Organisms Respond to Changes in Their Internal and External Environments | AQA A-Level Biology (7402)

Organisms Respond to Changes in Their Internal and External Environments

350 questions
28 subtopics
Paper 2, and available on Paper 3
Paper 2 and Paper 3

Organisms Respond to Changes in Their Internal and External Environments is examined on Papers 2 and 3 of AQA Biology, which draw on topics 5 to 8.

327 recall questions across 28 subtopics.

Sample questions from Organisms Respond to Changes in Their Internal and External Environments

Answer each one closed book first, then open the answer.

IAA, gravitropism and phototropism

How do low and high concentrations of IAA affect cell elongation in roots?

Show the answer
Low concentrations promote cell elongation in roots, while high concentrations inhibit it.
Rods, cones, colour vision and visual acuity

Define visual acuity.

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Visual acuity is the ability to distinguish between two points close together as separate points.
Depolarisation, action potentials and saltatory conduction

What happens to voltage-gated sodium channels during repolarisation?

Show the answer
They close.
Transmission at a cholinergic synapse

Describe what happens to acetylcholine after it is released into the synaptic cleft.

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It diffuses across the synaptic cleft and binds to specific receptors on the postsynaptic membrane.
Antagonistic muscle pairs and muscle fibre structure

How does an antagonistic muscle pair produce movement at a joint?

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One muscle contracts while the opposing muscle relaxes, pulling the bone in one direction; the roles reverse to produce movement in the opposite direction.
Slow twitch and fast twitch muscle fibres

What type of activity are slow twitch fibres best suited for?

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Endurance activities such as maintaining posture.
How insulin, glucagon and adrenaline act

What metabolic process does insulin promote by activating specific enzymes?

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Insulin activates enzymes that catalyse the conversion of glucose to glycogen (glycogenesis).
Osmoregulation, osmoreceptors and ADH

Which specific regions of the kidney does ADH target after travelling in the blood?

Show the answer
The distal convoluted tubule and collecting duct.

The 28 subtopics

One subtopic is one session. Work down the list.

Subtopic	What it covers	Questions
IAA, gravitropism and phototropism	Recall questions on why organisms respond to their environment, plant growth factors, how IAA affects cell elongation in roots and shoots, and how its redistribution causes gravitropism and phototropism.	15
Taxes, kineses, reflex arcs and choice chambers	Recall questions on taxes and kineses, the three-neurone reflex arc and why reflexes protect, and investigating woodlice or maggots with a choice chamber and the chi-squared test.	23
The Pacinian corpuscle and generator potentials	Recall questions on why receptors are specific to one stimulus, generator potentials, and how pressure deforms the lamellae of a Pacinian corpuscle to open stretch-mediated sodium ion channels.	14
Rods, cones, colour vision and visual acuity	Recall questions on the sensitivity and pigments of rods and cones, the three types of cone and colour vision, retinal convergence, visual acuity and where rods and cones lie in the retina.	21
The SAN, AVN, bundle of His and Purkyne tissue	Recall questions on myogenic heart muscle, how the sinoatrial node starts atrial systole, the delay at the atrioventricular node, and how the bundle of His and Purkyne tissue make the ventricles contract.	9
Chemoreceptors, baroreceptors and cardiac output	Recall questions on where chemoreceptors and baroreceptors are and what they detect, how the medulla changes heart rate through sympathetic and parasympathetic nerves, and cardiac output and stroke volume.	14
Motor neurone structure and the resting potential	Recall questions on the cell body, dendrites, axon, myelin sheath and nodes of Ranvier of a motor neurone, and how the sodium-potassium pump and membrane permeability set up the resting potential.	13
Depolarisation, action potentials and saltatory conduction	Recall questions on voltage-gated sodium and potassium channels in depolarisation and repolarisation, threshold, hyperpolarisation, the all-or-nothing principle, and conduction along non-myelinated and myelinated axons.	17
The refractory period and speed of conduction	Recall questions on the absolute and relative refractory periods and how they separate impulses, make them one-way and limit their frequency, and how myelination, axon diameter and temperature affect speed.	11
Synapse structure and the neuromuscular junction	Recall questions on the synaptic cleft, presynaptic and postsynaptic membranes, synaptic vesicles, mitochondria and receptor proteins, and the folded motor end plate of a neuromuscular junction.	11
Transmission at a cholinergic synapse	Recall questions on how an action potential opens calcium ion channels, how acetylcholine is released by exocytosis and binds its receptors, and how sodium ion entry triggers a new action potential.	8
Acetylcholinesterase, summation and inhibitory synapses	Recall questions on the breakdown and recycling of acetylcholine, why transmission is unidirectional, temporal and spatial summation, and how chloride ion channels at inhibitory synapses cause hyperpolarisation.	11
Neuromuscular junctions compared, agonists and antagonists	Recall questions on how a neuromuscular junction differs from a cholinergic synapse between neurones, and how agonist, antagonist and enzyme-inhibiting drugs change synaptic transmission.	8
Drug effects and potassium channels in hyperpolarisation	Recall questions on predicting the effects of drugs that block reuptake, block calcium channels or force neurotransmitter release, and how potassium ions leaving the postsynaptic cell cause hyperpolarisation.	8
Antagonistic muscle pairs and muscle fibre structure	Recall questions on how antagonistic pairs of muscles work against a skeleton to move a joint, fascicles, the multinucleate structure of muscle fibres, myofibrils and the sarcomere.	9
Sarcomere bands, actin, myosin and tropomyosin	Recall questions on the A-band, I-band and H-zone and how they change in contraction, the structure of myosin and actin filaments, tropomyosin, and the release of calcium ions.	12
The sliding filament cycle, ATP and phosphocreatine	Recall questions on how calcium ions move tropomyosin, cross-bridge formation, the power stroke and detachment, the roles of ATP in contraction and relaxation, and how phosphocreatine regenerates ATP.	14
Slow twitch and fast twitch muscle fibres	Recall questions on how slow and fast twitch fibres contract, why they differ in mitochondria, colour and energy stores, the activities each suits, and what happens to muscle when ATP runs out.	10
Control systems and why temperature, pH and glucose matter	Recall questions on homeostasis, the receptors, coordination centres and effectors of a control system, and why core temperature, blood pH and blood glucose concentration must stay within limits.	12
Negative and positive feedback	Recall questions on the stages of a negative feedback loop, why separate antagonistic mechanisms give finer control, why levels oscillate around a set point, and how positive feedback differs.	11
Glycogenesis, glycogenolysis and gluconeogenesis	Recall questions on how diet and exercise change blood glucose concentration, and when and from what the liver carries out glycogenesis, glycogenolysis and gluconeogenesis.	10
How insulin, glucagon and adrenaline act	Recall questions on how insulin binds its receptors and increases glucose uptake and glycogenesis, how glucagon acts on liver cells, and how adrenaline affects glycogen in liver and muscle.	8
The second messenger model, diabetes and the sugar debate	Recall questions on adenylate cyclase, cyclic AMP and protein kinase in the second messenger model, the causes and control of Type I and Type II diabetes, and the positions of health advisers and the food industry on sugar.	26
Glucose calibration curves and hormones affecting blood glucose	Recall questions on measuring glucose concentration with a colorimeter and a calibration curve, signal amplification by second messengers, and the effects of insulin, glucagon and adrenaline on blood glucose.	14
Osmoregulation, osmoreceptors and ADH	Recall questions on osmoregulation, osmoreceptors in the hypothalamus, where ADH is produced, stored and released, and how it makes the distal convoluted tubule and collecting duct more permeable to water.	10
Nephron structure and ultrafiltration	Recall questions on the Bowman's capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule and collecting duct, and how ultrafiltration in the glomerulus forms glomerular filtrate.	10
The proximal convoluted tubule and the loop of Henle	Recall questions on reabsorption of glucose and water in the proximal convoluted tubule and how its cells are adapted, and how the permeability of the two limbs of the loop of Henle concentrates the medulla.	12
The distal tubule, collecting duct and urine concentration	Recall questions on water reabsorption from the distal convoluted tubule and collecting duct, how high and low ADH levels change urine, loop of Henle length, and osmoregulation as negative feedback.	9

Organisms Respond to Changes in Their Internal and External Environments is 350 of the 1,977 questions in the guide.Get the guide, £8

How the guide is worked

Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.

Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.

Read the full method, the return schedule and the research behind it.