Question

Which one of the following statements is wrong.
a. Agar-agar is obtained from Gelidium and Gracilaria
b. Laminaria and Sargassum are used as a food
c. Algae increase the level of dissolved oxygen in the immediate environment
d. Algin is obtained from red algae and Carrageenan from brown algae

Answer 1

Algae is an aquatic organism that is capable of doing photosynthesis. There are different kinds of algae producing different substances. Such as green algae, brown algae, red algae, yellow-green algae, and golden algae.

Complete answer:
- Algin is obtained from brown algae and carrageenan is obtained from red algae.
- Carrageenan is present in red seaweeds. It is used to thicken a variety of foods, ice cream, salad dressings, chocolate milk, and jellies.
- Algin is present in brown seaweeds. It is a carbohydrate. It is used in the formation of various medicines.
- Algin is used to reduce the cholesterol levels and also decreases the levels of heavy chemicals such as barium, zinc, tin, mercury, cadmium which are taken up by the body.
- Agar-agar is a gelling agent with the unbranched polysaccharide. It is used in microbiology to solidify agents of liquid culture medium.
- Agar-agar is obtained from the red algae cell wall mostly from the species Gelidium and Gracilaria
- Laminaria and Sargassum both are the brown algae and they are cultivated as a crop.
- Algae are photosynthetic species which releases the oxygen in the environment by the photosynthesis.

Hence, the correct answer is option (D).

Additional information:
- The cell wall of brown algae is made up of the inner cellulose and outer gelatinous layer which has algin that is used as a stabilizer and an emulsifying agent.
- Red algae color is red due to the presence of phycoerythrin pigment. For example, carrageenans.
- Brown algae are brown due to the presence of pigment fucoxanthin. For example, algin.
- Algin and carrageenan are the carbohydrates.
- Algin is used to thicken moisturizers.

Note: Algae is an aquatic organism which is cultivated as a crop also such as Laminaria and Sargassum. It is a large and diverse group of photosynthetic organisms. They vary from unicellular to multicellular. They also differ in colors such as green algae, brown algae, red algae, yellow-green algae, and golden algae. Reproduction is from asexual to sexual reproduction. Diatoms are the unicellular algae. Agar is a gelatinous substance that has many industrial uses. Algae is also used as a source of energy.