Bioenergetics
Photosynthesis
Photosynthesis:
- Photosynthesis is a chemical reaction that occurs in the green chloroplasts of plants. Limiting factors
It needs light from the Sun. Aerobic respiration
- Energy has to be absorbed to make the photosynthesis reaction occur, so it is
Anaerobic respiration
endothermic.
Carbon Dioxide + Water à Glucose + Oxygen Exercise
6CO₂ + 6H₂O à C₆H₁₂O₆ + 6O₂ metabolism
- The carbon dioxide required for photosynthesis comes from the air. It enters the
leaves through the stomata. Water enters the plant through the roots and is transported to the leaves
in the xylem.
Limiting Factors:
- A limiting factor is an environmental factor that limits the growth, abundance or
distribution of an organism.
- As the light intensity increases, so does the rate of photosynthesis until a certain point
where it plateaus..
- As the carbon dioxide concentration increases, so does the rate of photosynthesis until a
certain point where it plateaus.
- As the temperature increases so does the rate of photosynthesis because the molecules
have more kinetic energy and therefore collide more until it reaches the optimum
temperature. After the optimum temperature, the enzymes start to denature so the
rate of reaction slows down.
!
- 𝑙𝑖𝑔ℎ𝑡 𝑖𝑛𝑡𝑒𝑛𝑠𝑖𝑡𝑦 = ! "
Aerobic Respiration:
- Respiration is the chemical reaction that transfers energy from the chemical energy
store in glucose to another chemical energy store.
- It is an exothermic reaction
- As aerobic respiration occurs in the presence of oxygen, the molecule of glucose is completely broken
down, producing a high yield of ATP and also carbon dioxide and water. This reaction takes place in the
mitochondria, and cells with high energy demands will have large numbers of them.
Glucose + Oxygen à Carbon Dioxide + Water + (ATP)
C₆H₁₂O₆ + 6O₂ à 6CO₂ + 6H₂O + (ATP)
- ATP is the abbreviation for an energy store called Adenosine Triphosphate. During the chemical reaction
of respiration, the chemical energy stored in glucose is transferred to the energy store that is ATP. This
ATP will be broken down to release energy when it is needed by the organism for a range of activities,
including:
o Muscle contraction
o Active transport to move substances against their concentration gradient
o To synthesise larger molecules from smaller ones to make new cell materials.
Anaerobic Respiration:
- When you do strenuous exercise and your body can’t supply enough oxygen to your muscles, they start
doing anaerobic respiration as well as aerobic respiration.
Glucose à Lactic Acid + ATP
- Anaerobic respiration does not transfer as much energy as aerobic respiration. This is because glucose
isn’t fully oxidised.
1
Photosynthesis
Photosynthesis:
- Photosynthesis is a chemical reaction that occurs in the green chloroplasts of plants. Limiting factors
It needs light from the Sun. Aerobic respiration
- Energy has to be absorbed to make the photosynthesis reaction occur, so it is
Anaerobic respiration
endothermic.
Carbon Dioxide + Water à Glucose + Oxygen Exercise
6CO₂ + 6H₂O à C₆H₁₂O₆ + 6O₂ metabolism
- The carbon dioxide required for photosynthesis comes from the air. It enters the
leaves through the stomata. Water enters the plant through the roots and is transported to the leaves
in the xylem.
Limiting Factors:
- A limiting factor is an environmental factor that limits the growth, abundance or
distribution of an organism.
- As the light intensity increases, so does the rate of photosynthesis until a certain point
where it plateaus..
- As the carbon dioxide concentration increases, so does the rate of photosynthesis until a
certain point where it plateaus.
- As the temperature increases so does the rate of photosynthesis because the molecules
have more kinetic energy and therefore collide more until it reaches the optimum
temperature. After the optimum temperature, the enzymes start to denature so the
rate of reaction slows down.
!
- 𝑙𝑖𝑔ℎ𝑡 𝑖𝑛𝑡𝑒𝑛𝑠𝑖𝑡𝑦 = ! "
Aerobic Respiration:
- Respiration is the chemical reaction that transfers energy from the chemical energy
store in glucose to another chemical energy store.
- It is an exothermic reaction
- As aerobic respiration occurs in the presence of oxygen, the molecule of glucose is completely broken
down, producing a high yield of ATP and also carbon dioxide and water. This reaction takes place in the
mitochondria, and cells with high energy demands will have large numbers of them.
Glucose + Oxygen à Carbon Dioxide + Water + (ATP)
C₆H₁₂O₆ + 6O₂ à 6CO₂ + 6H₂O + (ATP)
- ATP is the abbreviation for an energy store called Adenosine Triphosphate. During the chemical reaction
of respiration, the chemical energy stored in glucose is transferred to the energy store that is ATP. This
ATP will be broken down to release energy when it is needed by the organism for a range of activities,
including:
o Muscle contraction
o Active transport to move substances against their concentration gradient
o To synthesise larger molecules from smaller ones to make new cell materials.
Anaerobic Respiration:
- When you do strenuous exercise and your body can’t supply enough oxygen to your muscles, they start
doing anaerobic respiration as well as aerobic respiration.
Glucose à Lactic Acid + ATP
- Anaerobic respiration does not transfer as much energy as aerobic respiration. This is because glucose
isn’t fully oxidised.
1
