Explain why cocaine is able to bind to dopamine transporters. (2)
- dopamine & cocaine have similar shapes
- therefore, cocaine can fit into the transporters
Explain why a myelinated axon conducts impulses faster than non-myelinated axons. (3)
- in myelinated, depolarisation only occurs at nodes
- the nerve impulse jumps from node to node
- impulse does not travel along the whole length
Contrast the nervous system with the endocrine system. (3)
- nervous system transmits electrical impulses along neurones, endocrine syst. transmits hormones in blood
- nervous system = fast, endocrine syst = slower
- nervous system has short effect, endocrine = longer
Explain how these events lead to the effects seen by the eye. (3)
- photoreceptors detect change in light intensity from bright to dim light
- radial muscle contract, circular muscle relax
- pupil dilates
Explain how a lower temp can affect the speed of an action potential. (2)
- slower movement down conc. gradient
- of ions
Describe and explain the difference of rod and cone cells in nocturnal mammals. (3)
- nocturnal mammals have more rods & fewer cone cells
- rods not at outer retina
- bcs rods have high sensitivity to light
Explain sequence of events that occur in rod cells in light and dark conditions. (6)
In light:
- light bleaches photosensitive pigment
- inside of rod cell is hyperpolarised
- impulse sent along optic nerve
In dark:
- sodium ions actively transport out of cell
- action potentials are prevented
- no impulse sent to optic nerve
Compare and contrast MRI & fMRI. (4)
Similarities:
- create clear image of soft tissues
- both can be used to identify areas of damaged tissues in brain
Differences:
- fMRI scans show active brain regions, MRI does not.
- fMRI allows brain structure & function to be studied in real time, MRI only produces static images.
Explain the importance of critical period in development of visual cortex. (2)
- neurones must be stimulated soon after birth to form synapses
- in order for neurones to be organised correctly in visual cortex
State 2 arguments against animal research. (2)
- many animals experience pain/distress during research
- animals unable to give consent, many believe they should have same safety & welfare rights as humans
Name 2 possible treatments for Parkinsons disease under treatment. (2)
- gene therapy
- stem cell therapy
Define: vector. (2)
- a carrier of gene
- into another cell
Give 2 possible advantages of using micro-organisms in genetic engineering. (2)
- unicellular organisms do not require much space
- less ethical concerns as they do not feel pain
Define: personalised medicine. (2)
- development of targeted drugs to treat human diseases
- based on individuals genotype
Give 2 possible issues with personalised medicine. (2)
- very expensive due to research costs so unavailable to many
- could cause distress to patient if they know the only available medicine may not work for them
