!!! Flashcards
advantages of atp
- releases energy instantaneously
- releases relatively small amount of energy
calcium ions and atp role in muscle contraction
- Calcium ions diffuse into myofibrils from
(sarcoplasmic) reticulum; - (Calcium ions) cause movement of tropomyosin
(on actin); - (This movement causes) exposure of the
binding sites on the actin; - Myosin heads attach to binding sites on actin;
- Hydrolysis of ATP (on myosin heads) causes
myosin heads to bend; - (Bending) pulling actin molecules;
- Attachment of a new ATP molecule to each
myosin head causes myosin heads to detach
(from actin sites)
Explain how the resting potential of –70 mV is maintained in the sensory neurone when no pressure is applied
- Membrane more permeable to potassium ions
and less permeable to sodium ions; - Sodium ions actively transported/pumped out
and potassium ions in;
Explain how applying pressure to the Pacinian corpuscle produces the changes in membrane potential recorded by microelectrode P.
- (Pressure causes) membrane/lamellae to
become deformed/stretched; - Sodium ion channels in membrane open and
sodium ions move in; - Greater pressure more channels open/sodium
ions enter;
The membrane potential at Q was the same whether medium or heavy pressure
was applied to the finger tip. Explain why.
- Threshold has been reached;
- (Threshold or above) causes maximal response
/ all or nothing principle;
Multiple sclerosis is a disease in which parts of the myelin sheaths surrounding neurones are destroyed. Explain how this results in slower responses to stimuli.
- Less/no saltatory conduction / action
potential/impulse unable to ‘jump’ from node to node; - More depolarisation over length/area of
membranes;
Suggest why the plasmids were injected into the eggs of silkworms, rather than into the silkworms.
- (If injected into egg), gene gets into all/most of
cells of silkworm; - So gets into cells that make silk;
Suggest why the scientists used a marker gene and why they used the EGFP gene
- Not all eggs will successfully take up the
plasmid; - Silkworms that have taken up gene will glow;
What would the scientists have inserted into the plasmid along with the spider gene to ensure that the spider gene was only expressed in the silk glands of the silkworms?
Promoter (region/gene);
Suggest two reasons why it was important that the spider gene was expressed only in the silk glands of the silkworms.
- So that protein can be harvested;
2. Fibres in other cells might cause harm;
Explain why the scientists measured the rate of production of oxygen in this investigation.
- Oxygen produced in light-dependent reaction;
- The faster (oxygen) is produced, the faster the
light-dependent reaction;
The scientists suggested that mutant plants producing more chlorophyll b would grow faster than normal plants in all light intensities.
Explain how these data support this suggestion
At all light intensities, chloroplasts from mutant
plants:
1. Have faster production of ATP and reduced
NADP;
2. (So) have faster/more light-independent
reaction;
3. (So) produce more sugars that can be used in
respiration;
4. (So) have more energy for growth;
5. Have faster/more synthesis of new organic
materials;
what causes muscle fatigue
lactate from anaerobic respiration
Explain why the student set up Tube 1.
- To show light does not affect DCPIP;
2. To show chloroplasts are required;
Explain the advantage of the student using the IC50 in this investigation.
Can compare different chemicals/weedkillers
Explain how chemicals which inhibit the decolourisation of DCPIP could slow the growth of weeds.
- Less/no ATP produced;
- Less/no reduced NADP produced;
- Less/no GP reduced/converted to TP;
Give two reasons why pancreas transplants are not used for the treatment of type II diabetes.
- (Usually)Type II produce insulin;
- Cells/receptors less sensitive/responsive (to insulin)
OR
Faulty (insulin) receptors; - (Treated/controlled by) diet/exercise;
Explain how donepezil could improve communication between nerve cells
- Less/no acetylcholine broken down;
- Acetylcholine attaches to receptors;
- (More) Na+ enter to reach threshold/for depolarisation/action potential/impulse;
Suggest and explain two reasons why there is a high frequency of the E280A mutation in Yaramul
- Isolated so inbreeding/low genetic
diversity/small gene pool; - Allele inherited (through generations) from
(common) ancestor;
Explain why natural selection has not reduced the frequency of the E280A
mutation in the population
- AD/symptoms develops late/at 49;
2. Have already reproduced;
The age at which the E280A mutation is expressed to cause AD can vary
Suggest and explain one reason for this.
1. Epigenetics/environment/named factor e.g. stress, alcohol, toxins, diet, exercise, smoking; 2. methylation (of genes) OR acetylation (of histones);
One scientific study which analysed chromosome 14 involved 102 individuals. The scientists recorded a sample size of 204. In this sample they detected 75 E280A mutations but only 74 potential AD cases
Suggest explanations for the figures the scientists recorded
- One person was homozygous dominant/has
two dominant alleles
Suggest why a DNA probe for the mutated triplet was not considered a suitable
method for detection of the E280A mutation
1. (GCA/triplet) is common/found in other places; 2. Would not know if it was the mutation/allele/gene OR Produces ‘false positives’;
Explain why a log scale is used to record the number of cells.
Large range/difference/increase in numbers;
What is meant by a genome?
- (All) the DNA in a cell/organism;
Explain why the antibody binds to the transcription factor.
- (Transcriptional factor/antibody) has a
specific/tertiary structure/shape; - Complementary (shape/structure);
Use Figure 8 to explain what ‘precipitated DNA’ consists of
- DNA, transcription factor and antibody;
Suggest how single-stranded cDNA could prevent transcription of the P34 gene.
- Binds to P34 gene/DNA/mRNA
Describe the roles of two named types of enzymes used to insert DNA fragments into box plasmids.
- Restriction (endonuclease/enzyme) to cut
plasmid/vector; - Ligase joins gene/DNA to plasmid/vector;
Suggest two features of the structure of different proteins that enable them to be separated by gel electrophoresis.
- Mass/number of amino acids/polypeptides;
- Charge;
- R groups (differ);
Why does substitution mutation change structure of a protein
- Substitution is one base swapped for another
- This changes the base triplet that that base was part of, the triplet then coded for a different amino acid
- Different amino acid changes primary structure of protein, which determines the tertiary structure of the protein
- Tertiary structure of the protein is therefore changed
Why decreased calcium ions inhibits muscle contraction
- calcium ions bind to a protein attached to tropomyosin, cause it to change shape, pull tropomyosin out of actin-myosin binding site exposing it
- so that myosin heads can bind, forms actin myosin cross bridge, pull actin over myosin causing muscle to contract as sarcomere shortens
- so if calcium ions are decreased, tropomyosin blocks binding sites, less contraction
- calcium also activates ATP hydrolyse (ATP -> ADP + Pi), energy used for contraction, so if less calcium then less energy
Why use pencil instead of ink in chromatography
- Ink would dissolve in solvent and pigments separate as solvent spreads up chromatogram
Method to separate pigments
- Place chromatogram in beaker of solvent, solvent shouldn’t go above pencil line
- Solvent moves up paper and carries different pigments at different rates
Why is different coloured pigments in leaves advantageous?
- Can absorb different wavelengths of light
Role of glucagon
- Produced in alpha cells in islets of Langerhans in pancreas
- Activates glycogenolysis and gluconeogenesis, decreases rate of respiration in cells
Role of insulin
- Increases permeability of membrane to glucose, more uptake
- Activates glycogenesis
Why does inhibiting adenylate Cyclase reduce glucose concentration
cannot form cAMP from ATP, does not activate protein kinase a, does not convert glycogen to glucose, process inhibited glucose concentration remains low.
photoionisation
Light hits chlorophyll, electrons become excited, leave chlorophyll and move to higher energy level, move down ETC
What is a DNA probe
- single stranded base sequence complementary to desired gene with label attached
How is DNA cut
- Restriction endonuclease, cuts DNA at specific palindromic recognition sequences (recognition sites)
reason for lid on petri dish
so it wouldn’t evaporate so IAA conc the same in each dish
explain the banding pattern from muscle diagram
- The centre of the sarcomere appears darker due to the overlap of both actin and myosin filaments (A band)
- The peripheries of the sarcomere appear lighter as only actin is present in this region (I band)
- The dark A band also contains a slightly lighter central region where only the myosin is present (H zone)
explain why converting pyruvate to lactate allows the continued production of atp by anaerobic respiration
Regenerates / produces NAD
(NAD used) in glycolysis.
Explain how two features of the design of this investigation helped to ensure the validity of any conclusions obtained. (zebrafish)
large sample size therefore representative
and use of a control group for comparisons
gluconeogenesis
the synthesis of glucose from non-carbohydrate sources
more insulin =
more glut4 proteins, absorb more glucose by active transport, reduces glucose conc
