Class X, NCERT
(CBSE) Science (Biology)
Chapter 6, LIFE PROCESSES
Cbse Ncert Solution Study Materials
Nutrition
All living organisms require energy to carry on
various maintenance processes. This energy comes from the outside the body of
the individual organism. Some organism utilize simple inorganic substances such
as carbon dioxide and water, whereas other organisms utilize complex substances
which are required to be digested before they can be utilized for various life
processes such as growth, maintenance and repair. So, “Nutrition” is a process
by which a source of energy from outside the body of the organism, which we
call food, is transferred to inside the body of the organism.
modes of nutrition
There are two modes of nutrition - Autotrophic and
Heterotrophic.
Autotrophic Nutrition - In this type of nutrition food is synthesized by the organism itself
(autotrophs) from simple inorganic raw materials such as CO2 and H2O.
The essential elements of Autotrophic Nutrition are the presence of green
pigment (Chlorophyll) and Sunlight. All green plants and some bacteria have
this type of nutrition.
Heterotrophic Nutrition -
Some organisms are unable to synthesize their own food. These organisms rather
obtain their food directly or indirectly from autotrophs. This food is then
broken down with the help of some enzymes. This mode of nutrition is called ‘Heterotrophic
Nutrition’. In this type of nutrition no pigment or sunlight is required. All
animals, fungi and some bacteria have this type of nutrition.
photosynthesis
Photosynthesis is the process by which
chlorophyll-containing cells in plants synthesize food in the form of
carbohydrates, carbon dioxide and water using sunlight. The raw materials
required for photosynthesis are carbon dioxide and water and the products
formed are carbohydrates and oxygen. The process can be represented as:
1. Light
Reactions : This reaction takes place in the presence of light. Events
occuring during Light Reactions are -
a. absorption of light energy by
chlorophyll molecules.
b. splitting of water molecules
into hydrogen and oxygen atoms.
c. formation of ATP and NADPH2
2. Dark
Reactions : This reaction does not require direct light and occurs in the
stroma of the chloroplasts. During this phase, reduction of CO2
takes place to form carbohydrates.
Nutrition in amoeba
Amoeba takes in food using temporary finger-like
extensions of the cell surface, called pseudopodia, which fuse over the
food particle forming a food - vacuole. Inside the food vacuole, complex
substances are broken down into simpler ones which then diffuse into the
cytoplasm.
Nutrition in human beings
Eating nutritious food is healthy because it supplies
essential nutrients required to sustain life. It is by the process of digestion
that the nutrients present in the food are utilized by the human body. The
following are the different digestive organs and their functions -
Mouth
Digestion of food begins in the mouth. It comprises
of the following parts -
Teeth: Tear and
break down the food.
Saliva: Contains a
digestive enzyme called salivary amylase, which help to break down starch into
sugar.
Tongue: It is a
sense organ with taste buds. Its muscular movements help to move the food from
the mouth into inside.
pharynx
It opens into the oesophagus (which leads to the
stomach) and trachea (which leads to the lungs). Pharynx is a common passageway
for food and air.
oesophagus
The peristaltic movements of the longitudinal smooth
muscles in oesophagus push the food into the stomach and also prevent the
chewed food material from moving back into the mouth.
stomach
The stomach stores and mixes the food from
oesophagus with the gastric juice. The main components of gastric juice, which
is secreted by gastric glands present in the walls of the stomach, are HCl,
mucus, and pepsynogen.
small
intestine
1. It is the longest part of the elementary canal
and is made up of three parts - duodenum, jejunum, and ileum.
2. The length of the small intestine depends on the
type of food consumed by the organism and hence, differ ijn various animals.
3. It also produces intestinal juice from glands
present in the wall which helps in further digestion of the food.
4. Other digestive juices like - bile juice (which
causes emulsification of fats) and the pancreatic juice (for digesting proteins
and emulsified fats) mix with the food in the small intestine.
5. The small intestine is the site for complete
digestion of carbohydrates, proteins and fats.
6. The digested food is then absorbed through the
intestinal walls and transported to the various parts of the body.
large
intestine
The indigestible material and water enters the large
intestine. The large intestine performs the function of storage of wastes
(faeces) before they are excreted from the body via the anus.
atp
The energy released during the process of
respiration is used to form high energy ATP (adenosine tri-phosphate) molecules. ATP is
known as energy currency of the cell and it is used as cellular fuel for most
cellular processes. ATP is called ‘energy currency’ of the cell because the
energy required for various life activities is released by mitochondria in the
form of ATP molecules, which is used by the body performing various activities.
For example, energy stored in ATP is used to bring about energy requiring
activities of cell such as photosynthesis, protein synthesis and muscle
contraction.
lymphatic system
Lymph is another fluid connective tissue, which
helps in the process of transportation. Some pores are present in the walls of
the capillaries and through these pores, small amounts of plasma, proteins, and
blood cells escaped into the intercellular spaces in the tissues to form the
tissue fluid or lymph. It is similar to the plasma of blood but colourless and
contains less protein. Lymph drains into lymphatic capillaries from the
intercellular spaces, which joined to form large lymph vessels.
Functions of the Lymph:
1. It acts as a reservoir of water, salts and
digested food.
2. It carries digested food and fats from the small intestine. Lymphatic
vessels present in the intestinal villi absorb fatty acids.
3. It contains phagocytes that can engulf and destroy
bacteria. and other foreign particles.
function of kidneys
Kidneys form a part of human excretory system.
Different functions of kidneys are as follows:
1. Kidneys filter waste products from the blood e.g.
various nitrogenous wastes such as urea, uric acid etc.
2. Kidneys play an important role in the formation
of urine.
3. It helps us in maintaining the water balance of
our body by removing excess fluids.
4. It is the basic filtration unit of the excretory
system.
5. They also make hormones that keep the bones
strong and healthy.
Additional CBSE Class 10 Science Sample Questions Answers
Q.1: Which pigment captures solar energy?
Ans: Chlorophyll
Q.2: Name any three life processes.
Ans: Nutrition, respiration and blood circulation
Q.3: Answer the following questions:
(i) What is the first reaction in
photosynthesis?
(ii) In which form do plants store food?
Ans: (i) The first reaction in photosynthesis is the
photolysis of water.
(ii) The product of photosynthesis is glucose, which is
stored in plants in the form of starch.
Q.4: What are the inorganic sources used by
plants for making food?
Ans: Carbon dioxide, water and sunlight.
Q.5: Briefly describe the
digestive functions of liver and pancreas.
Ans: Liver :
1. The liver secretes bile which is stored in the gall
bladder from where it is sent to the duodenum whenever needed.
2. The bile breaks down the fat droplets into small fat
globules. This phenomenon is known as emulsification of the fat.
Pancreas :
1. Pancreas secretes a juice which is sent to the
duodenum.
2. Pancreatic juice contains different enzymes. The
Trypsin, which digests proteins into peptones, and the pancreatic amylase,
which digests starch into sugar. The lipase which breaks down the emulsified
fats.
3. It also produces hormones - insulin and glucagon. This
insulin is a very important hormone that regulates the sugar level in blood.
Ncert (Cbse) Biology ‘Life Processes’ - further study
- CBSE Science, Class X | Chapter 6, LifeProcesses | NCERT Textbook Exercise (Answers)
- Life Processes | Class 10, CBSE Biology| Chapter 6, NCERT Science Textbook In-text Questions - Answers
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