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170 Cards in this Set
- Front
- Back
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what is photoionisation |
when light energy is absorbed by chlorophyll in the photosystems. The electrons in the chlorophyll are given more energy and eventually leave the molecule the chlorophyll is now a positively charged ion. |
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How is some of the energy from released electrons conserved |
the production of ATP from ADP and phosphate the reduction of NADP to NADPr |
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What is chemiosomotic theory |
the movement of released electrons through the electron carriers which in turn transport H+ ions from the stroma into the thylakoid. The H+ ions move down the concentration gradient and travel through the ATP synthase which then catalyses the production of ATP |
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what is photolysis and what are the products of the photolysis of water |
the break down of a compound by light energy H2O → 2H+ + 0.5O2 + 2e- |
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What is the function of the Light dependent reaction |
to produce ATP and NADPr for the light-dependent reaction |
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outline the reaction catalysed by rubisco |
ribulose bisphosphate and carbon dioxide to form two molecules of glycerate 3-phosphate |
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What does glycerate 3-phosphate converted into using which molecules |
2 molecules of GP using 2ATP and 2NADPr to form 2 molecules of triose phosphate |
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what proportion of triose phosphate is regenerated into RuBP |
5 out of 6 |
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how many turns of the calvin cycle produce one hexose sugar |
6 |
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what are the three potential organic substances produced from the calvin cycle |
carbohydrates lipids- glycerol produce from TP and fatty acids from GP Amino acids- GP |
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What is the pigment found in photosytem I and what is its adsorption rate |
chlorophyll A 700nm |
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what is the pigment found in photosytem II and what is its adsorption rate |
chlorophyll B 680nm |
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what are the 4 limiting factors of photosynthesis |
Light intensity (of a certain wavelength) temperature carbon dioxide at 0.04% water |
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what is the purpose of respiration |
to produce ATP |
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What is the first stage of reparation both anaerobic and aerobic |
glycolysis |
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where does gylcolysis occur and is it an anaerobic or aerobic process |
in the cytoplasm anaerobic |
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what are the two stages of glycolysis |
phosphorylation and oxidation |
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outline phosphoryltion in glycolysis |
glucose is phosphorylated using a phosphate from an ATP producing glucose phosphate and ADP. glucose phosphate is then phosphorylated too by ATP forming hexose biphosphate. Hexose biphosphate is unstable so collapses to form 2 molecules of triose phosphate. |
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outline oxidation in glycolysis |
Triose phosphate loses a H+ ion to form pyruvate. NAD collects the H+ ion to form NADr this reaction forms two ATP per TP |
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If respiration is purely anaerobic, what happens to the pyruvate produced through glycolysis in plants and yeast |
pyruvate →ethanal → ethanol |
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If respiration is purely anaerobic, what happens to the pyruvate produced through glycolysis in animals and some bacteria
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pyruvate →lactate |
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how is alcoholic and lactate fermentation useful for respiration |
the oxidised NAD produced can be used in further glycolysis and therefore more ATP is produced |
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how does pyruvate move from the cytoplasm to the mitochondrial matrix |
by active transport |
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outline the link reaction |
pyruvate from glycolysis is decarboxylated simultaneously the pyruvate is oxidised ( producing NADr) this forms acetate. The acetate then reacts with acetyl coenzyme A. |
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How many link reactions occur per glucose molecule |
Two pyruvate molecules form from one glucose so the link reaction occurs twice |
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outline how acetyl CoA enters the Krebs cycle |
Acetylcoenzyme A reacts with a 4C compound to form a 6C compound coenzyme A is released. |
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What happens to the 6C compound in the krebs cycle |
decarboxylation occurs and dehydrogenation also occurs which produces NADr. The product is a 5C compound |
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how is the 4C formed from the 5C |
decarboxylaton occurs 2 NADr are produced 1 FADr is produced and 1 ATP molecule |
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Outline oxidative phosphorylation |
Hydrogen atoms are released by NADr and FADr. The atoms split into H+ ions and electrons the electrons move down the electron carrier chain losing energy to the carriers this energy is used by the carriers to pump protons into the inter membrane spaces. chemiosmosis etc etc |
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what is a stimulus |
any change in the internal or external environment |
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what is a tactic response or taxis |
a directional response to a stimulus |
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what is a kinetic response or kinesis |
non directional movement in response to a stimulus |
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What are receptors and effectors |
receptors detect a specific stimuli effectors are cells which bring about a response e.g muscle cells |
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what are sensory, motor and relay neurones |
sensory- transmit electrical impulses from receptors to the CNS motor- transmit electrical impulses from the CNS to the effectors relay- transmit impulses between sensory and motor neurones |
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What is a simple reflex |
a rapid involuntary response to a stimulus |
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Why do we have simple reflexes |
quicker so we avoid damage to the body e.g burns |
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what is a reflex arc |
a sensory, neurone a relay neurone and a motor neurone |
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What is a tropism |
a response by a plant to a directional stimulus |
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What is Phototropism and what role does indoleactic acid play in it. |
response to light moves to the more shaded part of the shoot/root in shoots this elongates the cell in roots this inhibits growth |
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what is gravitropism and what role does indoleactic acid play in it |
response to gravity the IAA moves to the underside of the shoots/roots in shoots elongates the cells in roots inhibits growth |
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How does IAA move around the plant |
through diffusion and active transport over short distances, through the phloem over long. |
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What do pancinian corpscles detect |
they detect mechanical stimuli e.g pressure and vibrations |
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outline the structure of the pancinian corpuscle |
. |
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outline the production of a generator potential in a pancinian corpuscle |
the lamellae become deformed and press on the sensory nerve ending. This causes the sensory neurones membrane to stretch deforming the stretch mediated sodium ion channels so Na+ diffuse into the cell creating a generator potential |
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photoreceptors in the eye can be separated into rods and cones. which detect colour respond to colour |
cones |
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how are the differences in sensitivity to light of rods and cones explained
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many rods join one bipolar neurone so many weak generator potentials combine to trigger an action potential cones join one biopolar neurone so it takes more light to trigger an action potential |
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how are the differences in the sensitivity to colour of rods and cones explained
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rods and cones contain different optical pigments so therefore absorb different wavelengths of light
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explain the difference in visual acuity
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because many rods join one bipolar neurone so light from different rods cannot be distinguished one cone joins to one bipolar neurone so individual action potentials form cones can be detected |
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what does myogenic mean
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a muscle cell which can contract and relax without receiving signals from nerves
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what is and what is the role of the sinoatrial node
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a small mass of tissue on the wall of the right atrium. It sets the rhythm of the heartbeat by sending out regular waves of electrical activity so the right and left atria contract at the same time. |
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what prevents electrical activity produced by the SAN from stimulating the ventrical cells
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a band on non- conducting collagen tissue
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what is the atrioventricular node
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the node which receives an electrical impulse from the SAN and allows a short delay for the atria to empty before passing electrical activity onto the bundle of His.
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what is the bundle of His
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a group of muscle fibres that conducts the waves of electrical activity between the ventricles to the apex of the heart.
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what is the Purkyne tissue and how does it contract the heart muscles.
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the muscle fibers which split from the apex along the left and right ventricles. This causes contraction from the bottom up
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where are pressure receptors located
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the aorta and carotid arteries
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what are the pressure receptors response to high pressure and low pressure
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high pressure- impulses sent through neurones to the medulla, which sends impulses along the parasympathetic neurones. Ach is release which binds to receptors on SAN causing heart rate to slow down low pressure- same thing but noradrenaline is released |
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what are the chemoreceptors response to high blood O2 and low O2
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high conc- impulses sent through neurones to the medulla, which sends impulses along the parasympathetic neurones. Ach is release which binds to receptors on SAN causing heart rate to slow down to return conc down to normal
low conc- same thing but noradrenaline is released heart rate increases to increase conc. |
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in any ecosystem what do plants synthesise organic compounds from |
aquatic or atmospheric CO2 |
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what are most of the sugars synthesised by plants used for |
respiratory substrates |
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what are the sugars used for which are not consumed in respiration |
production of biological molecules which make up the biomass of the plant |
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name two ways the biomass of a plant can be measured |
mass of carbon the organism contains dry mass of tissue per given area per unit time |
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what is the process called to estimate the energy stored in dry biomass |
calorimetry |
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what is gross primary production |
the chemical energy store in plant biomass, in a given area or volume. |
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what is net primary production |
the chemical energy store in a plant biomass after respiratory losses to the environment have been taken into account |
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outline what NPP can be used for/by |
plant growth and reproduction, available to other trophic levels |
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what is the formula for net production of consumers |
N = I - F + R I chemical energy store in food F energy lost to the environment in poo and wee R respiratory losses |
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identify the role of saprobionts in decomposition |
undertake extracellular digestion by secreting enzymes to break down dead plants animals and their waster products. organic molecules are broken down into their inorganic ions |
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what is the role of mycorrhizae in nutrient cycles |
increase the surface area of plants roots system so there is an increase rate of water and ion uptake. |
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what is the role of bacteria in nitrogen fixation |
it turns atmospheric nitrogen into ammonia to form ammonium ions in solution that can be used by plants. the plants provide these bacteria with carbohydrates |
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what is the role of bacteria in ammonification |
when nitrogen compounds from dead organisms are turned into ammonia by saprobionts which then form ammonium ions. |
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outline the role of bacteria in nitrification |
nitrifying bacteria change ammonium ions into nitrites then other nitrifying bacteria change the nitrites into the nitrates |
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outline the role of bacteria in denitrification |
when nitrates in the soil are converted into nitrogen gas, occurs under anaerobic conditions. |
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what is leaching |
when water soluble compounds in the soil re washed away |
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what is eutrophication |
the rapid growth of algae, plants die from lack light, ammonification bacteria decrease oxygen conc so aquatic life dies |
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outline the structure of a myelinated neurone |
. |
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how is a resting membrane potential established
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there are more positive ions outside of the cell than in, so the membrane is polarised. the sodium potassium pumps use active transport to transport 3 Na+ ions out of the cell and 2 K+ ions into the cell the K+ ions then travel down the conc. gradient through carrier proteins.
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how is an action potential established
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when a neurone is stimulated sodium ion channels open and if enough open this cause a rapid change in potential difference and depolarisation occurs.
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what is the refractory period and why is it important
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when sodium an potassium ion channels cant be made to open again. this ensures action potentials form discrete impulses and have a limited frequency
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what is the all or nothing principle
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an action potential will not fire until a certain threshold of potential difference is met. the action potential is always the same change in voltage
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what are the three factors which affect the speed of conduction of action potentials
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myelintation axon diameter temperature |
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how does myelination affect conduction of action potentials
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the myelin sheath is an electrical insulator and called a Schwann cell. Depolarisation only occurs at at the nondes of ranvier and the impulse jumps form node to node. if nonmyelinated neurones the impulse travels the whole length of the axon membrane, which is slower.
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how does axon diameter affect conduction of action potentials
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there is less resistance to the flow of ions in larger cells than in the cytoplasm of smaller cells, with less resistance depolarisation reaches other parts of the neurone cell faster.
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how does temperature affect the conduction of action potentials
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the speed of conduction increases as the temperature increase because the ion diffuse faster
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outline the structure of a synaptic junction
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why are impulses at the synapse unidirectional
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only the post synaptic membrane has recpetors on It
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how is a nerve impulse transmitted across a cholinergic synapse
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the action potential arrives at the synaptic knob, this stimulatrs the voltage gated calcium ion channels to open. The influx of Ca2+ ions causes vesicles to fuse with the presynaptic membrane releasing acetylcholine into the synaptic cleft by exocytosis
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outline spatial summation
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two or more presynaptic neurones release neurotransmitters onto the same postsynaptic neurone, the small amount of neurotransmitter from the multiple neurones is enough to reach the threshold in the post synaptic neurone to trigger an action potential
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outline temporal summation
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where two or more nerve impulses arrive in quick succession from the same presynaptic neurone, this makes the action potential more likely because there is more neurotransmitter released
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outline the structure of a neuromuscular junction
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how doe the transmission across a neuromuscular junction differ from a synapse
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the post synaptic cleft has lost of folds which store AChE the post synaptic cleft has more receptors than other synapses when a motor neurone fires an action potential in normally triggers a response in a muscle cell |
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what happens at inhibitory synapses
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inhibitory neurotransmitters are released from the PrSN which hyper polarise the PoSN prevent it from firing an action potential
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What muscle is the agonist and which is the antagonist |
agonist- contacts antagonist- relaxes |
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what is found in A bands and I bands in sacromeres |
A - myosin and actin I - actin |
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what is the role of calcium ion in muscle contraction |
bind to a protein attached to tropomyosin which pulls the tropomyosin out of the actin-myosin binding site so actin-myosin cross bridges can be formed It also activates the enzyme ATP hydrolase |
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how is ATP used in muscle contraction |
the energy released causes the ATP head to bend back |
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outline the ATP-phosphocreatine system |
ADP + PCr → ATP + Cr (creatine) PCr runs out after a few seconds so is used in short bursts |
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What is the location and properties of slow twitch muscle fibres |
muscles used for posture good for endurance activitiesm release energy slowly through aerobic respiration. |
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what is the location and properties of fast twitch muscle fibres |
eyes legs etc. short bursts of speed and power, release energy through anaerobic respiration |
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What is homeostasis |
physiological control systems that maintain the internal environment within restricted limits |
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what is the maintenance of a stable core temperature important |
increased temperature increase kinetic energy so metabolic reactions happen faster if the temperature is too high hydrogen bonds break in enzymes tertiary structure denaturing it |
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what is the importance of maintaining a stable blood pH |
too high or too low the hydrogen and ionic bonds break denaturing the enzyme |
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why is it important to control glucose concentration |
enough glucose is needed to effectively respire. too high and the water potential is reduced leading to water being removed from the body |
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What is negative feedback |
when process' counteract the change in the internal environment to return levels to normal range |
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what is positive feedback |
mechanism which amplify a change |
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what are the two factors that influence blood glucose concentration |
diet- consumption of glucose exercise- glucose used in respiration |
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what is glycogenesis glycogenolysis gluconeogenesis and where does it take place |
glucose into glycogen glycogen into glucose glycerol or amino acids into glucose in the liver cells |
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how does insulin lower blood glucose levels
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it binds to the receptors on liver and muscle cells opening more channel proteins and also activates enzymes involved in glycogenesis, causing the cells to take up more glucose and respire more
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how does glucagon raise blood glucose levels
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binds to specific receptors on liver cells activating enzymes involved in glycogenolysis and glucongenesis
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how does adrenaline raise blood glucose levels
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binds to receptors on liver cells and activates enzymes involved in glycogenolysis
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what is the second messenger model
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adrenaline and glucogen bind to specific receptors on liver-cell membranes it activates and enzyme called adenylate cyclase, which then converts ATP into a second messenger called cyclic AMP . This then activates an enzyme called protein kinase A, which activates a cascade inside the cell resulting glycogenolysis
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what is type one diabetes and how is it treated
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the immune system attacks the Beta cells in the islets of Langerhans so they cant produce insulin it is treated with insulin therapy |
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what is type tow diabetes and how is it treated
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when the Beta cells cant produce enough insulin or when the bodys cells don't respond properly to insulin. changes to diet and exercise are needed and eventually insulin therapy |
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what is osmoregulation
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the control of water potential of the blood
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what is the role of the hypothalamus in osmoregulation
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it detects changes in water potential through osmoreceptors, these change in volume as water travels in/out of the cell
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what is the role of the posterior pituitary in osmoregulation
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the osmoreceptors send signals to the PPG wich then releases a hormone called antidiuretic hormone into the blood.
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what is the role of antidiuretic hormone In osmoregulation
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ADH bind to cells in the DCT, which causes aquaporins to be inserted into the membrane
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what Is the structure of a nephron
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what is the genotype of an organism
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the genetic constitution of an organism
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what is the phenotype of an organism
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the expression of the genotype and its interaction with the environment |
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what is a dominant, recessive and codominant allele
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recessive- charactersitics which only exist in the phenotype if two copies are present co dominant- when both alleles are expressed in the phenotype because neither one is recessive |
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what is epistasis |
when the expression of one genes prevents the expression of another |
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what is recessive and dominant epistasis |
two copies of the epistatic allele have to be present to mask the expression of another gene, whereas in dominant only one epistatic allele has to be present
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what is a population
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a group of organisms of the same species occupying a particular space at a particular time that can potentially interbreed
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what is the gene pool |
the complete range of alleles in a population |
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what are the conditions under which the hardy Weinberg principle applies
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a large population no movement of organisms into and out no mutations no natural selection random mating |
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what is the Hardy-Weinberg equation and what is its prediction |
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what are the two reasons for the range in phenotype in a population
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genetic and environmental factors
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what is the primary source of genetic variation and what are the other sources |
mutation meiosis and the random fertilisation of gametes |
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what is evolution
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the change in allele frequencies in a population over time
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what is the principle of natural selection based upon
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organisms with phenotypes providing selective advantages are likely to produce more offspring and pass on their favourable alleles to the next generation
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what is stabilising selection
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when individuals with in a population with alleles near the middle of the bell curve are more likely to survive reproduce and pass on their alleles
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what is the difference between directional and disruptive selection |
alleles are advantageous at either extreme of the distribution curve wereas in directional only one end of the curve is advantageous
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what is allopatric and sympatric speciation
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allopatric- when a geographical barrier seperates two populations sympatric- when random mutations create sexual separation |
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why is genetic drift only important in small populations
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in larger populations chance factors tend to even out across the whole population
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what is abiotic and biotic conditions |
abiotic- non-living part of an ecosystem biotic- living feature of an ecosystem |
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what is a niche |
the abiotic and biotic role a species has within an ecosystem |
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what is the carrying capacity of an ecosystem determined by |
the effect of abiotic factors interactions between organisms |
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what is interspecific and intraspecific competition |
inter- when organisms of the different species compete for the same resources intra- when organisms of the species compete for the same resources |
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for what type of organism populations are quadrats used to estimate their population size |
slow moving or non-motile |
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what assumptions are made when using mark-release capture |
the marked sample has enough time and opportunity to mix back in with the population the marking hasnt affected the individuals chances of survival there are no changes in population size over the time period |
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what is a pioneer species |
a species which is the first to colonise an area |
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why causes the stages in succession |
organisms change their abiotic conditions so it becomes more suitable for other organisms to live in |
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what is a climax community |
the largest and most complex community of plants and animals that an ecosystem can support |
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what is the purpose of conservation |
to preserve natural resources |
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name two times mutation to DNA can occur |
during DNA replication spontaneously |
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name the 6 types of mutation |
addition deletion substitution inversion duplication translocation |
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what is the affect of mutations |
polypeptide function due to changes in amino acid sequence |
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how can the types of mutations that can occur to the DNA be separated into two groups |
frame shifting and non frame shifting |
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what is a totipotent stem cell |
a stem cell which can divide and produce any type of body cell |
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how does cell specialisation occur in regards to totipotent cells |
totipotent cells only translate parts of their DNA |
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when are totipotent stem cells present |
only in the first few cell divisions in mammalian embryos |
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what can the pluripotent stem cells divide into |
any body cell apart from except placental cells |
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why are unipotent stem cells necessary for the regeneration of heart muscle cells |
cardiomyoctyes can't replicate themselves |
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what is the role of oestrogen in initiating gene expression |
oestrogen bind to an oestrogen receptor which forms a O-Or complex. the complex moves from the cytoplasm into the nucleus. it then binds to specific DNA sites the complex acts as a activator of transcription |
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define epigenetics |
Epigenetics involves inheritable changes in gene function without changes to their DNA base sequences
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outline the main characteristics of a benign tumour |
not cancerous covered in fibrous tissues to stop spread of tumour harmless but can put pressure on organs and cause blockages |
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outline the main characteristics of a malign tumour |
cancerous grow rapidly invade surrounding tissue spread through blood and lymphatic system |
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outline the role of suppressor genes and pro to oncogenes in the control of cell division |
suppressor genes slows cell division by producing a protein that stops cells or destroys them proto oncogenes stimulate cell division through production of proteins which make cells divide |
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who does oestrogen levels affect breast cancer |
causes cells to divide more so higher chance of mutations and quicker progression of tumours. |
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why is it difficult for scientists to convert an organisms genome into its proteome |
the presence of introns and regulatory genes |
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what does recombinant DNA technology involve |
the transfer of fragments of DNA from one organism, or species to another |
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describe 3 methods scientists can use to produce a fragment of DNA |
conversion of mRNA to DNA using reverse transcriptase using restriction enzymes to cut a fragment gene from DNA Using a gene machine |
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what is a DNA probe |
a short piece of DNA which is complementary to the base sequence of a certain allele. Also has a label attached e.g radioactive or fluorescent |
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explain variable number tandem repeats
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the genome consists of introns which can repeat next to each other again and again. The number of repeats varies from person to person, and so the probability of two people having the same VNTR is very low. |
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what is the formula for the circumference and area of a circle |
circumfrence = 2πr area = πr2 |
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what is the formula for the surface area and volume of a sphere |
SA = 4πr2
volume = 4/3 πr3 |
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outline what y = mx + c means |
c= Y interCept m= gradient |
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What statistical test would a scientist use if he wanted to compare the effectiveness of a new drug to a placebo and why |
student t because he's comparing two sets of data |
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what statistical test would a scientist use if he wanted to compare the observed phenotypic ratio to the expected one and why |
chi squared - grouped data to see if data is statistically different |
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What statistical test would a scientist use to work out the degree to which increased folic acid intake in pregnant mothers and instances of spina bifida |
spearmans rank |
