Nutrition in Animals
I. Fill in the blanks:
(a) The main steps of nutrition in humans are
ingestion, digestion, absorption, assimilation
and egestion.
(b) The largest gland in the human body is
liver.
(c) The stomach releases hydrochloric acid and
digestive juices which act on food.
(d) The inner wall of the small intestine has
many finger-like outgrowths called villi.
(e) Amoeba digests its food in the
food vacuole.
II: Mark 'T' if the statement is true and 'F'
if it is false:
(a) Digestion of starch starts in the
stomach. (F)
(b) The tongue helps in mixing food with
saliva. (T)
(c) The gall bladder temporarily stores bile.
(T)
(d) The ruminants bring back swallowed grass
into their mouth and chew it for some time. (T)
III: Choose it:
(a) Fat is completely digested in the small intestine
(i) stomach
(ii) mouth
(iii) small intestine
(iv) large intestine
(b) Water from the undigested food is absorbed mainly in the Large intestine
(i) stomach
(ii) food pipe
(iii)small intestine
(iv) Large intestine
IV: Match the items of Column I with those in Column II:
Food components Product(s) of
digestion
Carbohydrates Sugar
Proteins Amino
acids
Fats Fatty acids and glycerol
V. Answer the following:-
1. What are villi? What is their location and
function?
Ans: Villi are tiny finger-like projections
originating from the walls of the small intestine. They increase the
surface area for absorption of the digested food. The blood vessels present inside the villi can absorb the
nutrients from the digested food.
Structure of a villis.
2: Where is the bile produced? Which
component of the food does it help to digest?
Ans: Liver secretes the bile juice which is stored
in the gall bladder. Bile plays an important role in the digestion of fats.
3: Name the type of carbohydrate that can be
digested by ruminants but not by humans. Give the reason also.
Ans: Cellulose is a type of carbohydrate that can
be digested by ruminants and not by humans. Ruminants have a large sac-like
structure between small and large intestine where the food containing cellulose is
digested by the action of certain bacteria. On the other hand, humans cannot digest cellulose, as the cellulose digesting enzymes are
absent in them.
4 :Why do we get instant energy from glucose?
Glucose is a simple sugar. Carbohydrates,
when consumed, have to be digested into glucose. As glucose can be easily
absorbed in
blood, it provides energy to the body. Hence, when glucose is directly taken,
it does not have to be digested and thus acts as an
instant source of energy.
5: Which part of the digestive canal is
involved in:
(i) absorption of
food - Small intestine
(ii) Chewing of food - buccal cavity.
(iii) Killing of bacteria - Stomach
(iv) complete digestion of food - small intestine
(v) formation of faeces - Large intestine
6: Write one similarity and one difference between the nutrition in Amoeba
and human beings.
Ans:
Both Amoeba and humans require energy for the growth and
maintenance of their bodies. This energy is derived from the food that they
eat. The food that they consume is always in a complex form and is therefore
broken down into simpler forms by the process of digestion. Hence, both these
organisms are heterotrophs.
7: Label the
following figure of the digestive system.
Ans:
8: Can we survive
only on raw, leafy vegetables/grass? Discuss.
Ans: No. Humans cannot
survive only on raw, leafy vegetables, or grass. It is because the grass is
rich in cellulose, which is a type of carbohydrate that humans are not able to
digest due to the absence of cellulose-digesting enzymes.
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