Question

Reticulate chloroplast occur in
a) Ulothrix
b) Oedogonium
c) Spirogyra
d) Chlamydomonas

Answer 1

Hint: Oedogonium has meshwork like chloroplast, Ulothrix has band-shaped chloroplast, Spirogyra has spiral-shaped chloroplast while Chlamydomonas has cup-shaped chloroplast.

Complete answer: Green algae are fascinating organisms. Apart from the variety found in their thallus organizations, ranging from single-celled to colonies, they present a variety of shapes of chloroplasts in their cells.

The chloroplast is a characteristic feature of green algae or Chlorophyceae. A chloroplast is a double membrane-bound structure, primarily involved in the process of photosynthesis and storage of starch. They contain the green pigment called chlorophyll present in the thylakoid membranes that occur in two to six bands per chloroplast. Thylakoids are not free. The glucose is stored in the form of starch, just like higher plants. The starch is stored in the chloroplasts of green algae in special structures called pyrenoids. The pyrenoids are made up of layers of starch.

There are following shapes of chloroplasts that are most notably present in different species of green algae:

>Cup-shaped as in Chlamydomonas, Volvox
>Discoid as in Vaucheria, Chara
>Girdle shaped or band-shaped in Ulothrix
>Reticulate shaped or meshwork-like as in Oedogonium
>Spiral shaped as in Spirogyra
>Stellate or star-shaped as in Zygnema

Therefore, the correct answer is option B.

Note: In red algae, the thylakoids of chloroplasts are not bound. They are freely present in the stroma of the chloroplast.
>In higher plants, the chloroplast follows the only discoid shape. The variety of shapes as seen in green algae is not seen in higher plants like gymnosperms and angiosperms.