Problem 7 - Biology Concepts and Applications

Question

Accessory pigments of _____ allow them to carry out photosynthesis at greater depths than other algae. a. euglenoids b. green algae c. brown algae d. red algac

Step-by-Step Solution

Answer

Red algae can carry out photosynthesis at greater depths due to their accessory pigments.

Step 1: Identifying the Question

The question asks which accessory pigments allow a group of algae to perform photosynthesis at greater depths than other algae. We need to identify the group of algae and their pigments.

Step 2: Understanding Accessory Pigments

Accessory pigments extend the range of light wavelengths that can be used in photosynthesis. In deeper waters, where light is less intense, certain pigments allow algae to absorb light efficiently.

Step 3: Evaluating the Options

Red algae contain accessory pigments called phycobiliproteins, which allow them to absorb blue and green light, penetrating the furthest in water. This allows red algae to photosynthesize at greater depths.

Step 4: Conclusion

Based on the knowledge that red algae have phycobiliproteins, which enable them to carry out photosynthesis efficiently in deep waters, option d, red algae, is the correct answer.

Key Concepts

Accessory Pigments

In the world of photosynthesis, accessory pigments play a starring role in helping plants and algae harness light. These pigments are special molecules that absorb light at wavelengths not efficiently absorbed by the main pigment, chlorophyll. This broadens the spectrum of light that can be used for photosynthesis.
Accessory pigments include compounds like carotenoids, phycobiliproteins, and xanthophylls. Each type of pigment absorbs different wavelengths of light, allowing the plant to capture energy across a broader spectrum. For instance:

• Carotenoids absorb mostly blue and green light and appear orange or yellow.
• Phycobiliproteins absorb red and orange light and give a bluish color.

These pigments are crucial for plants living under low light conditions, such as at greater depths in water bodies. By absorbing additional wavelengths of light, accessory pigments help optimize the energy acquired for photosynthesis.

Red Algae

Red algae, also known as Rhodophyta, thrive in various aquatic environments, from shallow coastal waters to the depths of the ocean. One distinct feature of red algae is their vivid red color, which is due to accessory pigments called phycobiliproteins.
Red algae are outstanding at photosynthesis, especially at greater depths where many other algae cannot survive. This capability is attributed to their ability to absorb blue and green light efficiently, which penetrates deeper into the ocean than other wavelengths.

• They contain chlorophyll a, which primarily absorbs red and blue light.
• Phycobiliproteins expand their light absorption capacity, enhancing the use of available light.

Despite their name, not all red algae are red. They can vary in color from green to black, depending on the concentration of pigments. Red algae serve as crucial components in marine ecosystems, providing habitat and food for various marine organisms.

Phycobiliproteins

Phycobiliproteins are a group of accessory pigments found in certain algae like red algae, cryptophytes, and cyanobacteria. These proteins are highly effective at capturing light energy, which they transfer to chlorophyll for photosynthesis.
They are water-soluble, allowing them to exist in the aqueous environments of chloroplasts. Phycobiliproteins consist of:

• Phycocyanin - gives a bluish tint and absorbs orange and red light.
• Phycoerythrin - imparts a red color and efficiently captures blue light.

The presence of these proteins enables algae to survive and thrive in low-light environments, like the deep sea. Phycobiliproteins also have industrial applications such as fluorescent tracers in biological research, thanks to their bright colors and light-harvesting efficiency. Their ability to absorb complementary wavelengths to chlorophyll maximizes the use of available light, making these proteins indispensable to deep-dwelling photosynthetic organisms.