2019 AS Paper 1 Flashcards
(19 cards)
3 ways in which the DNA in a chloroplast is different from DNA in the nucleus
- shorter
- circular DNA, nucleus is linear
- fewer genes
Give a difference between the structure of DNA vs RNA
DNA has deoxyribose, RNA has ribose
Name structures X (bottom of tRNA) and W (top of tRNA)
X = anticodon
W = amino acid binding site
Why do not all mutations cause a change in the structure of a polypeptide
- DNA are degenerate (more than one triplet can code for the same amino acid)
- may occur in introns (don’t code for proteins)
What is a monoclonal antibody
antibodies with the same tertiary structure
One of example of using monoclonal antibodies in medical treatment
targets specific cells/diseased cells
Describe the role of antibodies in producing a positive result in an ELISA test
- antibodies attach to complementary antigen
- a second antibody with an enzyme attached is added and attaches to the antigen
- substrate is added to induce a colour change
Suggest a method other than a colorimeter to measure the quantity of reducing sugar in a solution
filter and dry the precipitate, then find the mass
How does a colorimeter improve the repeatability of the student’s results
gives a more accurate reading
Why is it more useful to calculate an index of diversity than to record species richness
it measures the population of each species, useful as there may be alot of some species
Suggest how the scientist measured the rate of water flow in the river
measure time to fill container of known volume
One way the sampling procedure can be standardised
less oxygen at site 1 so less respiration
Why would the figure not be seen with an optical microscope
has longer wavelengths so a lower resolution
Name an organelle found in both a chloroplast and a prokaryotic cell
ribosomes
Describe 3 properties of this solution and explain how each property prevents damage to organelles
- cold, prevents enzyme activity
- buffered, prevents pH change and denaturing of enzyme
- isotonic, prevents lysis of organelles
Describe and explain the advantage of the counter-current principle in gas exchange across a fish gill
water and blood flow in the opposite directions, maintaining the concentration gradient of oxygen along the lamellae
Explain how the active site of an enzyme causes a high rate of reaction
lowers activation energy, induced fit causes active site to change shape so ES complex causes bond to break
Describe a biochemical test to confirm the presence of protein
add biuret solution, colour change to purple if present
Describe 2 ways in which all dipeptides are similar and 1 way they’re different
Similar:
- all contain amine (NH2) group at end
- all contain carboxyl group (COOH) at end
Different:
- contain different R groups
