Assessment Feedback Oct 23 Flashcards
Define photolysis
The splitting of a water molecule using light energy
Define photoionisation
When light energy ‘excites’ electrons in an atom or molecule, giving them more energy and causing them to be released. The release of electrons causes the atom or molecule to become a positively charged ion.
How to carry out chromatography?
- Get chromatography paper and draw a pencil line a few cm up
- Add some solvent to a beaker and cut part of a leaf and press down on your point of origin
- Place the paper into the solvent ensuring it doesn’t touch the origin line
- Allow solvent to move up the paper and remove from solvent before it touches the top of the paper
Why is the origin line in pencil?
Pencil is insoluble so wont mix with the plant pigments
What are enzymes and what is their role?
Enzymes catalyse metabolic reactions - both at a cellular level
They lower activation energy
Name 4 factors effecting enzyme activity
Temperature
pH
Substrate concentration
Enzyme concentration
What is the difference between competitive and non competitive inhibitors ?
Competitive = Similar shape to the substrate so they take the place of the active site which prevents substrates from binding. This will prevent enzyme substrate complexes forming
Non-competitive = Bind to the enzyme away from the active site. This causes the tertiary structure to change shape so the active site changes shape meaning that the substrate molecules can no longer bind to it. This prevents enzyme substrate complexes forming.
What happens to pyruvate during anaerobic respiration in animals and why?
Pyruvate is combine with NADH to form NAD+ and lactic acid
pyruvate + NADH –> lactic acid + NAD+
This reaction regenerates NAD+ so this can be recycled back into glycolysis so this can continue even without oxygen, so a small amount of ATP can still be produced.
Why is lactic acid converted back into pyruvate when oxygen is supplied?
Lactic acid is harmful and can cause cramps
Pyruvate is used in aerobic respiration which makes 32 ATP compared to 2 ATP made in anaerobic respiration
Describe what happens in the Krebs cycle
Acetyl CoA from link reaction combines with 4c molecule to form 6c molecule of citrate. CoA is removed to go back into link reaction
6c compound is decarboxylated to form 5c compound and dehydrogenation also occurs. The hydrogen produced is used to form NADH
5c compound is then converted to 4c compound by decarboxylation and dehydrogenation. Producing one molecule of FADH and 2x NADH. ATP is also produced
What are the roles of the co-enzymes NAD, FAD and co-enzyme A in the Krebs cycle?
NAD = acceptor of hydrogen ion and electrons
FAD = acceptor of hydrogen ion and electrons
CoA = after being removed when acetyl CoA combines with 4c compound to form 6c compound, it goes back to the link reaction to be used again
Compare the primary and secondary immune responses
Primary = When pathogen enters the body it activates an immune response. The primary response is slow because there aren’t may b cells that can make the antibody needed to bind to it. After being exposed to the antigen both T and B cells produce memory ells which stay in the body for a long time.
Secondary = If the same pathogen enters the body again, the immune system will produce a quicker stronger response as clonal selection happens faster and memory b cells are activated to produce antibodies.
Why does the secondary response lead to immunity?
The secondary response often gets rid of the pathogen before you begin to show any symptoms as there are more memory cells which can produce more antibodies at a quicker pace.
What is antigenic variation and what causes it?
Pathogens changing their surface antigens
It is caused by changes in the genes of the pathogens
How can antigenic variation effect the success of a vaccination programme ?
It can make vaccination programmes difficult as when you are infected for a second time the memory cells from the first infection wont recognise this as of the different antigens
