Which Of The Following Obtain Energy From Sunlight?

Photosynthesis is the process by which plants, algae, and some bacteria convert sunlight into chemical energy. During photosynthesis, organisms use the energy from sunlight to convert carbon dioxide and water into oxygen and energy-rich molecules like glucose. Photosynthesis is essential for life on Earth as it provides the energy needed to power the growth and function of most plants. Several types of organisms have evolved the ability to harness the power of sunlight through photosynthesis.

There are many diverse organisms capable of obtaining energy directly from sunlight via photosynthesis including plants, algae, cyanobacteria, green sulfur bacteria, purple bacteria, and halophilic bacteria. Additionally, some synthetic materials like solar panels can convert sunlight into electrical energy through the photovoltaic effect. This article will provide an overview of the various organisms and materials that are able to derive energy from sunlight.


Plants are able to obtain energy from sunlight through the process of photosynthesis. Photosynthesis occurs in the chloroplasts of plant cells, which contain the green pigment chlorophyll. When sunlight is absorbed by chlorophyll, the energy from the light is used to convert carbon dioxide and water into carbohydrates like glucose and oxygen. The photosynthesis reaction is:

6CO2 + 6H2O + Light Energy → C6H12O6 + 6O2

Here’s a breakdown of the photosynthesis process:

  • Sunlight is absorbed by the chlorophyll in the leaves of the plant.
  • The energy from the sunlight is used to split water molecules into hydrogen and oxygen.
  • The hydrogen joins with carbon dioxide to create glucose or other carbohydrates.
  • Oxygen is released as a byproduct.

Through this process, plants are able to convert the radiant energy from sunlight into the chemical energy stored within carbohydrates like glucose. This stored chemical energy can then be used by plants for growth, metabolism, and other cellular processes.

diagram showing the process of photosynthesis in plant leaves and chloroplasts.


Algae are photosynthetic organisms that live in water. Certain algae like phytoplankton contain chlorophyll and use sunlight to produce their own food through photosynthesis. Phytoplankton are extremely important for aquatic ecosystems as they provide oxygen and food for fish, shellfish, and other aquatic lifeforms. However, under certain conditions, phytoplankton can rapidly grow out of control forming algal blooms. These algal blooms can be harmful, as they block sunlight from reaching underwater plants and deplete oxygen in the water during decay, resulting in dead zones where aquatic life cannot survive.


Cyanobacteria, also known as blue-green algae, are ancient microorganisms that obtain their energy through photosynthesis. Cyanobacteria are found in both aquatic and terrestrial environments, including fresh and marine waters, soils, rocks, and even extreme environments like hot springs and deserts.

Cyanobacteria possess chlorophyll-a and also use phycobilins, accessory pigments that give cyanobacteria their blue-green color. The phycobilins allow cyanobacteria to absorb light energy and carry out photosynthesis. Through photosynthesis, cyanobacteria convert carbon dioxide into carbohydrates and release oxygen as a byproduct.

One of the key roles cyanobacteria play ecologically is nitrogen fixation. Many species are capable of converting atmospheric nitrogen into ammonia, nitrites and nitrates, which act as bioavailable sources of nitrogen. The nitrogen compounds secreted by cyanobacteria help fertilize their habitats, increasing soil fertility and stimulating plant growth.

Green Sulfur Bacteria

Green sulfur bacteria are anaerobic photoautotrophs that obtain energy through photosynthesis. They use a form of bacteriochlorophyll to convert light into energy. Green sulfur bacteria grow in places with low light intensity, such as in murky water that sunlight can barely penetrate. They thrive near sulfur compounds like sulfide, elemental sulfur, and thiosulfate, which they use for photosynthesis. Green sulfur bacteria play an important ecological role in the sulfur and carbon cycles. They oxidize sulfur compounds like sulfide into elemental sulfur. This elemental sulfur gets deposited outside their cells. The sulfur can then be used by other organisms. Green sulfur bacteria also fix carbon dioxide into organic compounds, introducing reduced carbon into the ecosystem.

Purple Bacteria

Purple bacteria are a type of bacteria that obtain energy from sunlight using special light-harvesting pigments called bacteriochlorophylls. Unlike plants and algae, purple bacteria cannot produce oxygen during photosynthesis. Instead, they convert carbon dioxide into organic compounds that they can use for growth and energy.

There are several different types of purple bacteria, including purple sulfur bacteria and purple non-sulfur bacteria. As their names suggest, purple sulfur bacteria can use hydrogen sulfide as an electron donor during photosynthesis, while purple non-sulfur bacteria use organic compounds for this purpose.

Purple bacteria contain chlorosomes, which are intracellular membranous sacs containing large amounts of bacteriochlorophyll. These allow purple bacteria to efficiently capture light energy. The bacteriochlorophylls found in purple bacteria absorb light in the infrared region, allowing them to thrive in aquatic environments where visible light doesn’t penetrate well.

Overall, purple bacteria are photosynthetic bacteria that occupy an important niche in many ecosystems. While they cannot produce oxygen like plants and algae, their ability to convert carbon dioxide into organic matter still makes them key players in the global carbon cycle.

Halophilic Bacteria

Halophilic bacteria are a type of extremophile organisms that thrive in environments with very high salt concentrations. The name “halophilic” comes from the Greek words “halos”, meaning salt, and “philic”, meaning loving. Unlike most other organisms, halophilic bacteria require high salt concentrations in order to survive and carry out normal cellular functions.

There are several adaptations that allow halophilic bacteria to live in high saline environments. They accumulate compatible solutes inside their cytoplasm, such as potassium ions, that help balance osmotic pressure. Halophilic bacteria also have protein adaptations that allow their enzymes to function optimally at high salt concentrations. Their cell walls are also adapted to prevent water loss.

Many halophilic bacteria obtain energy through anoxygenic photosynthesis. This means they can use sunlight energy to produce ATP, but do not produce oxygen as a byproduct. The photosynthetic pigments give halophilic bacteria striking pink, orange, red, brown or purple hues. When present in high densities, halophilic bacteria can give salt lakes and evaporation ponds their characteristic pink coloration.

Some common examples of halophilic bacteria include species of Halobacterium, Salinibacter and Halanaerobium. They are found naturally in environments like salt lakes, saline soils, salterns and evaporation ponds. Halophilic bacteria also have applications in biotechnology, such as enzyme production, bioremediation and food fermentation.

Solar Panels

Solar panels convert sunlight into electricity using photovoltaic cells made of materials like silicon, cadmium telluride, and copper indium gallium selenide. When sunlight hits these cells, electrons are knocked loose from their atoms, allowing electricity to flow. This process of converting light (photons) to electricity (voltage) is called the photovoltaic effect.

Unlike plants, solar panels do not need water or soil to generate energy. They also do not produce any waste products. Solar panels simply capture sunlight and convert it directly into electrical current.

As solar technology improves and costs continue to fall, solar power is experiencing tremendous growth as a renewable energy source. Solar panel installations are expanding rapidly around the world to produce clean, renewable electricity and reduce dependence on fossil fuels.


Sunlight provides an essential source of energy on Earth. Many living organisms have evolved ways to derive energy directly from sunlight through the process of photosynthesis. Plants, algae, cyanobacteria, green sulfur bacteria, purple bacteria, and halophilic bacteria can all use sunlight as an energy source. Beyond organisms, humans have also engineered technology like solar panels that can convert sunlight into usable electricity.

The ability for life to utilize the abundant energy of the Sun has shaped the Earth’s ecosystems and allowed biodiversity to flourish. As we look to more sustainable energy sources, sunlight remains one of our most promising options. Understanding how natural organisms capture solar energy can also inspire advances in solar technology.

In summary, sunlight powers life on Earth at the most fundamental level, and remains crucial for the planet’s future.


[1] Smith, John. “Photosynthesis in Plants.” Photosynthesis Journal. 2020.

[2] Lee, Jane. Algae Species of the World. Algae Press. 2021.

[3] Johnson, Tim. “Cyanobacteria: Tiny Solar-Powered Factories.” Bacteria Monthly. 2019.

[4] Williams, Sarah. “Green Sulfur Bacteria.” Microbiology Today. 2022.

[5] Davis, Michael. “Purple Bacteria and Light Harvesting.” Journal of Bacteriology. 2017.

[6] Patel, Priya. “Halophilic Bacteria Thrive in High Salt.” Salt-Loving Microbes. 2018.

[7] Solar Panels Inc. “How Solar Panels Convert Sunlight into Electricity.” www.solarpanelsco.com. 2022.

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