Nucleic Acids

Question 1

describe how ATP is resynthesised in cells

Answer 1

from adp and phosphate
by ATP synthase
during respiration/photosynthesis

Question 2

give two ways the hydrolysis of ATP is used in cells

Answer 2

to provide energy for other reactions

to add phosphate to other substances and make them more reactive it change shape

Question 3

what is evidence of Scanning electron microscope

Answer 3

can see a 3D image

Question 4

what is the bond between phosphate and Penrose sugar called

Answer 4

phosphodiester

Question 5

describe the function of DNA helicase

Answer 5

breaking hydrogen bonds

Question 6

describe the function of DNA polymerase

Answer 6

joins nucleotides by forming phosphodiesterase bond

Question 7

Compare ATP and DNA

Answer 7

ATP has ribose and DNA nucleotide has deoxyribose
ATP has 3 phosphate groups and DNA has 1
ATP, base always adenine and in in DNA bases can vary

Question 8

describe the link between oxygen concentration, rate of respiration and rate of uptake of potassium ions

Answer 8

greater rate of oxygen consumption leads to greater rate of respiration and greater rate of uptake
oxygen required for respiration
respiration produces ATP/releases energy
pottasium ions taken up by active transport which requires energy

Question 9

explain decrease in the vegetable disk size when placed in water

Answer 9

water potential inside potato higher

water moves out by osmosis

Question 10

other than ethical reason, why would you choose animals such as cats?

Answer 10

1 are mammals so likely to have same physiology as humans
2 small enough to keep in laboratories
3 can use in large number

Question 11

why can monitoring the pH of mixture show that lipids are present in a substance (when the lipase is added to substance)

Answer 11

hydrolysis of lipase produces fatty acids

this lowers pHl

Question 12

describe how you can use emulsion test to show seed contains lipids

Answer 12

crush DO NOT ADD WATER
dissolve into alcohol
add water AFTER
White emulsion shows presence of lipid

Question 13

does correlation show causation?

Answer 13

no, perhaps a third factor

Question 14

how to work out number of water molecules produced from a diagram

Answer 14

count number of Xs and Rs

Question 15

why are hydrogen bonds important for cellulose?

Answer 15

holds chains together by forming cross links which forms microfibrils providing strength
hydrogen bonds are strong in large numbers

Question 16

why is the shape of a starch molecule important to function in cells

Answer 16

spiral shape which makes it compact

Question 17

explain two ways fatty acids are important to formation of new cells

Answer 17

fatty acids used to make phospholipid
phospholipid in membranes
more phospholipids more membranes made

fatty acids respired to release energy
more triglycerides, more energy released
energy used for cell production

Question 18

other than being smaller give two ways in which prokaryotic DNA is different from Eukaryotic DNA

Answer 18

prolaryotic dna has cirular/non linear DNA
is not associated with proteins
no non coding DNA

Question 19

how is the dna of a virus different from that of other organisms
usw knowledge of dna to suggest the difference

Answer 19

in virus dna A does not equal T neither does equal to C
so no base pairing
dna is not double stranded

Question 20

during replication, nucleotides can be added only in a 5’ to 3’ direction, explain why

Answer 20

dna polymerase
is specific
so only complementary with 5’ end
shape of 5’ is different from 3’ end

Question 21

explain why maltase catalyses the hydrolysation of maltose

Answer 21

active site has specific shape
this is complementary to substrate(maltose)
so only maltose can bind
to form an enzymesubstrate complex

Question 22

explain the structure of cellulose and how it’s adapted for it’s function in cells

Answer 22

1 made from β glucose 
2 joined by condensation 
3 1:4 link
4 flipping over alternate molecules
5 hydrogen bonds linking long unbranched straight chains, this collectively adds to the strenght
6 cellulose makes cell wall strong 
7 can resist turgor pressure 
8 bonds difficult to break
9 resis digestion