mock questions Flashcards
describe the events following the release of acetylcholine that leads to the stimulation of this contraction ( do not include the events following/after the release of calcium ions in the myofibril) 3 marks
acetylcholine diffuses towards the postsynaptic membrane of the sacromere and binds to complimentary receptors, causing an action potential causing calcium ions to be released in the sarcoplasmic reticulum
inhibitory synapses cause hyperpolarisation in the post synaptic neurones explain how this inhibits synaptic transmission
- chloride ions bind to receptors on post synaptic neurone causing the neurone to have extra negative charge as it is hyper polarised so more sodium ions are needed to reach threshold
What is the I band?
actin FILAMENT
what is the H zone?
myosin FILAMENT
What is the A band
actin FILAMENT and myosin Filament
what is the Z zone
boundaries of a sarcomere
explain how the difference in glycogen concentration is related to the different properties of fast and slow twitch muscle fibres
-more glycogen in fast twitch muscles, quicker muscle contraction than slow muscle fibres
-fast twitch muscle fibres rely more on anaerobic respiration(glycolysis) which is a faster process
whist slow twitch muscle fibres are used in aerobic conditions for endurance exercise
what happens to photosynthesis if the electrons transport chain is stopped?
- less hydrogen ions move via facilities diffusion down ATP synthase
-so less ATP is catalysed - less NADP is reduced to form NADPH
-NADPH and ATP is needed to reduce GP to TP - less TP means less glucose is produced slowing down photosynthesis
in photosynthesis why are small amount of heat released
electrons absorb light energy, heat released when moving down electron transfer chain
Explain the loop Henley
Ascending limb is water impermeable and actively transports sodium ions out into medulla, lowers water potential.
The descending limb is water permeable, so water moves out via osmosis into medulla
Using the graph, Can you conclude that the insect pest resistant to Bt toxin found in the years 2002
to 2005 was the same insect species? Explain your answer.
No because on the graph it shows the number of insects rather than the type of insects
One farmer stated that the increase in the use of Bt crop plants had caused a
mutation in one of the insect species and that this mutation had spread to other
species of insect. Was he correct? Explain your answer.
- different species of insects can’t interbreed so cant pass on alleles to offspring
- mutations random
- ## rate of mutations is affected by environment
There was a time lag between the introduction of Bt crops and the appearance of
the first insect species that was resistant to the Bt toxin.
Explain why there was a time lag.
-mutation with favoruable allele in few insects, increase survival pass onto offspring, many generations to increase allele frequency
Suggest one source of this DNAof a dead animal.
bones
What can you conclude about the effect of hunting on genetic diversity in otters?
-hunting reduces the genetic diversity of otters, few surviving, increase inbreeding more of one allele
why are the low genetic diversity is some populations
- small population
- inbreeding
describe how you would estimate the number of plants in a field
- lay out 2 tape measures at 90 degrees
-use a random generator to get coordinates
-count the number of plants in the quadrant
-repeat multiple times to get a large sample size - calculate the mean number of plants through adding up the number of plants recorded divided by by the number of quadrats placed
if a plant is taking up large quantities of nutrients, what does that mean for other species of plants ?
-interspecific competition ( different species competing for nutrients in soil)
- less water water and minerals for other plants for photosynthesis
- less glucose means less proteins which are needed for growth
describe how you would insert a gene into a plasmid vector
-add promoter region and terminator region to DNA fragment (for transcription)
-heat shock the membrane to make it more permeable
- same restriction endonuclease which cut DNA fragment is used to cut recognition site in plasmid to get complimentary sticky ends
- DNA ligase added to join strands together.
describe how you could determine the size of the different DNA fragments produced in gel electrophoresis/ nylon sheet
-compare the bands of DNA with those of a DNA ladder ( know DNA sizes)
