NCERT Class 10 Science Chapter 6 Notes Life Processes- Download PDF Notes

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The chapter Life Processes covers important topics like nutrition, respiration, transportation, and excretion in plants and animals. To revise faster and save time during exam prep, students can download the NCERT notes for class 10 Science chapter 5 PDF. This PDF is perfect for offline study and quick revision. The NCERT Notes for Class 10 Science explain each process step-by-step.

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Life Processes Class 10 Notes

It is interesting to see that even a small organism like an amoeba has to eat, breathe, and remove waste just like us. In the Life Processes Class 10 Notes, these life processes are explained simply. It helps to understand how our own body works every day to keep us alive. The notes for the chapter are given below for your better understanding:

What Are Life Processes?

• In a living body, energy is supplied by food. It can be categorised as a carbon source.

• The food source has to be broken up into smaller molecules in the body to derive energy.

• This whole process of deriving energy from food particles is known as nutrition.

• Also, for carrying out nutrition, various oxidising and reducing chemical reactions take place in our body. This involves oxygen, which is obtained from the outer atmosphere into our body by a process known as respiration.

• In some organisms, specific organs are not responsible for carrying out some specific functions, and one simple process called diffusion is sufficient to provide life.

• But in the case of complex organisms such as humans, every single tissue is assigned a particular task to be done.

• As our body already has food and oxygen in a particular part of the body and these need to be transported to other parts of the body where they are required.

• There must be a transportation system to transport that oxygen and food from one part of the body to another part of the body.

• While carrying out various chemical reactions using carbon sources and oxygen, various by-products are produced in our bodies, which are harmful to our health.

• Those products are removed from our body, and that is done by a process known as excretion.

Nutrition

• We need energy for anything that we do. That energy is derived ultimately from food.

• In order to get energy, different ways are used by different organisms.

• Some organisms obtain their food in the form of simple inorganic compounds, i.e. carbon dioxide and water, which can be seen in plants and bacteria.

• Whereas other organisms use complex food particles, and then that complex food particle needs to be broken down into a simpler form, which is done by some biocatalytic enzymes.

• These kinds of organisms that are dependent on their food on other organisms are known as heterotrophs.

• For example, animals, including human beings. Simple organisms such as plants that can make their food are known as autotrophs.

Autotrophic Nutrition

• In plants, carbon dioxide and water are taken up from the outside environment, and in the presence of sunlight, chlorophyll is converted into carbohydrates and oxygen by the process of photosynthesis.

• The end products that are obtained are both utilised.

• Carbohydrates are used to provide energy in the plant body, and oxygen is released in autotrophic nutrition.

• It is further taken up by animals for the process of respiration. Carbohydrates are stored in the form of starch.

The following events take place during the process of photosynthesis :

(i) Light energy is absorbed by chlorophyll.
(ii) Light energy is converted to chemical energy, and water molecules are split into hydrogen and oxygen.
(iii) Carbon dioxide is reduced to carbohydrates.

• All these steps don’t take place one after another, but can take place in different sequences in different organisms.

• For example, in desert plants, carbon dioxide is taken up at night, whereas sunlight is absorbed by chlorophyll in the morning.

• In the plants, some green-coloured pigments can be seen after looking into their sectional view, and those are known as chloroplasts. They contain chlorophyll.

Stomata are tiny pore-like structures that are present at the surface of leaves. Two major works associated with the stomata are

1. Gaseous exchange is the exchange of carbon dioxide and oxygen

2. Loss of water by transpiration.

• The closing and opening of the pore are functions of the guard cell.

• With the increase in the amount of water, guard cells swell up, resulting in the opening of the stomata pore, whereas guard cells shrink in the absence of water, resulting in the closing of the stomatal pore.

• Various experiments can be carried out to prove the necessity of these four components, which are sunlight, chlorophyll, water, and carbon dioxide, in the process of photosynthesis.
  Carbon dioxide is taken up by the plants from the animals that are released in the process of respiration.

• Water is gained by them through their roots from the soil, and chlorophyll is present in their leaves.

• Sunlight they get from the atmosphere, and also there is a need for some new chemicals like nitrogen, magnesium, etc, which are obtained from the soil itself.

Heterotrophic Nutrition

• Food that is taken by organisms to obtain energy is different in the case of different organisms.

• In the same way, the breakdown of the consumed food also involves different processes.

• Some organisms break down their food outside the body and then absorb it. For example, fungi, yeast, bread mould, mushrooms, etc.

• Also, there are some organisms that break down those complex food molecules inside their body and then absorb their nutrition, for example, animals like human beings.

• Some organisms derive their nutrition from other plants and animals without killing them. This kind of nutrition is known as parasitic nutrition, which is used by various parasites like Cuscuta, lice, ticks, leeches, etc

How Do Organisms Obtain Their Nutrition?

• Since the food and the way in which it is taken are different in different organisms, the digestive system is also different. For example, in a single-celled organism, the whole digestion takes place through the entire body surface.

• As the complexity of an organism increases, particular organs of the body are assigned particular tasks in digestion.

• In amoeba, its finger-like projections surround the food, forming a food vacuole.

• Inside this food vacuole, the complex substances are broken down into simpler substances and then transferred into the cytoplasm. The undigested food is removed from the body.

• In amoeba, the shape is formless, but that is not the case with paramecium, which has a special, shoe-shaped shape and a particular spot for food digestion.

• In a paramecium, food is transported to that spot with the help of Cilia.

Nutrition in Human Beings

The alimentary canal is responsible for digestion in humans. The alimentary canal starts from the mouth and ends with the terminal part of the digestive tract. In between, different organs have particular assigned functions for digestion. The process of digestion is to break down complex food particles into smaller ones and derive nutrition. Breaking down complex food particles starts in the mouth itself. The complex food particles are crushed into smaller pieces by teeth in the mouth. Also, big food particles such as starch are converted into simpler forms of sugar by an enzyme known as salivary amylase. It is released from saliva. Peristaltic movements are caused by the muscles that are responsible for pushing food in the alimentary canal in the forward direction.

• From the mouth, the food passes into the stomach through a food pipe, which is also known as the oesophagus.

• The stomach helps in the digestion of food by releasing digestive juices. The gastric gland of the stomach releases hydrochloric acid. Also, one protein-digesting enzyme known as pepsin is released in the stomach. It acts only in an acidic medium, which is provided by hydrochloric acid, and to protect our body from excess acid, mucus is present in the stomach.

• Food is then transported to the small intestine through a sphincter. The small intestine is the largest part of the digestive system, and its size varies according to the food eaten by the organism. For example, in herbivores as cellulose is hard to digest, which is why they have having much larger small intestine as compared to carnivores, which digest meat more easily to be digested.

• The small intestine is the major part of the digestion of carbohydrates, proteins, and fats. In the small intestine, the secretion from the liver and pancreas is also released.

• The pancreatic enzymes that are released can only work in a basic medium, but as food that is obtained from the stomach is acidic, that’s why liver secretes bile juice, which makes the medium basic. Bile juice is also responsible for the process of emulsification, which is the breaking down of large fat globules into smaller ones.
  
  

• The pancreas secretes pancreatic juice, which has enzymes, for example, trypsin, which is responsible for protein digestion and lipases, which are responsible for fat digestion. Also, the wall of the small intestine secretes Intestinal juices which are responsible for converting proteins into amino acids, fats into fatty acids and glycerol, carbohydrates, etc.

• The digested food is absorbed by small finger-like projections known as villi. These are responsible for increasing the surface area of absorption.
  
  
  

• Also, as different blood vessels are present in these villi, the digested food is transported to the whole body through them. Also, the undigested food is passed down into the large intestine, where extra water is absorbed, and faecal matter is passed out from the body through the anus by the sphincter ani muscles.

• 

  Respiration

  After digestion, there occurs a need for the breakdown of those simpler food molecules into energy in the cells, and that process is completed with the help of oxygen. Some organisms release carbon dioxide and water as the end product. While in some organisms, different methods other than this are used. But still, in all these methods, the first step is always the breakdown of 6-carbon glucose into a 3-carbon molecule known as pyruvate.

• This conversion takes place always in the cytoplasm further this Pyruvate can be converted into ethanol and carbon dioxide in yeast during the process of fermentation, as in this case breakdown of glucose takes place in the absence of oxygen that’s why this process is known as anaerobic respiration whereas when glucose is converted into pyruvate in the presence of oxygen in mitochondria the process is known as aerobic respiration.

• The energy released in aerobic respiration is far more than that which is released in anaerobic respiration.

• When there is a lack of oxygen in the muscles, then Pyruvate is converted into lactic acid, which is also a three-carbon molecule, and the accumulation of which in animal cells leads to cramps while doing exercises.

• The energy, which is released during this cellular respiration is used to synthesise a molecule known as ATP that is required to carry out various endothermic reactions in our body.

• We know that terrestrial organisms can take up oxygen from the atmosphere, but aquatic organisms take up the dissolved oxygen from water.

• In humans, the air enters our body through the nostrils and it’s filtered there with the help of fine hairs present in the passage. The mucus present in the passage also helps to control dirt.
  
  

• Then, passing through the throat that has cartilage to ensure that air doesn’t collapse, air passes into the lungs.

• In the lungs, there are several branches present known as Bronchioles that further lead into balloon-like structures that are known as alveoli. Their surface is covered with blood vessels.

• After the air is filled in the lungs, the alveoli are filled with the air and that results in their expansion.

• Carbon dioxide from the blood is taken up into alveoli, and oxygen from the alveoli is taken into blood vessels, from there it's transported to all other cells of the body.
  When the body size is larger, for example, in human beings, then the diffusion alone cannot carry out the transport of gases.

• So some pigments are responsible for the gaseous transfer.

• In human beings, one coloured pigment known as haemoglobin in the blood is responsible for the uptake of oxygen because of its high affinity with oxygen.

Transportation

• Blood is the carrier of food, oxygen, and waste material.

• Blood is a connective tissue that has major components as plasma.

• All these cells in the blood are suspended in plasma, and plasma transports food, nitrogen waste, salts, etc.

• In blood, oxygen is transported through RBCs.

• Thus, we can conclude that there’s a need for one pumping organ as well as a network of vessels for transportation, and also a backup option for the same in case the transport system gets damaged.

Transportation in Human Beings

Our Pump - the Heart

• The pumping organ in our body is a muscular organ known as the heart, which is separated into different chambers to ensure that oxygen-rich blood doesn't mix with carbon dioxide-rich blood.

• There is a need to transport carbon dioxide-rich blood to the lungs in order to get oxygen in exchange, and that oxygen-rich blood then needs to be carried into the heart so that it can be pumped back into all the cells of our body.

• After oxygen-rich blood from the lungs is carried up to the left atrium of the heart then it contracts so that it can pass into the left ventricle, which in response relaxes to fill the blood into it. After this, the contraction in the left ventricle results in the release of blood into different parts of the body.

• In a similar way, the deoxygenated blood is brought up into the right atrium, which contracts to receive the blood.

• Later, it transfers blood into the right ventricle in the same way, after which the contraction of the right ventricle results in the transfer of deoxygenated blood into the lungs.

• As ventricles are responsible for the transfer of blood into organs, they have much thicker walls as compared to Atria.

• Also, valves are present in the heart to ensure that blood is not pumped back into the heart while contracting.

Oxygen enters the blood in the lungs

• The separation of the left side and right side of the heart is useful to keep deoxygenated blood away from mixing with oxygenated blood. This proves to be helpful in the organism, which is involved in maintaining its body temperature. So constant energy is needed.
• In an organism in which the temperature is dependent on the ambient temperature, i.e., the temperature of the surroundings, mixing in deoxygenated and oxygenated blood doesn’t pose any problem, for example, in amphibians.
• Amphibians have a three-chambered heart, whereas in complex organisms like human beings, blood passes through the heart two times, thus completing two cycles.
• The transportation of blood is known as double circulation. In fish, only a single cycle takes place where oxygen is taken up by the gills is forcefully passed up into the blood, and that is further transported in the body.

The tubes - blood vessels

Three major blood vessels are involved in the process of transportation. They are arteries, veins, and capillaries. All three of them have their differentiating characteristic. We can tabulate the same as always :

Maintenance by platelets

In case we face any injury, and any of our body’s veins are damaged, it will result in a reduction of pressure. This will ultimately result in a decrease in the efficiency of pumping. To avoid this, blood has platelet cells, which circulate and make a plug at the place of leakage, known as blood coagulation.

Lymph

There’s another type of fluid present in the body, which is formed when some materials from the arteries, like plasma, proteins, and RBCs, are released into the intercellular spaces. It’s dissimilar to the plasma as it is colourless and has less protein. The major function of lymph is to carry fat in our body. It also drains extra fluid from the intercellular spaces back into the blood.

Transportation in Plants

• As we have seen earlier, plants take up carbon dioxide from the atmosphere to carry out photosynthesis.

• In plants, the soil is the nearest source of nutrients, having all the nutrients like nitrogen, minerals, phosphorus, etc.

• As the complexity of the plant body increases then the diffusion process alone cannot transport the required materials, such as water, from one part of the body to other parts, and that calls for the need for a much better transportation system.

• As plants do not move, and also most of their parts are dead in the form of sclerenchyma tissue that is why they need comparatively less energy.

• The water that is obtained by the roots is transported to other parts of the plant with the help of Xylem is a water-conducting tissue, and the photosynthetic food that is formed in the leaves is transported to other parts of the plant with the help of phloem, which conducts the food in the plant body.

Transport of water

• In plants, the Xylem tissue of roots, leaves, and stems is all interconnected to form a network.

• The xylem tissue, which is in contact with the root tip, actively takes up the iron from the soil.

• It creates a difference between the concentration of iron in the soil and the root, which results in the transfer of water from the soil to the root and ultimately to different plant parts.
  But in large plants, there occurs a need for a much stronger method for the transport of water.

• During evaporation, when the loss of water takes place through stomata by the process of transpiration, a sectional pull is created at the roots, which pushes water from the roots to the higher parts of the plant.

• In the daytime, when stomata are open then this transpirational pull is a major driving force for water transportation.

Transport of food

• Transportation of the photosynthetic products from leaves to other parts of the plant body is done by sieve tubes and companion cells.

• Phloem is responsible for the transportation of photosynthetic products as well as amino and other products.

• In this case, the transportation takes place in both upward as well as downward directions, whereas that is not the case with Xylem.

• There, the transportation takes place only in the upward direction.

• Unlike the xylem, which only physical forces are responsible, the chemical energy of ATP is used to transport the food from the place where pressure is high to the parts where pressure is low.

Excretion

Till now, we are very well aware of how gaseous wastes are released from the plant body as well as the human body, but during the metabolic reactions, nitrogen and other harmful products are also produced in our body. Technically, the metabolic process of removal of metabolic waste is known as excretion. In a simple organism, it's done by the process of diffusion, where the waste product is directly diffused into the surrounding water.

Excretion in Human Beings

• In human beings, the excretory system includes a pair of kidneys, a pair of ureters, one urinary bladder, and the urethra.

• Kidneys form urine, and the urine that is released from the kidneys passes to the urinary bladder through the ureters, and then it’s stored there until it is released from the body through the urethra.

• In the kidney cluster of blood vessels are present around a cup-like structure of a coiled tubular part and that cup-like structure is known as Bowman's capsule.
• In each kidney functional unit, a nephron is present and they are packed close to each other.

• In the initial filtrate, glucose, water, and minerals are selectively reabsorbed, after which waste substance passes from the kidney into tube-like structures known as ureters, which connect the kidney to the urinary bladder, and the urine is released through the urethra.

Excretion in Plants

• Plants use completely different ways of excretion, as oxygen is a by-product of photosynthesis and is released through stomata.
• Extra water is excreted from their body through the process of transpiration, and they also have the advantage of losing their dead cell parts that are dead.
• They also secrete gums and resins, and also store some waste products in their cellular vacuoles.
• They can also excrete some of the waste products in the soil

Subject-Wise NCERT Solutions

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Chapter 5 Previous Year Questions and Answers

Some of the questions which have come up in past years from the chapter are given below. To solve these questions easily, students can use the NCERT Class 10 Science Chapter 5 Notes Life Processes.

Question 1. Depict the correct order of the holozoic mode of nutrition.

Option 1. Digestion→ Egestion →Absorption→ Assimilation →Ingestion

Option 2. Absorption→ Digestion→Ingestion → Assimilation→ Egestion

Option 3.Ingestion→ Digestion→ Absorption→ Assimilation →Egestion

Option 4. Ingestion→Digestion→ Assimilation→Absorption → Egestion

Answer :

Holozoic nutrition consists of five steps :

• Ingestion: Complex food is first taken inside the body through an opening
• Digestion: Complex food is then converted into simple soluble form through the process of digestion
• Absorption: Simplified food is further absorbed
• Assimilation: The absorbed food is then made available to the body through the process of Assimilation
• Egestion: The food that is not digested or the undigested food is removed from the body through the process of Egestion.

Hence, the correct option is (3) Ingestion→ Digestion→ Absorption→ Assimilation →Egestion

Question 2. The function of stomata is

Option 1. Gaseous exchange

Option 2. Intake of carbon dioxide

Option 3. transpiration

Option 4. All of the above

Answer :

Stomata are tiny pores present on the leaves that bring about the gaseous exchange, intake of carbon dioxide and transpiration.

Hence, the correct option is (4) All of the above

Question 3. The actual waste excreted out of a human body is 1-2L because of the process of

Option 1. Diffusion

Option 2. Osmosis

Option 3. Absorption

Option 4. Reabsorption

Answer :

The actual volume excreted is only 1L - 2L a day. It happens because the remaining filtrate is reabsorbed in the kidney tubules.

Hence, the correct option is (4) Reabsorption

Chapter-Wise NCERT Class 10 Notes Science

Here are the direct links to access the notes for each of the 13 chapters: