Topic 5 - Energy Transfers In and Between Organisms Flashcards
Acetyl coenzyme A
A two-carbon molecule formed in the link reaction when acetate reacts with coenzyme A. It is oxidised in the Krebs cycle.
Andenosine Triphosphate (ATP).
Universal energy carrier found in all living cells.
Aerobic Respiration
A form of cellular respiration that takes place in the presence of oxygen and produces carbon dioxide, water and ATP. It involves four main stages: glycolysis, link reaction, krebs cycle and oxidative phosphorylation.
Equation:
- C6H12O6 + 602 —-> 6CO2 + 6H2O
Ammonification
The production of ammonia when saprobiontic microorganisms feed onorganic nitrogen-containing compounds. Ammonium ions are formed and added to the soil.
Anaerobic respiration
A form of cellular respiration that takes place in the absence of oxygen. In animals, lactate is produced. In plants and microorganisms, ethanol and carbon
dioxide are produced. Less ATP is formed than in aerobic respiration.
Artificial fertilisers
Man-made compounds generally containing nitrogen, phosphorus and potassium that are used to increase the mineral content of soils.
ATP Synthase
Man-made compounds generally containing nitrogen, phosphorus and
potassium that are used to increase the mineral content of soils.
Biomass
The total mass of organic material, measured in a specific area over a set time
period. This can be calculated in terms of dry mass or mass of carbon per given area.
Calorimetry
A technique used to estimate the chemical energy store in dry biomass.
Carnivores
Animals that prey on and eat other animals. They can be secondary or tertiary
consumers.
Chemiosmotic theory
The synthesis of ATP through the movement of protons down their
concentration gradient across a semi-permeable membrane, catalysed by ATP synthase.
Chlorophyll
A photosynthetic pigment located in the thylakoids of chloroplasts that absorbs light energy and becomes ionised.
Coenzymes
Molecules that help enzymes carry out their function e.g. NAD, FAD, NADP.
Consumers
Organisms that feed on other organisms to obtain energy.
Denitrification
The conversion of nitrate ions to nitrogen gas by denitrifying bacteria.
Denitrifying bacteria
Anaerobic microorganisms found in waterlogged soils responsible for the reduction of nitrate ions to nitrogen gas.
Ecosystem
The community of organisms (biotic) and non-living (abiotic) components of an
area and their interactions.
Efficiency of energy transfer
The efficiency of energy transfer between trophic levels is calculated using:
percentage efficiency = (energy available after transfer/ energy available before transfer) x 100
Electron acceptor
Oxygen acts as the final electron acceptor in the electron transfer chain:
½O2 + 2e- + 2H+ ⟶ H2O
Electron transfer chain
A series of electron carrier proteins that transfer electrons in a
chain of oxidation-reduction reactions.
Eutrophication
When a body of water becomes excessively rich with nutrients (often from
fertilisers).
FAD
A carrier molecule that becomes reduced when it takes up protons and electrons
during the Krebs cycle, forming reduced FAD.
Food chain
Describes the feeding relationships between organisms and the resultant stages of biomass transfer. It takes the form:
producer ⟶ primary consumer ⟶ secondary consumer ⟶ tertiary consumer
Food web
The interconnection of many different food chains in a habitat.
Glycerate 3-phosphate (GP)
A three-carbon molecule which is reduced by reduced NADP in the light-independent stage of photosynthesis to form two molecules of triose phosphate
(TP). This requires ATP.
Glycolysis
The first stage of aerobic and anaerobic respiration that takes place in the cytosol of the cell and breaks down glucose into two molecules of pyruvate. Two molecules of ATP and two molecules of reduced NAD are also formed.
Gross primary production (GDP)
The total amount of chemical energy stored in plant
biomass in a set area or volume.
Herbivores
Animals that eat plants, also known as primary consumers.
Krebs cycle
A series of oxidation-reduction reactions in the matrix of the mitochondria in
which acetyl coenzyme A is oxidised generating reduced NAD, reduced FAD, ATP and
carbon dioxide.
Leaching
The loss of nutrients from the soil due to rainwater.
Light-dependent reaction
The second stage of photosynthesis that uses light energy to
produce ATP, reduced NADP and oxygen (by-product). It takes place in the thylakoids of the chloroplast.
Light-independent reaction
The second stage of photosynthesis that uses light energy to
produce ATP, reduced NADP and oxygen (by-product). It takes place in the thylakoids of the chloroplast.
Limiting factor
A variable that limits the rate of a particular reaction.
Link reaction
The second stage of aerobic respiration that takes place in the mitochondrial matrix and converts pyruvate into acetyl coenzyme A and carbon dioxide. Reduced NAD is also formed. Overall:
Pyruvate + NAD + CoA ⟶ acetyl CoA + reduced NAD + CO2
Mycorrhizae
Mutualistic associations between some species of fungi and the roots of many
plants that retain water and minerals around the roots.
NAD
A carrier molecule that becomes reduced when it takes up protons and electrons
during aerobic respiration, forming reduced NAD.
NADP
A carrier molecule that becomes reduced when it takes up protons and electrons
during the light-dependent stage of photosynthesis, forming reduced NADP.
Natural fertilisers
Dead and decaying organic matter used to increase the mineral content
of soils.
Net primary productivity (NPP)
The chemical energy store that remains when energy losses due to respiration are subtracted from the total energy store. This is used in plant
growth or reproduction and is also available to other trophic levels.
Net primary production (NPP) = gross primary production (GPP) - respiratory losses (R)
Net production of consumers (N)
Calculated by subtracting the chemical energy lost dueto respiration (R) and as a result of excretion and egestion (F) from the chemical energy stored in ingested food (l).
N = I - (F + R)
Nitrification
The conversion of ammonium ions to nitrate ions by nitrifying bacteria. This takes place in two stages:
- ammonium ions are oxidised to nitrite ions
- nitrite ions are
oxidised to nitrate ions.
Nitrifying bacteria
Aerobic microorganisms found in the soil responsible for the oxidation of ammonium ions to nitrate ions.
Nitrogen cycle
The cycle through which nitrogen moves between living organisms and the environment, involving ammonification, nitrification, nitrogen fixation and denitrification.
Nitrogen fixation
The conversion of atmospheric nitrogen gas into nitrogen-containing compounds by nitrogen-fixing bacteria in the soil or root nodules of legumes.
Nitrogen-fixing bacteria
Microorganisms responsible for the conversion of atmospheric
nitrogen gas into nitrogen-containing compounds. They can be free-living or mutualistic.
Oxidation
The loss of electrons, gain of oxygen or loss of hydrogen in a substance.
Oxidative phosphorylation
The synthesis of ATP from reduced coenzymes and oxygen in the electron transfer chain of aerobic respiration.
Phosphorus cycle
The cycle through which phosphorus (in the form of phosphate ions) moves between living organisms and the environment. This involves absorption by plants, feeding, digestion and excretion by animals, sedimentation and erosion of rocks and the decay of guano, bones and shells.
Photoionsation
The process by which a molecule of chlorophyll is ionised. A chlorophyll molecule absorbs light energy causing a pair of electrons within it to become excited, raised to a higher energy level, and leave the molecule.
Photolysis
The splitting of a molecule of water in the presence of light that occurs during
the light-dependent stage of photosynthesis. This produces protons, electrons and oxygen:
H2O ⟶ 2H+ + 2e- + ½O2
Photosynthesis
A complex metabolic pathway that consists of three main stages:
- capturing of light energy
- light-dependent reaction
- light-independent reaction.
Overall, in the presence of light:
6CO2 + 6H2O ⟶ C6H12O6 + 6O2
Primary productivity
The rate of primary production; the energy fixed by photosynthesis in a given area in a given period of time (kJ ha-1 year-1).
Producers
Photosynthetic organisms at the start of the food chain that manufacture biomass (using light energy, carbon dioxide, water and mineral ions) for all living things.
Pyruvate
A three-carbon molecule produced in glycolysis. In aerobic respiration, pyruvate is oxidised to acetate in the link reaction. In anaerobic respiration it is converted to lactate (animals) or ethanol and carbon dioxide (plants and microorganisms).
Reduction
The gain of electrons, loss of oxygen or gain of hydrogen in a substance.
Ribuse Biphosphate (RuBP)
A five-carbon compound which reacts with carbon dioxide in the light-independent stage of photosynthesis to form two molecules of glycerate 3-phosphate (GP).
Rubisco
An enzyme that catalyses the reaction of RuBP and carbon dioxide in the light-independent stage of photosynthesis.
Saprobionts
Microorganisms that break down dead plant and animal material into simpler organic matter to obtain nutrients. Also known as saprophytes.
Secondary productivity
The rate of secondary production; the rate at which animals convert the chemical energy in plants they eat into their own biomass in a given area in a given period of time (kJ ha-1 year-1).
Substrate-level phosphorylation
The synthesis of ATP by the transfer of a phosphate group from a phosphorylated intermediate to ADP.
Triose phosphate (TP)
A three-carbon compound formed in the light-independent stage of photosynthesis that may be converted into useful organic substances or used to regenerate ribulose bisphosphate (RuBP).
Trophic level
The position of an organism in a food chain
