BIOLOGY AQA AS 74011 PAPER 1 [WELL VERIFIED]

BIOLOGY AQA AS 7401\1
PAPER 1 [WELL VERIFIED]




• 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. - ANS✔✔---- 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. - ANS✔✔---- 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;
This fat substitute cannot be digested in the gut by lipase.
Suggest why. - ANS✔✔---- (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. -
ANS✔✔---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. - ANS✔✔---- From ADP and
phosphate;
- By ATP synthase;
- During respiration/photosynthesis;
Give two ways in which the hydrolysis of ATP is used in cells. -
ANS✔✔---- 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? - ANS✔✔---
(Can see) 3D image