What Makes Autotrophs Essential for Life on Earth?
Autotrophs often refer to organisms that prepare their own food. Autotrophs can prepare their food either by using light, chemicals, water, carbon dioxide or any other component of the environment. Organisms that produce their own food are known as autotrophs and since due to their this property they are referred to as producers. Producers produce their food either by chemicals, light etc. Producers produce their own food by a popular profession known as photosynthesis. Photosynthesis is the process by which plants or other green organisms prepare their own food by using the sunlight.
Plants are the most common type of autotrophs but if we talk about other autotrophic animals there can be many such as green algae, which lives in water. These algae when together in large form are known as seaweeds, phytoplankton and some bacteria are also some type of autotrophs. They can be either photoautotrophs or chemoautotrophs.
If we talk about photoautotrophs then they use the process of photosynthesis in which energy of sunlight is used to prepare food or glucose from the carbon dioxide from air and water from the soil. All plants whether they are shrubs, fir, trees, mosses or algae they all are the photoautotrophs that prepare their food by using energy from the sun.
Saying about chemoautotrophs, they prepare their food by chemosynthesis. Such autotrophs do not produce their food from the sunlight but from the chemicals. These autotrophs survive in an extremely toxic environment. Often when there is a combination of hydrogen sulphide or methane with oxygen food is produced by them. In such a dictionary extremely toxic chemicals are needed for oxidation. Let us take an example of bacteria that live in volcanoes. In volcanoes Sulphur is oxidised to produce their own food. Bacteria that live in extremely deep oceans are also chemoautotrophs.
Beside this there are organisms that are dependents on other organisms or on these autotrophs that prepare their own food that is they just get good from autotrophs and cannot prepare their own food like autotrophs. Further details about the autotrophs you will get from this article. In this article you will get information about autotrophs, importance of these autotrophs, further details about their types, examples of autotrophs and what is the Difference between the autotrophs and heterotrophs . Beside this at the end toys are provided with frequently asked questions that will help to clear most of your queries. Vedantu has specially designed this article for your help to understand autotrophs well.
The organisms in an ecosystem that act as primary producers in a food chain are known as autotrophs. Their major source of energy is harnessed from sunlight through the photosynthesis process, because of this reason they are also known as photoautotrophs. Along with that they also obtain their energy through the oxidation process and because of that they are known to be chemoautotrophs. Through chemical processes, they make organic substances into an inorganic form. One of the major features of autotroph is that they do not consume other organisms as consumed by heterotrophs. In the word ‘autotrophs’, ‘auto’ means self and ‘troph’ means food i.e. they are the organism which feeds itself, without taking assistance of any other organism.
Importance of Autotrophs
Autotrophs have their own specific importance in society, as without them no other life form can exist in society. Plants are the one which create sugar by taking carbon dioxide, gas and sunlight by the process called photosynthesis. Because of this reason, they are called producers. They form the base for the formation of higher ecosystems i.e. they act as a base for energy pyramids and also provide fuel to heterotrophs.
From this, we can say that the first life on earth must be an autotroph. Heterotrophs are further evolved from autotrophs.
Types of Autotrophs
On the basis of the process of obtaining energy, autotrophs are classified into two types, they are:
Photoautotrophs
These are the organisms that obtain their energy from sunlight to make organic material. Examples of autotrophs are plants, green algae, and bacteria which perform photosynthesis. All of these photoautotrophs perform photosynthesis to make their food. In photosynthesis, the word photo means light and synthesis means to prepare or to make. In this process, organisms capture sunlight and use their energy to perform important biochemical processes such as making ATP. The amount of fuel or energy prepared by photoautotrophs is more than any other organisms like heterotrophs.
Whereas some photoautotrophs take carbon from the atmosphere and use this carbon for preparing sugar and other molecules that store the Sun’s energy in their molecular bonds.
Chemoautotrophs
These are the organisms that obtain their energy from inorganic chemical processes. They are majorly found in deep water where the source of sunlight is almost negligible. For obtaining energy they use volatile chemicals such as molecular hydrogen, hydrogen sulphide, elemental sulphur, ferrous iron, and ammonia as their energy sources.
Examples of Autotrophs
Some of the common examples of autotrophs are:
A.Plants
B.Algae- Green algae and red algae
C.Bacteria such as cyanobacteria
D.Lichens located in the tundra region are autotrophic in nature as they are considered to be primary producers as they undergo mutualism and combine photosynthesis by algae.
Different Terms Related to Autotrophs
A. Energy Pyramid – It is a structure that explains the flow of energy in different organisms.
B.Heterotroph – These are organisms that are dependent on another organism for food. Example: animals like Goat, Lion etc.
C.Photosynthesis – In this process phototrophs do the extraction of energy from sunlight.
Difference Between Autotrophs and Heterotrophs
MCQ Questions
1. From the options below, which of the following is not an example of photoautotrophs?
A. Daisies
B. Iron bacteria
C. Cyanobacteria
D. None of the above.
Ans: Iron bacteria
2. Which of the following organisms first appeared on the earth surface?
A. A photoautotroph.
B. A chemoautotroph.
C. Neither of the above.
D. No one knows.
Ans: Neither of the above
FAQs on Autotrophs: Meaning, Types, and Importance
1. What are autotrophs?
An autotroph is an organism that can produce its own food using simple substances from its surroundings, such as light, water, and carbon dioxide. Because they create their own nourishment, they are known as producers in the food chain. All food chains on Earth begin with autotrophs. Plants, algae, and some types of bacteria are the most common examples.
2. What are the main types of autotrophs?
Autotrophs are primarily categorised into two types based on the energy source they use:
Photoautotrophs: These organisms harness light energy to create food through a process called photosynthesis. They convert inorganic materials like carbon dioxide and water into energy-rich organic compounds like glucose. Examples include all green plants, cyanobacteria, and algae.
Chemoautotrophs: These organisms use energy from chemical reactions to make their food, a process called chemosynthesis. They oxidise inorganic substances such as hydrogen sulfide, ammonia, or iron to generate energy, and do not need sunlight. Examples include nitrifying bacteria and sulphur bacteria found in deep-sea vents.
3. What is the difference between autotrophs and heterotrophs?
The main difference between autotrophs and heterotrophs is their method of obtaining energy. Autotrophs are self-feeders that produce their own food through photosynthesis or chemosynthesis. They are the producers of an ecosystem. In contrast, heterotrophs are 'other-feeders' that cannot synthesise their own food and must consume other organisms for energy. Animals, fungi, and most bacteria are examples of heterotrophs, acting as consumers or decomposers.
4. What are some common examples of autotrophs?
Autotrophs are diverse and essential to life. Common examples include:
Plants: Nearly all plants, from tiny mosses to giant redwood trees, are photoautotrophs.
Algae: This group includes phytoplankton, seaweeds, and kelp, which are major producers of oxygen.
Cyanobacteria: Often called blue-green algae, these bacteria perform photosynthesis.
Chemosynthetic Bacteria: This includes bacteria like Nitrosomonas and Nitrobacter in the soil, which are vital for the nitrogen cycle.
5. Why is photosynthesis so important for autotrophs?
Photosynthesis is the fundamental process by which photoautotrophs convert light energy into chemical energy stored in glucose molecules. This glucose serves as their food, fuelling all metabolic activities, including growth and reproduction. Essentially, it is how they feed themselves. A critical byproduct of this process is oxygen, which is released into the atmosphere and is essential for most life on Earth, including humans.
6. Are mushrooms and other fungi considered autotrophs?
No, mushrooms and other fungi are not autotrophs; they are heterotrophs. Specifically, they are saprotrophs. They cannot perform photosynthesis because they lack chlorophyll. Instead, they obtain nutrients by secreting digestive enzymes onto dead organic matter (like fallen leaves or logs) and then absorbing the broken-down molecules. This makes them essential decomposers in the ecosystem, not producers.
7. How do chemoautotrophs make food without sunlight?
Chemoautotrophs thrive in environments devoid of sunlight by using a process called chemosynthesis. Instead of light energy, they harness chemical energy released from the oxidation of inorganic molecules present in their environment, such as hydrogen sulfide, methane, or ammonia. This captured energy is then used to fix carbon dioxide into organic compounds (food), powering their life processes in a way analogous to photosynthesis.
8. Can an organism be both an autotroph and a heterotroph?
Yes, some fascinating organisms known as mixotrophs can function as both autotrophs and heterotrophs. For example, Euglena, a single-celled protist, performs photosynthesis in the presence of light but can absorb nutrients from its environment in the dark. Similarly, carnivorous plants like the Venus flytrap are photosynthetic but supplement their nutrient intake by trapping and digesting insects, which is a heterotrophic behaviour, especially in nutrient-poor soils.
9. Where are chemoautotrophs typically found in the real world?
Chemoautotrophs are masters of survival in extreme environments. They are commonly found in locations such as:
Deep-Sea Hydrothermal Vents: They form the base of entire ecosystems, using chemicals like hydrogen sulfide from the vents as an energy source.
Soil and Water: Nitrifying bacteria play a crucial role in the nitrogen cycle by converting ammonia into nitrates, making nitrogen available to plants.
Caves and Hot Springs: Bacteria in these locations can derive energy from iron, sulfur, or other minerals.
10. Why are plants classified as photoautotrophs and not chemoautotrophs?
Plants are classified as photoautotrophs because their entire energy-production system is based on capturing sunlight. They contain the pigment chlorophyll in specialised organelles called chloroplasts, which are specifically adapted to absorb light energy. This light energy drives the process of photosynthesis. Plants lack the metabolic machinery to extract energy from inorganic chemical compounds, which is the defining feature of chemoautotrophs.
