Question

A Euglena is a one celled organism with some very interesting features. One of these features is the presence of eyespots, which allow the euglena to detect light. When a one celled organism detects light and moves towards it, this is known as ____________.

Answer 1

When a one called organism detects light and moves towards it this is known as ......Flagellum

Answer 2

Answer: Positive phototaxis

Step-by-step explanation:

• Taxis is defined as the movement of organism under a stimulus. The stimulus can be light, food etc.

• Phototaxis is the movement of an organism when the stimulus is light. (Photo + taxis = light + taxis).

• Taxis is one of the many innate behavioural responses.

• There is a difference between tropism and taxis as tropism simply refers to a growth towards/away from the stimulus for e.g phototropism is shown by plants by growing towards the direction of sunlight. However, taxis is not growth but the movement towards/away from the stimulus .

• Phototaxis that is the movement when the stimulus is light is of two types:

1. Positive phototaxis - when an object move towards light. E.g euglena.

2. Negative phototaxis- when an object moves away from light. This is seen in insects such as cockroaches.