1.
Food and Nutrition
1
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2.
All Living things need food for growth and to repair the wear and tear
of their body.
Mostly all plants can make their own food , they are called
autotrophs.
All animals , plants like dodder and funguses are dependent on other
plants or animals for food. They are called as heterotrophs.
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3.
There are various items in our food such as rice , bhakari , chapatis
, pulses, sprouts , leafy vegetables , fruits , eggs , fish .
There are starchy foods like chapati , bhakari , rice . Carbohydrates
form a major part of these foods.
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4.
We have protein rich food like pulses , whole pulses , meat , fish
We get salts and vitamins from fruits , cucumber , carrot , leafy
vegetables. We get fats from oil and ghee.
We get water from food we eat , drinking water , juices of fruits.
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5.
All these nutrition's are necessary for nurishment.
A diet which includes all these constitutes in right proportions is called a balance
diet.
We get energy from carbohydrates, protines as well as fats.
Vitamins are necessary for ensuring that all life processes are carrried out
smoothly.
The elements in salt are necessary for brining about the functions of enzymes.
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6.
Eating food for nourishment is called as ingest.
Different living things ingest or take food in different ways.
Ex. Multicellular animals ingest through mouth. Honey bee , butterfly
,mosquito not have mouth instead they have tube like part called
proboscis.
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7.
Unicellular animals like Amoeba not have parts like hands , legs , mouth
etc. It is a unicellular animals. It can take food from any part of the
surface of it’s body.
It engulfs , or surrounds the particle from all sides and ingests it into the
cell. Then enzymes act on the food particle and it get digested. It leaves
behind the undigested part and moves away using pseudopodia.
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8.
Multicellular animals eat food through mouth , it passes through
alimentary canal and moves forward through different organs.
As it moves forward , food constituents chemical substances which
absorbs into the blood .
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9.
Digestion means food constituents are broken down by the
action of enzymes into simple chemical substances .
They are later absorbed into the blood , through blood it reaches
to all parts of the body.
Then it is used for the growth and repairs of the body.
The process of food becoming the part of body is called as
assimilation.
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10.
A frog has a tongue in its mouth . It is attached to the front of it’s mouth.
When a frog sees an insect, it opens it’s mouth and throws out it’s
tongue towards the insect and pulls the insect into it’s mouth.
The insect is then carried through the oesophagus into the stomach,
where it is digested and then assimilated.
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11.
Human digestive system has following steps
The digestion starts from mouth.
When morsel of food is put into mouth, it is chewed fine by the
teeth. The salvia secreted from the salivary glands is mixed with the
food an the mouth. The fat starts to break here.
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12.
The bolus of food is
pushed forward from mouth
and passes through the
oesophagus into the
stomach.
There, it is acted upon by
the digestive juices from
stomach. Breaks down
proteins , carbohydrates ,
and making food acidic.
Further it passed to small
intestine .
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13.
In small intestine
neutralization of acidic
food takes place.
Substances formed by
the breakdown of
proteins and fats are
absorbed in small
intestine.
Intestinal juices break
down proteins and fats
and are absorbed in to
the body. Insulin created
by pancreas regulates
the level of sugar present
in blood. Food is further
passes to large intestine.
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14.
Salt and mainly water
present in food is
absorbed in large
intestine. Further it
passes to rectum and
expulsion of faeces
takes place through
anus .
Human digestive
system consist of parts
like mouth ,
oesophagus , stomach ,
small intestine , large
intestine , pancreas ,
gall bladder and anus.
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15.
Green plants can prepare their own food. For this they use chlorophyll
, sun light , carbon dioxide , and water and salt absorbed by roots.
from soil.
The process of preparing food by green plants is as followes
Sun light
Water + Carbon dioxide Food + Oxygen + Water
Chlorophyll ( Carbohydrate)
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16.
Plants uses carbon dioxide for food preparation can be explained
from following experiment.
Place a potted green plant in a dark room for two days , so that it
will use the food it has produced and new food will not be produced.
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17.
Fix one leaf in a glass bottle in such a way , that half of the leaf is
inside the bottle where as half of the leaf is outside the bottle.
Put potassium hydroxide pellets in it so that it will absorb carbon
dioxide present in the bottle.
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18.
Place the pot in sunlight for the day. Then pluck the leaf off the
plant at its stalk.
Take some ethyl alcohol in a beaker and place the leaf in it .
Place the beaker in boiling water and heat it.
The chlorophyll dissolves in the alcohol and the leaf becomes
colorless.
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19.
Take some water in a shallow dish and wash the colorless leaf in it. Change the
water in the dish and add a few drops of iodine solution to it.
The part of the leaf that was inside the jar does not become blue. The part that
was outside the jar turns blue . It means that starch was formed in this part.
The part inside the bottle received sunlight and water , but the potassium
hydroxide in the bottle absorbs the carbon dioxide from the air in the bottle .
Hence photosynthesis could not take place in side the bottle.
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