The diagram shows a simple respirometer used to measure the rate of respiration. Soda lime is used to absorb carbon dioxide.
Which way will the drop of liquid move if the organisms are respiring aerobically?
Correct Answer: \( \boxed{\mathbf{B}} \)
During aerobic respiration, the organisms continuously consume oxygen. The carbon dioxide produced is absorbed by the soda lime, reducing the total volume of gas inside the respirometer. This creates a lower pressure, causing the drop of liquid to move towards the organisms (left).
What occurs during the stages of respiration?
| Option | Stage of respiration | Decarboxylation | Reduced NAD produced |
|---|---|---|---|
| A | Glycolysis | No | No |
| B | Link reaction | Yes | No |
| C | Krebs cycle | Yes | Yes |
| D | Electron transport chain | No | Yes |
The diagram shows the chemical reaction that occurs during the last step of anaerobic respiration in human skeletal muscle cells. What is the purpose of this reaction?
Correct Answer: \( \boxed{\mathbf{A}} \)
During anaerobic respiration, pyruvate is reduced to lactate, regenerating NAD+ from reduced NAD. The regenerated NAD+ is required for glycolysis to continue producing ATP in the absence of oxygen. This allows the release of energy from glucose breakdown to continue even when oxygen is unavailable.
