F212 Unofficial Mark Scheme

1a)i) I put that fins help with living underwater - they help push the body through water (1)
ii) I put that flat eyes help with living on the sea bed - you can see laterally/horizontally so can more easily view prey living on the sea bed (1)
b) Chloroplasts, cell walls, and large/permanent vacuoles are present in plant cells but not animal cells. (2)
c) Evidence for evolution that's not fossils: (6)
-Biological molecules (in common with most organisms)
-> Cytochrome C primary structure, RNA, etcetera.
-DNA nucleotide sequence.
-Similarity of structures equals a closer evolutionary relationship


2a) 'Extracellular' - secreted from cell, exocytosis, outside cell (1)
b)i) Time (1)
ii) Explanation of how the amylase active site is complementary to the starch substrate, forming an enzyme-substrate complex. As starch concentration increases, more enzyme-substrate complexes can be formed, increasing the rate of reaction. The amylase concentration acts as a limiting factor - all available active sites are forming enzyme-substrate complexes - so the graph plateaus; rate has reached its maximum. (5)
iii) pH, the H+ ion concentration, can affect and break bonds in the protein's tertiary structure e.g. ionic bonds, even denaturing the protein. This can affect the rate of reaction - extraneous variable that needs controlling. (3)
iv) Temperature; concentration of amylase (2)
c)i) (3)
Alpha glucose monomers vs beta glucose monomers;
All monomers facing same direction vs orientation of each monomer changes alternately;

ii) Insolubility and tensile strength; mini explanation of why this helps function of cell wall


3a) Nymphaea (1)
b) The plants' habitats may have been destroyed by *insert human action here*; protection from predators; protection from being stolen (3)
c) Less cost; take up less space; last longer; harvesting them does less damage to the ecosystem (3)
d) Random sampling - regular distances across habitat; random coordinates generated; GPS. Description of quadrats; Simpson's index of biodiversity (4)
e) Not all species discovered; speciation constantly occurring; extinction constantly occurring (3)


4a) Primary structure: BD (sequence of amino acids, peptide bonds) (4)
Secondary structure: AE (localised folding, hydrogen bonds)
Tertiary structure: FG (ionic bonds, 3D shape)
Quaternary structure: C (alpha and beta units)
b) Water is polar molecule; charge distribution; delta positive hydrogen atom attracted to delta negative oxygen atom (3)
c) Metabolic reactions take place in solution, so without solvency we wouldn't be able to conduct metabolic processes w/biological molecules (3)


5a) Most physical characteristics are inherited genetically from parents (1)
b) A, B, C and D have a common ancestor; B, C and D are more closely related to each other than A; B and C most closely related (2)
c) More empirical evidence for natural selection now - fossil record, seeing bacteria become resistant to antibiotics (2)
d)i) A gene codes for a specific protein (1)
ii) DNA replication: Double helix can be untwisted; hydrogen bonds easy to break by helicase; free nucleotides can bond to the exposed nucleotides by purine-pyrimidine rules; polymerase seals up the sugar-phosphate backbones (5)
e)i) Speciation (1)
ii) Sea geographically separates the Galapagos islands, allowing for allopatric speciation (1)


6a) Health - absence of disease; physical, mental and social wellbeing (2)
b)i) 185.2 (2)
ii) Smoking increases chance of dying of both lung cancer and CHD; increases chance more of dying of lung cancer than of CHD
c) Cardiovascular system (NOT tar and smoker's cough)
-Nicotine; release of adrenaline; higher heart rate and higher blood pressure; damage to artery endothelium; atherosclerosis and atheroma forming from cholesterol deposited under endothelium; can block lumen; nicotine makes platelets sticky, increasing chance of thrombus and heart attack
-Carbon monoxide; binds to haemoglobin; less oxygen diffuses into heart muscle for aerobic respiration
(7)


7a)i) Higher meat mass, muscle mass (1)
ii) Artificial selection; selective breeding; take highest productivity animals and breed them; breed the offspring with highly productive animals; repeat over many generations (4)
b)i) All nutrients required for growth and metabolic reactions ingested in appropriate proportions (2)
ii) Glycerol; UNSATURATED fatty acid; ester bond (3)
iii) Saturated fats in milk and beef; fat stored in adipose cells; obesity; higher intake of lipids than is necessary (3)
c) Dehydrates organism; water leaves by osmosis; water potential gradient; can't conduct metabolic reactions (3)


8a) Antigens; specific; memory; strains; mutation (5)
b) Bacteria don't have an immune system - they are resistant to antibiotics (3)


Marks were something like this

why is C for quantenary structure isnt that for secondary structure and the initial folding of polypeptide, E is the quantenary structure?

well I am ****ed.

woahh over 80% Thank God!
Thanks Made some daft mistakes here and there but I'm happy