Unit 3 // AOS2 Textbook definitions Flashcards
The definitions of specific words that come directly from the textbook
Photoautotroph
An organism capable of undertaking photosynthesis
Photosynthesis
The process of capturing light energy to power the production of glucose and oxygen from carbon dioxide and water
Mesophyll cell
A plant cell type found in leaves that contain large amounts of chloroplasts
Chloroplast
A membrane-bound organelle only found in plant and photoautotroph cells that is the site of photosynthesis
Stoma (pl. stomata)
A small pore on the leaf’s surface that opens and closes to regulate gas exchange
Xylem
Vascular tissue in plants responsible for transporting water and minerals from the roots to the leaves
Light-dependent stage
The first stage of photosynthesis, where light energy splits water molecules into oxygen and hydrogen inside the thylakoid membranes
Thylakoid
A flattened sac-like structure housed inside the chloroplast. Each thylakoid is made up of chlorophyll-containing membrane enclosing a lumen. Thylakoids are the location of the light-dependent stage of photosynthesis
Granum (pl. grana)
A stack of thylakoids
NADPH
A coenzyme that is a proton (H+) and electron carrier in photosynthesis
Photolysis
The process in which molecules are broken down by the action of light
Light-independent stage
The second stage of photosynthesis where carbon dioxide is used to form glucose in the stroma of a chloroplast. Also known as Calvin Cycle
Stroma
The fluid substance that makes up the interior of chloroplasts. It is the site of the light-independent stage of photosynthesis
Rubisco
A pivotal enzyme involved in initial carbon fixation during the light-independent stage of photosynthesis
Carbon fixation
The process in living organisms where inorganic carbon, typically within carbon dioxide, is converted into organic compounds such as glucose. Carbon fixation is a central part of the light-independent stage of photosynthesis
Inorganic compound
A compound that does not contain a carbon-hydrogen bond, e.g. carbon dioxide
Organic compound
A compound containing a carbon-hydrogen bond, e.g. glucose
Photorespiration
A wasteful process in plants initiated by Rubisco that limits photosynthesis
Affinity
The tendency of a molecule/atom to bind or react with another molecule/atom
C3 plants
Plants with no evolved adaptation to minimise photosynthesis
Mesophyll cell
A plant cell type found in leaves that contain large amounts of chloroplasts
C4 plants
Plants that minimise photorespiration by separating initial carbon fixation and the remainder of the Calvin Cycle over space
Bundle-sheath cell
A plant cell type that is the site of most of the Calvin Cycle in C4 plants
CAM plants
Plants that minimise photorespiration by separating initial carbon fixation and the remainder of the Calvin Cycle over time
Rate (Factors affecting Photosynthesis)
The speed at which a chemical reaction proceeds
Plateau
To reach a state where no further change occurs
Saturation point
The point at which a substance (e.g. an enzyme) cannot receive more of another substance (e.g. a substrate)
Limiting factor
A factor that prevents the rate of reaction from increasing
Limiting reagent
A reactant that prevents the rate of reaction from increasing
Cellular respiration
The process by which cells create usable energy in the form of ATP from a series of biochemical reactions, involving the breakdown of glucose
Glucose
A simple 6-carbon sugar molecule with the formula C6H12O6
Aerobic cellular respiration
Cellular respiration that occurs in the presence of oxygen. Involves three stages, during which glucose and O2 are converted into ATP, CO2 and water
Anaerobic fermentation
A metabolic pathway that occurs in the absence of oxygen. Involves glycolysis, followed by further reactions that convert pyruvate into lactic acid in animals, or ethanol and CO2 in yeast
Glycolysis
The first stage of aerobic cellular respiration in which glucose is converted to two pyruvate molecules
Krebs cycle
The second stage of aerobic cellular respiration, where multiple reactions occur to create ATP, NADH, FADH2, and the waste product CO2.
Electron transport chain
The third stage of aerobic cellular respiration, in which a series of protein complexes embedded in the inner membrane of a mitochondrion harness the stored energy in NADH and FADH2 to generate large amounts of ATP
Cytosol
The aqueous fluid that surrounds a cell’s organelles inside the plasma membrane
Mitochondrial matrix
The space inside the inner membrane of a mitochondrion. The site of the Krebs cycle
Crista (pl. cristae)
The folds of the inner membrane of a mitochondrion. The site of the electron transport chain
Pyruvate
A three-carbon molecule that can be formed from the breakdown of glucose via glycolysis
Nicotinamide adenine dinucleotide (NAD)
A coenzyme that acts as a proton (H+) and electron carrier in cellular respiration. NAD can cycle between its NAD+ and NADH forms, depending on the reaction it takes part in
Flavin adenine dinucleotide (FAD)
A coenzyme that acts as a proton (H+) and electron carrier in cellular respiration. FAD can cycle between its FAD and FADH2 forms, depending on the reaction it takes part in
Coenzyme A
A large organic non-protein molecule that plays a key role in the modification of pyruvate to allow it to enter the Krebs cycle. Also known as CoA
Acetyl-CoA
The product of the link reaction where pyruvate is conjugated to coenzyme A, creating the primary input into the Krebs cycle
ATP synthase
An enzyme in the inner mitochondrial membrane that uses the concentration gradient of H+ to synthesise ATP from ADP and Pi
Yeast
Unicellular eukaryotic organisms from the kingdom Fungi
Lactic acid fermentation
The process of anaerobic fermentation in animals, where pyruvate produced via glycolysis is converted to a lactic acid
Lactic acid
A 3-carbon molecule that is the product of anaerobic fermentation in animals. Also known as lactate
Ethanol
A 2-carbon alcohol molecule that is produced along with carbon dioxide during anaerobic fermentation in yeast, bacteria and plants
Ethanol fermentation
The process of anaerobic fermentation in yeasts, where pyruvate produced via glycolysis is converted to ethanol and carbon dioxide. Also known as alcohol fermentation
Fossil fuel
Fuel that formed over tens of millions of years from the remains of dead organic material. Fossil fuels are considered non-renewable
Non-renewable
Refers to a resource that is replenished at a slower rate than it is being used, meaning that it will eventually run out
Biofuel
Fuel that is created from organic material known as biomass
Biomass
Organic material, including plants, animal by-products, and biological waste material. Biomass can be sourced from many industries, including farming, forestry and food manufacturing
Renewable
Refers to a resource that can typically be replenished at the same (or faster) rate than it is being used, meaning it is unlikely to run out
Carbon neutral
A state in which there is no net release of carbon dioxide into the atmosphere, meaning that there is a balance between the amount of CO2 that is emitted during combustion of a fuel and how much was originally absorbed during the formation process of that fuel
Fermentation
The anaerobic chemical breakdown of high energy organic molecules, typically via the action of enzymes. For many plants, fermentation involves the conversion of glucose to ethanol and carbon dioxide
Bioethanol
A type of biofuel that is produced via the anaerobic fermentation of plants such as sugarcane or corn
Hydrolysis
A chemical reaction in which water is used to break down the chemical bonds of a substance
Food vs fuel debate
A central concern of large-scale biofuel manufacturing that questions the validity of using arable farmland to produce fuel, rather than food
First-generation biofuels
Biofuels produced from edible food crops such as corn or sugarcane. These compete directly with agricultural land
Second-generation biofuels
Biofuels produced from non-edible crops such as agricultural and forestry residues and municipal waste. These typically compete less with agricultural land
