The reactions that build and break down molecules in cells, the liver's job with lactic acid, and measuring respiration rate with a respirometer.
What you will learn
- Define metabolism and give examples of building and breaking down reactions
- Describe what happens to lactic acid in the liver (Higher)
- Explain how a respirometer works
- Calculate oxygen uptake per minute and per gram
All the reactions in a cell
Metabolism is the sum of all the reactions in a cell or the body.
Enzymes control them, and the energy comes from respiration.
- glucose → starch (plants), glycogen (animals) or cellulose (plant cell walls)
- one glycerol + three fatty acids → a lipid
- glucose + nitrate ions → amino acids, then amino acids → proteins
- respiration breaks glucose down
- excess amino acids are broken down, and urea is made to be excreted
Higher: lactic acid from muscles is carried in the blood to the liver and converted back into glucose.
The rest of this lesson and its 10 practice questions are locked.
In this lesson
- All the reactions in a cell
- A respirometer
- Try it: From distance to volume
10 practice questions, marked as you go; about 20 minutes in all.
Key terms
Metabolism, Liver
In this unit: Bioenergetics: photosynthesis and respiration
Photosynthesis and its rate, limiting factors and the pondweed practical, aerobic and anaerobic respiration, exercise and metabolism.