BIOLOGY AQA AS 74011
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 stran...
• 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;
Describe the difference between the structure of a triglyceride molecule and the
- ANS✔✔---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 -
ANS✔✔---- Add ethanol, then add water;
, -White (emulsion shows lipid)
Describe how a saturated fatty acid is different from an unsaturated fatty acid -
ANS✔✔---Unsaturated has (at least one) double bond (between carbons)
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.
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
name the part of the mitochondrion labelled X in Figure 2 - ANS✔✔---
Crista/cristae
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