Problem 22 - Objective Biology for NEET

Question

A first action spectrum of photosynthesis was described on the basis of experiment performed by T. W. Engelmann on _________ algae. (a) Green (b) Red (c) Brown (d) All of these

Step-by-Step Solution

Answer

(a) Green

Step 1: Understand the question

Read the question carefully. The question is asking specifically on what type of algae T. W. Engelmann performed his experiment.

Step 2: Recall information about T. W. Engelmann's experiments

Engelmann, in his experiment, used a prism to expose different segments of a filamentous green alga to different wavelengths of light. By doing this, he was able to determine which regions of the spectrum were most effective at driving photosynthesis. Thus, the algae was of the green variety.

Step 3: Answer the question

Based on historical scientific knowledge, T. W. Engelmann performed his experiments on Green algae. Hence the correct answer is (a) Green.

Key Concepts

Action Spectrum

The action spectrum of photosynthesis represents the effectiveness of different wavelengths of light in driving photosynthesis. Using a prism, scientists can split light into its component colors, each having a distinct wavelength. By measuring the photosynthetic activity—oxygen production or changes in chlorophyll fluorescence—you can observe which wavelengths are most efficient. Typically, light between blue and red wavelengths is most utilized in photosynthesis. Key reasons include:

• The absorption characteristics of chlorophyll, the direct driver of photosynthesis, peak in these regions.
• Other pigments like carotenoids complement chlorophyll and help capture more light energy.

Understanding the action spectrum allows researchers to optimize growth conditions for plants, ensuring maximum light absorption and energy conversion.

T. W. Engelmann

T. W. Engelmann was a pioneering scientist whose experiments paved the way for our understanding of photosynthesis' action spectrum. In the late 19th century, Engelmann used a prism to disperse light across the spectrum and expose regions of a filamentous alga to various wavelengths. He observed the response of aerobic bacteria to identify which wavelengths were most effective. Bacteria congregated around algae regions where oxygen production and photosynthesis were most active. This demonstrated:

• That blue and red light wavelengths are most efficient for photosynthesis.
• The principle that specific wavelengths can significantly affect photosynthetic activity.

Engelmann's work laid the foundation for future research in plant biology and light-plant interactions.

Green Algae

Green algae played a crucial role in Engelmann's experiment as they were the biological material used to map the effectiveness of light wavelengths. Green algae contain chlorophyll a and b, which are green pigments that efficiently absorb light, especially in the blue and red spectrums. They act as an excellent model organism for photosynthesis research:

• Green algae's observed responses to light provide insights into natural photosynthetic efficiency.
• They serve as a basis for understanding the energy transfer and conversion in plants.

Because of their simplicity and similar light-utilizing capabilities to higher plants, green algae remain widely studied in photosynthetic research today.

Photosynthesis Experiment

Photosynthesis experiments like Engelmann's are critical for understanding how light interacts with plant life to produce energy. In Engelmann's setup, he exposed green algae to a range of light wavelengths and used aerobic bacteria to identify areas of high photosynthetic activity. These experiments illuminate several aspects of photosynthesis:

• They visually demonstrate which parts of the spectrum are used most efficiently by plants.
• Provide evidence that can influence agricultural practices to optimize light conditions for crops.
• Help unravel the complexity of photosynthetic mechanisms and their dependence on light.

Engelmann’s methodological innovation continues to influence experiments exploring light effectiveness, deepening our understanding of the fundamental processes of life.