Mock: Bio Mols Pt 2 Flashcards
post-2015 exam qs
Give two ways in which the properties of ATP make it a suitable source of energy in biological processes.
- Energy released in small / suitable amounts;
- Soluble;
[3. Involves a single / simple reaction;]
Reject “broken down easily / readily”. Reject “quickly / easily resynthesised”
Humans synthesise more than their body mass of ATP each day. Explain why it is necessary for them to synthesise such a large amount of ATP
- ATP cannot be stored / is an immediate source of energy; 2. ATP only releases a small amount of energy at a time
Suggest three reasons why it is more efficient to attach lactase to the beads
- (Lactase / beads) can be reused / not washed away;
- No need to remove from milk
- Allows continuous process;
The lactose-free milk made after hydrolysis with lactase tastes sweeter than the cow’s milk containing lactose.
Suggest why.
(Lactose hydrolysed to) galactose and glucose
So more sugar molecules;
Give two ways in which the structure of starch is similar to cellulose.
- Are polymers / polysaccharides / are made of monomers / of monosaccharides;
- Contain glucose / carbon, hydrogen and oxygen;
Give two ways in which the structure of starch is different from cellulose.
- Starch monomers: alpha glucose, cellulose: beta glucose
2. Starch has helical shape, cellulose forms fibrils
Explain one difference in the structure of the starch molecule and the cellulose molecule shown in the diagram above
Position of hydrogen and hydroxyl groups on carbon atom 1 inverted
In the control experiments, cooked wheat was chopped up to copy the effect of chewing.
Suggest a more appropriate control experiment. Explain your suggestion.
Add boiled saliva;
Everything same as experiment but salivary amylase denatured.
In humans, the enzyme maltase breaks down maltose to glucose. This takes place at normal body temperature.
Explain why maltase:
• only breaks down maltose
• allows this reaction to take place at normal body temperature. (5 marks)
- Tertiary structure / 3D shape of enzyme (means);
- Active site complementary to maltose / substrate
- Description of induced fit;
- Enzyme is a catalyst / lowers activation energy / energy required for reaction
5 . By forming enzyme-substrate complex;
Describe competitive and non-competitive inhibition of an enzyme (5 marks)
- Inhibitors reduce binding of enzyme to substrate / prevent formation of ES complex;
(Competitive inhibition), - Inhibitor similar shape (idea) to substrate;
- (Binds) in to active site (of enzyme);
- (Inhibition) can be overcome by more substrate;
- Inhibitor binds to site on enzyme other than active site;
- Prevents formation of active site / changes (shape of) active site
Describe and explain the link between oxygen concentration, rate of respiration and rate of uptake of potassium ions
greater rate of oxygen consumption / leads to greater rate of respiration and greater rate of uptake
oxygen required for respiration;
respiration produces ATP / releases energy;
potassium ions taken up by active transport
Other than ethical reasons, suggest two reasons why they chose to use cats as model organisms
(Are mammals so) likely to have same physiology / reactions as humans Large number (available)
A triglyceride does not contain sucrose or glycosidic bonds. Give one other way in which the structure of a triglyceride is different to olestra
Contains glycerol
Hydrogen bonds are important in cellulose molecules. Explain why
- Hold chains together
2. Hydrogen bonds strong in large numbers
Explain two ways in which fatty acids are important in the formation of new cells
Fatty acids used to make phospholipids;
Fatty acids respired to release energy used for cell production
Describe the primary structure of proteins
(Sequence of AAs) Joined by peptide bonds;
Formed by condensation reactions;
Describe how proteins are digested in the human gut.
Hydrolysis of peptide bonds;
Endopeptidases break polypeptides into smaller peptide chains; Exopeptidases remove terminal amino acids;
Dipeptidases hydrolyse / break down dipeptides into amino acids
Other than being smaller, give two ways in which prokaryotic DNA is different from eukaryotic DNA.
(Prokaryotic DNA)
1. Circular / non-linear (DNA);
2. Not (associated) with proteins / histones
(no references to plasmids!!)
The events that take place during interphase and mitosis lead to the production of two genetically identical cells. Explain how
DNA replicated;
(Involving) specific / accurate / complementary base-pairing;
Accept: semi conservative replication
(Ref to) two identical / sister chromatids;
Each chromatid / moves / is separated to (opposite) poles / ends of cell.
During replication, the two strands of a DNA molecule separate and each acts as a template for the production of a new strand.
Use your knowledge of enzyme action to explain why the arrows point in opposite directions.
!!!shape of the nucleotides is different / nucleotides aligned differently!!!!
And DNA has antiparallel strands
Enzymes have active sites with specific shape;
Only substrates with complementary shape / only the 3’ end can bind with active site of enzyme / active site of DNA polymerase
HSV can remain inactive inside the body for years. Explain why this virus can be described as inactive
No more (nerve) cells infected (Because) virus is not replicating.
Use your knowledge of enzyme action and DNA replication to explain why new nucleotides can only be added in a 5’ to 3’ direction
- Reference to DNA polymerase;
- (Which is) specific;
- Only complementary with / binds to 5’ end (of strand);
- Shapes of 5’ end and 3’ end are different / description of how different.
Which organ produces maltase
Pancreas
Give one function of lysosomes
Break down cells
Scientists treated liquid from strain A with a protein-digesting enzyme before adding it to a culture of human cells. No cell damage was recorded.
Suggest why there was no damage to the cells.
- Enzyme (a protein) is broken down (so no enzyme activity);
- No toxin (as a result of protein-digesting enzyme activity);
- (So) toxin is protein.
How could an antidote can reduce poisoning by cyanide
(Antidote reacts with / binds to cyanide) so cyanide cannot bind to enzyme / cytochrome oxidase
The movement of the woodlice in low relative humidity is an advantage to their survival. Explain how
Low humidity results in more woodlice moving
So increased movement increased chance of leaving dry / unfavourable environment so reduce water loss / reduce evaporation;
Describe the structure of a cellulose molecule and explain how cellulose is adapted for its function in cells (6 marks)
- made from β-glucose;
- joined by condensation / removing molecule of water / glycosidic bond
- 1 : 4 link specified or described;
- “flipping over” of alternate molecules;
- hydrogen bonds linking chains / long straight chains;
- cellulose makes cell walls strong / cellulose fibres are strong;
