NCERT Solution for
class 7th in Science Subject
Chapter 2 : Nutrition In Animals
Question 1: Fill
in the blanks:
(a) The main steps of
nutrition in humans are __________, __________, ___________, __________
and __________
(b) The largest gland in the
human body is __________.
(c) The stomach releases
hydrochloric acid and ________ juices which act on food.
(d) The inner wall of the
small intestine has many finger-like outgrowths called __________.
(e) Amoeba digests its food
in the __________.
Answer:
(a) ingestion,
digestion, absorption, assimilation and egestion.
(b) liver.
(c) digestive
(d) villi.
(e) food
vacuole.
Question 2:
Mark ‘T’ if the statement is true and ‘F’
if it is false:
(a)Digestion of starch starts in the
stomach. (T/F)
Answer:
false
(b)The tongue helps in mixing food with saliva.
(T/F)
Answer:
true
(c)The gall bladder temporarily stores bile.
(T/F)
Answer:
true
(d)The ruminants bring back swallowed grass
into their mouth and chew it for
some time. (T/F)
Answer:
true
Question 3:
Tick mark the correct answer in each of the
following:
(a) Fat is completely
digested in the
(i) stomach
(ii) mouth
(iii) small intestine
(iv) large intestine
Answer :
(iii)Small intestine
(b) Water from the undigested
food is absorbed mainly in the
(i) stomach
(ii) food pipe
(iii) small intestine
(iv) large intestine
Answer :
(iv)Large intestine
Question 4:
Match the
items of Column I with those given in Column II:
Column I
|
Column II
|
Food components
|
Product(s) of digestion
|
Carbohydrates
|
Fatty acids and glycerol
|
Proteins
|
Sugar
|
Fats
|
Amino acids
|
Answer:
Column I
|
Column II
|
Food components
|
Product(s) of digestion
|
Carbohydrates
|
Sugar
|
Proteins
|
Amino acids
|
Fats
|
Fatty acids and glycerol
|
Question 5:
What are villi? What is
their location and function?
Answer:
Villi are tiny finger-like
projections originating from the walls of the small intestine.
They increasethe 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 villus
Question 6:
Where is the bile produced? Which
component of the food does it help to digest?
Answer:
Liversecretes the bile juice which
is stored in the gall bladder. Bile plays an important role in
thedigestion of fats.
Question 7:
Name the type of carbohydrate
that can be digested by ruminants but not by humans. Give the reason also.
Answer:
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 containingcellulose is digested by the action of certain bacteria. On
the other hand, humans cannot digest cellulose, asthe cellulose digesting
enzymes are absent in them.
Question 8:
Why do we get instant energy
from glucose?
Answer:
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
directlytaken, it does not have to be digested and thus acts as an instant
source of energy.
Question 9:
Which part of the digestive canal is involved in:
(i) absorption of food ____.
(ii) chewing of food ____.
(iii) killing of bacteria
____.
(iv) complete digestion of
food ____.
(v) formation of faeces ____.
Answer:
(i) small intestine
(ii) buccal cavity
(iii) stomach
(iv) small intestine
(v) large intestine
Question 10:
Write one similarity and one difference between the nutrition in
Amoeba and human beings.
Answer:
Similarity between nutrition in Amoeba and human beings:
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 istherefore broken down into simpler forms by
the process of digestion. Hence, both these organisms areheterotrophs.
Differences between nutrition in Amoeba and human beings:
Digestion in Humans Digestion in
Amoeba
human beings
|
Amoeba
|
Humans have a mouth and a complex digestive system.
|
Mouth and digestive system are absent inAmoeba.
|
Digestive juices are secreted in the buccal cavity,
stomach, and small intestine.
|
Digestive juices are secreted in the food
vacuole.
|
Digestion of carbohydrates, proteins, and fats starts in
separate regions.
|
All the food components are digested in
the food vacuole.
|
Question 11:
Match the items of
Column I with suitable items in Column II.
Column I
|
Column II
|
Salivary gland
|
Bile juice secretion
|
Stomach
|
Storage of undigested food
|
Liver
|
Saliva secretion
|
Rectum
|
Acid release
|
Small intestine
|
Digestion is completed
|
Large intestine
|
Absorption of water
|
Answer:
Column I
|
Column II
|
Salivary gland
|
Saliva secretion
|
Stomach
|
Acid release
|
Liver
|
Bile juice secretion
|
Rectum
|
Storage of undigested food
|
Small intestine
|
Digestion is completed
|
Large intestine
|
Absorption of water
|
Question 12:
Label the following figure of
the digestive system . A part of human digestive system
Answer:
Human digestive system
Question 13:
Can we survive only on raw,
leafy vegetables/grass? Discuss.
Answer:
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.