Introduction to Life Processes: Let us get an introduction to Life Processes here. The planet on which we live comprises of living things and non-living things. Interactions between the living and non-living are essential to maintain the ecological balance on the Earth. But, How do we know that certain things are living while others are non-living?

Living things are made up of cells and have a fixed lifespan. During their lifespan, they perform various functions for their existence on the Earth. These functions are called Life Processes. In contrast, non-living things do not perform life-sustaining functions. Humans, plants, animals, and microorganisms perform a few essential life processes in common. Read this article to learn what are life processes and know about the importance of life processes.

What are Life Processes? An Overview

Definition: The most basic question of Science is what are life processes. Life processes are the vital functions of living organisms that are necessary for the maintenance and continuation of life.
Physiology is the branch of biology that is concerned with the life processes of an organism and the functions of different organs and tissues.

Common Types of Life Processes

There are the following life processes or physiological activities that are performed by living beings. Knowing these types of life processes are essential to understanding what are life processes:

1. Nutrition
2. Respiration
3. Transportation
4. Excretion
5. Reproduction
6. Growth

Nutrition in Organisms

Nutrition is the process of intake of food (nutrients) to provide energy for several physical and physiological activities. A healthy diet contains all the essential nutrients in sufficient amounts.

1. Carbohydrates and fats are energy-giving foods.
2. Proteins are body-building foods that contribute to growth. 
3. Small quantities of Minerals and vitamins contribute to a disease-life. Therefore these are called protective foods.

Comparison between Nutrition in Plants & Humans

Nutrition in Plants	Nutrition in Humans
Plants exhibit the autotrophic mode of nutrition. They synthesise their food through the process of photosynthesis.	Human beings cannot prepare their food and exhibit a heterotrophic mode of nutrition.
The process of photosynthesis involves the synthesis of glucose (sugar) from carbon dioxide and water in the presence of sunlight. The energy released during this process is utilised by plants.	Nutrition in humans involves ingestion, digestion, assimilation, absorption, and egestion. Since food is wholly engulfed and digested inside the alimentary canal, therefore, it is termed holozoic nutrition.
Leaves and herbaceous stems are the sites of photosynthesis.	Humans have an alimentary canal and associated glands (liver, pancreas) for the digestion of food.

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Fig: Nutrition in Plants & Humans

Saprophytic and parasitic are two other modes of heterotrophic nutrition most often exhibited by fungi, worms, and microorganisms. Saprophytes feed on dead and decaying plant and animal parts. Parasites derive nutrition from the host.

Respiration in Organisms

Respiration is a biochemical process. It involves the breakdown of nutrients for the liberation of energy. Oxygen is usually required for respiration. The word equation for respiration is summed up as follows:
Glucose + Oxygen ? Carbon dioxide + Water + Energy (ATP)
Respiration takes place in all living cells all of the time because cells need a constant supply of energy to stay alive. Respiration can be classified based on the presence and absence of oxygen. These are named aerobic respiration and anaerobic respiration.

1. Aerobic respiration is the oxidative breakdown of food. It occurs in all complex organisms, including plants and animals. The energy released is relatively more than anaerobic respiration.
   C₆H₁₂O₆ + 6O₂ ? 6CO₂ + 6H₂O + 38 ATP
2. Anaerobic respiration involves the breakdown of food in the absence of oxygen and releases a small amount of energy. Yeast and some bacteria undergo anaerobic respiration. This can be summed up in the below-mentioned equation:
   C₆H₁₂O₆ ? 2C₂H₅OH + 2CO₂ + 2 ATP
3. Our body cells might also exhibit anaerobic respiration during strenuous exercises and physical labour.
   C₆H₁₂O₆ ? 2C₃H₆O₃ (lactic acid) + 2CO₂ + 2ATP

Comparison between Respiration in Plants & Humans

Respiration in Plants	Respiration in Humans
Plants lack a highly organised respiratory system.	Humans have a respiratory system that consists of a pair of lungs and air tubes (trachea, bronchi).
The oxygen diffuses through the root hairs, lenticels, and stomata, respectively, in roots, stem, and leaves.	The O2 inhaled during breathing reaches the alveoli in the lungs and then diffuses into the blood capillary that surrounds the alveoli.
The carbon dioxide is released into the atmosphere through the same structures.	On the contrary, CO2 diffuses from the body cells into capillaries and then into alveoli for exhalation.
Gaseous transport occurs through simple diffusion.	Gaseous transport to and away from the body cells occurs through blood.
Respiration in plants occurs at a slow rate.	Respiration in humans and animals is relatively fast.

Fig: Respiration in Plants & Human

Transportation in Organisms

Complex organisms like plants and humans have highly organised body structures. Each cell requires food, oxygen, and water for its vital activities, and hence leads to the life sustainability of an organism. Oxygen, water, food, and other substances may be picked up at one end of the body. Thus, transportation is a life process in which the substances synthesised or released in one part are moved to the other part of the body. The transport system in the plant is less elaborate than in humans and other complex animals.

Comparison between Transport in Plants & Animals

Transport in Plants	Transport in Animals
Transport in plants takes place through a vascular tissue system that comprises the xylem and phloem.	Transport in animals takes place through the blood circulatory system that comprises blood, heart, and blood vessels.
Xylem transports water and mineral nutrients in an upward direction. (from roots to other parts of the plant). Phloem transport food in the downward direction (from leaves to roots and stem)	In humans, blood serves as a transport medium for nutrients, respiratory gases, enzymes, hormones, metabolic wastes. Digested food is absorbed from the villi into the blood capillaries and reaches the body cells.
Gases (oxygen & carbon dioxide) can be directly diffused into plant cells, hence do not require any transport medium.	1. Heart receives oxygenated blood from the lungs through pulmonary veins and pumps to body organs through arteries. 2. The deoxygenated blood is carried to the heart through the vena cava and supplied to the lungs through the pulmonary artery for oxygenation. Hence, blood serves as the medium of gaseous transport to the target organ.

Fig: Transport in Humans & Plants

Excretion in Organisms

Excretion is the process of removal of toxic metabolic wastes from the body. Different organisms excrete through different processes depending on their body complexity. Simple and unicellular organisms excrete their wastes through the body surface. If the metabolic wastes get accumulated in the body, it slows down the other life processes and hence adversely affects the health of living beings. The process of excretion is simple and slow in plants compared to humans.

Comparison between Excretion in Plants & Humans

Excretion in Plants	Excretion in Humans
Plants do not have specific organs for excretion. The excretion takes place through the stomata of leaves, lenticels of the stem, and roots.	Humans have a well developed urinary system for the excretion of nitrogenous wastes. A pair of kidneys are involved in the formation of urine. The urine reaches the urinary bladder through the ureters and is excreted out through the urethra.
Gaseous wastes produced by plants are carbon dioxide, water vapour, and oxygen. These are released through stomata and lenticels.	Gaseous wastes produced by humans are water vapour and carbon dioxide. These are released through the lungs.
Solid metabolic wastes are removed by the shedding of leaves, peeling of bark, and falling of fruits.	Skin also serves as an excretory organ as it releases sweat and sebum from the glands.
Gums, Resins, essential oils are the main excretory products.	Ammonia, uric acid, and urea are the main excretory products.

Fig: Excretion in Plants & Humans

Reproduction in Organisms

Reproduction is the biological process in which new individuals of the same kind are produced from the parent and ensure the perpetuation of the same species. This process ensures the continuity of life on Earth. Based on the parents involved, reproduction is of two types, namely, asexual reproduction and sexual reproduction. Asexual reproduction involves either of the parents for the production of offspring. This type of reproduction is exhibited by primitive animals such as Amoeba, Planaria, Hydra, etc. Some plants like Bryophyllum, potatoes, etc., also reproduce asexually. Humans exhibit a sexual mode of reproduction.

Comparison between Reproduction in Plants & Humans

Reproduction in Plants	Reproduction in Humans
Plants reproduce asexually (through vegetative parts) as well as sexually.	Humans reproduce through sexual means.
Plants have flowers as organs of sexual reproduction. Stamens are the male reproductive part, and the pistil is the female reproductive part of a flower.	Humans have ovaries and testes as primary reproductive organs, respectively, in females and males.
Flowers can be unisexual or bisexual. They produce either pollen grains (containing male gametes) or ovules (containing female gametes), or both based on sexuality.	Ovaries produce non-motile eggs in females, and testes produce motile sperms in males.
Fertilisation of male and female gametes is assisted by pollinating agents. A process of double fertilisation leads to the formation of an embryo and endosperm. The embryo develops seeds, and the endosperm provides nutrition to the developing seed.	Fertilisation occurs in the fallopian tube and leads to the formation of a zygote and further proceeds with embryonic development.

Fig: Reproduction in Humans & Plants

Growth in Organisms

Growth is one of the characteristics of living beings that refers to the permanent increase in the dry mass and the size of the organism. All living beings are made up of cells. Cells undergo the process of cell division and therefore contribute to the growth of the organ and organisms.

1. Our body cells exhibit mitosis that contributes to the growth and replacement of damaged cells.
2. Reproductive cells exhibit meiosis that restores the number of chromosomes in the zygote (fertilised cell of sexual reproduction) and contributes to the variations in living beings by the exchange of sister chromatids in a pair of homologous chromosomes.

Comparison between Growth in Plants & Humans

Growth in Plants	Growth in Humans
Growth in plants continues throughout the lifespan.	Growth in humans and other animals stops at a certain age.
Growth in plants is localised to certain regions such as roots, stem, buds, etc.	Growth in humans is diffused that leads to the overall increase in the size and mass of the body.

Fig: Growth in Plants & Human

Importance of Life Processes

Life processes are of great importance in sustaining life on the planet. The major significance of different life processes are described below:

1. Nutrition in living organisms promotes a healthy and disease-life by maintaining the proper functioning of different organs and organ systems.
2. Respiration is essential to provide energy to each and every cell for performing vital activities.
3. Transport of substances is essential to fulfil the requirement of essential substances within the body of an organism.
4. Excretion is essential for the elimination of toxic substances, thereby regulating water content, \(pH\) of body fluids, etc.
5. Reproduction ensures the continuity of different life forms on the Earth.
6. Growth contributes to the replacement of damaged cells and tissues by promoting cell division and cell differentiation.
7. The life processes of living things are fundamental to their survival.

Summary

Living organisms exhibit various characteristics which distinguish them from non-living things. The overall functioning of different body organs and organ systems contribute to the survival of life. The functioning of different organs and organs systems that support the life of organisms are called life processes. Nutrition, respiration, transportation, excretion, reproduction are the main life processes performed by every living being to ensure its survival on the Earth.

FAQs

Q.1: What is life, and what are life processes?
Ans: Life is described as certain aspects of living beings that separate them from dead matter. The functions that are essential to maintain life are called life processes.

Q.2: What are the five examples of life process?
Ans: Nutrition, respiration, transportation, excretion, and reproduction are the example of life process life processes, and they are essential to sustain life.

Q.3: What are the two types of nutrition?
Ans: Autotrophic and heterotrophic are the two types of nutrition.

Q.4: What are the two types of respiration?
Ans: On the basis of the presence and absence of oxygen, respiration is classified as aerobic respiration and anaerobic respiration.

Q.5: What are the two types of transportation in plants?
Ans: Plants show the following two types of transportation:
1. Transport of water and minerals through the xylem.
2. Transport of food substances through the phloem.

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