Introduction to Nutrition: Definition, Types & Importance

You have landed on the right page to learn and have an Introduction to Nutrition. Nutrition is the complex physiological and biochemical process by which every living organism obtains energy in order to support life and various metabolic activities. Food provides us with nutrition and energy which is needed for our daily work. Every person has a different requirement of nutrition and energy.

We get energy from the food we consume. Food is a vital component that provides the energy needed for growth, repair, and other life processes. All these are included in the life process called nutrition. Continue reading to know more.

What Do You Mean by Nutrition?

The life process by which the body obtains food and utilizes the nutrients present in it for growth, energy and development is called nutrition.

What are Nutrients?

Nutrients based on the amounts required in an organism can be broadly classified into two categories: macronutrients and micronutrients.

1. Macronutrients: (Macro = large) Those nutrients which are required by the body of an organism in subsequently large amounts, i.e. in grams and mainly functions to provide energy are called macronutrients. Carbohydrates, fats and proteins are examples of macronutrients. 
2. Micronutrients: (Micro = small) Those nutrients which are required by the body of an organism in trace or very small amounts, i.e. in micrograms or milligrams and mainly to maintain vital functions as well as metabolic state of a body, they are called macronutrients. Vitamins and minerals are examples of micronutrients.

Types of Nutrition

There are basically two modes of nutrition

1. Autotrophic Nutrition
2. Heterotrophic Nutrition

1. Autotrophic Nutrition

In this type of nutrition, organisms use inorganic materials and by the process of photosynthesis prepare their food in the presence of sunlight. Organisms that make their own food are called autotrophs or producers. Green plants, algae and some bacteria are autotrophs.

2. Heterotrophic Nutrition

All animals including man and non-green plants obtain their food directly or indirectly from plants. They can be divided into different categories depending on the nature of the food.

Types of Heterotrophic Nutrition

Heterotrophic organisms cannot prepare their own food as they lack chlorophyll. Some organisms derive their food by feeding on dead and decaying bodies or living in or on the bodies of other living organisms. Some organisms depend on each other and help to derive nutrition. Based on their mode of nutrition, heterotrophic nutrition can be classified as:

i) Saprotrophic Nutrition:– Organisms feeding on dead and decaying organic matter are called saprotrophs. Many fungi like Polyporus, Ganoderma, Agaricus, etc., grow on the dead woods, dead bodies, and obtain nutrition from these.

Fig: Saprotrophic Nutrition in Fungi

ii) Parasitic Nutrition:– Parasites are organisms that survive on some other organism (called the host) and harm them while obtaining nutrition. Parasites that can survive on the body of other organisms are called ectoparasites (like a head louse, ticks, Cuscuta plant).

On the other hand, endoparasites survive inside the body of other organisms (like tapeworms).
Parasitic plants develop special structures called haustoria for penetration and absorption of nutrition from the host. Balanophora and Striga are achlorophyllous plants and are total root parasites.

Fig: Parasitic Nutrition in Cuscuta

iii) Symbiotic Nutrition:– The type of nutrition in which two different organisms benefit from each other and survive by sharing shelter and food, is called symbiotic nutrition. Example: Lichens, Rhizobium (living in the root nodules of leguminous plants).
In a lichen, the algal and fungal partners help each other in surviving. The algal component of a lichen is autotrophic. It provides food material to the fungal component in the lichen. In return, the fungus provides shelter to the alga.

Fig: Symbiotic Nutrition in Lichens

iv) Holozoic Nutrition: The process of nutrition in which organisms ingest their food in solid or liquid form is called holozoic nutrition. All the vertebrates and some unicellular organisms show holozoic nutrition.

Modes of Nutrition in Animals

(i) Herbivores:– Animals that feed on plants are called herbivores or primary consumers as they get their food directly from plants.
Example: Cow, buffalo, goat, sheep, etc.

Fig: Zebra- A herbivore

(ii) Carnivores:– Animals that eat the flesh of other animals are called carnivores or secondary consumers.
Example: Tiger, wolf, lion, cheetah, leopard, etc.

Fig: Lion- A carnivore

(iii) Omnivores:– Animals that can consume both plants and animals are called omnivores. Example: Human beings, crows, etc.

Fig: Crow- An omnivore

(iv) Frugivores:– A frugivore is an animal that mostly consumes raw fruits or juicy, tender and tasty plant parts such as roots, shoots, nuts and seeds. Frugivores are highly dependent on the abundance and nutritional composition of fruits.

Fig: Monkey- A frugivore

Most of the frugivore animals help in seed dispersal for the plants. For example, when a monkey consumes fruit and throws its seed, there is a chance of the seed germinating under proper environmental conditions. This way the plant and the animals interact and remain connected.
(v) Sanguivores:–The Latin name of sanguivores is Sanguivorous Satanicus. The animals which feed on the blood of other living organisms is called sanguivores.
Example: Mosquitoes, bloodsucking spiders, vampire moths, leech, ticks, etc.

Fig: Leech- A sanguivore

Insectivorous Plants

Insectivorous plants, like the Pitcher plant, Venus flytrap, Sundew plant and Bladderwort, are considered partial heterotrophs. They grow in nitrogen-deficient soil and fulfil their nitrogen requirements by trapping small insects. They can also perform photosynthesis, as they have chlorophyll.

For example, in a Pitcher plant, the leaf lamina is modified to form a pitcher-like structure and the leaf tip is modified into a lid. When an insect happens to enter a pitcher, the lid is closed. The insects thus get trapped in the picture where it is then digested.

Fig: Insectivororous Plant

Importance of Nutrition

The process of nutrition helps us to fulfil our daily need of food and nutrients which is required for our physical and mental growth.

1. Proper nutrition promotes the growth of a baby during pregnancy.
2. It helps to maintain health and body weight.
3. It helps to fight against diseases and chronic disease leading to overall health and well-being.

Summary

Food provides us with nutrition and energy, which are attributes to the growth and development of each and every living organism. Nutrition, which is obtained from the chemicals present in food, called nutrients, manifests strength and immunity in our body. Proper nutrition helps in maintaining good health. It also protects us from chronic diseases leading to a healthy life.

Frequently Asked Questions

Q.1. Why is nutrition important in our daily life?
Ans: The process of nutrition helps us to fulfil our daily need of food and nutrients which is required for our physical and mental growth.

Q.2. What are herbivores?
Ans: Animals that feed only on plants and plant products are called herbivores.

Q.3. Why do we need food?
Ans: Food is required by the body for various purposes:
1. For energy required to perform various functions to sustain life
2. For growth
3. For repair of damaged tissue or injured body parts
4. For protection from diseases and infection
5. For maintenance of chemical composition of cells

Q.4. Is covid a parasite?
Ans: Viruses are obligate, intracellular parasites that cannot multiply without a host cell. While coronaviruses target the human body to multiply and enter our body through the nasopharyngeal route.

Q.5. What are the main 2 types of nutrition?
Ans: The two types of nutrition are (1) autotrophic nutrition and (2) heterotrophic nutrition.

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