Question

Which of the following algae have a cup shaped chloroplast?
(A) Spirogyra
(B) Volvox
(C) Chlamydomonas
(D) Chlorella

Answer 1

Hint:
Algae are eukaryotic, autotrophic, chlorophyll containing thallophytes. They are classified based on the pigments present. Among all the algae, algae belonging to class Chlorophyceae, also known as green algae possess large chloroplast and into which, abundance of chlorophyll pigment is found. Chloroplasts are found in different shapes in different organisms of class Chlorophyceae.

Complete answer:
Algae are eukaryotic, autotrophic, chlorophyll containing thallophytes (plants). They may be freshwater or marine water living. Algae are classified on the basis of the pigments found. They are
(i) Chlorophyceae (green algae)
(ii) Phaeophyceae (brown algae)
(iii) Rhodophyceae (red algae)

Chloroplasts are abundantly present in organisms that belong to the class Chlorophyceae, hence the name green algae.
The genus Chlorophyceae consists of unicellular, colonial or filamentous algae. They are usually green in colour because of the pigments chlorophyll a and b. These pigments are found to be localised in definite chloroplasts. The chloroplasts (green plastids) may be disc-shaped, plate-like, girdle-shaped, reticulate, spiral or ribbon-shaped, cup-shaped in different species. Examples of green algae include Chlamydomonas, Volvox, Ulothrix, Spirogyra, Chara, etc.
Chlamydomonas possess cup-shaped chloroplast, whereas Ulothrix possess girdle-shaped chloroplast. Likewise, Spirogyra possess spiral shaped chloroplasts.

Hence the correct answer is OPTION(C)

Note: Remembering the examples under each class of algae is essential in answering these types of questions. Genus of Chlamydomonas has a single large cup-shaped chloroplast into which pyrenoids like structure are present. Under the same class, different species possess different shapes of chloroplast which are involved in a common process called photosynthesis.