Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
58 Cards in this Set
- Front
- Back
![Complete this table [3]](https://images.cram.com/images/upload-flashcards/48/30/18/18483018_m.png)
Complete this table [3] |
|
|
The diagram below shows the arrangement of actin and myosin in a sarcomere. A form of muscle disease is caused by a mutated allele. This leads to the production of myosin molecules which are unable to bind to other myosin molecules, preventing muscle contraction. Use the diagram below and your knowledge of how muscles contract to suggest why [3] |
-Can’t form myosin filaments -Can’t pull actin -Myosin moves -Can’t move actin towards each other and so sarcomere can’t shorten |
|
|
Describe how a Pacinian Corpuscle produces a generator potential when stimulated [3] |
-Increased pressure deforms the stretch mediated sodium ion channels -So sodium ions flow in -Causing depolarisation, which creates a generator potential |
|
|
Damage to the myelin sheaths of neurones can lead to problems controlling the contraction of muscles. Suggest one reason why [2] |
-Action potentials travel more slowly -So there is a delay in contraction |
|
|
Explain how a hydrophobic molecule can easily pass into a neurone in the body [1] |
-They are lipid soluble so can pass through the phospholipid bilayer |
|
|
Scientists investigated the use of substances called cannabinoids to control muscle problems caused by MS. Cannabinoid receptors are found in the presynaptic membrane of neuromuscular junctions. When a cannabinoid binds to its receptor, it closes calcium ion channels. Suggest how this could prevent muscle contraction [4] |
-Prevents the influx of calcium ions into the presynaptic membrane -So the synaptic vesicles don’t fuse with the membrane and don’t release neurotransmitter -Neurotransmitter does not diffuse across synaptic cleft and does not bind to receptors -So no action potential can be generated because there is not influx of sodium ions |
|
|
Cannabinoids contain substances found in cannabis but don’t enter the brain tissue and instead only enter the neuromuscular junctions. Suggest why treating someone who has MS with cannabinoids rather than cannabis would be better [2] |
-Won’t affect brain synapses -Won’t damage brain -Only affect target area |
|
|
Give one similarity and one difference between a taxis and a tropism [2] |
-Both are a directional response -Taxis is a movement of the whole organism, but a tropism is a growth response |
|
|
Define a taxis [1] |
-A movement towards or away from a stimulus |
|
|
A myelinated axon conducts impulses faster than a non-myelinated axon. Explain why [3] |
-In a myelinated axon, depolarisation only happens at the nodes of ranvier -Causing a saltatory jump -So the action potential does not travel along the whole length of the axon, which is faster |
|
|
What is the role of phosphocreatine in providing energy during muscle contraction? [2] |
-Provides phosphates -To create ATP |
|
|
Describe the role of tropomyosin in muscle contraction [2] |
-Moves out of the way when calcium ions bind to it -To allow myosin to bind to form crossbridge |
|
|
Describe the role of myosin in muscle contraction [2] |
-Head of myosin binds to actin and pulls actin past -Then detaches from actin and moved further along -Using ATP |
|
|
Explain the advantage of having high amount of glycogen around fast muscle fibres [2] |
-Glycogen breaks down to give lots of ATP for anaerobic respiration -Anaerobic respiration is not very efficient in ATP production so glycogen provides ATP |
|
|
Explain the advantage of a large amount of capillaries around slow muscle fibres [2] |
-Give lots of oxygen supply -Giving good glucose supply -For more aerobic respiration |
|
|
Explain how IAA causes a root to bend [2] |
-Greater growth on opposite side of IAA concentration -Because IAA inhibits root growth -So root bends to side of IAA |
|
|
Serotonin is a neurotransmitter which is released in some synapses in the brain. Describe how Serotonin causes depolarisation in the post-synaptic membrane [3] |
-Diffuses across synaptic cleft -Causes sodium ions to open -Sodium ions enter cell causing depolarisation |
|
|
Why is it important that neurotransmitters are transported back out of synapses? [2] |
-If not removed, keeps binding to receptors -Keeps causing action potentials -Stopping information being carried across synapse |
|
|
Describe how LH is involved in the mammalian oestrous cycle [2] |
-Stimulates ovulation/release of the egg from ovary Stimulates formation of corpus luteum -Stimulates the release of oestrogen and progesterone |
|
The diagram below shows the system controlling the concentration of testosterone in a man’s body. If the concentration of testosterone in a man’s blood starts to rise above the normal level, this system leads to a reduction in testosterone. Use the diagram below to explain how [3] |
-Inhibition of hypothalamus so less GnRH -Inhibition of pituitary so less LH and FSH -So no stimulation of testes to make testosterone |
|
|
A contraceptive pill has been developed for men which uses testosterone to prevent sperm production. Use the figure above to explain how this works [2] |
-Keeps testosterone high -To inhibit GnRH, LH, and FSH production |
|
|
Explain how the homeostatic response stops blood glucose from falling when left without food for long periods of time [3] |
-Release of glucagon -Leads to formation of glucose -From non-carbs and amino acids |
|
|
Explain how the formation of glycogen in liver cells leads to a lowering of blood glucose concentration [2] |
-Glucose concentration in liver cells falls -Below that in blood -Creates glucose concentration gradient -Glucose enters cells by facilitated diffusion |
|
|
The destruction of developing follicles can lead to a much higher FSH concentration in young females than normal. Explain your knowledge of hormonal interactions to explain why [2] |
-No oestrogen produced by follicle -So no negative feedback on FSH from oestrogen -On pituitary gland |
|
|
What is the role of RNA polymerase during transcription? [1] |
-To join nucleotides together to form mRNA |
|
|
The genetic code is described as being degenerate. What does this mean? [1] |
-One amino acid can be coded for by more than one triplet |
|
|
What is a codon? [2] |
-Triplet -That codes for an amino acid |
|
|
Why is the genetic code described as universal? [1] |
-Because the same triplet codes for the same amino acid in all organisms |
|
|
The genetic code uses four different bases. What is the maximum number of different DNA triplets that can be made from these bases? [1] |
-64 |
|
|
Name the processes that removes base sequences from pre-mRNA to form mRNA [1] |
-Splicing |
|
|
An exonic single base deletion can lead to the production of a non-functional protein. Explain why [3] |
-Mutation causes all subsequent triplets to be frame shifted -Changes amino acid sequence after mutated base -Affects hydrogen bond placement -Changes tertiary protein structure |
|
|
What effect might an intronic single base substitution have on the protein produced? Explain your answer [2] |
-Introns are non-coding -So no difference since introns are not translated |
|
|
A mutation in a tumour suppressor gene can result in the formation of a tumour. Explain how [2] |
-Tumour suppressor gene inactivated and can’t control rate of cell division -So cell division gets out of control and tumour develops |
|
|
Not all mutations result in a change in the amino acid sequence of the encoded polypeptide. Explain why [2] |
-The mutation could be in an intron -The code is degenerate so the mutation could be inconsequential |
|
|
Some cancer cells have a receptor protein in their cell surface membrane that binds to a hormone called growth factor. This stimulates cancer cells to divide. Scientists have developed a monoclonal antibody that stops this mutation. Use your knowledge of antibodies to explain how this works [3] |
-Antibody has a specifically shaped binding site -Which is complementary to the receptor protein -Which prevents growth factor binding to receptor competitively |
|
|
What is a transcription factor? [2] |
-A protein molecule which moves from cytoplasm to DNA -Binds to specific genes -Leading to the promotion or blocking of RNA production |
|
|
Some transcription factors lead to the production of proteins which remove electrons and protons from reduced NAD in the mitochondrion. Suggest how the inhibition of a transcription factor could lead to neurone death [3] |
-Prevents mRNA formation -Prevents production of protein -Fewer electrons transported to electron transport chain -Fewer protons for proton gradient -So not enough ATP produced to keep neurone alive |
|
|
Which bases bond together in RNA? [2] |
A-U G-C |
|
![What about the diagram below shows that the sequence is palindromic? [1]](https://images.cram.com/images/upload-flashcards/48/31/38/18483138_m.png)
What about the diagram below shows that the sequence is palindromic? [1] |
GGATCC same as CCTAGG backwards |
|
|
mRNA can be converted to cDNA. Name the enzyme used in this process [1] |
-Reverse transcriptase |
|
|
DNA methylation is a process by which substances called methyl groups attach to cytosine or adenine. This prevents transcription. Explain how this prevents the expression of a gene [3] |
-It prevents the binding of the transcription factor -Preventing the RNA polymerase from working -It prevents specific base pairing of nucleotides -So no mRNA can be made -So mRNA can’t be translated and expressed |
|
|
When using restriction endonucleases, explain why it is important to use the same restriction endonuclease on each DNA sample [2] |
-To cut the DNA at the same recognition sequence -To get fragments with the required gene from each sample |
|
|
Explain why primers only bind to specific DNA fragments [2] |
-Because they have specific base sequences -Which are complementary to their target alleles |
|
|
When investigating DNA after using a DNA probe, explain why it is a good idea to look at cells which are in mitosis [2] |
-Because the chromosomes are visible -So it is easier to see where the probes are attached |
|
|
Name the enzyme used to produce cDNA [1] |
-Reverse transcriptase |
|
|
Explain why DNA probes only detect targeted alleles [2] |
-Probe base sequences are complementary to target allele -Forms base pairs -So attaches to target allele |
|
A scientist carries out a DNA probe to determine whether a husband and wife carry a genetic mutation which causes a serious genetic disorder in homozygous carriers. The graph below shows the DNA probe results. Explain how the geneticist came to the conclusion that the couple were both carriers of the gene [3] |
-Carriers are heterozygous -Both have DNA which binds to 50% of probe -Probe binds to healthy allele -So only one copy of the exon in the DNA has the healthy allele |
|
|
Explain why DNA probes are usually used for exons and not introns [3] |
-Introns are not expressed -Exons code for amino acid sequences -Mutations can cause amino acid sequence changes -Which produce faulty proteins -But introns don’t |
|
|
Which methods could a scientist use to find the base sequence of a gene? [2] |
-Restriction mapping -Base sequencing |
|
|
Suggest two ways in which the use of a questionnaire may affect the reliability of data [2] |
-Patients may lie -Patients may not know how much {factor} they do |
|
|
When a statistical test is carried out which yields a result of P<0.01, what does this mean? [2] |
-The differences are significant -The probability of a difference being down to chance is less than 1% |
|
|
When a statistical test is carried out which yields a result of P=0.047, what does this mean? [2] |
-Differences are significant -Since probability of the results being down to chance -Are less than 5% |
|
|
Explain why it is important to use a control group when conducting experiments [2] |
-For comparison with other groups -To see the effect of no action |
|
|
What measurements would you need to calculate the rate of CO2 production in an area? [2] |
-Volume of co2 production -Area size -In given time |
|
|
ESSAY: |
-Homeostasis -Digestion and absorptions -Cells -Lung function -Gas exchange -Passage of water through plant -Nutrient cycles -Response to stimuli -Neurones -Tissue fluid and its formation -Control of blood glucose concentration -Negative feedback -Gene expression |
|
|
ESSAY: How energy is transferred within and between organisms |
-Photosynthesis -Energy transfer through ecosystems -Food production -Digestion -Absorption -Mass transport -Respiration -ATP -Simuli and responses -Muscle contraction -Nerve impulses |
|
|
ESSAY: The membranes of different types of cells are involved in many different functions |
-Membrane function as selectively permeable barrier -Transport mechanisms across membranes -Absorption and co-transport of sodium ions and glucose -Photosynthesis, chloroplasts, thylakoids -Protein secretion -Surface receptors -Cell division -Vertical and horizontal gene transmission -Pacinian corpuscle -Tropisms and IAA movement -Synaptic transmission -Muscle contraction -Hormones -Osmosis |
|
|
There are many types of relationships and interactions between organisms |
-Pathogens and effects on host -Cholera -TB -Taxonomy -Classification and evolution -Inheritance and evolution -Genetic code - universal -Behaviour -Populations and evolution -Relationships within ecosystems - predator and prey -Energy transfer within ecosystems -Nutrient cycles -Succession, biodiversity -Human impacts -GMO, selective breeding -Antibiotic resistance |
