Question

Gas vacuoles are found in (a) Blue-green bacteria (b) Purple bacteria (c) Green photosynthetic bacteria (d) All of these

Short answer

The correct answer is (d) All of these.

Step-by-step solution

Identification of Bacteria Types

Look closely at the types of bacteria mentioned. All of them are known to possess gas vacuoles: Blue-green bacteria, Purple bacteria, and Green photosynthetic bacteria.

Analyse Options

Now, study the four given options. None of them exclude the others and the option (d) suggests that all these bacteria have gas vacuoles.

Final Selection

Based on the knowledge that gas vacuoles can be found in all listed types of bacteria, option (d) - All of these, seems to be the correct answer.

Key concepts

Blue-Green Bacteria

Blue-green bacteria, commonly known as cyanobacteria, are fascinating microorganisms that have been around for billions of years. They are known for their distinctive blue-green color, which is a result of the pigments called phycobiliproteins and chlorophyll that they use for photosynthesis. This process allows them to convert sunlight into energy, just like plants. However, cyanobacteria stand out because they were among the first organisms to perform oxygenic photosynthesis, significantly contributing to the oxygenation of Earth's atmosphere.

One unique feature of blue-green bacteria is their ability to form gas vacuoles. These vacuoles are tiny, gas-filled structures that help the bacteria float on water surfaces, optimizing their exposure to sunlight. Gas vacuoles are flexible, allowing these organisms to adjust buoyancy depending on environmental conditions. By rising or sinking in the water, cyanobacteria can find the perfect light conditions essential for efficient photosynthesis.

Cyanobacteria can be found in various environments, from oceans to freshwater bodies and even in extreme habitats, like hot springs. Understanding their role in ecosystems is important as they form the base of many aquatic food chains and play a key role in nutrient cycling.

Purple Bacteria

Purple bacteria are another fascinating group of bacteria known for their vibrant hues, which can range from purple to red, depending on the type of pigments they contain. These pigments, primarily bacteriochlorophylls and carotenoids, are crucial for their ability to carry out photosynthesis.

Unlike blue-green bacteria, purple bacteria perform a different type of photosynthesis called anoxygenic photosynthesis. This means they do not produce oxygen as a byproduct. Instead, they use light energy to convert carbon dioxide into organic compounds, using hydrogen sulfide or organic molecules rather than water as an electron donor. This makes them versatile in environments where oxygen is limited.

• Found in various aquatic environments, including sediments and the bottom of lakes.
• Gas vacuoles assist with buoyancy, allowing them to adjust to different light conditions.

Similar to blue-green bacteria, purple bacteria can regulate their position in water by inflating or deflating their gas vacuoles, ensuring optimal light conditions for photosynthesis.

Green Photosynthetic Bacteria

Green photosynthetic bacteria, which consist of different groups like green sulfur bacteria and green non-sulfur bacteria, are known for their adaptation to environments with low light levels. They possess distinctive pigments that allow them to capture light energy efficiently.

Green sulfur bacteria, for example, use sulfide or sulfur as electron donors during photosynthesis. They typically reside in the deeper anoxic layers of lakes and other aquatic environments, where they thrive under dim light conditions. Like other photosynthetic bacteria, they avoid producing oxygen as a byproduct.

• Commonly found deeper in water bodies where light penetration is minimal.
• Utilize gas vacuoles for buoyancy, allowing them to adjust to available light intensities.

The flexibility in using gas vacuoles to control buoyancy helps green photosynthetic bacteria position themselves in ideal light conditions for their unique photosynthetic processes. Understanding these bacteria helps us appreciate the diversity of life that has adapted to varied environments on Earth.