Questions on Algae
Multiple-Choice Questions – Algae
1. Algae are best described as:
A) Unicellular animals
B) Non-photosynthetic plants
C) Photosynthetic aquatic organisms
D) Saprophytic fungi
E) Heterotrophic bacteria
2. Which of the following is not a group of algae?
A) Chlorophyta
B) Rhodophyta
C) Phaeophyta
D) Basidiomycota
E) Chrysophyta
3. The green pigment essential for photosynthesis in algae is:
A) Xanthophyll
B) Phycocyanin
C) Carotene
D) Chlorophyll
E) Melanin
4. Algae differ from plants mainly because:
A) They are multicellular
B) They do not have chloroplasts
C) They lack true roots, stems, and leaves
D) They live only on land
E) They do not reproduce
5. Red algae belong to the group:
A) Chlorophyta
B) Rhodophyta
C) Phaeophyta
D) Cyanophyta
E) Chrysophyta
6. The brown color of brown algae is due to:
A) Chlorophyll a
B) Carotenoids
C) Xanthophylls
D) Fucoxanthin
E) Phycobilins
7. Which of the following is a unicellular algae commonly used in studies?
A) Ulva
B) Laminaria
C) Chlamydomonas
D) Fucus
E) Sargassum
8. Algae are primarily found in:
A) Deserts
B) Underground
C) Aquatic environments
D) Inside insects
E) Rocks
9. Which of these algae is used in making agar?
A) Euglena
B) Chlorella
C) Spirogyra
D) Gelidium
E) Volvox
10. The economic importance of algae includes:
A) Producing oxygen
B) Source of food
C) Biofuel production
D) Industrial uses (e.g., agar, alginate)
E) All of the above
11. Which algae group is thought to be most closely related to land plants?
A) Rhodophyta
B) Phaeophyta
C) Chlorophyta
D) Euglenophyta
E) Dinoflagellates
12. Euglenoids are unique among algae because they:
A) Are multicellular
B) Have cell walls made of cellulose
C) Are always autotrophic
D) Can be both autotrophic and heterotrophic
E) Live only in saltwater
13. Diatoms are known for their:
A) Chloroplasts shaped like spirals
B) Silica-based cell walls
C) Ability to form spores
D) Parasitic lifestyle
E) Red pigment
14. The red pigment found in red algae is called:
A) Phycocyanin
B) Chlorophyll b
C) Fucoxanthin
D) Phycoerythrin
E) Xanthophyll
15. Algae that contribute significantly to marine ecosystems as primary producers are:
A) Basidiomycota
B) Diatoms
C) Amoebas
D) Fungi
E) Protozoa
16. Which of the following best defines planktonic algae?
A) Algae that live inside rocks
B) Algae attached to surfaces
C) Algae living in the soil
D) Algae that float freely in water
E) Algae in dry air
17. Which group of algae is multicellular and macroscopic?
A) Chlorophyta only
B) Dinoflagellates
C) Rhodophyta and Phaeophyta
D) Cyanobacteria
E) Diatoms
18. The process by which algae bloom in nutrient-rich water is called:
A) Sedimentation
B) Eutrophication
C) Carbonation
D) Desiccation
E) Calcification
19. Which of the following is a colonial green alga?
A) Volvox
B) Euglena
C) Chlamydomonas
D) Gelidium
E) Diatom
20. Algae play an important role in the carbon cycle because they:
A) Break down dead material
B) Fix nitrogen
C) Absorb CO₂ during photosynthesis
D) Release methane
E) Decompose plastics
Answer Key with Explanations
1. C – Algae are photosynthetic and mostly aquatic organisms.
2. D – Basidiomycota is a fungal group, not algal.
3. D – Chlorophyll is the primary pigment for photosynthesis.
4. C – Algae lack vascular tissues and true plant organs.
5. B – Rhodophyta is the red algae group.
6. D – Fucoxanthin gives brown algae their color.
7. C – Chlamydomonas is a model unicellular alga.
8. C – Most algae are found in freshwater or marine environments.
9. D – Gelidium is a red alga used to make agar.
10. E – Algae are ecologically and economically valuable in many ways.
11. C – Chlorophyta share many features with land plants.
12. D – Euglenoids can photosynthesize and also ingest food.
13. B – Diatoms have cell walls made of silica (glass-like).
14. D – Phycoerythrin gives red algae their color.
15. B – Diatoms are key primary producers in oceans.
16. D – Planktonic algae are free-floating in aquatic environments.
17. C – Many Rhodophyta and Phaeophyta species are large and multicellular.
18. B – Eutrophication leads to algal blooms in nutrient-rich waters.
19. A – Volvox forms spherical colonies of green algae.
20. C – Algae absorb CO₂ and release oxygen via photosynthesis.
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