane; fuse with membrane; deposit enzymes outside cell

VASCULAR TISSUES CROSS-SECTION LEAF QUESTION
-Xylem on top, phloem on bottom (DON'T label the middle, that's cambium)
-Vascular bundle

BALLOONS
The balloon expands because pulling the rubber sheet down increases the volume inside the bell jar, which decreases the pressure, so air is sucked into the balloons down the pressure gradient
Tidal volume: Volume of air moved in and out of the lungs from a 'normal' breath at rest
How to demonstrate it: Pull the rubber sheet down and release it (in tandem with a student's even
breaths at rest?)
Vital capacity: Maximum volume of air that can be inspired + maximum volume of air that can be
expired
How to demonstrate it: Pull the rubber sheet down as far as it can go without the balloons bursting

TISSUE FLUID/HAEMOGLOBIN/BOHR SHIFT
a) Why erythrocytes don't enter the tissue fluid:
They're too big, 7 micrometres, can't fit through the fenestrations of the capillary wall
b) Haemoglobin transporting oxygen:
High affinity for oxygen; 4 haem groups, each of which can bond to one oxygen molecule; transported
around body in blood; oxygen released to tissues where there is a low O2 partial pressure
c) How hydrogencarbonate ions are made:
Carbonic anhydrase; reaction of water and carbon dioxide to make H2CO3; dissociation into H+ ions
and hydrogencarbonate ions
d) Carbon dioxide reaction:
Bohr shift. The H+ ions produced due to the high partial pressures of carbon dioxide bind to haemoglobin and displace the oxygen atoms, so they diffuse out of the haemoglobin into the actively respiring tissue.

GREX
a) Mitosis (asexual reproduction)
b) 3 is where differentation starts
c) Cell signalling
d) There is cell signalling with the folic acid and bacteria; and the cAMP (specific complementary
receptors...molecules...trigger response...)
e) They can be adapted to this by having specific, complementary receptors in their plasma membranes
to the molecules folic acid and cAMP, e.g. glycoproteins

TRANSLOCATION
Observations:
2 and 3 means that charged particles (H+ ions) are transported out and then back into the companion
cells, due to the changes in pH; against concentration gradient
4 means that the process is an active process requiring ATP from aerobic respiration.
Gap fill:
Active transport, concentration, facilitated, diffusion, ARGH (amino acids is definitely correct; waiting for confirmation on glucose/fructose/maltose)

DEFINITIONS
-Homologous pair (of chromosomes)
-Organ system
-Open circulatory system
-Apoplast pathway
-Ultrastructure
-Meiosis
-Exocytosis

What did people get to the maths question?

50,000 hours but I'm not entirely sure

I wasnt sure if it was 50000 or 17

i thought it was a vein not a vascular bundle?