Algae - 2

Sexual reproduction: Dictionary meaning — reproduction involving the formation and fusion of gametes.
Explanation — In algae, sexual reproduction involves the participation of gametes and results in the formation of a new individual after their fusion.

Fusion: Dictionary meaning — the joining or union of two cells, nuclei or other structures to form a single unit.
Explanation — During sexual reproduction, two gametes unite and their contents combine to form a single cell called a zygote.

Gametes: Dictionary meaning — specialized reproductive cells that participate in sexual reproduction.
Explanation — The two gametes involved in sexual reproduction fuse with each other to form a zygote, which can subsequently develop into a new individual.

Two gametes: Dictionary meaning — two reproductive cells that unite during sexual reproduction.
Explanation — Sexual reproduction in algae takes place through the fusion of two gametes, bringing their genetic material together.

Gametes: Dictionary meaning — specialized reproductive cells that participate in sexual reproduction.
Explanation — In algae, gametes fuse with another gamete during sexual reproduction to form a zygote.

Flagellated: Dictionary meaning — having one or more flagella, which are whip-like structures used for movement.
Explanation — Flagellated gametes possess flagella and are capable of movement. In Ulothrix, the gametes are flagellated.

Similar in size: Dictionary meaning — having approximately the same size or dimensions.
Explanation — In both Ulothrix and Spirogyra, the two gametes involved in fusion are similar in size.

Ulothrix: Dictionary meaning — a genus of filamentous green algae commonly found in freshwater habitats.
Explanation — In Ulothrix, the gametes are flagellated, motile and similar in size.

Non-flagellated: Dictionary meaning — lacking flagella, the structures used for active movement.
Explanation — Non-flagellated gametes do not possess flagella and therefore cannot actively swim.

Non-motile: Dictionary meaning — incapable of active movement from one place to another.
Explanation — Since the gametes of Spirogyra are non-flagellated, they are non-motile and cannot move actively.

Spirogyra: Dictionary meaning — a genus of filamentous green algae characterized by spiral-shaped chloroplasts.
Explanation — In Spirogyra, the gametes are non-flagellated, non-motile and similar in size.

Isogamous: Dictionary meaning — a type of sexual reproduction in which two gametes that are similar in size and usually similar in form fuse with each other.
Explanation — When sexual reproduction occurs through the fusion of two gametes that are similar in size, the process is called isogamy or isogamous reproduction.

Iso: Dictionary meaning — equal or same.
Explanation — The prefix 'iso-' indicates equality or similarity, referring to the similar size of the gametes.

Gametes: Dictionary meaning — specialized reproductive cells that participate in sexual reproduction.
Explanation — In isogamy, the two gametes are similar in size and fuse to form a zygote.

Fusion: Dictionary meaning — the joining or union of two cells or structures to form a single unit.
Explanation — The two similar-sized gametes unite during sexual reproduction and form a zygote.

Eudorina: Dictionary meaning — a genus of colonial green algae belonging to the family Volvocaceae.
Explanation — Species of Eudorina show anisogamous sexual reproduction, in which the two fusing gametes are dissimilar in size.

Anisogamous: Dictionary meaning — a type of sexual reproduction involving the fusion of two gametes that are dissimilar in size.
Explanation — When two gametes of unequal size fuse during sexual reproduction, the process is termed anisogamous reproduction or anisogamy.

Dissimilar in size: Dictionary meaning — different or unequal in size or dimensions.
Explanation — In anisogamy, the two gametes involved in fusion are unequal in size, unlike isogamy in which the gametes are similar in size.

Fusion: Dictionary meaning — the joining or union of two cells or structures to form a single unit.
Explanation — The two dissimilar gametes unite during sexual reproduction and form a zygote.

Oogamous: Dictionary meaning — a type of sexual reproduction in which a large, nonmotile female gamete fuses with a smaller, motile male gamete.
Explanation — In oogamy, the female gamete is large and stationary, while the male gamete is smaller and capable of movement. Their fusion results in the formation of a zygote.

Large: Dictionary meaning — having greater size or dimensions compared with another structure.
Explanation — The female gamete in oogamous reproduction is larger than the male gamete.

Nonmotile (static): Dictionary meaning — incapable of active movement from one place to another.
Explanation — The female gamete remains stationary and does not actively move toward the male gamete.

Female gamete: Dictionary meaning — the reproductive cell that participates in sexual reproduction and contributes genetic material to the zygote.
Explanation — In oogamy, the female gamete is large and nonmotile and fuses with the smaller male gamete.

Smaller: Dictionary meaning — having less size or dimensions compared with another structure.
Explanation — The male gamete is smaller in size than the female gamete in oogamous reproduction.

Motile: Dictionary meaning — capable of active movement.
Explanation — The male gamete is motile and can move toward the nonmotile female gamete for fusion.

Male gamete: Dictionary meaning — the reproductive cell that fuses with a female gamete during sexual reproduction.
Explanation — In oogamy, the male gamete is smaller and motile and fuses with the large, nonmotile female gamete.

Volvox: Dictionary meaning — a colonial green alga belonging to the family Volvocaceae.
Explanation — Volvox is an example of an alga that exhibits oogamous sexual reproduction.

Fucus: Dictionary meaning — a genus of marine brown algae commonly known as rockweeds.
Explanation — Fucus is another example of an alga that shows oogamous sexual reproduction.

Useful to man: Dictionary meaning — beneficial or helpful to human beings.
Explanation — Algae are useful to humans in many ways, including their important role in food, industry, medicine and maintaining ecological balance.

Carbon dioxide fixation: Dictionary meaning — the process of converting inorganic carbon dioxide into organic compounds, mainly through photosynthesis.
Explanation — During photosynthesis, algae absorb carbon dioxide from their surroundings and convert it into organic food, thereby fixing carbon into organic matter.

Photosynthesis: Dictionary meaning — the process by which chlorophyll-containing organisms use light energy to synthesize organic food from carbon dioxide and water.
Explanation — Algae use chlorophyll to capture light energy and convert carbon dioxide and water into organic food, while releasing oxygen.

At least half: Dictionary meaning — not less than one-half or 50 percent.
Explanation — The statement indicates that algae are responsible for at least 50% of the total carbon dioxide fixation carried out on Earth.

Total carbon dioxide fixation on Earth: Dictionary meaning — the overall conversion of atmospheric or dissolved carbon dioxide into organic compounds by photosynthetic organisms.
Explanation — Algae make a major contribution to global carbon fixation by absorbing carbon dioxide during photosynthesis.

Photosynthetic: Dictionary meaning — capable of carrying out photosynthesis using light energy, carbon dioxide and water to produce organic food.
Explanation — Algae are photosynthetic because they contain chlorophyll and use light energy to prepare food through photosynthesis.

Dissolved oxygen: Dictionary meaning — oxygen gas present in a dissolved state in water.
Explanation — Aquatic organisms use dissolved oxygen present in water for respiration and other biological activities.

Increase: Dictionary meaning — to become greater in amount, level or quantity.
Explanation — During photosynthesis, algae release oxygen into the surrounding water, causing the amount of dissolved oxygen to increase.

Immediate environment: Dictionary meaning — the surrounding area or habitat directly around an organism.
Explanation — The oxygen released by algae during photosynthesis increases the dissolved oxygen level in the water surrounding them.

Paramount importance: Dictionary meaning — having the greatest importance or being of the highest significance.
Explanation — Algae are extremely important in aquatic ecosystems because they form the foundation of food supply and energy flow.

Primary producers: Dictionary meaning — organisms that produce organic food from inorganic substances, mainly through photosynthesis.
Explanation — Algae are primary producers because they use light energy, carbon dioxide and water to synthesize organic food through photosynthesis.

Energy-rich compounds: Dictionary meaning — organic substances that store chemical energy and can be used as a source of energy by organisms.
Explanation — Algae produce energy-rich organic compounds such as carbohydrates during photosynthesis. These compounds provide energy to organisms that consume algae.

Food cycles: Dictionary meaning — the movement and transfer of food, nutrients and energy among organisms within an ecosystem.
Explanation — Energy-rich compounds produced by algae are transferred through aquatic food chains and support successive levels of aquatic organisms.

Aquatic animals: Dictionary meaning — animals that live mainly in water.
Explanation — Aquatic animals depend directly or indirectly on algae for food and energy, making algae an important foundation of aquatic food systems.

Given Statement - They are of paramount importance as primary producers of energy-rich compounds which form the basis of the food cycles of all aquatic animals.

Marine algae: Dictionary meaning — algae that live and grow in seawater or marine environments.
Explanation — Porphyra, Laminaria and Sargassum are examples of marine algae that are used by humans as food.

Porphyra: Dictionary meaning — a genus of marine red algae.
Explanation — Many species of Porphyra are edible marine algae and are used as food.

Laminaria: Dictionary meaning — a genus of large marine brown algae commonly known as kelps.
Explanation — Species of Laminaria are edible algae and are used as food in some regions.

Sargassum: Dictionary meaning — a genus of marine brown algae commonly found in coastal waters and floating seaweed communities.
Explanation — Many species of Sargassum are used as food and are also important components of marine ecosystems.

70 species: Dictionary meaning — a group of seventy different species or kinds of organisms.
Explanation — The statement indicates that about 70 species of marine algae are used as food, including many species of Porphyra, Laminaria and Sargassum.

Used as food: Dictionary meaning — consumed by humans or other organisms as a source of nutrition.
Explanation — These marine algae can be eaten and provide nutrients, making them useful food resources.

Given Statement - Many species of Porphyra, Laminaria and Sargassum are among the 70 species of marine algae used as food.

Marine brown algae: Dictionary meaning — algae that live in marine environments and generally contain the brown pigment fucoxanthin.
Explanation — Certain marine brown algae produce large amounts of hydrocolloids such as algin, which have important commercial uses.

Marine red algae: Dictionary meaning — algae that live mainly in marine environments and contain red pigments such as phycoerythrin.
Explanation — Certain marine red algae produce hydrocolloids such as carrageen, which are commercially useful.

Hydrocolloids: Dictionary meaning — substances that absorb or hold water and form thick or gel-like mixtures when mixed with water.
Explanation — Hydrocolloids produced by algae can hold water and are therefore useful in many commercial products.

Algin: Dictionary meaning — a hydrocolloid obtained mainly from brown algae that has strong water-holding and thickening properties.
Explanation — Algin is obtained from brown algae and is commercially used because it can absorb water and form thick or gel-like substances.

Carrageen: Dictionary meaning — a hydrocolloid obtained from certain red algae and used as a thickening or gelling substance.
Explanation — Carrageen is obtained from red algae and is commercially useful because of its ability to thicken and form gels.

Used commercially: Dictionary meaning — used in products or processes for business and industrial purposes.
Explanation — Algin and carrageen are commercially valuable because their water-holding, thickening and gelling properties make them useful in various industries.

Given Statement - Certain marine brown and red algae produce large amounts of hydrocolloids (water holding substances), e.g., algin (brown algae) and carrageen (red algae) which are used commercially.