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
Explain the appearance of W and Z
W has 4 cells/nuclei since it is at the end of second division of meiosis
Z has 2 cells/nuclei as it is at the end of first division of meiosis
W shows haploid cells/cells containing N chromosomes
Cells in W contain half the mass of DNA of cells in Z
Between Z and W chromatids have separated
In Z homologous chromosomes have separated
Investigate whether there is a difference in seed size in two populations of trees
Use RANDOM SAMPLE of seeds from each population
Use LARGE SAMPLE to be REPRESENTATIVE of whole population
Idea of what size was measured
CALCULATE A MEAN and STANDARD DEVIATION
Use the STUDENTs T TEST
Analyse if there is SIGNIFICANT DIFFERENCE between the MEANs of two populations
Exercise causes an increase in heart rate. Describe the role of receptors
Chemoreceptors Detect rise in co2/H+/carbonic acid/fall in pH
Baroreceptors detect rise in blood pressure
Send impulses to cardiac centre/medulla oblongata
More impulses to SAN
By sympathetic (nervous system for chemoreceptors)
By parasympathetic (nervous system for baroreceptors)
Benefit of activating AMPK during. Exercise
Less/no malonyl CoA
More fatty acids moved into mitochondria
Respiration/oxidation of fatty acids provides ATP
How can introducing infertile mosquitoes stop spread of malaria
Compete with fertile males to mate/for food/resources
Intraspecific competition
Do not reproduce/breed
Reduces population
Describe mark release recapture
Capture/collect/sample, mark and release
Leave time for mosquitoes to disperse before second sampling/collection
Population= no in first sample x no in second sample/no marked in second sample
Radiation effectiveness
Radiation affects their attractiveness/courtship/survival/life span
Why release more transgenic males every week
To maintain number/competition as they die/ have a short life span
The trained mice were able to exercise longer than the control mice, explain why?
More aerobic respiration produces more ATP
Anaerobic respiration delayed
Less/no lactate
How to covert mm to micrometers
X1000
Why keep water potentials the same
Osmosis does not occur
Does not shrink/burst/lyse/shrivel organelle
Why set up tube 1 (no chloroplasts,DCPIP with light)
To show light does not affect DCPIP
To show chloroplasts are required
Explain results for tube 3 (blue to colourless)
Reduction of DCPIP by electrons
From chlorophyll/ light dependent reaction
Advantage of using IC50
Provides a standard/reference point
Can compare different chemicals/weed-killers
Can compare different concentrations of chemicals/weed-killers
How chemicals which inhibit decolorisation of DCPIP could slow the growth of weeds
Less/no ATP produced
Less/no reduced NADP produced
Less/ no GP reduced/converted to TP
How mychorrizae benefit
Get carbohydrate/amino acid/vitamin
Why an increase in shoot biomass is a measurement of net primary productivity
Represents dry mass/mass of carbon
Represents gross production minus respiratory losses
Evaluate the effect on plant productivity of adding AMF species and addin phosphate to the soil
For the control an increase in phosphate increases plant growth
For entrophosphora an increase in phosphate reduces plant growth
Scutellospora reduces plant growth compared to the control
Enthrophosphora and glom is increase plant growth compared to control
No SD to determine significance
Only 20 weeks of growth
Underground/ root growth is not known
Two reasons why pancreas transplants are not used for the treatment of type 11 diabetes
Usually type 2 produce insulin
Cells/receptors less sensitive/ responsive to insulin
Treated/controlled by diet and exercise
Evaluate the use of IPS cells to treat type 1 diabetes in humans
Effective as group A/with IPS treated lower than group B with diabetes
Effective as group A similar to group C/without diabetes
Investigation done on mice and not humans
Only shows results for 12 weeks l/ short-time period/ long-term effects are not known
A population of summer squash plants produced only green and yellow fruit. The % of plants producing yellow fruits is 36%. Use HW to work out heterozygotes for gene B
1-0.36= 0.64
Square root 0.64=0.8
2x0.8x0.2= 0.32
A dna sample is hydrolysed by enzymes before the sample is added to the reaction mixture
Explain why?
To remove any DNA present
As this DNA would be amplified/replicated
Why does DNA replication stop in PCR?
Limited number of primers/nucleotides
Why produce a variety of primers
Base sequence differs
Different complementary primers required
Gene pool meaning
All the alleles in a population
Define sympathetic speciation and how it differs from allopathic speciation
Occurs in the same habitat/population/environment
Mutation causes different flowering times
Reproductive separation/isolation
No gene flow
Gene pools remain separate
Different alleles passed on
Change in allele frequencies
Disruptive natural selection
Eventually different species cannot interbreed to produce fertile offspring
Explain how donepezil could improve communication between nerve cells
Less/no acetylcholine broken down
Acetylcholine attaches to receptors
More Na+ to reach threshold for depolarisation
Why a high frequency of mutation
Isolated so inbreeding/low genetic diversity/small gene pool
Allele inherited through generations from common ancestor
Why natural selection has not reduced frequency of mutation
Symptoms develop late
Have already reproduced
She at which mutation is expressed varies. Explain why?
Epigenetics/environment/names factor e.g. stress/diet/exercise/alcohol/toxins/diet/smoking
Methylation of genes
Acetylation of histones
Suggest why DNA probe is not suitable for detection of mutation
GCA triplet is common/found I. Other places
Would not know if it was the mutation/allele/gene
Glycogen v cellulose
Cellulose is made up of beta glucose and glycogen alpha glucose monomers
Cellusose has a straight chain and glycogen is heavily branched
Glycogen has 1-4 and 1-6 glycosidic bonds. Cellulose only has 1-4 glycosoidic bonds
