respiration

• What is aerobic respiration?

  Aerobic respiration is the splitting of a respiratory substrate to release carbon dioxide as a waste product.
• What happens to hydrogen during aerobic respiration?

  Hydrogen is reunited with atmospheric oxygen, releasing a large amount of energy.
• What is anaerobic respiration?

  Anaerobic respiration occurs in the absence of oxygen.
• How is respiration characterized?

  Respiration is a multi-step process controlled and catalyzed by specific intracellular enzymes.
• What are the steps in respiration?

  1. Glycolysis
  2. Link Reaction
  3. Krebs Cycle
  4. Oxidative Phosphorylation
• Where does glycolysis take place?

  Glycolysis takes place in the cytoplasm of the cell.
• What are the products of glycolysis from one molecule of glucose?

  From one molecule of glucose, 2 molecules of ATP, 2 molecules of reduced NAD (NADH), and 2 molecules of pyruvate are formed.
• What happens to pyruvate in anaerobic respiration?

  In anaerobic respiration, pyruvate is further converted into lactate with the help of NADH.
• What is the role of lactate in the liver?

  Lactate is converted back to pyruvate in the liver.
• What occurs during the Link Reaction?

  In the Link Reaction, 2 molecules of pyruvate are transported into the mitochondria, where decarboxylase removes a molecule of CO2 and reduces NAD.
• What is formed from the acetate in the Link Reaction?

  The acetate formed combines with coenzyme A to form acetyl coenzyme A.
• How many molecules of acetyl coenzyme A are formed per glucose molecule in the Link Reaction?

  Per glucose molecule, 2 molecules of acetyl coenzyme A are formed.
• Where does the Krebs Cycle occur?

  The Krebs Cycle occurs in the matrix of the mitochondria.
• What is the starting molecule for the Krebs Cycle?

  The starting molecule for the Krebs Cycle is acetyl coenzyme A.
• How many times does the Krebs Cycle turn per molecule of glucose?

  The Krebs Cycle turns 2 times per molecule of glucose.
• What are the products of the Krebs Cycle per molecule of glucose?

  Per molecule of glucose, 2 ATP molecules, 6 NADH molecules, 2 FADH molecules, and 4 CO2 molecules are produced.
• What is the process of oxidative phosphorylation?

  1. Reduced NAD (NADH) binds to Complex I, releasing protons and electrons.
  2. Reduced FAD (FADH) binds to Complex II, releasing protons and electrons.
  3. Electrons are passed down a chain of protein complexes (Complex I to IV).
  4. Protons are pumped into the intermembrane space, creating a proton gradient.
  5. Protons move through ATP synthase to produce ATP.
• What is the final acceptor of electrons in oxidative phosphorylation?

  The final acceptor of electrons is oxygen.
• What is created when electrons combine with protons and oxygen in oxidative phosphorylation?

  Water is formed when electrons combine with protons and oxygen.
• What does the proton gradient created in oxidative phosphorylation do?

  The proton gradient provides energy for ATP synthase to produce ATP.
• What is an ecosystem composed of?

  • All organisms living in a particular area (community)
  • All non-living elements of that environment
• What factors control the distribution and abundance of organisms in a habitat?

  The distribution and abundance of organisms are controlled by biotic factors (living) and abiotic factors (non-living).
• What is the role of a species in its habitat called?

  The role of a species in its habitat is called its niche.
• What is the source of all energy in ecosystems?

  The Sun is the source of all energy in ecosystems.
• What are autotrophs?

  Autotrophs are organisms that produce their own food.
• What are heterotrophs?

  Heterotrophs are organisms that cannot synthesize their own food.
• What percentage of chemical food energy is passed on between organisms in the food chain?

  Only around 10% of chemical food energy is passed on between organisms in the food chain.
• What are the ways energy is lost in the food chain?

  • Uneaten parts (e.g., bones)
  • Decay of dead material (e.g., bacteria)
  • Excretion (energy lost in faeces)
  • Exothermic reactions (heat lost in respiration)
• What is the formula for calculating percentage efficiency of energy transfer?

  Percentage efficiency = (energy transferred / total energy) x 100
• How is biomass measured?

  Biomass can be measured in terms of mass of carbon or dry mass of tissue per given area per given time.
• How can the chemical energy stored in dry biomass be estimated?

  The chemical energy stored in dry biomass can be estimated using calorimetry.
• What is net primary productivity (NPP)?

  NPP is the rate at which energy is transferred into organic molecules that make up new plant biomass after respiratory losses.
• What is gross primary productivity (GPP)?

  GPP is the rate at which energy is incorporated into organic molecules in plants during photosynthesis.
• What is the relationship between NPP and GPP?

  NPP = GPP - R, where R represents respiratory losses.
• What is the net production of consumers (N) calculated by?

  N = I - (F + R), where I is the energy in ingested food, F is energy lost in faeces, and R is respiratory losses.
• What are the stages of the nitrogen cycle?

  1. Ammonification
  2. Nitrification
  3. Denitrification
  4. Nitrogen fixation
• What occurs during ammonification?

  During ammonification, microbes break down organic matter to ammonia in a two-stage process.
• What is nitrification?

  Nitrification is the process where nitrifying bacteria convert ammonia to nitrate ions in an oxidation reaction.
• What happens during denitrification?

  During denitrification, nitrate ions are converted to nitrogen gas by denitrifying bacteria.
• What is nitrogen fixation?

  Nitrogen fixation is the process where nitrogen gas is fixed into other compounds by nitrogen-fixing bacteria.