Algae - 3
1
Agar obtained from Gelidium and Gracilaria is used for which of the following purposes?
Practice
A
Only as a food source for aquatic animals
B
To grow microbes and in the preparation of ice-creams and jellies
C
To produce algin and carrageen
D
Only to increase dissolved oxygen in water
✅ Show Answer
✔ Correct Answer:
B
(To grow microbes and in the preparation of ice-creams and jellies)
💡 Explanation
Agar: Dictionary meaning — a jelly-like substance obtained from certain red algae and used as a solidifying or gelling agent.
Explanation — Agar is a useful commercial product obtained from certain red algae. It can form a gel and is therefore used in laboratories and food preparation.
Gelidium: Dictionary meaning — a genus of red algae from which agar is obtained.
Explanation — Species of Gelidium are important sources of agar, which is extracted from their algal bodies.
Gracilaria: Dictionary meaning — a genus of red algae that is an important source of agar.
Explanation — Species of Gracilaria are also used to obtain agar for commercial and laboratory purposes.
Grow microbes: Dictionary meaning — to allow microorganisms such as bacteria and fungi to multiply and develop.
Explanation — Agar is used in laboratories as a solid medium on which microbes can grow and be studied.
Ice-creams: Dictionary meaning — frozen sweet foods usually made from milk or cream and other ingredients.
Explanation — Agar can be used in the preparation of ice-creams because its gelling and stabilizing properties help improve the texture of the product.
Jellies: Dictionary meaning — soft, semi-solid foods that have a gel-like consistency.
Explanation — Agar is used in making jellies because it forms a firm gel when mixed with water and allowed to set.
Given Statement - Agar, one of the commercial products obtained from Gelidium and Gracilaria are used to grow microbes and in preparations of ice-creams and jellies.
Explanation — Agar is a useful commercial product obtained from certain red algae. It can form a gel and is therefore used in laboratories and food preparation.
Gelidium: Dictionary meaning — a genus of red algae from which agar is obtained.
Explanation — Species of Gelidium are important sources of agar, which is extracted from their algal bodies.
Gracilaria: Dictionary meaning — a genus of red algae that is an important source of agar.
Explanation — Species of Gracilaria are also used to obtain agar for commercial and laboratory purposes.
Grow microbes: Dictionary meaning — to allow microorganisms such as bacteria and fungi to multiply and develop.
Explanation — Agar is used in laboratories as a solid medium on which microbes can grow and be studied.
Ice-creams: Dictionary meaning — frozen sweet foods usually made from milk or cream and other ingredients.
Explanation — Agar can be used in the preparation of ice-creams because its gelling and stabilizing properties help improve the texture of the product.
Jellies: Dictionary meaning — soft, semi-solid foods that have a gel-like consistency.
Explanation — Agar is used in making jellies because it forms a firm gel when mixed with water and allowed to set.
Given Statement - Agar, one of the commercial products obtained from Gelidium and Gracilaria are used to grow microbes and in preparations of ice-creams and jellies.
🎯 Conclusion
Agar is a useful product obtained from red algae such as Gelidium and Gracilaria. It is used in laboratories to grow microbes and is also used to make foods such as ice-creams and jellies.
2
Which unicellular alga is rich in proteins and is used as a food supplement even by space travellers?
Practice
A
Chlorella
B
Gelidium
C
Gracilaria
D
Sargassum
✅ Show Answer
✔ Correct Answer:
A
(Chlorella)
💡 Explanation
Chlorella: Dictionary meaning — a genus of unicellular green algae that contains chlorophyll and is rich in proteins.
Explanation — Chlorella is a very small, single-celled green alga. It is rich in proteins and is therefore useful as a nutritional food supplement.
Unicellular: Dictionary meaning — consisting of only one cell.
Explanation — Chlorella consists of a single cell, and this one cell carries out all the basic life processes of the organism.
Alga: Dictionary meaning — a simple, usually aquatic, chlorophyll-bearing organism that can make its own food by photosynthesis.
Explanation — Chlorella is an alga because it contains chlorophyll and can prepare its own food through photosynthesis.
Rich in proteins: Dictionary meaning — containing a large or useful amount of proteins.
Explanation — Chlorella contains a high amount of protein, making it valuable as a source of nutrition.
Food supplement: Dictionary meaning — a substance taken in addition to normal food to provide extra nutrients.
Explanation — Chlorella can be used as a food supplement to provide additional nutrients, especially proteins.
Space travellers: Dictionary meaning — people who travel or work in outer space.
Explanation — Chlorella has been considered useful for space travellers because it is rich in nutrients and can serve as a compact food supplement.
Given Statement - Chlorella, a unicellular alga rich in proteins, is used as food supplement even by space travellers.
Explanation — Chlorella is a very small, single-celled green alga. It is rich in proteins and is therefore useful as a nutritional food supplement.
Unicellular: Dictionary meaning — consisting of only one cell.
Explanation — Chlorella consists of a single cell, and this one cell carries out all the basic life processes of the organism.
Alga: Dictionary meaning — a simple, usually aquatic, chlorophyll-bearing organism that can make its own food by photosynthesis.
Explanation — Chlorella is an alga because it contains chlorophyll and can prepare its own food through photosynthesis.
Rich in proteins: Dictionary meaning — containing a large or useful amount of proteins.
Explanation — Chlorella contains a high amount of protein, making it valuable as a source of nutrition.
Food supplement: Dictionary meaning — a substance taken in addition to normal food to provide extra nutrients.
Explanation — Chlorella can be used as a food supplement to provide additional nutrients, especially proteins.
Space travellers: Dictionary meaning — people who travel or work in outer space.
Explanation — Chlorella has been considered useful for space travellers because it is rich in nutrients and can serve as a compact food supplement.
Given Statement - Chlorella, a unicellular alga rich in proteins, is used as food supplement even by space travellers.
🎯 Conclusion
Chlorella is a tiny, single-celled alga that is rich in protein. Because it provides useful nutrition, it can be used as a food supplement, even for space travellers.
3
Into which three main classes are algae divided?
Practice
A
Chlorophyceae, Phaeophyceae and Rhodophyceae
B
Chlorophyceae, Bryophyceae and Rhodophyceae
C
Phaeophyceae, Gymnospermae and Angiospermae
D
Rhodophyceae, Pteridophyceae and Phaeophyceae
✅ Show Answer
✔ Correct Answer:
A
(Chlorophyceae, Phaeophyceae and Rhodophyceae)
💡 Explanation
Algae: Dictionary meaning — simple, chlorophyll-bearing organisms that are mostly aquatic and prepare their own food by photosynthesis.
Explanation — Algae are simple photosynthetic organisms that occur mainly in aquatic environments and show different forms and characteristics.
Three main classes: Dictionary meaning — three major groups into which organisms are classified based on their characteristics.
Explanation — Algae are traditionally divided into three main classes based on features such as pigments, stored food and body structure.
Chlorophyceae: Dictionary meaning — the class of green algae, commonly called green algae.
Explanation — Members of Chlorophyceae are commonly green because chlorophyll is the major photosynthetic pigment. Examples include Chlamydomonas, Volvox, Ulothrix and Spirogyra.
Phaeophyceae: Dictionary meaning — the class of brown algae, commonly called brown algae.
Explanation — Members of Phaeophyceae are generally brown because of the presence of the pigment fucoxanthin. Examples include Laminaria and Sargassum.
Rhodophyceae: Dictionary meaning — the class of red algae, commonly called red algae.
Explanation — Members of Rhodophyceae are generally red because of pigments such as phycoerythrin. Examples include Porphyra, Gelidium and Gracilaria.
Given Statement - The algae are divided into three main classes: Chlorophyceae, Phaeophyceae and Rhodophyceae.
Explanation — Algae are simple photosynthetic organisms that occur mainly in aquatic environments and show different forms and characteristics.
Three main classes: Dictionary meaning — three major groups into which organisms are classified based on their characteristics.
Explanation — Algae are traditionally divided into three main classes based on features such as pigments, stored food and body structure.
Chlorophyceae: Dictionary meaning — the class of green algae, commonly called green algae.
Explanation — Members of Chlorophyceae are commonly green because chlorophyll is the major photosynthetic pigment. Examples include Chlamydomonas, Volvox, Ulothrix and Spirogyra.
Phaeophyceae: Dictionary meaning — the class of brown algae, commonly called brown algae.
Explanation — Members of Phaeophyceae are generally brown because of the presence of the pigment fucoxanthin. Examples include Laminaria and Sargassum.
Rhodophyceae: Dictionary meaning — the class of red algae, commonly called red algae.
Explanation — Members of Rhodophyceae are generally red because of pigments such as phycoerythrin. Examples include Porphyra, Gelidium and Gracilaria.
Given Statement - The algae are divided into three main classes: Chlorophyceae, Phaeophyceae and Rhodophyceae.
🎯 Conclusion
Algae are divided into three main classes: Chlorophyceae, Phaeophyceae and Rhodophyceae. In simple words, these are the green algae, brown algae and red algae groups.