Biology Easter Revision

What is ACTH?
A hormone secreted by the pituitary gland in response to stress. It triggers the release of steroidal hormones e.g.cortisol from the cortex of the adrenal gland
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What must be activated for adrenaline to be released from the medulla of the adrenal gland?
The sympathetic nervous system.
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What is glycogenolysis?
The conversion of glycogen to glucose.
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Why do erector pili muscles contract in response to stress?
To make the hairs stand on end so the animal looks bigger.
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What are baroreceptors?
pressure receptors in the aorta and the vena cava
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Where are chemoreceptors invlolved in the stress response located?
the aorta, the carotid artery and in the medulla oblongata
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What happens when adrenaline binds to specific receptors in the heart?
the cardiac muscle contracts more frequently and with more force
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What is the sarcolema?
The cell membrane of muscle fibre cells
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What are Transverse (T) tubules and what is their role?
Inward folds in the sarcolema which spread electrical impulses throughout the sarcoplasm so they reach all parts of the muscle fibre.
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Where are calcium ions, needed for muscle contraction, released from?
The sarcoplasmic reticulum
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Which protein are thick myofilaments made of?
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Which protein are thin myofilaments made of?
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Describe an A band
A dark band that contain thick myosin filaments and some overlapping actin filaments
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Describe an I Band
A light band that contains thin actin filaments only
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What is a Z line?
The mark of the end of a sarcomere
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What is found in the H zone?
myosin filaments only
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What happens to each of the zones/bands during muscle contraction?
I band gets shorter, H zones get shorter, A bands stay the same length
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Where does the light-dependent stage of photosynthesis take place?
In the thylakoid membrane of the chloroplast
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What is the light energy absorbed by the photosystems used for?
making ATP from ADP+Pi (Photophosphorylation), making reduced NADP, splitting water into protons, electrons and oxygen (Photolysis)
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What does non-cyclic photophosphorylation produce?
ATP, reduced NADP and O2
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What does cyclic photophosphorylation produce?
ATP only
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Which type of neuron has short dendrites and a long dendron?
sensory neurones
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Which type of neuron has many short dendrites and one long axon?
Motor neurones
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Which type of neuron has many short dendrites and many short axons?
Intermediate (relay) neurones
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Which type of hormones are secreted by the adrenal cortex
Steroid-based hormones
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Which type of hormones are secreted by the adrenal medulla?
protein-based hormones
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How does the adrenal cortex increase blood volume and pressure?
it increases uptake of Na+ and H2O by the kidneys
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What does the hepatic vein do?
Takes the deoxygenated blood away from the liver
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What does the hepatic portal vein do?
Birngs blood from small intestine which is rich in digestion products.
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What do Kupferr cells do?
Remove bacteria and break down old RBC
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What do hepatocytes do?
break down harmful substances onto less harmful substances which reenter the blood
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What are sinusoids?
Capillaries in the liver lobule
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What are canaliculi?
tubes in the bile duct.
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Why is the efferent arteriole smaller than the afferent arteriole?
so that the blood in the glomerulus is under high pressure
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Which parts of the nephron are involved in osmoregulation?
Loop of henle, DCT and collecting duct
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Which pancreatic cells secrete glucagon?
alpha cells
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Which pancreatic cells secrete insulin?
beta cells
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Name an important auxin
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What is the apical bud?
The shoot tip at the top of a flowering plant
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What do auxins encourage?
Apical dominance- they stimulate the growth of the apical bud whilst inhibiting the growth of side shoots and lateral buds
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Why is apical dominance important?
1) saves energy 2) allows plants to grow tall very fast- past the samller plants to reach the sunlight
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Why do side shoots start to form near the bottom of really tall plants?
because auxins are produced in the apical bud and so become less concentrated the further from the apical bud you are
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What do gibberellins stimulate?
Seed germination, stem elongation, side shoot formation, flowering
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How do giberellins differ to auxins?
They don't inhibit plant growth in any way
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How go gibberellins promote seed germination?
they trigger the breakdown of starch into glucose. The plant embryo can then use the glucose to begin respiring and release the energy it needs to grow
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What hormone inhibits giberellin?
Abscicic acid
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Describe the machanism of leaf loss.
A layer of cells called the abscission layer develops at bottom of leaf stalk. Ethene stimulates the cells in the abscission layer to expand breaking the cell walls and causing the leaf to fall off.
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Why is ethene used for fruit production?
It stimulates the breakdown of cell walls, breakdown of chlorophyll and conversion of starch into sugars
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List the commercial uses of auxin
Selective weedkillers, rooting powder
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Describe the mechanism of stomatal closure.
ABA binds to receptors on guard cell membrane. Ion channels open so Ca2+ can enter cytosol from vacuole. increased [Ca2+] causes other ion channels to open and ions leave guard cells. Water follows, guard cells become flaccid-stomata close.
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What neurotransmitter to parasympathetic neurones release?
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The hypothalamus produces hormones which control the...?
Pituitary gland
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What does the medulla oblongata automatically control?
Breathing rate and heart rate.
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What is the function of the cerebrum?
It allows you to see, hear, learn and think
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What are the functions of the cerebellum?
Muscle coordination, posture and coordination of balance
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What does the standard deviation measure?
The amount of spread from the mean.
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Why is working out the standard deviation better than just working out the range?
The standard deviation is a better measure of spread as it is less affected by extreme values
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How far do error bars on a graph extend?
One standard deviation above and below the mean.
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Where does the Calvin Cycle take place?
The stroma of the chloroplast
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How many carbons does ribulose bisphosphate have?
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What is the role of the RuBisCo enzyme?
To catalyse the reaction between RuBP and carbon dioxide
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How is glycerate-3-phosphate converted into triose phosphate?
It is converted using the energy from the light-dependent reaction. Also requires hydrogen ions from the reduced NADP from the light dependent reaction.
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Why does the Calvin cycle need to turn 6 times in order for one hexose sugar to be made?
Because 5 out of every 6 molecules of TP are used to regenerate RuBP
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How are lipids synthesised from the products of the calvin cycle?
Made using glycerol which is synthesised from TP and fatty acids which are synthesised from GP
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In total how many ATP and reduced NADP are needed to produce 1 hexose sugar?
18 ATP and 12 reduced NADP
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Why do plants look green?
Because they absorb the red and blue wavelengths of light but reflect green.
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Other than denaturing of enzymes, what are the four other factors which may cause the rate of photosynthesis to drop dramatically at very high temperatures.
Stomatal closure to avoid water loss, damage to thylakoid membranes lowering no. of sites available for e- transfer, damage to chloroplast membrane- enzymes released into the cell, chlorophyll damaged reduce amount of pigment to abosrb light energy
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Why can water stress also reduce the rate of photosynthesis?
Stomata close to conserve water, but then carbon dioxide can't enter
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Briefly describe glycolysis.
The splitting of one molecule of glucose (6C) into two smaller molecules of pyruvate (3C)
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What happens to the two pyruvate molecules after glycolysis?
They are actively transported into the mitochondria for the Link Reaction
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During which stage of respiration is no ATP produced?
the Link reaction
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What happens during the link reaction?
Pyruvate is decarboxylated, NAD is reduced by collecting the hydrogen from pyruvate to turn it into acetate. Acetate is combined with coenzyme A to from acetyl CoA
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What is the purpose of the Chi-squared test?
To allow you to see whether your results are likely to be due to chance or not.
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What is a transgenic organism?
An organism that has been genetically engineered to inlcude a gene from a different species.
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What two forms can vectors come as?
plasmids and bacteriophages (viruses that infect bacteria)
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What two forms can vectors come as?
plasmids and bacteriophages (viruses that infect bacteria)
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Why must the vector DNA be cut with the same restrcition enzymes as used to isolate the DNA fragment containing the desired gene?
to ensure that the sticky ends are complementary.
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Describe the process of ligation.
The vector DNA and DNA fragment are mixed togehter with DNA ligase, which joins up the sugar phosphate backbones of the two bits
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Define tidal volume
The volume of air breathed in and out in each normal breath
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What is a normal tidal volume for an adult?
0.4dm cubed
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What two things can antigens be made of?
Either proteins or polysaccharides
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What is vegetative propogation?
The production of plant clones from non-reproductive tissues e.g. roots and leaves
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What are Rhizomes, and name a plant that propogates using Rhizomes.
they're stem structures that grow horizontally underground away from the parent plant. New shoots and roots develop from nodes. e.g. Bamboo
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What is another word for a runner?
A stolon
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What means to elm trees use to propogate themselves?
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Name a popular type of leaf cutting.
Split vein cutting
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What are the arguments FOR artificial plant cloning?
Desirable genetic characteristics passed on, plants can be grown in any season, less space is required using tissue culture than traditional growing methods
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What are the arguments AGAINST artificial plant cloning?
No genetic variation- all susceptible to same diseases, production costs are high, needs training of skilled workers, contamination may result in complete loss of plant.
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Other cards in this set

Card 2


What must be activated for adrenaline to be released from the medulla of the adrenal gland?


The sympathetic nervous system.

Card 3


What is glycogenolysis?


Preview of the front of card 3

Card 4


Why do erector pili muscles contract in response to stress?


Preview of the front of card 4

Card 5


What are baroreceptors?


Preview of the front of card 5
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