AQA-74011-JUN16 Flashcards
Which features are present in a bacterium compared to a HIV particle?
- RNA
- Cell Wall
- Enzyme Molecules
- Capsid = 2 marks
Bacterium:
- RNA
- Cell Wall
- Enzyme molecules
HIV particle:
- RNA
- Enzyme molecules
- Capsid
The complementary strand is made the same way as a new complementary strand is made during semi-conservative replication of human DNA
Describe how the complementary strand of HIV DNA is made. = 3 marks
1) Complementary nucleotides/bases pair: A to T and C to G
2) DNA Polymerase;
3) Nucleotides join together, forming a new strand between which phosphodiester bonds form.
Contrast the structures of DNA and mRNA molecules to give 3 differences. = 3 marks
1) DNA is double stranded/double helix and mRNA is single-stranded
2) DNA is very long and RNA is short
3) Thymine in DNA and Uracil in RNA
4) Deoxyribose in DNA and Ribose in RNA
5) DNA has base pairing and RNA doesn’t/ DNA has hydrogen bonds and RNA doesn’t
6) DNA has introns/non coding sequences and mRNA doesn’t
Describe the difference between the structure of a triglyceride molecule and the structure of a phospholipid molecule. = 1 mark
-In a Phospholipid, one fatty acid is replaced by a phosphate
Describe how you would test for the presence of a lipid in a food sample. = 1 mark
1) Add ethanol, than add water.
2) White emulsion shows positive for lipid
Describe how a saturated fatty acid is different from an unsaturated fatty acid. = 1 mark
-Saturated fatty acid has only single bonds/ no double bonds
OR
-Unsaturated fatty acids has (at least one) double carbon-carbon bond.
The structure of a fat substitute differs from that of a fat.
This fat substitute cannot be digested in the gut by lipase.
Suggest why. = 2 marks
1) The fat substitute is a different/wrong shape/not complementary
OR
Bond between glycerol/fatty acid and propylene glycol different (to that between glycerol and fatty acid)/ no ester bond
2) Unable to fit/bind to (active site of) lipase/ no stable ES complex formed.
A fat substitute is a lipid. Despite being a lipid, it cannot cross the cell-surface membranes of the cells lining the gut.
Suggest why it cannot cross cell-surface membranes = 1 mark
- It is hydrophilic
- It is polar
- It is too large/big
Cells constantly hydrolyse ATP to provide energy.
Describe how ATP is resynthesized in cells. = 2 marks
1) From ADP and phosphate
2) By ATP synthase
3) During respiration/photosynthesis
Give 2 ways in which the hydrolysis if ATP is used in cells. = 2 marks
1) To provide energy for other reactions/named process
2) To add phosphate to other substances and make them more reactive/change their shape.
What evidence in a photo can suggest that a scanning electron microscope was used? = 1 mark
-Can see 3D image
The letters P,Q,R,S and T represent ways substances can move across membranes:
P - Diffusion through the phospholipid bilayer
Q - Facilitated diffusion
R - Active Transport
S - Co-Transport
T- Osmosis
Which letter represents the way these substances move across membranes?
1) Transport through a channel protein
2) Transport of small, non-polar molecules
3) Transport of glucose with sodium ions = 3 marks
1) Transport through a channel protein = Q
2) Transport of small, non-polar molecules = P
3) Transport of glucose with sodium ions = S
Y is a protein. One function of Y is to transport cellulose molecules across the phospholipid bilayer.
Substrate also enters at one end of the protein.
Using this information, describe the other function of Y.
= 2 marks
1) (Y is) and enzyme/has active site/forms stable ES complex
2) That makes cellulose/attaches substrate to cellulose/joins beta glucose
OR
3) Makes cellulose/forms glycosidic bonds
4) From beta glucose
In the cell wall, bonds hold the cellulose molecules together side by side.
Which bond describes the type of bond that holds the cellulose molecules together side by side?
- Ester
- Hydrogen
- Ionic
- Peptide = 1 mark
-Hydrogen
Name the products of the hydrolysis of sucrose. = 1 mark
- glucose
- fructose
