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Life Processes

Autotrophic Nutrition in plants (Group B)

We know that all living organisms require food to survive. Organisms consume nutrients, which enable them to carry out various body functions.

Nutrition is the process in which an organism consumes food, which is then utilized by the body.

Modes of nutrition

Autotrophic Nutrition: The term ‘autotroph’ is derived from the Greek word ‘Auto’ meaning self and ‘trophos’ meaning nutrition.

In this mode of nutrition, organisms prepare or synthesize their own food with the help of inorganic raw materials. These organisms are known as autotrophs. All green plants and some bacteria are autotrophs.

Heterotrophic Nutrition: The term ‘heterotroph’ is derived from the Greek words ‘Heteros’ meaning different or other, and ‘trophos’ meaning nutrition.

In this mode of nutrition, organisms obtain energy from the intake of complex organic substances, generally from plant and animal sources. These organisms are known as heterotrophs. All fungi and animals and some bacteria are heterotrophs. 

Let us study about various types of heterotrophs.

Herbivores: These are the animals that feed directly on plants. For example, cow, goat, rabbit etc.

Carnivores: The animals that feed on herbivores are known as carnivores. For example, tiger, lion etc.

Omnivores: This includes the animals which eat both plants and animals. For example, humans etc.

Saprophytes: These are the organisms that feed on dead and decayed organic matter. For example, bacteria, mushroom etc.

Parasites: These are the organisms that live inside or on the body of other living organisms called the Host and obtain food from them. For example, Cuscuta plant that obtains food from green plants, Ascaris that lives in the intestine of humans etc.

Insectivorous plants: Some plants live in the areas where the soil is deficient in nitrogen. These plants trap insects and obtain nitrogen from them. These plants are called as insectivorous plants

Summary of differences between autotrophs and heterotrophs

Autotrophs

Heterotrophs

They obtain energy by preparing food from inorganic substances such as CO2 and water in the presence of sunlight.

They obtain energy from complex organic substances by consuming plants or other animals.

These organisms are called producers as they manufacture their own food.

These organisms utilize the food manufactured by producers. Hence, they are called consumers.

Green plants, algae are autotrophs.

Animals and fungi are heterotrophs.

Do You Know?

  • Plants do not always have an autotrophic mode of nutrition. They can be parasitic, carnivorous, or saprophytic.

  • Rafflesia is a root parasite. It draws water and minerals from the roots of other plants.

  • Cats are purely obligate carnivores. They cannot digest fruits, vegetables, pulses, grains etc. They need a high level of protein in their diet. They lack an efficient system for digesting plant products. A cat’s digestive system is specialized to suit a carnivorous eating habit.

We know that all living organisms consume some form of nutrients to sustain life. Animals consume plants or other animals. Plants consume carbon dioxide and water from the environment to produce food.

Therefore, the process of taking in a source of energy (food) from outside the body of an organism to inside is known as nutrition.

Do you know what mode of nutrition is carried out in plants? Plants have an autotrophic mode of nutrition. The term ‘autotrophic’ is derived from the Greek word ‘Auto’ meaning self and ‘troph’ meaning nutrition.

In this mode of nutrition, plants prepare or synthesize their own food with the help of inorganic raw materials. Thus, they are known as autotrophs.

Let us explore how plants prepare their own food.

Photosynthesis

Energy is essential for all life processes. All living organisms require nutrition. What is the ultimate source of nutrition on Earth?

The sun is the ultimate source of energy on Earth. Energy from the sun is captured by plants and converted into usable form. Thus, the origin of all foods is the food prepared by plants. This food is also consumed by animals.

Autotrophs such as green plants and some bacteria prepare or synthesize their own food. They are capable of trapping solar energy with the help of a green pigment called chlorophyll. This trapped solar energy is then converted into chemical energy of food using CO2 and H2O.

Photosynthesis is the process by which chlorophyll-containing cells present in leaves synthesize food in the form of carbohydrates by using carbon dioxide, water and sunlight.

Therefore, the raw materials required for photosynthesis are CO2 and H2O and the products formed are carbohydrates and O2.

Hence, the process can be represented as:

Let us discuss the raw materials required for photosynthesis.

How are raw materials consumed by plants?

The raw materials required for photosynthesis are CO2 and H2O and the products formed are carbohydrates and O2.

Entry of raw materials

  • Plants obtain water through their roots. Water is then transported to all plant parts with the help of the xylem.
  • Exchange of gases (entry of CO2 and release of O2) occurs through the stomata.

Stomata are tiny pores present mainly on the surface of leaves. They are also present on the surface of young stems and roots.

Stomata consist of a stomatal opening or stoma, which is surrounded by two distinct epidermal cells known as guard cells. The opposing inner walls of the guard cells are thick and inelastic. The remaining walls are thin and elastic.

How do plants control the opening and closing of the stomata?

Two phases of photosynthesis

The process of photosy...

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