Question
1:
Which of
these is not a part of nutrition?
(a)
digestion
(b)
absorption
(c)
egestion
(d)
excretion
ANSWER:
(d)
excretion
Ingestion,
digestion, absorption, assimilation and egestion are the five steps of
nutrition. Excretion is not a part of nutrition.
Question
2:
The
pointed teeth in your mouth are
(a)
permolars
(b)
incisors
(c)
molars
(d)
canines
ANSWER:
(d)
canines
The
pointed teeth in our mouth are called canines. They help us in piercing and
tearing the food.
Question
3:
The last
part of digestion of food takes place in the
(a)
stomach
(b)
small intestine
(c)
large intestine
(d)
oesophagus
ANSWER:
(b)
small intestine
The last
step of digestion of food takes place in the small intestine.
Question
4:
Which of
the following organs does not secrete digestive juices?
(a)
stomach
(b)
small intestine
(c)
liver
(d)
oesophagus
ANSWER:
(d)
oesophagus
Oesophagus
does not secrete any digestive juice. The stomach, small intestine and liver
secrete digestive juices.
Question
5:
The
greatest amount of digestion of food in humans takes place in the
(a)
mouth
(b)
stomach
(c)
small intestine
(d)
large intestine
ANSWER:
(c)
small intestine
Mostly,
the digestion of food takes place in our small intestine.
Question
6:
Breaking
down of food into simple soluble compounds is called
(a)
ingestion
(b)
digestion
(c)
nutrition
(d)
egestion
ANSWER:
(b)
digestion
Through
the process of digestion, food is broken down into simple soluble compounds.
Question
7:
During
digestion, fats are changed into
(a)
amino acids
(b)
fatty acids and glycerol
(c)
sugar
(d)
glucose
ANSWER:
(b)
fatty acids and glycerol
During
digestion, fats are converted to fatty acids and glycerol.
Question
8:
Bile is produced
in the
(a)
stomach
(b)
small intestine
(c)
pancreas
(d)
liver
ANSWER:
(d)
Liver
Bile is
a digestive juice which is produced in the liver.
Question
9:
The
teeth that are used for biting an apple are
(a)
incisors
(b)
canines
(c)
pre-molars
(d) molars
ANSWER:
(a)
Incisors
Incisors
are the front teeth that are used to bite the food. Hence, we use incisors to
bite an apple.
Question
10:
What
kind of teeth do you think are especially developed in carnivores?
(a)
incisors
(b)
canines
(c) pre-molars
(d)
molars
ANSWER:
(b)
Canines
Carnivores
have specially developed canines which help them to tear the meat.
Question
11:
How does
a frog catch its prey?
ANSWER:
A frog catches its prey using its long and
sticky tongue.
Question
12:
How does
a spider digest its food?
ANSWER:
A spider
injects digestive juices into the body of its prey, which digest their body
parts. Thus, a spider digests its food.
Question
13:
Name the
organs that make up the human alimentary canal.
ANSWER:
Organs
that make up the human alimentary canal are mouth, pharynx, oesophagus,
stomach, small intestine, large intestine and anus.
Question
14:
What is
the difference between milk teeth and permanent teeth?
ANSWER:
Milk
teeth are twenty in number.
Permanent
teeth are 32 in number.
Milk
teeth start falling out by the age of 6 years.
Permanent
teeth does not fall throughout the life until their is any deficiency.
Question
15:
What is
saliva and where is it produced?
ANSWER:
Saliva
is the watery and slippery secretion produced inside the mouth.
Question
16:
What is
the function of taste buds?
ANSWER:
The
function of taste buds is to detect the various tastes like sweetness,
saltiness, sourness and bitterness of food.
Question
17:
How long
does food stay in the stomach?
ANSWER:
Food can
stay in the stomach from a few minutes to a few hours, depending on its type.
Solid food stays in the stomach for 4-5 hours, but liquid food remains only for
a few minutes.
Question
18:
How does
the presence of acid in the stomach help?
ANSWER:
The acid
in the stomach helps in digesting proteins. It also kills the bacteria that
enter the stomach through food.
Question
19:
List and
explain in one sentence each, the various process involved in nutrition in
animals.
ANSWER:
The
various process involved in obtaining nutrition in animals are as follows:-
1)
Ingestion- The process of taking food inside our mouth is known as ingestion.
2)
Digestion- The process of breaking down food into molecules is known as
digestion.
3)
Absorption- The process of absorbing the digested food through the villi of
small intestine is known as absorption.
4)
Assimilation- The process of producing energy from the absorbed food is known
as assimilation.
5)
Egestion- The process of removing the wastes from our body through the anus is
known as egestion.
Question
20:
Explain
through diagrams ingestion of food in
(a)
Amoeba
(b)
Hydra
ANSWER:
(a)
Ingestion
of food in Amoeba:
(b)
Ingestion
of food in Hydra:
Question
23:
Name the
four types of teeth in your mouth. What are their functions?
ANSWER:
The four
types of teeth in our mouth are:
1)
Incisors- They help us in biting and cutting the food.
2) Canines-
They help us in piercing and tearing the pieces of meat.
3)
Premolars- They assist the molars by holding the food with their cusps and also
crushing them.
4)
Molars- They help us in chewing and grinding the food so that it can be swallowed
easily.
Question
24:
What is
peristalsis?
ANSWER:
Peristalsis
can be defined as the wave like action of the muscles of the organs present in
the alimentary canal to push the food forward or downward.
Question
25:
What is
the function of
(a)
saliva
(b) bile
juice
(c)
pancreatic juice
ANSWER:
(a)
Saliva- It helps in breaking down the starch, present in food, into sugar. It
also makes the food wet and slippery, thereby making it easier to swallow.
(b) Bile
juice- It is secreted by the liver and helps in breaking down the fats, present
in the food, into fatty acid and glycerol.
(c)
Pancreatic juice- It is secreted by the pancreas and helps in converting starch
into sugar and proteins into amino acids.
Question
26:
What
happens to food in the
(a)
stomach
(b)
small intestine
ANSWER:
(a)
Stomach
secretes acid and digestive juices that kill the bacteria, if any, present in
the food. Further, the digestive juices break the proteins, present in the
food, into simpler substances, thereby digesting the food partially.
(b)
Small
intestine also secretes some digestive juices, and also receives the bile juice
secreted by the liver and the pancreatic juice secreted by the pancreas. The
bile juice along with the digestive juice converts the fats into fatty acids
and glycerol. The pancreatic juice breaks down the starch into sugar, and
proteins into amino acid.
Question
27:
Explain
how digested food is absorbed into the blood.
ANSWER:
The
digested food is absorbed inside the small intestine which have finger like
projections called villi in its inner wall. These villi comprise networks of
fine blood capillaries close to their surface. The food from the villi passes
into these capillaries thereby getting absorbed into the blood.
Question
28:
Briefly
explain the process of digestion in ruminants.
ANSWER:
The
stomach of a ruminant is divided into four chambers. As soon as the ruminant
swallows the food, it enters the first chamber called rumen where it gets
partially digested (converted to cud). From here, the food enters the second
chamber from where it again reaches the mouth for rumination, which is thorough
chewing. The food is again swallowed, and now it enters the third and the fourth
chamber for digestion. From here, it enters the small intestine for the
absorption of nutrients.
Question
29:
Digestion
is the process of breaking down of food into simple, _________ form.
ANSWER:
Digestion
is the process of breaking down food into simple soluble form.
Question
30:
What is
the name given to the process of using the absorbed food for producing energy?
ANSWER:
The
process of producing energy from the absorbed food is known as assimilation.
Question
31:
Name the
cavity in unicellular animals in which food in present.
ANSWER:
In
unicellular animals, food is present in the cavity called food vacuole.
Question
32:
Digestion
begins in the stomach. True of false?
ANSWER:
It is a
false statement, as the digestion of food begins in the mouth.
Question
33:
Saliva
helps by making the food wet. It does not have any other function.True or
false?
ANSWER:
False,
saliva not just makes the food wet but also breaks down the starch into sugar
which is easier to digest.
Question
34:
Where
does initial digestion of proteins take place?
ANSWER:
The
initial digestion of proteins takes place in the stomach.
Question
35:
The
white hard substance that covers the teeth is called ___________
ANSWER:
The
white hard substance that covers the teeth is called enamel.
Question
36:
In which
part of the digestive system is water absorbed from undigested food?
ANSWER:
Most of
the water from the undigested food is absorbed in the large intestine.
Question
37:
The
semi-digested food that is chewed again by ruminants is called __________
ANSWER:
The
semi-digested food that is chewed again by ruminants is called cud.
Question
38:
The
function of the villi is to hold the food in the spaces between them so that
food can be absorbed by the walls of the intestine.True or false?
ANSWER:
True.
Villi are finger-like projections that hold the food in the spaces between them
so that the food can be easily absorbed by the walls of the intestine.
Question
39:
Which
food do you think will take a longer time to get digested−sugar or beans (beans
contain lot of proteins)?
ANSWER:
As
compared to sugar, beans will take longer time for digestion, as they contain a
lot of proteins. The digestion of sugar starts in the mouth, while the
digestion of proteins starts in the stomach. So, the proteins of the beans will
take longer time to get digested.
Question
40:
Digestion
needs the help of two more systems in the body to provide energy from food.
Which
are these systems and how do they help?
ANSWER:
Two more
systems which help the digestive system to provide energy to our body are the
respiratory system and the cardiovascular system. The glucose absorbed in the
digestive system combines with the oxygen, taken in during respiration, to form
energy. These two are then transported throughout the body via blood of the
cardiovascular system.
Question
41:
If you
eat food while hanging upside down, do you think it will still go through the
alimentary canal? Give reasons.
ANSWER:
Yes.
Even if we eat food while hanging upside down, it will go through the
alimentary canal because of the process of peristalsis. The muscles of the
oesophagus will push the food downwards in a wave like action throughout the
alimentary canal.
Question 42:
Why does
food need to be digested?
ANSWER:
The food
needs to be digested so that it can be converted into simple soluble forms.
These simple soluble forms can provide energy to the body.
Question
43:
Digestion
of food in all animals occurs inside the body. Do you agree? Justify your answer.
ANSWER:
No,
digestion does not occur inside the body in all organisms. Certain animals such
as spiders inject their digestive juices in the body of their prey. These
juices digest the different body parts of the insect and it is then consumed by
spider. This process is called external digestion. Thus, all animals do not
show digestion inside their bodies.
Question
44:
Name two
animals that live on liquid food only.
ANSWER:
Animals
that live only on liquid food include housefly and mosquito.
Question
45:
In which
two organs does digestion of food in humans mainly occur?
ANSWER:
Most of
the digestion in humans occur in stomach and small intestine. The stomach
performs digestion by peristalsis and with the help of digestive juices. Small
intestine, on the other hand, digests food primarily with the help of digestive
juices.
Question
46:
Absorption
of digested food occurs in the stomach. Do you agree? Justify your answer.
ANSWER:
No, the
absorption of food does not occur in the stomach. The food that has been
digested in the stomach is further digested into absorptive form in the small
intestine. The completely digested food is absorbed by the inner lining (villi)
of the small intestine.
Question
47:
All
digestive juices are secreted by cells in the stomach and small intestine. Do
you agree? Give reasons.
ANSWER:
No, all
digestive juices are not secreted by the cells of small intestine and stomach.
Certain organs such as liver and pancreas also secrete digestive juices. The
liver secretes bile juice which is used for the digestion of fats. Pancreas, on
the other hand, produces pancreatic juice which digests starch and proteins
into their simpler constituents.
Question
48:
What
happens to food after it is digested, and absorbed by the blood?
ANSWER:
The food
that has been digested and absorbed is assimilated by the body. The absorbed
food is transported by the blood to different parts of the body. This absorbed
food is used by the cell for growth, reproduction and obtaining energy. Some of
the absorbed food is also stored for future use.
Question
49:
In what
way is the basic structure of the stomach of a cow different from the stomach
of a human?
ANSWER:
The
stomach of cows is composed of four chambers unlike human stomach which has a
single chamber. The food in cows is firstly introduced in the first chamber of
the stomach called rumen. In rumen, partial digestion of food occurs and the
partially digested food is called cud. Thereafter, it is passed to the second
chamber, from where it is reintroduced into the mouth for proper chewing.
Followed by proper chewing, the remaining chambers of the stomach carry out
complete digestion of food.
Question 50:
Saliva
helps by making the food wet. It does not have any other function.True or
false?
ANSWER:
False,
saliva not just makes the food wet but also breaks down the starch into sugar
which is easier to digest.
Question 51:
Where
does initial digestion of proteins take place?
ANSWER:
The
initial digestion of proteins takes place in the stomach.
Question
52:
The
white hard substance that covers the teeth is called ___________
ANSWER:
The
white hard substance that covers the teeth is called eenamel
Question
53:
The function
of the villi is to hold the food in the spaces between them so that food can be
absorbed by the walls of the intestine.True or false?
ANSWER:
True.
Villi are finger-like projections that hold the food in the spaces between them
so that the food can be easily absorbed by the walls of the intestine.
Question
54:
We can
see many overweight people but very few overweight animals. Why do you think
this is so?
ANSWER:
The main
reason of getting overweight is the over consumption of nutritious food (rich
in fat). We humans have this tendency of gorging on such fat rich foods which
lead to weight gain. However most of the animals do not consume such fat rich
food and have very little chances of getting overweight.
Question
55:
Tinto
loves to eat junk food. He is overweight. His friend Ayesha is very worried.
She constantly advices him to cut down on junk food and eat more fruits and
vegetables. Do you think she is right? What value does she show?
ANSWER:
Yes,
Ayesha is right in doing so. Junk food is not good for heath as it leads to
obesity. Obesity is one of the major cause for diseases like diabetes,
hypertension etc.
Ayesha’s
friend is already obesed and needs to loose weight to live a healthy life. Replacing
these junk foods with fruits and vegetables will help him to reduce weight and
also lead a healthy lifestyle.
1.
Question: 60
How alimentary canals are divided into
various parts?
Answer:
The canal can be divided into various
compartments:
(1)
The buccal cavity, (2) foodpipe or
oesophagus, (3) stomach, (4) small intestine, (5) large intestine ending in the
rectum and (6) the anus.
2.
Question: 61
What is alimentary canal?
Answer:
The food passes through a continuous
canal which begins at the buccal cavity and ends at the anus. The canal can be
divided into various compartments:
(1)
The buccal cavity, (2) foodpipe or
oesophagus, (3) stomach, (4) small intestine, (5) large intestine ending in the
rectum and (6) the anus. Is it not a very long path? These parts together form
the alimentary canal (digestive tract).
3.
Question: 62
What is ingestion?
Answer:
Food is taken into the body through the
mouth. The process of taking food into the body is called ingestion.
4.
Question: 63
Write a short note on mouth and buccal cavity.
Answer:
Food is taken into the body through the
mouth. The process of taking food into the body is called ingestion. We chew
the food with the teeth and break it down mechanically into small pieces. Each
tooth is rooted in a separate socket in the gums. Our teeth vary in appearance
and perform different functions. Accordingly they are given different names.
5.
Question: 64
What is the action of saliva on food?
Describe through an experiment.
Answer:
The saliva breaks down the starch into
sugars.
Aim: To know the action of Saliva on
food.
Materials Required:
Test tubes, dropper, iodine solution, boiled
rice.
Procedure:
Take two test tubes. Label them ‘A’ and
‘B’. In test tube ‘A’ put one teaspoonful of boiled rice; in test tube ‘B’ keep
one teaspoonful of boiled rice after chewing it for 3 to 5 minutes. Add 3–4 mL
of water in both the test tubes. Now pour 2–3 drops of iodine solution in each
test tube and observe.
Observation:
The colour of the solution in test tube
A will get changed to blue black as the starch in rice is not converted to
sugar, whereas the colour of the solution in test tube B changed to blue black.
Conclusion:
The saliva breaks down the starch into sugars
of the chewed boiled rice.
6.
Question: 65
What is tongue?
Answer:
The tongue is a fleshy muscular organ
attached at the back to the floor of the buccal cavity. It is free at the front
and can be moved in all directions.
7.
Question 66:
Write the functions of tongue.
Answer:
We use our tongue for talking. Besides,
it mixes saliva with the food during chewing and helps in swallowing food. We
also taste food with our tongue. It has taste buds that detect different tastes
of food.
8.
Questions 67:
What is tooth decay?
Answer:
Normally bacteria are present in our
mouth but they are not harmful to us. However, if we do not clean our teeth and
mouth after eating, many harmful bacteria also begin to live and grow in it.
These bacteria break down the sugars present from the leftover food and release
acids. The acids gradually damage the teeth. This is called tooth decay.
9.
Question 68:
How can we prevent tooth decay?
Answer:
One should clean the teeth with a brush
or datun and dental floss (a special strong thread which is moved between two
teeth to take out trapped food particles) at least twice a day and rinse the
mouth after every meal. Also, one should not put dirty fingers or any unwashed
object in the mouth.
10.
Question 69:
What is Dental floss?
Answer: A special strong thread which is
moved between two teeth to take out trapped food particles.
11.
Question 70:
How is food prevented from entering the
windpipe?
Answer:
During the act of swallowing a flap-like
valve closes the passage of the windpipe and guides the food into the food pipe.
If, by chance, food particles enter the windpipe, we feel choked, get hiccups
or cough.
12.
Question 71:
Describe stomach. And write it’s function.
Or what happens to the food in stomach?
Answer:
The stomach is a thick-walled bag. Its
shape is like a flattened J and it is the widest part of the alimentary canal.
It receives food from the food pipe at one end and opens into the small
intestine at the other.
The inner lining of the stomach secretes
mucous, hydrochloric acid and digestive juices. The mucous protects the lining
of the stomach. The acid kills many bacteria that enter along with the food and
makes the medium in the stomach acidic and helps the digestive juices to act.
The digestive juices break down the proteins into simpler substances.
13.
Question 72:
Describe small intestine. What happens to
the food in small intestine?
Answer:
The small intestine is highly coiled and
is about 7.5 metres long. It receives secretions from the liver and the
pancreas. Besides, its wall also secretes juices.
Liver which is the largest gland of the body
decreases bile juice and the bile juice gets stored in the gall bladder, from where
it generally reaches to small intestine and act on the partially digested food.
The bile plays an important role in the digestion of fats.
The pancreatic juice acts on
carbohydrates, fats and proteins and changes them into simpler forms. The
partly digested food now reaches the lower part of the small intestine where
the intestinal juice completes the digestion of all components of the food. The
carbohydrates get broken into simple sugars such as glucose, fats into fatty
acids and glycerol, and proteins into amino acids.
14.
Question 73:
What is the function of bile juice?
Answer:
The bile plays an important role in the
digestion of fats.
15.
Question 74:
Write a note about liver.
Answer:
The liver is a reddish brown gland
situated in the upper part of the abdomen on the right side. It is the largest
gland in the body. It secretes bile juice that is stored in a sac called the
gall bladder. The bile plays an important role in the digestion of fats.
16.
Question 75
What is pancreas?
Answer:
The pancreas is a large cream coloured
gland located just below the stomach. The pancreatic juice acts on
carbohydrates, fats and proteins and changes them into simpler forms.
17.
Question 76:
Define absorption and assimilation.
Answer:
The process of absorbing the digested
food through the villi of small intestine is known as absorption.
Assimilation- The process of producing
energy from the absorbed food is known as assimilation.
18.
Question 77:
Write the role of Villi.
Answer:
The villi increase the surface area for
absorption of the digested food. Each villus has a network of thin and small
blood vessels close to its surface. The surface of the villi absorbs the
digested food materials.
19.
Question 78:
Describe the process absorption.
Answer:
The digested food can
now pass into the blood vessels in the wall of the intestine. This process is
called absorption. The inner walls of the small
intestine have thousands of finger-like outgrowths. These are called villi (singular villus). The villi increase the surface area for
absorption of the digested food. Each villus has a network of thin and small
blood vessels close to its surface. The surface of the villi absorbs the
digested food materials. The absorbed substances are transported via the blood
vessels to different organs of the body where they are used to build complex substances such as the
proteins required by the body. This is called assimilation. In the cells, glucose breaks down with the help of oxygen into carbon
dioxide and water, and energy is released. The food that remains undigested and
unabsorbed enters into the large intestine.
20.
Question 79:
What happens to the glucose in the cell?
Answer:
In the cells, glucose breaks down with
the help of oxygen into carbon dioxide and water, and energy is released.
21.
Question 80:
What happens to the undigested food in large
intestine?
Answer:
The large intestine is wider and shorter
than small intestine. It is about 1.5 metre in length. Its function is to
absorb water and some salts from the undigested food material. The remaining
waste passes into the rectum and remains there as semi-solid faeces. The faecal
matter is removed through the anus from
Time-to-time. This is called egestion.
22.
Question 81:
Define egestion.
Answer:
Egestion- The process of removing the
wastes from our body through the anus is known as egestion.
23.
Question 82:
Define ruminants and rumination.
Answer:
Cows,
buffaloes and other grass-eating animals quickly swallow the grass and store it
in a part of the stomach called rumen. Here the food gets partially digested
and is called cud. But later the cud returns to the mouth in small lumps and
the animal chews it. This process is called rumination and these animals are
called ruminants.
24.
Question
83:
Write the digestion process in amoeba.
Answer:
Amoeba
is a microscopic single-celled organism found in pond water. Amoeba has a cell
membrane, a rounded, dense nucleus and many small bubble-like vacuoles (Fig.
2.10) in its cytoplasm. Amoeba constantly changes its shape and position. It
pushes out one, or more finger-like projections, called pseudopodia or false
feet for movement and capture of food. Amoeba feeds on some microscopic organisms.
When it senses food, it pushes out pseudopodia around the food particle and
engulfs it. The food becomes trapped in a food vacuole.
Digestive juices are secreted into the
food vacuole. They act on the food and break it down into simpler substances.
Gradually the digested food is absorbed. The absorbed substances are used for
growth, maintenance and multiplication. The undigested residue of the food is
expelled outside by the vacuole.
25.
Question 84:
Describe Human digestive system with diagram.
Answer:
Digestion Process
The process of digestion begins from the
mouth and ends in the small intestine – the large intestines’ main function is
to absorb the remaining water from the undigested food and enable bacterial
fermentation of materials that can no longer be digested.
The alimentary canal or the
gastrointestinal tract is a series of hollow organs and tubes that begins from
the mouth cavity and continues into the pharynx, through the stomach, small
intestines, large intestines, and finally ending at the anus. Food particles gradually
get digested as they travel through various compartments of the
gastrointestinal tract.
The digestion process takes place in the
following steps.
Ingestion
The very first step involves mastication
(chewing). The salivary glands, along with the tongue, helps to moisten and
lubricate food, before being pushed down into the food pipe.
Mixing and Movement
It involves the process of lubricating
and manipulating food and pushing it down the food through the food pipe (using
peristalsis), and into the stomach.
Secretion
The stomach, small intestine, liver, and
pancreas secrete enzymes and acids to aid the process of digestion. It
functions by breaking down food particles into simple components and easily
absorbable components.
Digestion
The process of converting complex food
particles into simpler substances in the presence of enzymes and acids secreted
by different digestive organs.
Absorption
This process begins in the small
intestine where most of the nutrients and minerals are absorbed. The excess
water in the indigestible matter is absorbed by the large intestines.
Excretion
The process of removing indigestible
substances and waste by-products from the body through the process of
defecation.
In a nutshell, the digestion process consists
of the six following steps:
Ingestion
Mixing and Movement
Secretion
Digestion
Absorption
Excretion
Question 85:
Describe ruminantDruminant system
with diagram.
Answer:
Digestion Process in Ruminants
The digestion process in Ruminants
begins by chewing and swallowing its food. Ruminants do not completely chew the
food they eat, but just consume or gulp as much they can and then swallow the
food. This is actually an adaptation by which these animals have evolved to
spend as little time as possible feeding so that they are not hunted down by
any predators while they are eating.
As mentioned earlier, the stomach of
these Ruminants is divided into 4 chambers – rumen, reticulum, omasum, and the
abomasum.
The process of digestion begins with the
first two chambers of the stomach, the rumen and reticulum by softening the
ingested matter. Later the microbes present in the rumen produces the cellulase
enzymes required to digest the cellulose.
Once the plant fibres have been broken
down to provide vitamins, proteins, and other organic acids, the nutrients are
absorbed into the animal’s bloodstream.
Coarse plants are sent further into the
next chamber for further digestion. Here is where the further bacterial action
takes place and the food is formed into soft chunks called the cud.
This cud produced is regurgitated back
into the animal’s mouth where they can be chewed again. The saliva of the cow
greatly aids in digesting the cud. After chewing, the food bypasses the two
chambers of the stomach and directly enters the third chamber. The walls of the
third chamber mash and compact the food molecules further, and then pass it to
the fourth chamber – the abomasum. The final digestion in the stomach is
carried by the abomasum and then passed to the intestine.
