1. Algae are ______ bearing, ______, ______ and ______ organisms.
Correct Answer: A
Algae are chlorophyll-bearing organisms that can perform photosynthesis. They have a simple thalloid body without true roots, stems or leaves. They are autotrophic in nature and are mostly found in aquatic environments, including both freshwater and marine habitats.
2. Algae can also be found in which of the following habitats?
Correct Answer: C
Although algae are mainly aquatic, they can also grow in diverse habitats such as moist stones, soils and wood. Some algae live in association with fungi forming lichens, and some are found on animals like sloth bear. This shows their adaptability to different environments.
3. Lichens are an association between:
Correct Answer: A
Lichens are symbiotic associations between algae and fungi. The algal component (phycobiont) prepares food by photosynthesis, while the fungal component (mycobiont) provides protection, water and minerals. This mutual relationship benefits both organisms.
4. The form and size of algae vary from:
Correct Answer: A
Algae show great variation in form and size. They may exist as simple colonial or filamentous forms, and some marine algae grow into large, complex plant-like bodies. This diversity reflects their adaptability and wide range of habitats.
5. An example of colonial form of algae is:
Correct Answer: A
Volvox is a colonial alga in which many cells live together in a coordinated colony. Each cell performs its functions but remains connected with others, forming a spherical colony.
6. Examples of filamentous forms of algae are:
Correct Answer: A
Filamentous algae are made up of long chains of cells arranged end to end, forming thread-like structures. Ulothrix and Spirogyra are classic examples of filamentous algae, commonly found in freshwater habitats.
7. Which of the following marine algae form massive plant bodies?
Correct Answer: A
Kelps are large marine brown algae that can grow into massive plant-like bodies, sometimes reaching several meters in length. They form underwater forests in oceans and are among the largest algae known.
8. Algae reproduce by:
Correct Answer: C
Algae show different modes of reproduction. They can reproduce vegetatively (by fragmentation), asexually (by spores like zoospores) and sexually (by fusion of gametes). This diversity in reproduction helps them survive in various environments.
9. In algae, vegetative reproduction occurs by ______ and each fragment develops into a ______.
Correct Answer: A
Vegetative reproduction in algae commonly occurs by fragmentation. In this process, the algal body breaks into smaller pieces called fragments, and each fragment grows into a new individual called a thallus.
10. Asexual reproduction in algae occurs by production of ______, the most common being ______.
Correct Answer: A
Asexual reproduction in algae takes place through the formation of spores. Among these, zoospores are the most common. Zoospores are motile and flagellated, allowing them to swim in water and develop into new algal individuals.
11. Zoospores are ______ and on germination give rise to ______.
Correct Answer: A
Zoospores are motile asexual spores that possess flagella, which help them move in water. After settling, they germinate and develop into new algal plants, ensuring rapid spread in aquatic environments.
12. Sexual reproduction in algae occurs by:
Correct Answer: C
Sexual reproduction in algae involves the fusion of two gametes (male and female). This process forms a zygote, which later develops into a new individual. It helps in genetic variation and adaptation.
13. Gametes that are similar in size but may be flagellated (Ulothrix) or non-flagellated (Spirogyra) represent:
Correct Answer: A
Isogamy is a type of sexual reproduction in which the fusing gametes are similar in size. These gametes may be motile (flagellated) as in Ulothrix or non-motile as in Spirogyra. Despite differences in motility, their similar size defines isogamy.
14. Fusion of two gametes dissimilar in size (as in Eudorina) is called:
Correct Answer: B
Anisogamy is a type of sexual reproduction in which the two fusing gametes are unequal in size. This is seen in organisms like Eudorina, where one gamete is larger than the other.
15. Fusion between one large non-motile female gamete and a smaller motile male gamete is called:
Correct Answer: C
Oogamy is a type of sexual reproduction in which a large, non-motile female gamete (egg) fuses with a smaller, motile male gamete (sperm). This is a more advanced form of sexual reproduction seen in many higher organisms.
16. Oogamous type of reproduction (fusion of large non-motile female gamete and small motile male gamete) is seen in:
Correct Answer: A
Oogamy is a type of sexual reproduction where a large, non-motile female gamete fuses with a small, motile male gamete. This type of reproduction is seen in organisms like Volvox and Fucus, representing a more advanced form of sexual reproduction.
17. Algae contribute approximately how much of the total CO₂ fixation on earth?
Correct Answer: C
Algae play a major role in global photosynthesis. They fix at least half of the total carbon dioxide on earth through photosynthesis, especially in aquatic ecosystems, contributing significantly to oxygen production and maintaining ecological balance.
18. Algae contribute approximately how much of the total oxygen on earth?
Correct Answer: C
Algae are responsible for producing a large portion of the earth’s oxygen through photosynthesis. Since they fix about half of the total carbon dioxide, they also contribute at least 50% of the total oxygen present in the atmosphere, especially through marine phytoplankton.
19. Photosynthetic algae increase the level of ______ in their immediate environment.
Correct Answer: B
Algae perform photosynthesis, during which they release oxygen as a by-product. This oxygen dissolves in water, thereby increasing the level of dissolved oxygen in their surroundings. This is important for the survival of aquatic organisms.
20. Algae are important in aquatic ecosystems because they act as:
Correct Answer: B
Algae are primary producers in aquatic ecosystems. They produce energy-rich organic compounds through photosynthesis, which form the base of the food chain. All aquatic animals ultimately depend on algae directly or indirectly for food.
21. Which of the following marine algae are commonly used as food?
Correct Answer: A
Several marine algae are used as food. Important examples include Porphyra, Laminaria and Sargassum. These algae are rich in nutrients and are consumed in many parts of the world, especially in coastal regions.
22. Marine brown and red algae produce large amounts of:
Correct Answer: B
Certain marine brown and red algae produce hydrocolloids, which are water-holding substances. These compounds are widely used in industries such as food, pharmaceuticals and cosmetics for their thickening and stabilizing properties.
23. Algin and carrageen are hydrocolloids obtained from:
Correct Answer: A
Hydrocolloids are water-holding substances produced by marine algae. Algin is obtained from brown algae, while carrageen is obtained from red algae. These are widely used in food and industrial applications as thickening and stabilizing agents.
24. Agar is obtained from which algae and used for:
Correct Answer: A
Agar is a commercial product obtained from red algae such as Gelidium and Gracilaria. It is widely used in microbiology laboratories as a culture medium to grow microbes. It is also used in food industries in the preparation of ice-creams and jellies due to its gelling properties.
25. Chlorella is a:
Correct Answer: A
Chlorella is a unicellular green alga. It is microscopic and capable of photosynthesis. Due to its high protein content and rapid growth, it is also used as a source of food and in research.
26. Chlorella, a protein-rich unicellular alga, is used as a food supplement even by ______.
Correct Answer: B
Chlorella is a unicellular alga rich in proteins, vitamins and minerals. Due to its high nutritional value and ease of cultivation, it is used as a food supplement, even by space travellers, where compact and nutrient-rich food is essential.
27. Algae are mainly divided into how many classes?
Correct Answer: B
Algae are broadly classified into three main classes based on pigments, stored food and cell wall composition. These classes are Chlorophyceae (green algae), Phaeophyceae (brown algae) and Rhodophyceae (red algae).
28. The three main classes of algae are:
Correct Answer: A
Algae are divided into three main classes: Chlorophyceae (green algae), Phaeophyceae (brown algae) and Rhodophyceae (red algae). This classification is based on differences in pigments, storage products and cell structure.