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Flashcards by ewelinaskula, updated more than 1 year ago
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Created by ewelinaskula
over 11 years ago
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| Question | Answer |
| The processes that occur in the electron transport chain are also known as oxidative phosphorylation. Suggest why this term is used | The movement of electrons along the chain is due to oxidation. The energy from electrons combines with inorganic phosphate and ADP to form ATP =phosphorylation |
| State one advantage of mitochondrial membrane being highly folded to form cristae to the electron transport chain | It provides large surface area for attachment of the coenzymes(NAD/FAD) and electron carriers that transfer the electrons along the chain |
| The oxygen taken up by organisms has an important role in aerobic respiration. Explain this role. | Oxygen is a final acceptor to the electrons and hydrogen ions(protons) in the electron transport chain. Without it the electrons would accumulate along the chain and respiration would cease |
| As part of which molecule does the oxygen taken in leave an organism after being respired | Water molecule |
| State 3 reasons for the small % of energy transferred at each trophic level | Some of the organism in not eaten; some parts are not digested and so are lost as faeces; some energy is lost as excretory material; some energy is lost as heat |
| Why most food chains rarely have more than 4 trophic levels | The proportion of energy transferred at each trophic level is small (less than 20%). After 4 trophic levels there is insufficient energy to support a large enough breeding population |
| Two advantages of using a pyramid of biomass rather than a pyramid of numbers when representing quantitative information on a food chain | In pyramid of no: no account is taken of size/the no of individuals of one species may be so great that it is impossible to represent them on the same scale as other species in the food chain |
| How pyramid of biomass for marine ecosystem may sometimes show producers (phytoplankton) with a smaller biomass than primary consumers(zooplankton) | At certain time of year zooplankton consume phytoplankton so rapidly that their biomass temporarily exceeds that of phytoplankton |
| Units to measure biomass | gm-2/ gm-3 |
| Net productivity (def) | Gross productivity - respiratory losses |
| Why productivity of an agricultural ecosystem is greater than that of a natural ecosystem | In an agricultural ecosystem additional energy is put in to remove other species, add fertilisers and pesticides. These reduce competition for light, water, co2, provide mineral ions, destroy pests and reduce disease. All these increase photosynthesis and hence productivity |
| What are the differences between the ways that energy is provided in a natural ecosystem and in an agricultural ecosystem | Natural ecosystem use only solar energy, agricultural Eco. use solar and additional energy from food and fossil fuels |
| How does rearing animals intensively in small covered enclosure increase their energy conversion rate | Movement is restricted so less energy is expended in muscle contractions/heat loss is reduced so less energy is expended maintaining body temp./the optimum amount and type of food for rapid growth can be provided/predators are excluded so no energy is lost to other organisms |
| Why keeping animals in the dark for longer periods might improve the energy-conversion rate | A longer dark period means more time is spent resting, less energy is expended, and more energy is converted into body mass |
| How many carbon molecules are there in a single molecule of pyruvate | 3 |
| What 2C molecule is pyruvate converted to during link reaction | AcetylCoA |
| In which part of the cell Krebs cycle takes place | Matrix of mitochondria |
| What are the biochemical outcomes of the LD reactions | - light energy is converted into chemical energy - the photolysis of water releases protons, electrons and oxygen gas - ATP and NADPH plus H+ are produced and available in the LI reactions where CO2 is reduced, forming triode sugar |
| Limits on the rate of photosynthesis | - temperature - light intensity and concentration of CO2 -compensation point - amount of light intensity on the light curve where the rate of photosynthesis exactly matches the rate of respiration. - greenhouse eliminate limiting factors - greenhouse provides CO2 for photosynthesis, conditions controlled so that the rate of photosynthesis is at max. |
| How much ATP is produced during aerobic respiration | - substrate-level phosphorylation; ATP produced by the direct transfer of a phosphate group of ADP from another reactive substance( occurs in presence or absence of oxygen) -oxidative phosphorylation- electrons are released of glycolysis, the link reaction and kerbs cycle. Electrons are accepted by coenzymes NAD and FAD which are reduced to NADH and FADH2. Ultimately those electrons are transferred to oxygen(final acceptor), transfer of electrons releases energy and ATP is produced (only in presence of oxygen) |
| How NAD is regenerated when muscle cell respire anaerobically | Oxidation of NADH transfers hydrogen atoms to pyruvate reducing it: -as result lactate is formed - pyruvate does not accumulate during glycolysis - NAD is regenerated and is available to accept more hydrogen atoms Regeneration of NAD is required if glycolysis is to continue. Without it glycolysis would stop. |
| How is NAD regenerated when yeast cells respire anaerobically | The carboxyl group of pyruvate is removed as co2 (decarboxylation catalysed by the enzyme decarboxylase) as result: - ethanal is formed Oxidation of NADH transfers hydrogen atoms to ethanal, reducing it: - ethanol is formed - pyruvate does not accumulate during glycolysis - NAD is regenerated and available to accept more hydrogen atoms |
| What is oxygen debt | The amount of oxygen required to metabolise excess lactate |
| The role of acetyl CoA in aerobic respiration | 2 carbon molecule that combines with a 4 C molecule oxaloacetate, producing a 6C molecule citrate, formation of acetyl CoA couples glycolysis with the Krebs cycle : link reaction |
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| Why are there a limited number of trophic levels in an ecological pyramid and links in a food chain | The number of trophic levels are links in a food chain is limited by the food energy available. As amount of food energy passing from one trophic level to the next decreases, so does the amount of living material that can be supported in each trophic level. When food energy dwindles to zero, trophic levels and links in food chains can no longer exist. |
| Why is pyramid of energy the best way of representing feeding relationships between organisms in different trophic levels. | Pyramids of numbers and biomass represent feeding relationships at a particular time. A pyramid of energy represents feeding relationships over a period of time. In other words, it takes account of rate of production and consumption of biomass and deals with problems of -difference in size of organisms - seasonal variations of biomass -the rapid turnover of small organisms relative to the consumer that depends on them |
| Eutrophication | Consequence of an increase in nutrients, especially nitrates and phosphates, that often leads to a decease in biodiversity (ponds, lakes) |
| Eutrophication causes: | *Aerobic bacteria decompose organic wastes- poisonous substances(ammonia) are released into solution *oxygen in solution is used up- fish and other wildlife living in the water die because of poisoning and lack of oxygen *anaerobic bacteria continue the breakdown of the organic wastes - water supports only those organisms able to survive when the concentration of oxygen in solution is low. - biodiversity reduced |
| Evolution is sometimes defined as a result of changes in the frequency of particular alleles. Explain the definition in terms of natural selection |
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| Summarise the different stages of photosynthesis | Light harvesting- light energy captured by chlorophyll and other light absorbing pigments LD reaction- captured light energy -splits water into H+ ions and oxygen- photolysis -is converted into the bond energy of ATP- photophosphorylation LI reaction H+ions released by photolysis combine with CO2 reducing it. Triose sugar formed |
| How structure of chloroplast maximises a rate of reaction | -chlorophyll and other light absorbing pigments cover the thylakoid membrane of each granum, their large surface maximises the capture of light |
| Carotenoids | A group of compounds which are also accessory pigments. Range in colours from pale yellow, orange to deep red. The accessory pigments absorb light at wavelengths different from those absorbed by chlorophyll a The energy of most of the spectrum of visible light blue-red is made available from photosynthesis. |
| Difference between non-cyclic/ cyclic photophosphorylation | In LD reaction Non-cyclic -its reactions follow a linear pathway Cyclic- electrons are recycled |
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