11 Questions
Which method of reproduction involves the fusion of two gametes that are dissimilar in size?
Anisogamous reproduction
Which type of algae form massive plant bodies in marine environments?
Kelps
What is the most common type of spore produced during asexual reproduction in algae?
Zoospores
In what way do algae contribute significantly to the environment?
By carrying out a significant portion of carbon dioxide fixation through photosynthesis
Which organism forms an association with algae to create lichen?
Fungi
What type of organisms are algae in terms of their feeding autonomy?
Autotrophic
Why are marine algae considered of paramount importance in aquatic ecosystems?
They are the main source of food for aquatic animals.
Which algae is known for producing hydrocolloids like algin and carrageen used commercially?
Laminaria
What commercial product is obtained from Gelidium and Gracilaria algae for various purposes including in ice-creams?
Agar
Which class do marine algae like Porphyra, Laminaria, and Sargassum belong to?
Phaeophyceae
What is the role of Chlorella in space travel according to the text?
It serves as a source of food for astronauts.
Study Notes
Characteristics of Algae
- Algae are chlorophyll-bearing, simple, thalloid, autotrophic and largely aquatic organisms
- They occur in a variety of habitats, including freshwater, marine, moist stones, soils, and wood
- Algae can be found in association with fungi (lichen) and animals (e.g., on sloth bears)
Structure and Size
- The form and size of algae are highly variable
- Colonial forms include Volvox, while filamentous forms include Ulothrix and Spirogyra
- Some marine forms, such as kelps, form massive plant bodies
Reproduction
- Algae reproduce by vegetative, asexual, and sexual methods
- Vegetative reproduction occurs through fragmentation, with each fragment developing into a thallus
- Asexual reproduction involves the production of spores, such as zoospores, which are flagellated and motile
- Sexual reproduction involves the fusion of two gametes, which can be isogamous, anisogamous, or oogamous
Importance of Algae
- Algae are responsible for at least half of the total carbon dioxide fixation on earth through photosynthesis
- They increase the level of dissolved oxygen in their immediate environment
- Algae are primary producers of energy-rich compounds, forming the basis of aquatic food cycles
- Many species of algae are used as food, with 70 species of marine algae being consumed
- Certain algae produce hydrocolloids, such as algin and carrageen, which are used commercially
- Agar, obtained from Gelidium and Gracilaria, is used to grow microbes and in food products
- Chlorella, a unicellular alga, is used as a food supplement and is rich in proteins
Classification
- Algae are divided into three main classes: Chlorophyceae, Phaeophyceae, and Rhodophyceae
Explore the key characteristics and diverse habitats of algae, including their occurrence in aquatic environments, moist stones, soils, and symbiotic relationships with fungi and animals. Learn about the variability in form and size of algae, from colonial to filamentous forms.
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