Several biological processes are essential for maintaining life in organisms. These processes are fundamental to the survival, growth, and reproduction of all living beings. The key life-sustaining processes include:

Nutrition and Respiration

Nutrition: The process of obtaining food and converting it into substances that can be assimilated by the body. Nutrition provides the energy and materials necessary for growth, repair, and energy production. It includes ingestion, digestion, absorption, and AssimilationAssimilation in biology refers to the process where living organisms integrate nutrients from their environment into their own bodies. It involves the conversion of food and nutrients into cellular components, essential for growth, energy, and repair. This process is a key part of metabolism in all living organisms. of food.

Respiration: This is the process of breaking down food, often with the use of oxygen, to release energy. This energy is vital for various cellular activities. Respiration can be aerobic (with oxygen) or anaerobic (without oxygen).

Excretion and Circulation

Excretion: The removal of metabolic waste products from an organism’s body. Excretion is crucial for maintaining a stable internal environment (HomeostasisHomeostasis is the process by which living organisms maintain a stable internal environment despite changes in external conditions. It involves regulating factors like temperature, pH, and electrolyte balance to ensure optimal functioning of cells and organs. This balance is crucial for health and survival in varying environmental conditions.) and preventing the accumulation of harmful substances.

Circulation: The transport of nutrients, gases (like oxygen and carbon dioxide), waste products, and other substances to and from cells. In complex organisms, this is carried out by the circulatory system, which includes the heart, blood, and blood vessels.

Growth and Reproduction

Growth: An increase in size and mass of an organism over time. Growth involves the synthesis of new materials and an increase in cell size and/or cell number.

Reproduction: The biological process by which new individual organisms are produced. Reproduction can be sexual or asexual and is essential for the continuation of a species.

Response to Stimuli
The ability to sense and respond to changes in the environment. This includes responses to physical, chemical, and biological stimuli, which are crucial for survival and adaptation.


The regulation of the internal environment to maintain a stable, constant condition, despite changes in the external environment. This includes regulation of temperature, pH, hydration, and other physiological parameters.

Cellular Organization and Adaptation

Cellular Organization: Maintenance of cellular structure and function is fundamental to life. This includes various cellular processes like protein synthesis, DNA replication, and cell division.

Adaptation: The process by which an organism becomes better suited to its habitat. AdaptationsAdaptations are traits or behaviors that evolve in living organisms, enabling them to survive and reproduce in their specific environments. These can be physical, like the camouflage of a chameleon, or behavioral, like birds migrating to warmer climates. Adaptations result from the evolutionary process of natural selection. can be structural, behavioral, or physiological and occur over generations through evolution.

These processes are interrelated and collectively ensure the survival, development, and reproduction of living organisms. The absence or malfunctioning of any of these processes can affect an organism’s health and its ability to sustain life.

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List of Questions of Class 10 Science Chapter 5

Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?
What criteria do we use to decide whether something is alive?
What are outside raw materials used for by an organism?
What processes would you consider essential for maintaining life?
What are the differences between autotrophic nutrition and heterotrophic nutrition?
Where do plants get each of the raw materials required for photosynthesis?
What is the role of the acid in our stomach?
What is the function of digestive enzymes?
How is the small intestine designed to absorb digested food?
What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?
What are the different ways in which glucose is oxidised to provide energy in various organisms?
How is oxygen and carbon dioxide transported in human beings?
How are the lungs designed in human beings to maximise the area for exchange of gases?
What are the components of the transport system in human beings?
Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?
What are the components of the transport system in highly organised plants?
How are water and minerals transported in plants?
How is food transported in plants?
Describe the structure and functioning of nephrons.
What are the methods used by plants to get rid of excretory products?
How is the amount of urine produced regulated?
How are fats digested in our bodies? Where does this process take place?
What is the role of saliva in the digestion of food?
What are the necessary conditions for autotrophic nutrition and what are its byproducts?
What are the differences between aerobic and anaerobic respiration?
How are the alveoli designed to maximise the exchange of gases?
What would be the consequences of a deficiency of haemoglobin in our bodies?
Describe double circulation of blood in human beings. Why is it necessary?
What are the differences between the transport of materials in xylem and phloem?
Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.

Last Edited: November 16, 2023