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PRE - FOUNDATION

NUTRITION
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CHAPTER

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CONTENTS autotrophs. (Gk. autos-self, trophe-nourishment).

• Nutrition e.g., Ferrobacillus (iron bacterium).

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• Type of Nutrition  Heterotrophic Nutrition :

• Autotrophic Nutrition • It is a mode of nutrition in which the organisms

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obtain readymade organic food from outside
• Heterotrophic Nutrition sources. The organisms that depend upon outside
• Digestive system of Human sources for obtaining organic nutritens are called

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heterotrophs. Heterotrophic nutrition is of three
• Alimentary canal S types - saprophytic, parasitic and holozoic.

 TYPE OF HETEROTROPHIC NUTRITION

 NUTRITION
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The process of intaking the food & utilization of 1. Saprophytic or Saprotrophic Nutrition :
food is called nutrition. It is a mode of heterotrophic nutrition in which food
is obtained from organic remains like dead
 Nutrient :
organisms, excreta, fallen leaves, broken twigs, food
• The different component of food that have distinct
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articles, etc. Organisms performing saprophytic

functions like providing energy, materials for nutrition are called saprophytes.
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body building, maintenance & regulation of

2. Parasitic Nutrition :
metabolism are called nutrient.
• It is a mode of hetrotrophic nutrition in which a
For example - Proteins, Minerals, Vitamin,
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living organisms flourishes by obtaining food from

Carbohydrates, fats.
another living organism. The lving organisms
 TYPE OF NUTRITION which obtains food and shelter from another
organism is called parasite. The organism which
 Autotrophic Nutrition : provides food and shelter to a parasite is known as
•
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It is a mode of nutrition in which organisms are able host. An external plant parasite is Cuscuta
to build up their own organic food from inorganic (Amarbel). It is a non-green plant that sends
raw materials with the help of energy. The organism haustroria or sucking roots into host plant for
performing autotrophic nturtion are called obtaining food and water.

Nutrition 1

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A ONE INSTITUTE – A SYNONYM TO SUCCESS, OFFICE – SCO 322, SECTOR 40 D, CHANDIGARH
PRE - FOUNDATION

3. Holozoic Nutrition :
• It is a mode of heterotrophic nutrition which
involves intake of solid pieces of food. Since solid
food is taken in, holozoic nutrition is also called
ingestive nutrition. The food may consist of
another animal, plant or its parts. Depending upon

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the source of food, holozoic organisms are of
three types – Herbivores, carnivores, omnivores.

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 Herbivores :
• (L.herba-plant, vorare-to eat). They are holozoic

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organisms which feed on plants or plant parts, e.g.,
Cow, Buffalo, Deer, Goat, Rabbit, Grasshopper,
Elephant, Squirrel, Hippopotamus.

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 Carnivores :
• They are animals which feed on other animals.
Carnivores are also called predators they hunt, kill

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and feed on their preys, e.g. Lion, Tiger, Leopard,
Snake, Hawk.

 Omnivores :
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• (L.omnis-all, vorare-to eat). They are holozoic
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organisms which feed on both plant and animal
materials, e.g. Cockroach, Ant, Pig, Crow, Rat,
Bear, Dog, Humans.

 Nutrition in Amoeba :
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• Protozoan protests carry out holozoic nutrition

through intracellular digestion.
Figure : HOLOZOIC NUTRITION IN AAMOEBA
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(i) Ingestion :
Some protests can ingest food particle from any • As soon as Amoeba comes in contact with a food
point on the surface (e.g., Amoeba) while others particle or prey, it throws pseudopodia all around
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have fixed points for the same (e.g., the same. The tips of encircling pseudopodia fuse
Paramoecium). Protozoans like Amoeba capture and the prey comes to lie in a vesicle or
food with the help of temporary finger-like phagosome. This method of intake of food is
called circumvallation. Amoeba can also ingest
processes called pseudopodia. Protozoans like
food by other methods like import, circumfluence
(Paramoecium have small hair-like processes
and invagination.
called cilia.) Beating of cilia creates current in
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water that pushes food particle through cytostome  DIGESTIVE SYSTEM OF HUMAN
or cell mouth. The process of ingestion of solid Digestive system is a group of organs & associated
food particle by a cell or unicellular organism is digestive glands that take part in ingestion,
called phagocytosis. digestive absorption of food & egestion of

Nutrition 2

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A ONE INSTITUTE – A SYNONYM TO SUCCESS, OFFICE – SCO 322, SECTOR 40 D, CHANDIGARH
PRE - FOUNDATION

undigestible matter. Digestive organs from a  Pharynx :

continuous canal called alimentary canal.
• It is short conical region that lies after the mouth
ALIMENTARY CANAL CONTAINS cavity.

FOLLOWING PARTS  Oesophagous :
Alimentary Canal in man is 9 metres long & • It is a long narrow muscular tube which leads to
consists of the following part

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the stomach. No digestive gland are present.
 Mouth :
 Stomach :
•

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Transverse slit like aperture.
• It lies below the diaphragm on the left side of
abdominal cavity is J-shaped.

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Mouth  Small Intestine :
Salivary gland
• It is convoluted tube and differentiated into 3

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Oesophagus regions, viz. Duodenum which is the first part of
(food pipe)
small intestine & is curved C-shaped; Jejunum,
Liver comparatively longer & more coiled and Ileum,
Stomach
Gall bladder
which is the last part of small intestine whose
Duodenum

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inner surface is folded to form villi, which
Small
Intestine IIeum Pancreas
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 Large Intestine :
Rectum
Anus • It is much shorter & wider than small intestine &
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is differentiated into three regions viz;
 Oral Cavity : • Caecum which is small rounded blind sac from
• It is bounded by lips & has cheeks, gums, teeth & which vermiform appendix arises;
tongue. • Colon is the inverted U-shaped tube
• The food taken inside oral cavity is masticated i.e. • The rectum opens to exterior through anus.
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mechanically broken into smaller particles before • No digestion takes place in large intestine, only
being swallowed.
absorption of water takes place.
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• The floor of the buccal cavity has a tongue

• In herbivores like horse, rabbit digestion of
bearing taste buds.
cellulose takes place in caecum.
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Man possesses teeth on both the jaws, there are 32

 Absorption :
teeth of four different types, namely incisors,
canines, premolars & molars. • In the small intestine (ileum) absorption of all
digested materials takes place.
 Dental Formula :
×2=x  Assimilation :
No.of teethin half part of upper jaw
×2=x • It is the process of utilisation of absorbed food for
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No.of teethin half part of lower jaw various body functions. The absorbed nutrients
• 2 1 2
In Man → I , C , Pm , M
3 8
= x2 are utilised to resynthesise complex molecules
2 1 2 3 8 like carbohydrates, protein & fats inside the cells.
= Total 32 teeths • Man cannot digest cellulose.

Nutrition 3

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A ONE INSTITUTE – A SYNONYM TO SUCCESS, OFFICE – SCO 322, SECTOR 40 D, CHANDIGARH
PRE - FOUNDATION

 Egestion : • Voluntary cotraction of abdominal muscles

• It is the process of elimination of undigested help in egestion of faeces.
food formed in the cells, or in the lumen of
large intestine (colon & rectum) through the
anus.

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TABLE : SUMMARY OF DIGESTION ENZYMES OF VARIOUS GLANDS WITH THEIR SECRETIONS
AND END PRODUCTS OF DIGESTION IN MAN

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Name of
S.No. Secretion Site of action Enzymes Food acts upon End product
gland

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1 Salivary glands Saliva Buccal cavity Salivary amylase Starch Maltose
2 Gastric glands Gastric Juice Stomach Pepsin Proteins Peptones & proteoses
Renin Casein of milk Paracasein

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HCl Stomach — Pepsinogen Pepsin
3 Liver Bile Duodenum — Fats Emulsification of fats
4 Pancreas Pancreatic Duodenum Amylase Starch & Glycogen Maltose & Isomaltose

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Juice Trypsin Proteins Peptones & peptides
S Lipase Emulsified fats Fatty acids & glycerol
5 Intestinal Intestinal Samall Amino acids
Erepsin Peptones & Peptides
glands Juice intestine Glucose
Maltase Maltose
Glucose & fructose
Sucrase Sucrose
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Glucose & galactose
Lactase Lactose
Monoglycerides & fatty
Lipase Triglycerides
acid
Lubrication of faecal
Mucous Large intestine — —
matter
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 NUTRITION IN PLANTS • Chlorophyll is green colour pigment.

 Photosynthesis :  Mechanism of Photosynthesis :

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• Photosynthesis is the primary mode of food • Photosynthesis is divided in 2 main steps

production in green plant. '' The process by which (A) light reaction (B) dark reaction
green plants synthesize food from simple
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 Light reaction :
substances carbon dioxide and water in the
presence of sunlight is called Photosynthesis'' • It is also called Hill Reaction.
• The process of photosynthesis can be represented • It occurs in grana of thylakoids.
in the form of chemical reaction, as given below :
• It is named as light reaction as it occurs only
6CO2 + 12H2O –→ C6H12O6 + 6H2O + 6O2
in presence of light.
Carbon Water Glucose Water Oxygen
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dioxide  Major Step :

 Photosynthetic Pigment : • Absorption of light by chlorophyll.
• The light energy must be absorbed by a suitable • Photolysis of water.
pigment i.e. chlorophyll (green pigment).
Nutrition 4

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PRE - FOUNDATION

• Reduction of CO2 to Carbohydrates.

• In this process ADP changes to ATP &  C4 Cycle or Hatch & Slakcycle :
inorganic phosphate. • 4-C compound i.e. oxaloacetic acid (OAA).
• Release of oxygen into atmosphere. • This cycle is found in many other tropical &
 Opening and Closing Stomata : subtropical monocots eg : Maize, Sorghum ,

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• The opening and closing of stomata depend
Wheat, Oat, Pearl, millet etc.

upon the turgid or flaccid state of the guard • In dicots also many such plants are known eg :

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Amaranthus, Chenopodium, Atriplex, Euphorbia
Subsidiary cells
etc. In some families of dicots Compositae,
Portulaceae, Nyctaginaceae.

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 Crassulacean Acid Metabolism (CAM) :
Nucleus • Certain plants, especially succulents which

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Inner thick
Wall of grow under extremely xeric (dry) condition,
guard cells
fix atmospheric CO2 in dark.
Chloroplasts Outer thin
wall of guard
cell
• Since the process was first observed in the

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APERTURE CLOSED APERTURE OPEN
plants belonging to family crassulaceae (eg.
cells. When guard cells are in turgid state the Bryophyllum, kalanchoe etc.) It was termed
crassulacean acid metabolism (CAM).
stomatal aperture opens and when guard cells
are in flaccid state the stomatal aperture
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closes. The inner wall of guard cells (towards is that their stomata remain open at night (in
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pore) is thick and outer wall (towards other dark) but closed during the day (in light).
epidermal cells) is thin. When the turgor
• Thus, CAM is a kind of adaptation in succulents
pressure of the guard cells is increased the
to carry out photosynthesis without much loss
outer thinner wall of the guard cell is pushed
of water.
out (towards the periphery) due to which a
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tension is created on the inner thicker wall

thus pulling the inner thicker wall towards the
periphery thus leading to the opening of
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stomatal aperture. On the contrary when the

guard cells are in a flaccid state the outer
thinner wall of guard cells returns to original
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position (moves towards pore) due to which

tension on the inner wall is released which
also returns to its original position and
stomatal aperture gets closed again.
 Dark Reaction :
•
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This reaction is not dependent on light. It is

also known as calvin – Benson Cycle or C3
cycle as first stable product is phosphogliceric
acid (PGA) a 3 carbon compound.

Nutrition 5

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EXERCISE # 1
(D) It can also occur in darkness
A. Single Choice Type Questions
Q.1 CO2 and O2 balance in atmosphere is due to
Q.8 Phloem always flows from a

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(A) Photorespiration (B) Photosynthesis
(A) Solar source to sugar sink
(C) Respiration (D) Leaf anatomy
(B) Sugar sink to sugar source

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Q.2 During photosynthesis the oxygen in glucose (C) Leaf to the xylem to the phloem
comes from (D) Leaf to a root
(A) Water

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(B) Carbon dioxide Q.9 With regards to natural eating habits, a human
(C) Both from water and carbon dioxide is
(D) Oxygen in air (A) An herbivore (B) A carnivore

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(C) An omnivore (D) A Granivore
Q.3 First stable compound in C3 cycle is
(A) Phosphoglyceraldehyde Q.10 Muscular contractions of alimentary canal are
(B) Phosphoglyceric acid (A) Circulation (B) Deglutition

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(C) Fructose-1-6 diphosphate (C) Peristalsis (D) Churning
(D) Glucose-6-phosphate
Q.11 Which of the following regions of the
Q.4
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Dark reaction of photosynthesis occurs in the
(A) Stroma of the chloroplast outside the
alimentary canal of man does not secrete a
digestive enzyme ?
lamellae
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(A) Oesophagus (B) Stomach
(B) Space between the two membranes of the (C) Duodenum (D) Mouth
chloroplast
(C) Membranes of the stroma lamellae Q.12 A digestive enzyme, salivary amylase, in the
(D) Thylakoid membrane of the grana saliva begin digestion of
(A) Protein (B) Nucleic acids
Q.5 A specific function of light energy in the
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(C) Fats (D) Carbohydrates

process of photosynthesis is to
(A) Activate chlorophyll Q.13 If you chew on a piece of bread long enough,
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(B) Split water it will begin to taste sweet because

(C) Synthesis of glucose (A) Maltase is breaking down maltose
(D) Reduce CO2 (B) Lipases are forming fatty acids
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Q.6 Digestion within a digestive tract is (C) Amylase is breaking down starches to
(A) Incomplete disaccharides
(B) Extracellular (D) Disaccharides are forming glucose
(C) The same as absorption Q.14 In the presence of lactase, lactose breaks
(D) An irreversible process
down into molecules of
Q.7 Dark reaction in photosynthesis is called so (A) Glucose and galactose
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because (B) Glucose and fructose

(A) It does not require light energy (C) Galactose only
(B) Cannot occur during daytime (D) Glucose only
(C) Occurs more rapidly at night
Q.15 Saliva has the enzyme
Nutrition 6

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(A) Pepsin (B) Ptyalin

Q.21 Where is bile produced ?
(C) Trypsin (D) Rennin
(A) In gall bladder
Q.16 Pepsin digests (B) In blood
(A) Proteins in stomach (C) In liver
(B) Carbohydrates in duodenum (D) In spleen
(C) Proteins in duodenum
Q.22 Ileum is

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(D) Fats in ileum
(A) First part of the small intestine
Q.17 Curding of milk in the stomach is due to the (B) Middle part of the small intestine

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action of (C) Last part of the small intestine
(A) Pepsin (B) Renin (D) Not a part of the small intestine
(C) HCl (D) Tenin

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Q.23 Largest gland in human body is
Q.18 Chief function of HCl is (A) Liver (B) Pancreas
(A) To maintain a low pH to prevent growth (C) Pituitary (D) Thyroid

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of micro-organisms
Q.24 The specific function of liver is
(B) To facilitate absorption
(A) Excretion
(C) To maintain low pH to activate pepsinogen
(B) Digestion
to form pepsin
(C) Histolysis

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(D) To dissolve enzyme secreted in stomach
(D) Glycogenesis and glycogenolysis
Q.19 If the stomach did not produce any hydrochloric
Q.25 The original function of the vertebrate
acid, which enzyme will not function ?
S stomach was
(A) Ptyalin (B) Trypsin
(A) Storage
(C) Pepsin (D) Collagenase
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(B) Digestion
Q.20 Chief function of bile is (C) Enzyme secretion
(A) To digest fat by enzymatic action (D) Absorption
(B) To emulsify fat for digestion
(C) To eliminate waste product
(D) To regulate process of digestion
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A

Nutrition 7

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A ONE INSTITUTE – A SYNONYM TO SUCCESS, OFFICE – SCO 322, SECTOR 40 D, CHANDIGARH
PRE - FOUNDATION

EXERCISE # 2

A. Very Short Answer Type Questions

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Q.1 Define heterotrophic nutrition.
Q.20 Name a digestive juice that has no enzymes.
Q.2 What are heterotrophs ? What is the role of this juice ?

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Q.3 Which types of organisms are called consumers ? Q.21 Name the various parts of large intestine.
What is the role of large intestine ?

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Q.4 What is saprophytic nutrition ?
C. Long Answer Type Questions
Q.5 Define saprophyte.

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Q.22 Explain the mechanism of nutrition of
Q.6 Define a hervivore.
Amoeba with the help of suitable diagram.
Q.7 What is carnivore ?
Q.23 Describe the various types of heterotrophic

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Q.8 Which type of animal is called omnivore ? nutrition.

Q.24 Briefly describe the digestive system of

Q.9 Define digestion.
S humans.
Q.10 What is ingestion ?
Q.25 What happens to food in the small intestine ?
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Q.11 Define egestion.
Q.26 Why chlorophyll is needed for photosynthesis.
Q.12 What is the mode of nutrition in Amoeba ?

Q.13 What type of digestion occurs in Paramoecium ?

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B. Short Answer Type Questions

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Q.14 Differentiate between autotrophic and

heterotrohic nutrition.
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Q.15 Distinguish saprophytes from parasites.

Q.16 Differentiate between photosynthetic and

holozoic nutrition.

Q.17 How do saprophytic organisms obtain their

nourishment ?
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Q.18 What is the importance of saprophytes ?

Q.19 What is the action of hydrochloric acid of

gastric juice ?

Nutrition 6

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