Topic 4: Bioenergetics Flashcards
(36 cards)
What is the word equation for photosynthesis?
Carbon dioxide + water → glucose + oxygen
What is the chemical symbol equation for photosynthesis?
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Why is photosynthesis described as an endothermic reaction?
Because it takes in energy from the surroundings in the form of sunlight.
How does temperature affect the rate of photosynthesis?
As temperature increases, so does the rate—up to a point. Too high and enzymes denature, slowing it down.
How does light intensity affect the rate of photosynthesis?
Higher light intensity increases the rate, but only up to a certain point where another factor becomes limiting (graph becomes plateaued).
How does carbon dioxide concentration affect photosynthesis?
More CO₂ increases the rate, until the plant reaches a maximum where CO₂ is no longer the limiting factor.
How does the amount of chlorophyll affect photosynthesis?
Less chlorophyll means less light is absorbed, reducing the rate of photosynthesis.
What is the inverse square law?
Light intensity is inversely proportional to the square of the distance from the light source (1/d²).
Why are limiting factors important in the economics of greenhouses?
Because controlling them (e.g. light, CO₂, temperature) maximises yield while keeping costs low.
How do you investigate the effect of light intensity on photosynthesis using pondweed?
Place pondweed in water under a light source and count oxygen bubbles produced at different distances.
What is the independent variable in the pondweed light intensity experiment?
The distance of the light from the plant (light intensity).
What is the dependent variable in the pondweed light intensity experiment?
The number of oxygen bubbles produced (rate of photosynthesis).
What are the control variables in the pondweed experiment?
Temperature, CO₂ levels, type/size of pondweed, volume of water.
Why does decreasing light intensity result in fewer oxygen bubbles?
Less light means less energy for photosynthesis, so less oxygen is produced.
How do plants use glucose for respiration?
Glucose provides energy for cellular processes through respiration.
How do plants store glucose?
As insoluble starch for long-term storage. Plant can break it down into glucose when photosynthesis isn’t happening (night/winter).
How do plants use glucose to make other substances?
To produce fats for storage, cellulose for cell walls, and amino acids for protein.
What do plants need to make proteins from glucose?
Nitrate ions from the soil, combined with glucose to form amino acids (proteins).
What is the word equation for aerobic respiration?
Glucose + oxygen → carbon dioxide + water
What is the chemical symbol equation for aerobic respiration?
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
Why is aerobic respiration an exothermic reaction?
It releases energy for the body to use.
What is the energy from respiration used for in the body?
Muscle contraction, maintaining body temperature, building larger molecules from smaller ones (eg. combining amino acids to form proteins).
What is the word equation for anaerobic respiration in muscles?
Glucose → lactic acid
What are the key differences between aerobic and anaerobic respiration in muscles?
Aerobic uses oxygen and releases more energy; anaerobic does not use oxygen and produces lactic acid.
