AskSia

Plus

9. Evidence indicates that phototaxis is linked to the energy state of the cell....

Apr 11, 2024

9. Evidence indicates that phototaxis is linked to the energy state of the cell. When energy is low Chlamydomonas moves towards light, when it is high, it moves away from the light. Which of the following would cause Chlamydomonas to move towards light? 1. Incubation with an uncoupler. 2. Addition of acetate to the growth media. 3. Blocking pyruvate transport into mitochondria. 4. Increasing rubisco expression. A. 1, 2 and 3 B. 1 and 3 C. 2 and 4 D. 4 only E. All of 1, 2, 3 and 4 are correct

Answer

B. 1 and 3

Solution

Incubation with an uncoupler would cause Chlamydomonas to move towards light because uncouplers disrupt the proton gradient across the mitochondrial membrane, which is necessary for ATP synthesis. Without ATP, the cell's energy state is low, triggering phototaxis towards light

Blocking pyruvate transport into mitochondria would also cause Chlamydomonas to move towards light because it would prevent pyruvate from being used in the Krebs cycle to generate ATP, thus lowering the cell's energy state

Addition of acetate to the growth media and increasing rubisco expression would not necessarily cause Chlamydomonas to move towards light, as these actions can contribute to energy production and thus increase the energy state of the cell

Key Concept

Phototaxis in Chlamydomonas is influenced by the cell's energy state, with low energy triggering movement towards light.

Explanation

Chlamydomonas moves towards light when energy is low, which can be induced by disrupting ATP synthesis or energy production pathways, such as by using uncouplers or blocking pyruvate transport into mitochondria.