The REAL 2017 Paper Flashcards
Role of ribosomes in producing polypeptide chain
mRNA binds to ribosome Idea of two codons binding sites tRNA with anticodons to bind Catalysed formation of peptide bond between amino acids (held by tRNA molecules) Moves along (mRNA to the next codon)
Describe the structure of glycogen
Polysaccharide of alpha glucose
Joined by glycosidic bonds
Branched structure
How glycogen acts as a source of energy
Hydrolyses to glucose
Glucose used in respiration
Cells of uterus adaptations
Membrane is folded so large surface area
Membrane has increased sa so fast diffusion
Large number of protein channels/carriers for facilitated diffusion
Large number of protein carriers for active transport
Large number of protein channels/carriers for co-transport
How sodium are transported into cell/hydrogen out of cell
Co-transport
Uses hydrolysis of ATP
Sodium ion and proton bind to protein
Protein changes shape (to move sodium ion and proton across the membrane)
Tissue fluid
Higher salt results in lower water potential of tissue fluid
So less water returns to capillary at the venule end by osmosis
OR
Higher salt results in higher blood pressure
So more fluid forced out of the capillary at arteriolar end
How bacteria divide
Binary fission
Replication of circular DNA
Division of cytoplasm to produce 2 daughter cells
Each with single copy of circular DNA
Explain shapes of enzyme-temperature curve
Both denatured by high temperature
Denaturalising faster at 60 degrees due to more kinetic energy
Breaks hydrogen/ionic bonds between amino acid R groups
Change in shape of the active site/ active site no longer complementary
so fewer enzyme-substrate complexes formed/substrate does not fit
Advantage to bacterium of secreting extracellular protease
To digest protein
So they can absorb amino acids for growth/reproduction/protein synthesis
So they can destroy a toxic substance
Action of membrane bound dipeptidases
Hydrolyse peptide bonds to release amino acids
Amino acids can cross cell membrane
Or dipeptidases cannot cross cell membrane
Maintain concentration gradient of amino acids for absorption
Ensure nearly maximum yield from protein breakdown
Suggest why human ATP synthase is not inhibited and bacterial ATP synthase is inhibited
Human ATP
Synthase has a different tertiary structure to bacterial ATP synthase
Has a different shape active site
Cannot winter human cells
Antibiotic give to mouse at 25mgkg-1 per day, how much given to 30g mouse
Convert units
30/1000 to kg
X25 =0.75
Using two antibiotics is better. Use knowledge of natural selection and evolution in bacteria to explain your answer
New/old antibiotic does not fully kill bacteria
Some bacteria are resistant to new/old antibiotic
Resistant bacteria will reproduce to produce more resistant bacteria
Use of both will kill bacteria resistant to other antibiotic
Unlikely bacteria are resistant to both antibiotics
Use of both antibiotics are likely to kill all bacteria
Evaluate the use of 24D as a herbicide
24D causes an increase and release of ions from wild oat cells and 24D does not affect/has little effect on wheat cells
For wheat difference is less than LSD
For wild difference is more than lsd
Loss of ions from cells likely to lead to plant death
No evidence here about death of plants as a result of ion loss
No evidence about other ecological/environmental impact
Shake and keep temperature constant
Maintain temperature so that the rate of diffusion of ions out of cells remains constant
So no change in fluidity of phospholipids
Shaking so all surfaces of the leaf discs are exposed to water/so all submerged
To maintain diffusion/concentration gradient for ions
Phagocytosis
Phagosome vesicles fuses with lysosomes
Virus destroyed by hydrolysis enzymes
Antigen from virus are displayed on cell MEMBRANE
How presentation of virus leads to secretion of antibody
Helper T cell binds to antigen (on antigen presenting cell)
This helper T cell stimulates specific B cell
B cell clones
B cell divides by mitosis
Forms PLASMA CELLS that release antibodies
Autoimmune response?
The antibody against virus will bind to collagen
This results in destruction of human cells
Insect gas exchange adaptations
Tracheoles have THIN WALLS so short diffusion distance to cells
HIGHLY BRANCHED so short diffusion distance to cells
HIGHLY BRANCHED= large surface area
Tracheae provide tubes full of air so fast diffusion
Fluid in the end of tracheoles that moves out into tissues during exercise so larger SA for gas exchange
Body can be moved by muscles to move air so maintain diffusion gradient/ concentration gradient o2 and co2
Adaptation of gills
Damselfly larvae have a higher respiratory rate
So uses more oxygen per unit mass/time
