Question

Euglena gracilis is a protist that has animal and plant-like characteristics. Because of its eyespot, Euglena exhibits phototaxis.
In an experiment, a culture of Euglena is placed in a petri dish and a piece of cardboard with a circle cut out of its center is placed over the petri dish, allowing light to enter only the center of the petri dish. After 30 minutes, the cardboard is removed and the culture is observed.
Which of these best describes the appearance of the Euglena culture after the 30 minutes?

• A. The petri dish has a uniform light green color indicating the Euglena culture have spread out across the dish.
• B. The petri dish has a concentrated dark green area where the circle was indicating that the Euglena culture moved toward the light source.
• C. The petri dish has a concentrated light green area where the circle was indicating that the Euglena culture moved away from the light source.
• D. The petri dish has a dark green ring around the perimeter of the petri dish indicating that the Euglena culture moved to the edges where the light was the strongest.

Answer 1

The correct option is A The petri dish has a uniform light green color indicating the Euglena culture have spread out across the dish.

$Euglena$ shows characteristics of a plant whenever sun light is avalible for photosynthesis so when the cardboard box with a hole in the center is placed on the petri dish the euglena will concentrate in the area where light is avalible.

So the correct option is 'The petry dish has a uniform light green color indicating the $Euglena$ culture have spread out across the dish'.