State the significance of the statement: p<0.05.

Outline the trends in capillary density in the results of this experiment.

Describe how increased capillary density could affect the aerobic capacity of muscle.

State the time when the point of fatigue occurred in the Epi–exercise group.

Compare and contrast the results for the water–no exercise group and the Epi–no exercise group.

Discuss the effect of exercise on the results of the experiment.

Analyse the effect of exercise on the presence of the mitochondrial proteins in the leg muscle.

Mitochondria are essential for aerobic respiration. Suggest one possible role of the proteins that were studied.

The scientists concluded that Epi significantly increased aerobic capacity in leg muscle.

Evaluate the strength of the evidence provided by all of the data for dark chocolate improving the aerobic capacity of athletes.

there is a significant «statistical» difference between two experimental values
OR
there is a less than 5 % chance that the difference is random
OR
95 % or more probability that results are due to the experiment «IV» and not random/can reject the null hypothesis
OR
there is a relationship/correlation between doing exercise and capillary density

OWTTE

a. exercise «significantly» increased the density with both water and Epi 

“both” or OWTTE must be mentioned

b. Epi «significantly» increased the density with and without exercise 

c. Epi–exercise had the greatest increase in the density
OR
Epi increases the density more than exercise alone

a. increases amount of blood taken to the muscle 

b. increases the delivery of oxygen/glucose/nutrients for aerobic respiration 

c. increases the removal of carbon dioxide/wastes
OR
increased gas exchange

175 «seconds»

Accept 170 to 180 «seconds».

a. in both cases the tension decreased over time  

b. Epi–no exercise lasts longer/more time until «onset of» fatigue «than water–no exercise» 

c. the rate of decrease in tension is the same/similar in both 

d. Epi–no exercise has more contractions per second before fatigue point «than water–no exercise»

Do not accept numerical comparisons without justification.

a. «exercise with» water has no impact 

b. «exercise with» Epi promotes higher levels of tension for more time 

c. «exercise with» Epi increases the time to fatigue

a. exercise has no/very little effect with water 

b. exercise with Epi increased III/IV 

c. «it appears that» exercise with Epi has no/very little effect on II
OR
Epi relative to water increases all 4
OR
exercise has little/no effect on protein I/II 

d. exercise with Epi «appears to» decrease I

a. protein channels
OR
pumps in membranes of mitochondria
OR
hormone binding sites 

b. structural/integral/peripheral/glyco/surface proteins 

c. enzymes/catalysts  

Accept verifiable names of specific membrane enzymes.

d. electron transport chain proteins

Limitations:

a. study done on mice and may not apply to humans 

b. levels of Epi administered in experiment may exceed levels in a sample of dark chocolate
OR
levels of Epi administered in experiment may have different levels in a sample of dark chocolate
OR
chocolate may have other components with unknown effects on aerobic capacity 

c. mitochondrial proteins may not improve aerobic capacity 

Strengths:

d. data supports as dark chocolate contains EPI 

e Epi improves capillary density and would therefore increase aerobic capacity 

f. Epi improves fatigue resistance 

g. Epi in combination with exercise improves it further 

h. Epi increases mitochondrial proteins therefore/presumably increasing aerobic capacity

OWTTE

Distinguish between the structure of amylose and the structure of amylopectin.

Suggest the reason for cellulose passing undigested through the human gut.

Draw an annotated diagram to show how a peptide bond is formed.

State two structural features that differ between RNA and DNA.

amylose unbranched/helical while amylopectin branched / vice versa

enzymes required to digest cellulose not present in the human gut OWTTE
OR
undigested cellulose provides bulk/fibre

a. correct structure of two amino acids 

b. H₂O lost 

c. C from COOH of one links to N of NH₂/NH₃⁺ from the other 

d. correct labelling of the peptide bond

e.g.

a. number of strands
OR
(usually) only one strand in RNA/two strands in DNA 

b. base composition
OR
uracil only in RNA / thymine only in DNA 

c. type of pentose
OR
ribose only in RNA / deoxyribose only in DNA

The figure represents a water molecule.

Draw a second water molecule to show how bonds can form between water molecules, including the name of the bond.

Water has important solvent properties. Explain these properties using an example to illustrate your answer.

a. similar water molecule drawn with oxygen on one molecule facing hydrogen on the other water molecule

b. one hydrogen bond drawn as a dotted/dashed line between the two water molecules and labelled

O and H do not have to be labelled but must be positioned correctly

eg :

Can get this mark even if atoms incorrect

a. water molecule is polar

    OR

    water has «weak» positive and negative charges

c. water forms hydrogen bonds with polar substances

d. positive/hydrogen side/pole of water attracted to negative ions

    OR

    negative/oxygen side/pole attracted to positive ions

e. glucose/other example dissolves because it is polar

    OR

    sodium chloride/other example dissolves because ions are attracted to water

[Max 3 Marks]

State one disaccharide and the two monomers from which it can be synthesized.

Disaccharide:

 1:

Monomers:

1:

and 2:

Discuss the roles of the enzymes secreted by the pancreas during digestion.

Compare and contrast cis-fatty acids and trans-fatty acids.

a. disaccharide name

    eg: lactose, glucose and galactose

b. both monomers that make up mpa

    eg: maltose, glucose and glucose

    eg: sucrose, glucose and fructose

a. amylase breaks down/catalyzes/hydrolyses starch to maltose

b. lipase breaks down/catalyzes/hydrolyses fats to fatty acids and glycerol

c. proteases/peptidases break down/catalyze/hydrolyze proteins into smaller
polypeptides/dipeptides/amino acids

Award [2] if all three enzymes and substrates named correctly and one further mark for all three products named
correctly.

Allow specific enzymes

a. both are unsaturated fatty acids

    OR

    both have two carbon atoms joined by a double bond

b. in cis-fatty acids the two H atoms are on the same side while in trans-fatty acids they are on opposite sides

    OR

    cis-fatty acids are healthier than trans-fatty acids

    OR

    cis-fatty acids have a lower boiling/melting point than trans

    OR

    cis-fatty acids have a kink «in the chain» but trans do not

Accept answer in an annotated diagram

Sketch a graph to show the effect of temperature on the activity of enzymes.

Explain enzyme–substrate specificity.

a. axes labelled correctly: x-axis as temperature AND y-axis as rate of reaction/enzyme activity 

b. correct shape of graph: increases gradually to max and then decreases more rapidly

Fall should be at least twice as steep as rise.

a. enzymes are proteins with specific 3-D geometry/shape 

b. enzymes with active site that binds with the substrate/reactants 

c. active site shape only allows it to bind with specific substrates «with complementary shapes» 

d. when enzyme-substrate complex formed allows reaction to occur 

e. products are released and enzyme returns to original shape and can be reused
OR
denaturing changes shape «of active site» so changes ability to bind with substrate

Accept marks from clear annotated diagrams.

Draw a molecular diagram of an amino acid to show its general structure.

Outline the role of ribosomes in translation.

Some blood proteins are involved in defence against infectious disease. Explain the roles of named types of blood proteins in different defence mechanisms.

a. COO– or COOH group at one end 

b. NH₂ or NH₃⁺ at the other 

c. CH in middle with H or R group attached

If shown expanded, then carbonyl oxygen must attach to C
If shown non-expanded, N of amine group must attach to C

a. translation is the production of polypeptides/proteins 

b. mRNA binds to the ribosome 

c. tRNA binds to the ribosome 

d. at the site where its anti-codon corresponds to the codon on the mRNA

OWTTE

e. amino acids of «consecutive tRNAs» bind by a peptide link «in the ribosomes» 

f. the ribosome moves along the mRNA
OR
continues with elongation of polypeptide chain

Accept annotated diagrams of the process.

a. clotting factors «are proteins» that initiate the clotting cascade/process 

b. fibrin «is a protein that» permits blood clotting
OR
allows the formation of a clot 

c. «the protease» thrombin converts fibrinogen to fibrin  

OWTTE

d. fibrin forms a mesh/clot that prevents the entry of pathogen/antigen into the blood 

e. antibodies are «specific» proteins that lymphocytes make 

f. each antibody corresponds to a specific pathogen/antigen
OR
antibodies are specific «to certain pathogens/antigens» 

g. antibodies create specific immunity 

h. plasma cells produce large amounts of «specific» antibodies
OR
memory cells retain the ability to produce «specific» antibodies 

i. immunoglobulins are antibodies against pathogens 

j. enzymes in phagocytic white blood cells may digest pathogens

Accept annotated diagrams of the process.