Modes of Nutrition

Modes of Nutrition: Nutrients are chemicals that give energy and biomolecules required for the many physiological activities. Nutrients are required by all living creatures for healthy functioning and development. Nutrients are food components such as carbohydrates, vitamins, minerals, lipids, and so on. These components are required for live creatures to survive.

However, they differ in how they meet this desire. Some animals consume simple inorganic molecules to achieve their nutritional needs, whereas others consume complex compounds. The mechanism of nourishment differs between animals. Nutrition is classified into two types based on the diverse ways of nutrition in living organisms., i.e. autotrophic nutrition and heterotrophic nutrition. Continue reading the article to know more about the different modes of nutrition.

The Different Modes of Nutrition

The following are the different modes of nutrition:

1. Autotrophic Nutrition
2. Heterotrophic Nutrition

Autotrophic Nutrition

In the autotrophic mode, organisms generate food on their own using basic inorganic substances such as water and carbon dioxide in the presence of light and chlorophyll. In other terms, photosynthesis is a process that converts light energy into food, such as glucose. These creatures are known as autotrophs. We may find autotrophic nutrition in plants, algae, and bacteria (cyanobacteria).

Carbon dioxide and water are transformed into carbohydrates during photosynthesis. These carbohydrates are stored in plants as starch. Plants then use the stored starch to generate the energy they require. The photosynthetic process is divided into three stages:

1. Absorption: The process where chlorophyll present in leaves traps the light coming from the sun is known as absorption.
2. Conversion: The process where the absorbed light energy gets converted into chemical energy and water absorbed will split into hydrogen and oxygen molecules is known as conversion.
3. Reduction: The process of reduction of carbon dioxide, i.e. hydrogen molecules combine with carbon to form carbohydrates (sugar molecules), is known as reduction.

All three events are not simultaneous. They may or may not occur in that order. Stomata are the apertures on leaves where gaseous exchange occurs and are controlled by plant guard cells. Through these stomatal holes, plants absorb and expel gases.

To prevent water loss in desert-like situations, guard cells block these pores throughout the day. Later, stomata will open at night to collect carbon dioxide and store it in vacuoles. They will utilise this stored carbon dioxide to produce photosynthesis during the day.

Plants depend on soil for micro and macro constituents in addition to photosynthesis. These elements are utilised to create proteins and other essential compounds needed for the body’s correct functioning and growth.

Heterotrophic Nutrition

Not every organism is able to prepare food on its own. Such organisms rely on others for nourishment. Heterotrophs are organisms that cannot manufacture food independently and must rely on other sources/organisms. This type of feeding is referred to as heterotrophic nutrition.

Heterotrophs are categorised into the following groups based on their mode of nutrition:

• Parasites (e.g. leeches, ticks)
• Saprophytes (e.g. mushrooms)
• Holozoic (e.g. humans, dogs)

Nutrition in Plants

There are two types of nutrition in plants, i.e. autotrophic and heterotrophic nutrition:

Autotrophic Nutrition in Plants: Photosynthesis

• Plants can produce their food through the process of photosynthesis.
• The site of photosynthesis is the chloroplast.
• Food production is primarily performed in leaves. The roots absorb water and nutrients from the soil and transport them to the leaves through vessels. Carbon dioxide enters the leaves via stomata, which are tiny openings on the leaves that are bordered by guard cells.
• Chlorophyll is a green pigment found in plants that helps the leaves gather energy from sunlight to produce their meal. Photosynthesis is the process of producing food in the presence of sunshine. As a result, the sun is the primary energy source for all living species.
• During photosynthesis, carbohydrates and oxygen are produced in the presence of sunlight with the help of water and carbon dioxide.
• Photosynthesis provides food to all living beings.
• One of the main components of life, oxygen, is released on earth by plants during photosynthesis.

Heterotrophic Nutrition in Plants

Some plants lack chlorophyll and must rely on other plants for sustenance via the heterotrophic method of feeding. These kinds of plant nourishment are known as Heterotrophic nutrition in plants, and so are referred to as parasites.

Heterotrophic Plants

The following are the different types of heterotrophic plants that are classified mainly on their mode of nutrition:

• Parasitic Nutrition
• Insectivorous Nutrition
• Saprophytic Nutrition
• Symbiotic Nutrition

Parasitic Nutrition

Some heterotrophic plants get their nutrition from other plants and animals. Such plants are referred to as parasite plants. The parasite, however, does not help the host.

For eg., Cuscuta, Cassytha

Insectivorous Nutrition

Some plants, known as carnivorous or heterotrophic plants, have particular structural traits that aid in the capture of insects. These plants digest the insects and get their nutrition by secreting digestive fluids. These plants flourish on mineral-deficient soil.

For eg., Pitcher plant, Venus flytrap

Saprophytic Nutrition

Saprophytic plants obtain their food from dead and decaying plants and animals. By secreting digestive fluids and absorbing nutrients, they disintegrate dead and rotting materials.

For eg., mushrooms, moulds.

Symbiotic Nutrition

Symbiotic plants are those that have a tight relationship with another plant from a different category. Both plants benefit from each other.

For eg., the association of fungi and trees.

Nutrition in Animals

The animals’ eating habits determine animal nutrition. Ingestion is the process of taking in food. Diverse animals have different methods of intake. Bees and hummingbirds, for example, suck nectar from plants, whereas pythons devour their prey and cattle eat on the grass.

Based on their eating habits, we can classify candidates into the following groups:

Herbivores: Animals that depend upon plants and fruits for nutrition are known as Herbivores. Cows, goats, sheep, and buffaloes are some examples of herbivores.

Carnivores: Animals that depend upon other animals for food are known as Carnivores. Lion, tiger, and wolf are some examples of carnivores.

Omnivores: This group of animals consume both plants and animals. Humans, bears, dogs, and crows are some examples of omnivores.

Types of Nutrition  in Animals

The following are the different types of nutrition in animals:

1. Filter Feeding: Filter feeding is commonly found in fishes, i.e. obtaining nutrients from particles suspended in water.
2. Deposit Feeding: The process of obtaining nutrients from particles suspended In the soil. This is the mechanism of ingestion used by earthworms.
3. Fluid Feeding: Consuming other organisms’ fluids to obtain nutrients is known as fluid feeding. This mode of intake is commonly found in honey bees and mosquitos.
4. Bulk feeding: obtaining nutrients by consuming the entire organism. Example: Python.
5. Ram Feeding and Suction Feeding: consuming prey through the surrounding fluids. Aquatic predators such as bony fish are known to use this ingestion technique.

Process of Nutrition in Animals

The following steps include the process of nutrition in animals:

Ingestion: The process of taking in food is known as ingestion.

Digestion: The process of breaking down the larger food particles into smaller, water-soluble particles is known as digestion.

Absorption: The process of absorption of digested food in the bloodstream through the intestinal wall.

Assimilation: Assimilation is the process where the absorbed food is utilised for energy, growth and repair of the cells of the body.

Egestion: The process of undigested food is removed out of the body in the faeces is known as egestion.

Nutrition in Simple Animals

The following points explain the steps of consuming nutrition in simple animals:

Amoeba

• Amoeba ingests food with the help of pseudopodia.
• Through the formation of vacuole, food is engulfed and digested with the help of digestive enzymes.
• Through the process of diffusion the digested food is absorbed directly into the cytoplasm.
• Energy is obtained from the absorbed food.
• By rupturing the cell wall, the undigested food is egested out of the body of amoeba .

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