12. Respiration Flashcards
(12 cards)
State the uses of energy in living organisms
- Muscle contraction
- Protein synthesis
- Cell division (to make new cells)
- Growth
- Active transport across cell membranes
- Generation of nerve impulses
- Maintaining a constant internal body temperature
Investigate the effect of
temperature on respiration in yeast
- Respiration in yeast: Add methylene blue dye to a suspension of living yeast cells in a test tube. Time taken for the dye to discolour is a measure of the rate of respiration of the yeast cells in the suspension
- Apparatus: Yeast suspension, glucose solution, test tubes, stopwatch, methylene blue, temperature-controlled water bath(s)
- Variables:
- Independent: Temperature
- Dependent: The rate of respiration (in yeasts)
- Controlled: Volume/concentration of dye added and yeast suspension, concentration of glucose, pH - Plot a graph: With ‘temperature’ (x-axis) against ‘time for colour change’ (y-axis). And convert ‘time for colour change’ into a unit of reaction rate
Describe the effect of
temperature on respiration in yeast
- As temperature increases in a solution: Molecules gain kinetic energy, moving around more. This results in more frequent enzymes and substrates (involved in respiration of cells) collisions with each other
- As temperature reaches above a certain point: Rate of respiration decreases in yeasts cells. Because enzymes (in respiration) begin to denature; altering the shape of their active site, unable to form enzyme-substrate complexes
Describe aerobic respiration
The chemical reactions in cells that use oxygen to break down nutrient molecules to release energy
State the word equation for aerobic respiration
Glucose + Oxygen → Carbon Dioxide + Water
State the balanced chemical equation for aerobic respiration
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
Describe anaerobic respiration
The chemical reactions in cells that break down nutrient molecules to release energy without using oxygen
State the word equation for anaerobic respiration in yeast
glucose → alcohol + carbon dioxide
State the balanced chemical equation for anaerobic respiration in yeast
C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂
State the word equation for anaerobic respiration in muscles during vigorous exercise
glucose → lactic acid
State what causes the oxygen debt
Lactic acid builds up in muscles and blood during vigorous exercise causing an oxygen debt
Outline how the oxygen debt is removed after exercise
- Continuation of fast heart rate: Lactic acid is transported from muscle cells, into the blood and to the liver
- Continuation of deeper and faster breathing: Larger amount of oxygen is taken into the blood for the aerobic respiration of lactic acid
- Aerobic respiration of lactic acid in the liver: Lactic acid is oxidised and CO₂ + H₂O is produced as a waste product
