Question

Which protist group/class best fits the following description: Autotroph with flagella that can cause bioluminescence or red tides in the ocean.

Select one:

a. Euglenozoans

b. Diatoms

c. Dinoflagellates

d. Ciliates

Answer 1

Correct option C.

Dinoflagellates.

These organisms are mostly marine and photosynthetic. They appear yellow, brown, or red depending on pigments present in their cells. Most of them have two flagella one lies longitudinally and the other transversely in a furrow between the wall plates. The flagella produce spinning movement, sothese protists are called whirling whips. Some marine dinoflagellates like Noctiluca show bioluminescence. Very often red dinoflagellates like gonyaulax undergo such rapid multiplication that they make the sea appear red. Toxins released by such large numbers may even kill other marine animals such as fish.

Incorrect options.

Option A

Euglenazones. These are fresh water organisms, They have two flagella but could not exhibits bioluminescence. It consists of photosensitive stigma or eye spot on the membrane of the reservoir. Thought they are photosynthetic in the prasence of sun light, when deprived of sunlight they behave like heterotrophs by predating on other small organisms.

Option B.

Diatoms:

These are chrysophytes these are found in fresh water as well as in marine environment . Most of them photosynthetic. They could not exhibit bioluminescence and absence of flagella.

Option D

Ciliates:

These are aquatic, actively moving organisms because presence of thousands of cillia. They have a cavity that opens to the outside of the cell surface. Which are not exhibit bioluminescence and also absence of flagella.