P1 - 2018

Question 1

Name the blood vessels that carry blood to the heart muscle.

Answer 1

Coronary arteries

Question 2

What is a monomer?

Answer 2

A monomer is a smaller repeating unit

Its a molecule from which larger molecules (polymers) are made

Question 3

Other than both being disaccharides,

give one similarity and one difference between the structures of lactulose and lactose.

Answer 3

sim: Both contain galactose
+ both a glycosidic bond

dif: Lactulose contains fructose, whereas lactose contains glucose

Question 4

faeces of people with constipation are dry + hard but can be treated by drinking lactulose which is soluble, but not digested or absorbed in the human intestine.

Use your knowledge of water potential to suggest why lactulose can be used to help
people suffering from constipation (2)

Answer 4

Lactulose lowers the water potential of faeces contents of the intestine

Water retained enters due to osmosis and softens the faeces

Question 5

Give two features of DNA and explain how each one is important in the semi-conservative replication of DNA

(3)

Answer 5

Weak hydrogen bonds between bases allow two strands to separate

Two strands, so both can act as templates

Complementary base pairing allows accurate replication

Question 6

what is the main biological molecule in a cell surface membrane?

Answer 6

phospholipids

Question 7

what is the main biological molecule in a cell wall?

Answer 7

glycoprotein

Question 8

Name the process by which prokaryotic cells divide

Answer 8

binary fission

Question 9

Describe how you would test a liquid sample for the presence of lipid and how you
would recognise a positive result. (2)

Answer 9

Mix sample with ethanol, then water

positive result will be a White/milky emulsion

Question 10

Name the taxon to which Drosophilidae belongs.

Answer 10

family

Question 11

What is the proteome of a cell?

Answer 11

The proteome is the full range of number of different proteins that a cell is able to produce at a given time

Question 12

Give two structural differences between a molecule of RNA (mRNA) and a molecule of transfer RNA (tRNA).

Answer 12

mRNA does not have hydrogen bonds, tRNA does

mRNA has more nucleotides

Question 13

Starting with mRNA in the cytoplasm, describe how translation leads to the production of a polypeptide.
(5)

Answer 13

1. mRNA associates with a ribosome
2. Ribosome finds the start codon
3. tRNA carries specific amino acid;
4. Anticodon to codon
5. Ribosome moves along to next codon

Question 14

State and explain the property of water that can help to buffer changes in temperature (2)

Answer 14

water has a relatively high specific heat capacity

and can gain/lose a lot of heat without changing temperature

Question 15

Water is used to hydrolyse ATP.

Name the two products of ATP hydrolysis.

Answer 15

Adenosine diphosphate

inorganic phosphate

Question 16

Describe the pathway taken by an oxygen molecule from an alveolus to the blood.

Answer 16

Across alveolar epithelium

Endothelium / epithelium of capillary

Question 17

Explain how one feature of an alveolus allows efficient gas exchange to occur.

Answer 17

The alveolar epithelium is one cell thick Creating a short diffusion pathway