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Chapter 2:-Nutrition in animals:-
Presentation
Concept 1 Different ways of taking
food
Concept 2 Digestion in humans
Keywords
1.Ingestion:-The process of taking food into the
body is called Ingestion.
2.Digestion:-Breakdown of complex components of
food into simpler substances is called digestion.
3.Absorption:- The process by which digested food
pass into the blood vessels in the wall of intestine.
4.Assimilation:- utilisation of food by the target
organ is called assimilation.
Or
Process by
which absorbed substances are used to build complex substances such as proteins
required by body.
5.Egestion:-The process of removal of faecal
matter through anus from time to time is called Egestion
6.Buccal
Cavity:-Oral cavity
that contains teeth , tongue and salivary glands.
7.Milk
teeth:-The first set
of teeth grows during infancy and they fall off at the age of 6 to 8 years.
8.Permanent
teeth:-Second set of
teeth that replace milk teeth.
9.Incisor:-Teeth for cutting and biting is
called incisor. They are 8 in number.
10.Canine:-Large , pointed teeth just behind the
incisors that are used for piercing and tearing of food.
11.Premolar:-Teeth for grinding and chewing. They
are 8 in number.
12.Molar:-Teeth for grinding and chewing is
called Molar..They are 12 in number.
13.Salivary
glands:- Glands
which secrets saliva.
14.Saliva:- liquid which breakdown starch into
simpler substances is called Saliva.
Liquid which
helps to make the food soften.
15.Oesophagus:- Food pipe that run along neck and
chest.
16.Liver:-Largest gland of body which secrets
bile juice is called Liver.
17.Gall
bladder:-A sac like
structure which store bile.
18. Bile:-A yellow green fluid made by liver
that store in gall bladder.
19.Pancreas:-A large cream coloured gland
located just below stomach.
20.Villi:- Inner wall of small intestine have
thousands of finger like outgrowth called Villi.
21.Amino
acids:-Proteins
break down into simple substances or molecules called amino acids.
22.Fatty
acids:-Building
blocks of fat in body is called fatty acids
23.Glycerol:-A colourless sweet liquid produce
by breakdown of fat is called glycerol.
Question
: What is villi ? What is their location and function ?
Answer :
Villi are tiny, finger-like projections found on the inner surface of the
small intestine. They are located in the small intestine and their
function is to increase the surface area for nutrient absorption. This
increased surface area allows for more efficient absorption of digested food
into the bloodstream.
Question:
Where is bile produced? Which component of the food does it help to digest ?
Answer :
Bile is produced in the liver and helps digest fats
Question
: Why do we get instant energy from glucose ?
Answer : We
get instant energy from glucose because it's a simple sugar that the body
can readily absorb and utilize
Ques: Boojho
took some grains of boiled rice in test tube ‘A’ and Paheli took boiled and
chewed rice in test tube ‘B’. Both of them poured 1 – 2 drops of iodine
solution into the test tube and observed the colour change. What colour change
would they have observed? Give reasons for your answer.
Answer :
Boojho would observe a blue-black color change in test tube A, while Paheli
would observe no color change in test tube B. This is because boiled rice
contains starch, which reacts with iodine to form a blue-black
complex. However, in test tube B, chewing breaks down the starch into
simpler sugars, which do not react with iodine
Ques :
‘A’ got her gall bladder removed surgically as she was diagnosed with stones in
her gall bladder. After the surgery, she faced problems in digestion of certain
food items when consumed in bulk. Can you tell which kind of food items would
they be and why?
Answer : After gallbladder removal, 'A' would
likely experience difficulty digesting fatty foods when consumed in large
quantities. This is because the gallbladder stores and concentrates bile,
which is essential for breaking down fats in the digestive system. Without
the gallbladder, the bile is released continuously and may not be concentrated
enough to efficiently digest large amounts of fat.
Ques :
Ruminants such as cows and buffaloes swallow their food hurriedly and then sit
restfully and chew their food. Can you reason why?
Answer :
Ruminants like cows and buffaloes swallow food quickly and then chew it later
because their digestive system is adapted to break down tough plant
matter, like grass, efficiently. They initially swallow the food into
their rumen, a specialized chamber in the stomach where it is fermented by
bacteria. Later, they regurgitate this partially digested food (the cud)
and chew it further before swallowing it again into the rest of their digestive
system
Ques :
Boojho and Paheli were eating their food hurriedly so that they could go out
and play during the recess. Suddenly, Boojho started coughing violently. Think
of the reasons why he was coughing and discuss with your friends.
Answer :
Boojho's violent coughing could be due to food entering his windpipe
instead of his esophagus. Eating too quickly, talking, or laughing while
eating can disrupt the swallowing mechanism, causing food to go down the wrong
path. This can lead to a choking sensation and a violent cough to dislodge
the foreign object.
Concept
3 Digestion in grass eating animals
Keywords
1.Cellulose:-A type of carbohydrates digested by
special bacteria present in rumens of ruminants.
2.Rumen:- Animals such as cow deer etc .
quickly swallow the grass and store it in a part of stomach called rumen.
3.Ruminant:- Animals which show rumination is
called Ruminant. Eg deer , cattle etc
4.Rumination:-The process in which animals chew
the cud which replaces in its mouth in small lumps is called Rumination.
Question
: Name the type of carbohydrates that can be digested by ruminants but not by
humans . Give the reason also.
Answer : The
type of carbohydrate that ruminants can digest but humans cannot
is cellulose
Concept
4 Feeding and digestion in Amoeba
Keywords
1.Amoeba:-A microscopic single celled organism
found in pond water.
2.Food
vacuole:-A sac like
structure which trap food for storage.
3.Pseudopodia:- False feet or finger like
projection seen in Amoeba to capture its prey .
Question : Write one similarity and one difference between
the nutrition in amoeba and human beings.
Answer : Similarity: Both amoebas and
human beings are heterotrophs, meaning they both obtain their nutrition by
consuming other organisms.
Differences :
Home Task
Q 1: Rohan observed that his pet cow was
chewing continuously even when it was not eating. Why do cows do that? What
does this indicate about their digestive system?
Q 2: If the salivary glands stop
functioning, how will it affect the digestion of food? Explain with reasons.
Q 3: A student examined a sample of food
under a microscope and saw amoebas surrounding it with pseudopodia. What
process was being observed? What does it tell us about the nutrition in amoeba?
Q 4: How is the process of digestion in a
ruminant animal different from that in humans? Mention any two differences.
Q 5: Amit complains of indigestion and
stomach pain after eating very quickly. What habits should he change, and why?
Q 6: Draw the diagram of the human digestive system. Label the following
parts:
Mouth Stomach Small intestine Large intestine
Also mention the function of any one of these parts.
Q 7: Why should we not lie down
immediately after eating a heavy meal? Relate your answer to the process of
digestion.
Q8: Why does food take longer to digest
in the stomach than in the mouth? What advantages does this provide to the
body?
Q9: Explain how the nutrients absorbed
in the small intestine reach different parts of the body. Which system is
involved apart from the digestive system?
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