exam qs + model ans Flashcards
Oct 2020: 2a) Describe the difference between niche and habitat
niche: role of species within its habitat in an ecosystem
habitat: where an organism lives
Oct 2020: 2c) i) Explain the importance of the different shell patterns in these two habitats (woodland and meadows)
- frequency of different shell patterns in different habitats (adaptation)
- provides camouflage
- provides protection from predators
- increases chance of survival (population increase)
- allows successful reproduction
Oct 2020: 2c) ii) Explain how a stats test can be used to determine if the number of shells with zero bands is significantly different in these two habitats
- T test
- if value is greater than critical value at p=0.05 the difference is significant
Oct 2020: 3a) i) State the location of the Calvin Cycle (LIR)
stroma
Oct 2020: 3a) ii) Describe the roles of the products of the light-dependent reactions in the Calvin Cycle
- ATP and reduced NADP
- ATP used to provide energy for Calvin Cycle
- reduced NADP used to convert GP to GALP
Oct 2020: 3b) i) State what is meant by the term ecosystem
- organisms and abiotic factors
Oct 2020: 3b) iii) Comment on the impact of these different types of ecosystem on global warming (tropical rainforest and salt marsh)
information from table shows:
- tropical rainforest: higher GPP, larger SA
- salt marsh: lower GPP, smaller SA
- tropical rainforests use a greater percentage of GPP in respiration
- they have a large SA
- therefore they release more CO2
- this is a greenhouse gas and contributes more to global warming
Oct 2020: 3c) Explain the importance of RUBISCO to the productivity of an ecosystem
- fixes inorganic carbon
- allows formation organic molecule from Calvin Cycle
- organic molecules allow energy transfer to the next trophic level
Oct 2020: 7a) Describe how eyes relay visual information to the brain
- light detected by rod cells
- rod cell membrane is hyperpolarised
- stops the release of glutamate
- bipolar neurone is depolarised
- impulse transmitted along optic nerve
- the the visual cortex of the brain
Oct 2020: 7b) Explain how the treatment of Parkinson’s disease overcomes the difficult of drugs passing from the blood in the brain
- L-dopa can cross the blood brain barrier
- L-dopa is converted to dopamine in the brain
Oct 2020: 7c) Explain how white blood cells swarm to accumulate at the site of inflammation
- histamines increase permeability of the capillaries
- histamine causes vasodilation
- increases blood flow to the site of inflammation
- WBC move from blood to the affected area
- cytokines attract WBC
Oct 2020: 7d) Protein projects out from the cell surface membrane of a WBC, how do these proteins help immune cells cross the blood brain barrier
- bind to receptors
- on endothelial cells
- stops immune cells from moving with the blood
- immune cells move between endothelial cells into the brain
Oct 2020: 7e) Give 2 ethical arguments to support the use of rats and mice with spinal cord injuries in these experiments
- spinal cord injuries are difficult to treat
2. animals tested need to have a well developed CNS
Oct 2020: 7f) Describe how antigens are presented to immune cells
- macrophages engulf antigens
- antigen is presented on the surface of antigen presenting cells
- CD4 receptors bind to antigen presenting cells
Oct 2020: 7g) Explain how a cytokine could modify the activity of a neural circuit
- cytokine binds to receptors on synaptic membrane
- opens ion channel
- affects the movement of ions across the membrane
- depolarises the cell membrane
- affects action potential as threshold is not reached
Oct 2020: 7h) Compare and contrast the structure of a sensory neurone and a motor neurone
similarities:
- both have axon
- both have a cell body that contains a nucleus
difference:
- location of cell body
Oct 2020: 7i) Describe what is meant by a critical period
- period of time during early development
- when the nervous system must be stimulated to develop properly
- so the synapses are strenghtened
- unstimulated synapses removed
Oct 2020: 7j) Explain how the critical period could be investigated using animal experiments
- infect animals at different times during early development
- investigate animals at different stages in development
- check for effects on learning
Oct 2020: 7k) Describe how bacteria can be genetically modified to produce a cytokine for the treatment of neurological and mental disorders
- isolate gene from human DNA
- use a bacterial plasmid
- cut human DNA and plasmid using the same restriction enzyme
- splice the gene and plasmid together using ligase
- put modified plasmids into bacterial cells
- reproduces lots of new bacterial cells (bacteria with the plasmids)
Oct 2020: 7l) Explain why a bone marrow transplant can be used to replace a flawed immune system
- bone marrow contains stem cells
- can differentiate into WBCs
What ensures nerve impulses travel one direction (2)
- refractory period
- Na+ channels cannot open immediately
What are the 4 phases of an action potential? (4)
- depolarisation
- repolarisation
- hyperpolarisation
- return to resting potential
How does a nerve impulse propagate to an adjacent membrane?
- depolarisation at site of action potential
- negative potential difference
- Na+ ion channels open at adjacent site
- depolarisation
What is meant by myelination? (2)
- Schwann cells
- wrapped around the axon
What are the Nodes of Ranvier? (2)
- short uncovered gaps
- between Schwann cells
Describe the events leading to the release of acetylcholine and its binding to the post synaptic neurone (4)
- action potential arrives
- depolarisation
- Ca2+ enters synaptic knob
- vesicles fuse with membrane
- acetylcholine diffuses across synaptic cleft and binds to receptors
IAA can interact with transcription factors to stimulate cells to produce proteins. Suggest how the presence of IAA can cause cells to produce proteins. (4)exa
- IAA binds to receptors
- IAA moves to the nucleus
- transcription factor activates a gene
- at promotor region
- allows formation fo mRNA
- translation produces protein
Respiration: Name molecule T and use the information in the Krebs cycle diagram to give a reason for your answer (2)
- molecule T: carbon dioxide
- carbon is removed from C6 or C5
Respiration: Suggest what would happen in the Krebs cycle if acetyl CoA became unavailable (3)
- stops the cycle
- C4 would accumulate
- C6 would not be synthesised
- carbon dioxide would reduce
Respiration: Explain what is meant by the term oxidative phosphorylation (3)
- involves the movement of electrons through an electron transport chain
- contains ATPase
- helps produce ATP by phosphorylating ADP
- idea of losing energy
- chemiosmosis
- oxygen is the final acceptor
Respiration: How many ATP molecules are synthesised in the mitochondria from one molecule of acetyl CoA?
12
Respiration: In which processes is ATP formed?
- glycolysis
- Krebs cycle
- electron transport chain
Respiration: Explain why some ATP is broken down during glycolysis (2)
- ATP supplies energy to break down glucose
- to produce GP
Respiration: Explain the role of the carrier molecules in the electron transport chain (3)
- receive H from reduced NAD / FAD
- break H bonds to H+ and e-
- electrons transferred by a series of redox reactions
- energy released used to pump H+ to intermembranal space
What is a resting potential stage?
- active transport of sodium potassium pump (3Na+ out and 2K+ in)
- membrane is more permeable to K+ and Na+ remains outside
- K+ leaks out
- -70mV
- negative potential difference
How does an action potential get triggered?
- neurone stimulated
- Na+ channels open, Na+ travels into neurone
- depolarisation
- threshold of -55mV, more Na+ channels open
- +30mV Na+ channels close, K+ channels open
- K+ leaves neurone, Na+ pumped out
- repolarisation
- hyperpolarisation when K+ leaves the cell
- K+ channels close
- resting potential is restored
