Biology AQA AS level 7401/1 Paper 1
• The human cell then makes a complementary strand to the HIV DNA.
The complementary strand is made in 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. - -- there are complementary
nucleotides/bases pair
- DNA polymerase used
- Nucleotides join together (to form new strand)/phosphodiester bonds form;
Contrast the structures of DNA and mRNA molecules to give three differences. - ✅✅--
DNA is double stranded/double helix and mRNA single-stranded;
- DNA (very) long and RNA short;
-Thymine/T in DNA and uracil/U in RNA;
- Deoxyribose in DNA and ribose in RNA;
✅✅
Describe the difference between the structure of a triglyceride molecule and the -
-In phospholipid, one fatty acid replaced by a phosphate
Describe how you would test for the presence of a lipid in a sample of food - ✅✅--
Add ethanol, then add water;
-White (emulsion shows lipid)
✅✅
Describe how a saturated fatty acid is different from an unsaturated fatty acid -
-Unsaturated has (at least one) double bond (between carbons)
This fat substitute cannot be digested in the gut by lipase. Suggest why. - ✅✅-- (Fat
substitute) is a different/wrong shape/not complementary
- Unable to fit/bind to (active site of) lipase/no ES complex formed;
Despite being a lipid, the substitute cannot cross the cell-surface membranes of cells
✅✅
lining the gut.
Suggest why it cannot cross cell-surface membranes. - -It is hydrophilic/is polar/is
too large/is too big;
✅✅
Cells constantly hydrolyse ATP to provide energy. Describe how ATP is resynthesised in
cells. - -- From ADP and phosphate;
- By ATP synthase;
- During respiration/photosynthesis;
Give two ways in which the hydrolysis of ATP is used in cells. - ✅✅
-- To provide
energy for other reactions/named process;
- To add phosphate to other substances and make them more reactive/change their
shape
✅✅
What is the evidence from Figure 2 that a scanning electron microscope was used to
take this photograph? - -(Can see) 3D image
name the part of the mitochondrion labelled X in Figure 2 - ✅✅-Crista/cristae
Y is a protein. One function of Y is to transport cellulose molecules across the
✅✅
phospholipid bilayer.
Using information from Figure 3, describe the other function of Y. - -- (Y is) an
enzyme/has active site/forms ES complex;
• The human cell then makes a complementary strand to the HIV DNA.
The complementary strand is made in 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. - -- there are complementary
nucleotides/bases pair
- DNA polymerase used
- Nucleotides join together (to form new strand)/phosphodiester bonds form;
Contrast the structures of DNA and mRNA molecules to give three differences. - ✅✅--
DNA is double stranded/double helix and mRNA single-stranded;
- DNA (very) long and RNA short;
-Thymine/T in DNA and uracil/U in RNA;
- Deoxyribose in DNA and ribose in RNA;
✅✅
Describe the difference between the structure of a triglyceride molecule and the -
-In phospholipid, one fatty acid replaced by a phosphate
Describe how you would test for the presence of a lipid in a sample of food - ✅✅--
Add ethanol, then add water;
-White (emulsion shows lipid)
✅✅
Describe how a saturated fatty acid is different from an unsaturated fatty acid -
-Unsaturated has (at least one) double bond (between carbons)
This fat substitute cannot be digested in the gut by lipase. Suggest why. - ✅✅-- (Fat
substitute) is a different/wrong shape/not complementary
- Unable to fit/bind to (active site of) lipase/no ES complex formed;
Despite being a lipid, the substitute cannot cross the cell-surface membranes of cells
✅✅
lining the gut.
Suggest why it cannot cross cell-surface membranes. - -It is hydrophilic/is polar/is
too large/is too big;
✅✅
Cells constantly hydrolyse ATP to provide energy. Describe how ATP is resynthesised in
cells. - -- From ADP and phosphate;
- By ATP synthase;
- During respiration/photosynthesis;
Give two ways in which the hydrolysis of ATP is used in cells. - ✅✅
-- To provide
energy for other reactions/named process;
- To add phosphate to other substances and make them more reactive/change their
shape
✅✅
What is the evidence from Figure 2 that a scanning electron microscope was used to
take this photograph? - -(Can see) 3D image
name the part of the mitochondrion labelled X in Figure 2 - ✅✅-Crista/cristae
Y is a protein. One function of Y is to transport cellulose molecules across the
✅✅
phospholipid bilayer.
Using information from Figure 3, describe the other function of Y. - -- (Y is) an
enzyme/has active site/forms ES complex;
