Problem 42 - Objective Biology for NEET

Question

The algae which possess chlorophyll \(\mathrm{a}, \mathrm{c}\), carotenoids and xanthophylls belong to (a) Green algae (b) Brown algae (c) Both (a) and (b) (d) None of these

Step-by-Step Solution

Answer

The algae which possess chlorophyll a, c, carotenoids and xanthophylls belong to brown algae.

Step 1: Analyze the given pigments

In the problem, we are given that the algae possess chlorophyll a, chlorophyll c, carotenoids and xanthophylls. Now we need to know which algae contain these pigments.

Step 2: Identify the type of algae

Green algae contain chlorophyll a and b, plus carotenoids. Brown algae, on the other hand, contain chlorophyll a, c, carotenoids and xanthophylls.

Step 3: Compare the given pigments with the types of algae

By comparing the given pigments with the pigments that each type of algae contain, it could be found that the algae that possess chlorophyll a, c, carotenoids and xanthophylls is brown algae.

Key Concepts

Chlorophyll

Chlorophyll is a green pigment found in the chloroplasts of plants, algae, and cyanobacteria. Its primary role is to absorb light, usually sunlight, and convert it into chemical energy through the process of photosynthesis. Chlorophyll captures light mostly in the blue and red wavelengths.

• Chlorophyll gives plants and algae their characteristic green color.
• Chlorophyll \( a \) is the most common form and crucial for photosynthesis.
• Chlorophyll \( c \) is less common and primarily found in certain algal groups like the brown algae.

Without chlorophyll, photosynthesis would not occur, making it essential for life on Earth. This pigment enables the conversion of carbon dioxide and water into glucose and oxygen, supporting the food chain.

Carotenoids

Carotenoids are a class of pigments that are typically yellow, orange, or red. These pigments play a significant role in photosynthesis, complementing the light absorption of chlorophyll by capturing different wavelengths that chlorophyll misses.

• Carotenoids help protect chlorophyll from damage by excess light.
• They are antioxidants, meaning they help neutralize harmful substances in cells.
• Carotenoids are found in all photosynthetic organisms, including plants and algae.

They also contribute to the vivid colors we see in many fruits and vegetables, which is why they are often used as natural food colorings.

Xanthophylls

Xanthophylls are a type of carotenoid pigment known for their yellow coloration. They are closely related to carotenoids but differ slightly in their chemical structure, which includes the presence of oxygen molecules.

• Xanthophylls contribute to light absorption in the range of blue wavelengths.
• They are particularly important in the pigmentation of yellow leaves and flowers.
• These pigments play a protective role by dissipating excess light energy during photosynthesis.

Incorporating xanthophylls and other pigments allows organisms to efficiently capture and utilize sunlight while safeguarding their photosynthetic machinery from damage.

Green Algae

Green algae are a large group of photosynthetic organisms that are predominantly green due to the presence of chlorophyll \( a \) and \( b \). These pigments are crucial for their ability to carry out photosynthesis.

• Primarily found in freshwater and marine environments.
• They contain chlorophyll \( a \), chlorophyll \( b \), and a range of carotenoids.
• Green algae are thought to be the ancestors of modern land plants.

They play a crucial role in aquatic ecosystems as major producers and contribute significantly to the oxygen supply.

Brown Algae

Brown algae are large, multicellular marine algae known for their characteristic brown color, derived from pigments such as fucoxanthin, a type of xanthophyll.

• They are predominantly found in marine environments.
• Their pigments include chlorophyll \( a \), chlorophyll \( c \), carotenoids, and xanthophylls.
• Includes members like kelps, which can form vast underwater forests.

Brown algae have adapted to thrive in cooler ocean waters, and they play an essential role in submerged ecosystems, offering habitat and food for various marine organisms. Their alginates are widely used in food and industry for their gel-forming properties.