Problem 222 - Objective Biology for NEET

Question

Assertion: Algae are autotrophic. Reason: Algae contain chlorophyll pigments.

Step-by-Step Solution

Answer

The assertion is correct. Because algae contain chlorophyll pigments, they are autotrophic and can conduct photosynthesis and create their own food.

Step 1: Understand terms

First, identify what the terms 'autotrophic' and 'chlorophyll' mean. Autotrophic organisms are those who synthesize their own food from inorganic substances using light or chemical energy. Chlorophyll is a pigment found in the chloroplasts of plant cells allowing the plant to absorb light energy for photosynthesis.

Step 2: Relate the terms to algae

It's known that algae contain chlorophyll, the pigment necessary for photosynthesis. Therefore, because they possess this pigment, they can carry out the process of photosynthesis, making their own food from light energy and inorganic substances. This verifies the assertion that algae are autotrophic.

Step 3: Formulate the conclusion

In conclusion, the reason provided-'Algae contain chlorophyll pigments'-backs up the assertion-'Algae are autotrophic'. Because algae contain chlorophyll, they are indeed autotrophic, capable of synthesizing their own food via photosynthesis.

Key Concepts

Autotrophic organisms

Autotrophic organisms are fascinating entities that can produce their own food. They do this by using inorganic materials in combination with light (or sometimes chemical) energy.
This process is crucial for life on Earth as it forms the base of food chains. Examples of autotrophic organisms include plants, some bacteria, and algae. Here’s what makes them special:

• They use sunlight or chemical reactions to convert simple inorganic substances such as water and carbon dioxide into complex organic compounds like glucose.
• This conversion is essential for their growth and survival.
• Because of this ability, autotrophic organisms do not rely on other organisms for food.

By being able to independently produce energy-rich compounds, they play a vital role in ecosystems by supplying energy to non-autotrophic organisms, which include humans and other animals.

Chlorophyll

Chlorophyll is a remarkable green pigment found in the chloroplasts of plant cells, and it's essential for photosynthesis. This pigment is what gives plants, algae, and certain bacteria their green color.
Without chlorophyll, these organisms wouldn't be able to perform photosynthesis effectively. Here are a few key points about chlorophyll:

• It absorbs light, primarily in the blue and red wavelengths, making it possible for plants to convert sunlight into chemical energy.
• Chlorophyll plays a critical role in the light-dependent reactions of photosynthesis, where sunlight is captured and used to make energy-rich molecules like ATP and NADPH.
• There are different types of chlorophyll, with Chlorophyll a being the most common in plants and algae.

This pigment not only facilitates the energy conversion process but also allows for the storage of that energy in a stable form. This is fundamental for the growth and development of autotrophic organisms.

Photosynthesis

Photosynthesis is one of the most vital biological processes occurring on our planet, allowing autotrophic organisms like algae to convert light energy into chemical energy.
This process not only supports the survival of these organisms but also provides oxygen to the atmosphere. Here’s a breakdown of the process:

• It consists of two main stages: the light-dependent reactions and the Calvin cycle (light-independent reactions).
• In the light-dependent reactions, chlorophyll captures light energy which is then used to produce ATP and NADPH.
• During the Calvin cycle, ATP and NADPH are used to convert carbon dioxide and water into glucose, a simple sugar that provides energy to the organism.

By making their own food through photosynthesis, algae and other autotrophic organisms contribute significantly to the global energy cycle, supporting a vast array of life forms.