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NCERT Class 10 Science Textbook Chapter 6 With Answer PDF Free Download
Chapter 6: Life Processes
How do we tell the difference between what is alive and what is not alive? If we see a dog running, a cow chewing cud, or a man shouting loudly on the street, we know that these are living beings.
What if the dog or the cow or the man were asleep? We would still think that they were alive, but how did we know that? We see them breathing, and we know that they are alive.
What about plants? How do we know that they are alive?
We see the green, some of us will say. But what about plants that have leaves of colors other than green? They grow over time, so we know that they are alive, some will say.
In other words, we tend to think of some sort of movement, either growth-related or not, as common evidence for being alive.
But a plant that is not visibly growing is still alive, and some animals can breathe without visible movement. So using visible movement as the defining characteristic of life is not enough.
Movements over very small scales will be invisible to the naked eye – movements of molecules, for example. Is this invisible molecular movement necessary for life?
If we ask this question to professional biologists, they will say yes. In fact, viruses do not show any molecular movement in them (until they infect some cells), and that is partly why there is a controversy about whether they are truly alive or not.
Why are molecular movements needed for life? We have seen in earlier classes that living organisms are well-organized structures; they can have tissues, tissues have cells, cells have smaller components in them, and so on.
Because of the effects on the environment, this organized, ordered nature of living structures is very likely to keep breaking down over time.
If order breaks down, the organism will no longer be alive. So living creatures must keep repairing and maintaining their structures. Since all these structures are made up of molecules, they must move molecules around all the time. What are the maintenance processes in living organisms?
6.1 What Are Life Processes?
The maintenance functions of living organisms must go on even when they are not doing anything particular.
Even when we are just sitting in class, even if we are just asleep, this maintenance job has to go on. The processes which together perform this maintenance job are life processes.
Since these maintenance processes are needed to prevent damage and breakdown, energy is needed for them. This energy comes from outside the body of the individual organism.
So there must be a process to transfer a source of energy from outside the body of the organism, which we call food, to the inside, a process we commonly call nutrition.
If the body size of the organisms is to grow, additional raw material will also be needed from outside.
Since life on earth depends on carbon-based molecules, most of these food sources are also carbon-based. Depending on the complexity of these carbon sources, different organisms can then use different kinds of nutritional processes.
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NCERT Solutions Class 10 Science Chapter 6 Life Processes
1. Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?
Multi-cellular organisms like humans have very big bodies and require a lot of oxygen to diffuse into the body quickly in order to meet the oxygen requirement. Diffusion is a slow process which will take a lot of time to circulate oxygen to all the body cells. Because of its slow nature diffusion is insufficient to meet the oxygen requirements of multicellular organisms like humans.
2. What criteria do we use to decide whether something is alive?
Walking, breathing, growth, and other visible changes can be used to determine whether something is alive or dead.
However some living things will have changes that are not visible to our eye; Hence, the presence of the life process is a fundamental criterion to decide whether something is alive.
3. What are outside raw materials used by an organism?
The outside raw material is used by organisms for food and oxygen. Raw material’s requirement varies on the complexity of the organism and the environment it is living.
4. What processes would you consider essential for maintaining life?
Life processes such as respiration, digestion, excretion, circulation, and transportation are essential for maintaining life.
5. How is food transported in plants?
Food is transported in plants by a special organ called phloem. Phloem transports food materials from leaves to different parts of a plant.
Transportation of food in phloem is achieved by the expenditure of energy from ATP. This increases osmotic pressure in the tissue causing water to move.
This pressure moves material in the Phloem to the tissues with less pressure. This is helping in the transportation of food materials as per the needs.
Life Processes NCERT Textbook With Solutions PDF Free Download