Question

Find out the total number of false statements: A. Cyanobacteria have chlorophyll 'a'like green plants. B. Bacteria which oxidizes various inorganic substance such as nitrates and ammonia and uses the released energy for ATP production are chemosynthesis autotrophic bacteria. C. Heterotrophic bacteria are less in abundance in nature. D. Majority of heterotrophic bacteria are decomposers. E. Chemosynthetic autotrophic bacteria play an important role in recycling of nutrients like nitrogen, phosphorus iron and sulphur. (a) 1 (b) 2 (c) 3 (d) 4

Short answer

(a) 1

Step-by-step solution

Evaluating Statement A

Cyanobacteria do indeed have chlorophyll 'a' like green plants, which allows them to perform photosynthesis. Therefore, this statement is true.

Evaluating Statement B

This statement is also true. Chemosynthesis autotrophic bacteria are indeed capable of oxidizing inorganic substances such as nitrates and ammonia, using the energy released for ATP production.

Evaluating Statement C

This statement is false. Heterotrophic bacteria, which obtain their nutrition from their environment, are not less in abundance in nature

Evaluating Statement D

This statement is true. A majority of heterotrophic bacteria are decomposers, meaning they break down organic material.

Evaluating Statement E

This statement is also true. Chemosynthetic autotrophic bacteria do play an important role in the recycling of nutrients like nitrogen, phosphorus, iron and sulfur. As discussed in step 2, these bacteria are able to use these substances for their metabolism and release them back into the environment as part of their waste products

Key concepts

Cyanobacteria

Cyanobacteria are a fascinating group of bacteria that are sometimes referred to as blue-green algae. However, unlike real algae, they are not plants but prokaryotic organisms. One of the most important features of cyanobacteria is their ability to carry out photosynthesis, much like green plants. They achieve this using chlorophyll 'a', which is also found in true plants. This makes them primary producers in many aquatic ecosystems, where they form the base of the food chain by converting carbon dioxide and sunlight into glucose and oxygen.

Besides being photosynthetic, cyanobacteria play a critical role in ecosystems by fixing atmospheric nitrogen. This process enriches the environment with nutrients that are essential for plant growth. Interestingly, some species of cyanobacteria can form symbiotic relationships, providing their nitrogen-fixing ability to the benefit of plants and other organisms.

However, cyanobacteria blooms can sometimes occur during conditions of excess nutrients in water bodies, leading to ecological imbalances. These blooms can produce toxins that are harmful to both aquatic life and humans. Thus, despite their importance, their populations need to be balanced to maintain healthy ecosystems.

Heterotrophic Bacteria

Heterotrophic bacteria are a diverse group of organisms that rely on consuming organic matter for growth and energy. They do not photosynthesize or rely on inorganic chemicals like chemosynthetic bacteria. Instead, they obtain their nutrients from the environment by breaking down complex organic substances.

These bacteria are incredibly abundant and essential for maintaining ecological balance. They play important roles as decomposers, breaking down dead organisms and waste products into simpler substances. This decomposition process is crucial because it recycles nutrients back into the ecosystem, making them available for plant use.

Despite their ubiquity and ecological importance, some people may misinterpret their role in nature, thinking there are fewer of them present. Rather, heterotrophic bacteria are everywhere, including in soil, water, and even in our bodies, where they form part of the normal microbiota.

Nutrient Cycling

Nutrient cycling is a fundamental ecological process that ensures the continuous availability of essential elements like nitrogen, phosphorus, iron, and sulfur within ecosystems. This cycle involves the movement and exchange of these elements between living organisms and the environment. One of the key players in nutrient cycling are bacteria, especially those that are chemosynthetic autotrophs and decomposers.

These bacteria are adept at transforming nutrients from one form to another, which is necessary for making these nutrients available to plants. For example, nitrogen-fixing bacteria convert atmospheric nitrogen into forms that plants can uptake and use for growth. Similarly, decomposer bacteria break down waste materials and dead organisms, releasing vital nutrients back into the soil.

Chemosynthetic autotrophic bacteria further contribute by oxidizing inorganic substances, releasing energy that facilitates nutrient cycling. Their activities ensure that nutrients do not become locked in environments but remain part of the ecological cycle.

Photosynthesis in Bacteria

Photosynthesis is a process not limited to plants; some bacteria can also perform it. In bacteria, like cyanobacteria, photosynthesis is similar to that in plants, using light energy to convert carbon dioxide into organic compounds, releasing oxygen as a byproduct.

Light-harvesting occurs in their cell membrane structures, called photosynthetic thylakoids, where chlorophyll a and other pigments capture sunlight. This captured energy is then used to split water molecules, releasing oxygen and energizing electrons that drive the conversion of carbon dioxide to glucose.

Photosynthetic bacteria play crucial roles in many ecosystems, from freshwater lakes to oceans, acting as primary producers. They form the foundation of food webs by providing energy-rich compounds that fuel all higher trophic levels. Understanding photosynthesis in bacteria helps in comprehending how life sustains itself in various environments and offers insights into potential applications like bioengineering and renewable energy development.