What is Nutrition?
Nutrition is the process by which living organisms obtain and utilise food to carry out vital life processes. It supplies the energy needed for growth, repair, and daily activities, making it one of the most important biological functions. The energy obtained from food fuels various cellular functions and helps organisms stay healthy and alive.
Autotrophic Nutrition
Autotrophic nutrition refers to the ability of certain organisms to produce their own food using simple inorganic substances like water and carbon dioxide. This process usually takes place in the presence of sunlight and a green pigment called chlorophyll, making [photosynthesis] the main pathway for food production in autotrophic organisms. Examples include green plants, algae, and some bacteria.
Key Stages in Photosynthesis
Light Absorption: Chlorophyll in the leaves traps sunlight.
Conversion of Energy: The light energy absorbed is converted into chemical energy, and water molecules split into hydrogen and oxygen.
Reduction of Carbon Dioxide: Hydrogen from water combines with carbon dioxide to form carbohydrates (sugars), which are then stored as starch.
Although the above steps help in understanding photosynthesis clearly, they do not always occur one after another in a strict sequence. Some organisms open or close special leaf pores called stomata at different times of the day to control the exchange of gases and conserve water.
Did you know? Some bacteria, called chemoautotrophs, synthesise their food using chemical energy (from inorganic compounds) instead of sunlight.
Heterotrophic Nutrition
Heterotrophic nutrition is found in organisms that cannot make their own food. Instead, they depend on other organisms for their nourishment. All animals, fungi, and some bacteria follow this type of nutrition. They are called heterotrophs, and they rely directly or indirectly on autotrophs for their energy needs.
Modes of Heterotrophic Nutrition
Parasitic Nutrition: Organisms live on or inside a host and derive nutrients at the host’s expense. Examples include ticks, tapeworms, and leeches.
Saprophytic Nutrition: Organisms feed on dead and decaying matter, secreting digestive enzymes onto it and then absorbing the nutrients. Fungi, such as mushrooms, follow this type.
Holozoic Nutrition: Organisms ingest solid or liquid food and then carry out digestion, absorption, and assimilation. Amoeba and humans exhibit holozoic nutrition by taking in complex substances and breaking them down into simpler ones.
Mode of Nutrition in Plants
Most plants show an autotrophic nutrition pattern, using sunlight, water, and carbon dioxide to make glucose. However, a few plants have additional or modified methods:
Insectivorous Plants (e.g., Pitcher Plants, Venus Flytraps): They trap insects to supplement their nitrogen requirements.
Parasitic Plants (e.g., Cuscuta or Dodder): They absorb nutrients directly from the host plant’s tissues.
In general, the mode of nutrition in plants remains primarily autotrophic, as they possess chlorophyll and carry out photosynthesis to produce their food.
Blue-Green Algae (Cyanobacteria)
Blue-green algae can be autotrophs, heterotrophs, or a mix of both (mixotrophs). Some species perform photosynthesis like plants, whereas others can switch to a heterotrophic mode if conditions require.
Quiz Time!
Test your understanding of modes of nutrition class 10 with the following questions:
1. Which type of nutrition involves an organism producing its own food using sunlight?
Answer: Autotrophic nutrition.
2. Name a mode of heterotrophic nutrition where organisms feed on dead organic matter.
Answer: Saprophytic nutrition.
3. Which structure in plant leaves mainly controls the exchange of gases during photosynthesis?
Answer: Stomata.
4. Give one example of an organism that shows holozoic nutrition.
Answer: Amoeba (humans also exhibit holozoic nutrition).
Related Topics
FAQs on Nutrition in Living Organisms: An Essential Life Process
1. Why is nutrition essential for all living organisms?
Nutrition provides the energy required for the growth, development, and maintenance of normal bodily functions. It also helps in repairing damaged tissues and supporting metabolic processes.
2. Are there organisms that can use both autotrophic and heterotrophic nutrition?
Yes. These organisms are called mixotrophs. Euglena is a common example, as it can photosynthesise in the presence of light and also switch to a heterotrophic mode if necessary.
3. What is the main difference between autotrophic and heterotrophic nutrition?
Autotrophic nutrition involves making food from simple inorganic substances (like carbon dioxide and water), while heterotrophic nutrition requires organisms to rely on other living or dead organisms for their food.
4. How do desert plants adapt their photosynthesis process to reduce water loss?
Many desert plants open their stomata at night to take in carbon dioxide and store it. This helps them conserve water during the hot daytime.
5. Can fungi carry out photosynthesis?
No. Fungi are heterotrophic. They lack chlorophyll and depend on dead or decaying organic matter or living hosts to obtain nutrients.
