The human body keeps its internal temperature at about 37 ∘C37\ ^\circ\text{C}37 ∘C.
A student investigates the effect of temperature on the activity of an enzyme from the human body. She measures the time taken for the reaction to finish at different temperatures.
The Table shows her results.
Table
| Temperature in ∘C^\circ\text{C}∘C | Time taken for the reaction to finish in s\text{s}s |
|---|---|
| 20 | 200 |
| 30 | 100 |
| 37 | 50 |
| 45 | 125 |
| 55 | no reaction |
Give the temperature at which the enzyme works fastest.
Use the Table.
Calculate the rate of reaction at 30 ∘C30\ ^\circ\text{C}30 ∘C.
Use the equation: rate=1time\text{rate} = \dfrac{1}{\text{time}}rate=time1
Explain why there was no reaction at 55 ∘C55\ ^\circ\text{C}55 ∘C.
Use the results to explain why it is important for the body to keep a constant internal temperature.
The internal environment of the body can be changed by internal changes and by external changes.
Give one example of an internal change and one example of an external change.
72 exam-style questions on OCR GCSE Biology 3.3 Maintaining internal environments, covering 3.3.1 Importance of a constant internal environment, 3.3.2 The skin and body temperature, 3.3.3 Insulin and blood sugar, 3.3.4 Glucagon and blood sugar, 3.3.5 Type 1 and type 2 diabetes, 3.3.6 Osmotic changes in body fluids, 3.3.7 Kidneys and water balance, 3.3.8 Structure of the kidney and tubule, 3.3.9 ADH and kidney tubule permeability, and 3.3.10 Responses to temperature and osmotic challenges. Each one has a worked solution and a mark scheme showing where the marks go.