3.5 Flashcards

Question

explain how ATP is synthesised during oxidative phosphorylation

Answer 1

-electrons and H+ ions are donated to the electron transport chain (located in the inner mitochondrial membrane) from NADH and FADH2 (generated during glycolysis, the Krebbs cycle and the Link reaction) -energy is relesed as these electrons and protons flow along electron transport chain, which can be used to pump H+ ions from the mitochondrial matrix into the intermembrane space -creates a concentration gradient and a pH gradient -so H+ ions flow through ATP synthase enzymes embedded in the inner mitochondrial membrane -allows ADP and Pi to react to from ATP

Answer 2

final terminal acceptor without it, the electron transport chain will stop running, and ATP will no longer be produced by chemiosmosis.

Answer 3

-reduced NAD transfers its hydrogens to ethanal to form ethanol -pyruvate is decarboxylated to ethanal -produces CO2 -ethanal is reduced to ethanol by the enzyme alcohol dehydrogenase Ethanal is the hydrogen acceptor Ethanol cannot be further metabolised; it is a waste product

Answer 4

-reduced NAD transfers its hydrogens to pyruvate to form lactate -pyruvate is reduced to lactate by enzyme lactate dehydrogenase -lactate can be further metabolised -it can be oxidised back to pyruvate which is then channelled into the Krebs cycle for ATP production (requires extra oxygen / oxygen debt, which explains why animals breathe deeper/faster after exercise) -it can be converted into glycogen for storage in the liver

Answer 5

-originates from the Sun -absorbed by plants during photosynthesis and converted into chemical energy -becomes biomass

Answer 6

-in food webs from producers to consumers -flows in one way

Answer 7

tropic level -each stage of the food chain food chain -describes a feeding relationship between organisms at different trophic levels -shows direction of energy transfer food web -many food chains linked together -organisms typically do not rely on a single food producer -photosynthetic organisms -use light energy, water, CO2 and mineral ions to produce organic substances consumer -organisms that obtain their energy by feeding on other organisms -primary: consumers that eat producers -secondary: consumers that eat primary consumers -tertiary: consumers that eat secondary consumers -secondary/tertiary consumers tend to be predators saprobiont (decomposer) -organisms that break down decaying or dead material into simple materials -e.g. fungi/bacteria -includes valuable minerals/elements -can be absorbed by plants

Answer 8

-total mass of living material in a specific area at a given time The mass of living material of the organism or tissue The chemical energy that is stored within the organism or tissue -measured using dry mass per given area, in a given time -units: grains per square metre (g m^-2) if an area is sampled -grams per square metre (g m^-3 )if volume is sampled The dry mass of an organism or tissue (in a given area) The mass of carbon that an organism or tissue contains The mass of carbon that a sample (i.e. an organism or tissue) contains is generally taken to be 50% of the dry mass of the sample -chemical energy store in dry mass can be measured by calorimetry

Answer 9

Gross primary production (GPP) = rate at which plants are able to store chemical energy via photosynthesis -only about 1% of the light falling on a plant is used in photosynthesis to produce glucose -99% of the light either passes through the leaf without hitting chloroplasts, is reflected off of the leaf, or is transferred to heat energy -after that 1% is successfully absorbed and used to form glucose, the quantity of energy now stored in glucose is the gross primary production Units: J m^-2 or kJ km^-2 -if there are no primary producers present in this area of land, there will be no gross primary production) Aquatic environments: kg m-3 or kJ m-3 NPP = chemical energy that is leftover in a plant after respiratory loss is known as the net primary production NPP = GPP - R -NPP represents the energy that is available to organisms at higher trophic levels in the ecosystem -e.g. as primary consumers (herbivores and omnivores) and decomposers

Answer 10

proteins, nucleic acid, etc NO3- ions active transport from the soil to the roots

Answer 11

Importance: -shows how nitrogen is recycled in ecosystems -nitrogen needed for proteins and DNA/RNA -78% of the atmosphere is nitrogen gas -plants and animals cannot access gaseous nitrogen -because they can’t break triple bond between nitrogen atoms -hence rely on certain bacteria to convert N2 (g) into nitrates, which can be taken up by plants -also shows how nitrogen in the nitrogen-containing compounds is then passed between trophic levels or between living organisms and the non-living environment The role of bacteria in the nitrogen cycle Nitrogen fixation: -carried out by nitrogen-fixing bacteria such as Rhizobium -bacteria convert nitrogen gas from atmosphere into ammonia, which forms ammonium ions (in solution) that can then be used by plants -nitrogen-fixing bacteria are found inside root nodules of leguminous plants (e.g. peas, beans and clover) -bacteria have a symbiotic (mutually beneficial) relationship with these plants -bacteria provide plants with nitrogen-containing compounds -plants provide the bacteria with organic compounds e.g. carbohydrates Ammonification: -nitrogen compounds in waste products (e.g. urine/faeces) and dead organisms are converted into ammonia -by saprobionts (type of decomposer including some fungi and bacteria) -ammonia forms ammonium ions in soil Nitrification: (aerobic) -ammonium ions in soil are converted by nitrifying bacteria (e.g. Nitrosomonas) into nitrites -different nitrifying bacteria (e.g. Nitrobacter) then convert these nitrites into nitrates -can be used by plants Denitrification: (anaerobic, in waterlogged soil) -produces nitrogen gas, which returns to the atmosphere -denitrifying bacteria use nitrates in the soil during respiration

Answer 12

-shows how phosphorus is recycled in ecosystems -phosphorus needed for: -phospholipids (cell membranes) -nucleic acids (DNA and RNA) -ATP Process: -phosphorus in rocks is slowly released into soil and water sources in the form of phosphate ions (PO₄³⁻) -done by the process of weathering (slow erosion of rocks over time) -PO₄³⁻ ions are taken up from soil by plants through their roots or absorbed from water by algae -PO₄³⁻ ions are transferred to consumers during feeding -saprobionts release PO₄³⁻ ions in waste products and dead organisms into soil/water during decomposition -can now be taken up and used once again by producers -may be trapped in sediments that, over very long geological time periods may turn into phosphorus-containing rock once again

Answer 13

-fungal associations between plants roots and beneficial fungi -increases SA for water and mineral absorption -acts as a sponge, holding water and minerals around the roots -makes plant more resistant to drought -also increases uptake of inorganic ions -mutualistic relationship with plants

Answer 14

Artificial fertilisers (e.g. ammonium nitrate) are inorganic. Artificial fertilisers are produced specifically for replacing nutrients. Natural fertilisers (e.g. composted food waste, manure) are organic. Natural fertilisers are taken from organic matter and used to replace nutrients. Eutrophication: -can happen when too much fertiliser is used -excess soluble nitrates and phosphates leach into water sources like ponds from the soil. -leads to the rapid growth of algae at the surface of the water source, sometimes called an 'algal bloom'. -algae then block light to plants and algae at lower depths. -these plants and algae die due to insufficient light for photosynthesis. -levels of aerobic saprobiontic bacteria increase as they decompose the dead plant material. -depletes oxygen levels in the water, results in the death of fish and other aquatic life, disrupting food webs. -anaerobic organisms increase in number, further decomposing dead material and releasing more nitrates and toxic wastes. Artificial fertilisers are particularly prone to leaching because their mineral nutrients dissolve easily in water, and are the main cause of eutrophication. The risk of eutrophication may also be increased with increased use of organic manures or animal slurry, human sewage, ploughing old grassland, or natural leaching. Fertilisers that are sprayed onto fields can leach through the soil or flow into ponds, rivers and lakes. Leaching is when water-soluble plant nutrients are lost from the soil. This causes a build up of nutrients in the water. algal overgrowth: plant death: Bacteria decompose the dead plants. As numbers of bacteria increase, the oxygen concentration in the water decreases. Fish and other organisms will now die because there is not enough oxygen.

3.5 Flashcards

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