Nutrition for Class X Biology

3. When we walk or ride a bicycle, we are using up
energy. Even when we are not doing any apparent
activity, energy is needed to maintain a state of
order in our body. We also need materials from
outside in order to grow, develop, synthesis
protein and other substances need in the body.
This source of energy and materials is the food
we eat.
Nutrition is the process of intake of nutrients by
an organism as well as the utilisation of these
nutrients by the organism.

4. • The general requirement of energy and materials is
common in all organisms, but it is fulfilled in different
ways. Some organisms use simple food material
obtained from inorganic source of CO2 and H2O. These
organisms, The autotrophs, include green plants and
some bacteria.
• Other organisms utilize complex substances. These
complex substances have to be broken down into
simpler ones before they can be used for the upkeep and
the growth of the body. To achieve this, organisms use
bio-catalysts called enzymes. Thus the heterotrophs
survival depends directly or indirectly on autotrophs.
Heterotrophic organisms include animals and fungi.

5. 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.

6. Heterotrophic Nutrition
Each organism is adapted to its environment. The
form of nutrition differs depending on the type and
availability of food material as well as how it is
obtained by the organism. For example, whether the
food source is stationary (such as grass) or mobile
(such as a deer)
There is a range of strategies by which the food is
taken in and used by the organism.

7. Heterotrophic nutrition
It is of three types
1. Saprophytic nutrition
2. Parasitic nutrition
3. Holozoic nutrition

8. Saprophytic nutrition
Some organisms break-down
the food material outside the
body and then absorb it.
Examples are fungi like bread
moulds, yeast and
mushrooms
In this organism releases
enzymes to out side
 These enzymes break the
complex substances which
are present in the dead
organic matter into simple
substances
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9. Parasitic nutrition
Organism gets its
food from the host
Ex- cuscuta.orchids
Ticks, lice, leeches

10. Holozoic nutrition
Some organisms take in whole material and break it
down inside their bodies.

11. Autotrophic 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.

13. Steps in photosynthesis
The process of photosynthesis occurs in two phases –
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

14. How the plant obtains carbon dioxide.
Through the stomata which are tiny pores present
on the surface of the leaves. Massive amounts of
gaseous exchange takes place in the leaves
through these pores for the purpose of
photosynthesis.

15. Chlorophyll is necessary for the photosynthesis
 Take a potted plant with variegated leaves – for
example, money plant or crotons.
 Keep the plant in a dark room for three days so
that all the starch gets used up.
 Now keep the plant in sunlight for about six
hours.
 Pluck a leaf from the plant. Mark the green
areas in it and trace them on a sheet of paper.
 Dip the leaf in boiling water for a few minutes.
 After this, immerse it in a beaker containing
alcohol.
 Carefully place the above beaker in a water-bath
and heat till the alcohol begins to boil.
 What happens to the colour of the leaf? What is
the colour of the solution?
 Now dip the leaf in a dilute solution of iodine
for a few minutes.
 Take out the leaf and rinse off the iodine
solution.
 Observe the colour of the leaf and compare this
with the tracing of the leaf done in the
beginning

17. Co2 is needed for photosynthesis
 Take two healthy potted plants which are nearly the
same size.
 Keep them in a dark room for three days.
 Now place each plant on separate glass plates. Place a
watch-glass containing potassium hydroxide by the side
of one of the plants. The potassium hydroxide is used to
absorb carbon dioxide.
 Cover both plants with separate bell-jars
 Use vaseline to seal the bottom of the jars to the glass
plates so that the set-up is air-tight.
 Keep the plants in sunlight for about two hours.
 Pluck a leaf from each plant and check for the presence
of starch as in the above activity.

19. Phases of Digestion
Ingestion
Digestion
Absorption & assimilation
Egestion

22. Amoeba feeds on microscopic animals and plants that float in a
water body. Its mode of nutrition is holozoic. The various steps of
nutrition are:
(i) Ingestion : Amoeba engulfs the food by forming pseudopodia.
When the food is completely encircled and the tips of encircling
pseudopodia touch each other, the membrane at that point
dissolves and the food is enclosed inside forming a food vacuole.
This intake of food is called ingestion.
(ii) Digestion : Inside the food vacuole, food gets digested by
digestive enzymes. The digested food diffuses into the cytoplasm.
(iii) Assimilation : The digested food is utilised by the cell. This is
termed assimilation.
(iv) Egestion : The undigested food remains in the food vacuole and
is thrown out of the body. This process is called egestion.

25. Digestion
It is necessary to move the food in a regulated
manner along the digestive tube so that it can be
processed properly in each part. The lining of
canal has muscles that contract rhythmically in
order to push the food forward. These peristaltic
movements occur all along the gut.

26. The Digestive Tract
A long
muscular tube
with many
sections and
areas.
Begins with the
mouth and ends
with the anus.

27. Path of Digestion
Mouth
Pharynx
Oesophagus
Stomach
Small Intestine
Large Intestine
Anus

28. Human digestive
system
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 maltose

29. 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.

30. Oesophagus
A straight muscular tube that is about
10 inches (25 cm) long which connects
the mouth with the stomach
Food takes about 4 to 8 seconds as it
passes through to the stomach.
Its walls contain smooth muscles that
contracts in wavy motion
(Peristalsis).
Peristalsis propels food and liquid
slowly down the esophagus into
the stomach.

31. Mechanism of Swallowing
Swallowing is a coordinated activity of the
tongue, soft palate, pharynx and esophagus.
Phases
Food is pushed into the pharynx by the
tongue. (voluntary)
Tongue blocks the mouth
Larynx (Adam’s Apple) rises so the
Epiglottis (a flap of tissue) can close the
opening of the trachea.

32. Peristalsis

33. 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 pepsinogen.
 The hydrochloric acid creates an acidic
medium which facilitates the action of
the enzyme pepsin
 The mucus protects the inner lining of
the stomach from the action of the acid
under normal conditions
 The exit of food from the stomach is
regulated by a sphincter muscle which
releases it in small amounts into the
small intestine

35. GASTRIC JUICE
3 components
1. HCl- Provides acidic medium required for the
functioning of Pepsin
2. Mucus -lubricates food and protects the gastric lining from
strong digestive juices.
3. Pepsin-major enzyme; converts proteins into peptides in the
presence of HCl.

36. Small Intestine
Site of greatest amount of digestion and absorption

37. 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.
Small intestine

38. Small Intestine
Has folded inner walls covered with fingerlike
projections (villi; sing. – villus)
absorbs digested food.
Villi increases the surface area of the small
intestine for greater absorption.

39. Intestinal villi
The inner wall of the small intestine posses
numerous finger like projections called villi,
which are for the absorption of nutrients. The
villi conatining microvilli.

41. Movement in small intestine:

42. Large Intestine

43. Large IntestineWaste is pushed into the expanded
portion (rectum) of the large intestine.
Solid waste stays in the rectum until it
is excreted through the anus as feces.
Appendix hangs on the right side of
the large intestine.

44. The unabsorbed food is sent into the large intestine
where more villi absorb water from this material. The
rest of the material is removed from the body via the
anus. The exit of this waste material is regulated by
the and sphincter.

45. Digestive glands which are located
outside the alimentary canal
1. Liver
2.Pancreas

46. Liver
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.

47. Pancreas
 Pancreas secretes a juice which is sent to
the duodenum.
 Pancreatic juice contains different
enzymes.
 The Trypsin, which digests proteins into
peptones
 The pancreatic amylase, which digests
starch into Maltose.
 The lipase which breaks down the
emulsified fats into fatty acids & glycerol