exam qs + model ans Flashcards
(36 cards)
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
