Subject Science(solution) Chapter 1 Food Where does it ...

Subject – Science(solution) Chapter – 1 Food – Where does it come from

Revision

Chapter – 2 Components of Food

➢ WHAT DO DIFFERENT FOOD ITEMS CONTAIN?

We know that each dish is usually made up of one or more ingredients,

These ingredients contain some components that are needed by our body. These

components are called nutrients.

The major nutrients in our food are named carbohydrates, proteins, fats,

vitamins and minerals.

In addition, food contains dietary fibres and water which are also needed by our body.

➢ Testing of different nutrients in our raw and cooked food.

a) Testing of Carbohydrate

There are many types of carbohydrates. The main

carbohydrates found in our food are in the form of starch

and sugars. We can easily test if a food item contains

starch.

Test for Starch(Carbohydrate)

Take a small quantity of a food item or a raw ingredient.

Put 2-3 drops of dilute iodine solution on it .

Observe if there is any change in the colour of the food item.

Did it turn blue-black?

A blue-black colour indicates that it contains starch.

b) Test for Protein

If the food you want to test is a solid, you first need to make a paste of it or

powder it.

Put some of this in a clean test tube, add 10 drops of water to it and shake the

test tube.

Now, using a dropper, add two drops of solution of copper sulphate and ten

drops of solution of caustic soda to the test tube.

Shake well and let the test tube stand for a few minutes.

A violet colour indicates presence of proteins in the food item.

c) Test for Fats

Take a small quantity of a food item.

Wrap it in a piece of paper and crush it. Take care that the paper does not

tear.

Now, straighten the paper and observe it carefully.

Does it have an oily patch?

Hold the paper against light.

Are you able to see the light faintly, through this patch?

An oily patch on paper shows that the food item contains fat.

Note

The food items may sometimes contain a little water. Therefore, after you

have rubbed an item on paper, let the paper dry for a while

Exercise

1. What do you mean by Nutrients?

We know that each dish is usually made up of one or more ingredients,

These ingredients contain some components that are needed by our body. These

components are called nutrients.




2. What are different Nutrients?




3. Write the steps to test –

a) Carbohydrate

b) Proteins

c) Fats

solution -

a) Testing of Carbohydrate

There are many types of carbohydrates. The main

carbohydrates found in our food are in the form of starch

and sugars. We can easily test if a food item contains

starch.

Test for Starch(Carbohydrate)

Take a small quantity of a food item or a raw ingredient.

Put 2-3 drops of dilute iodine solution on it .

Observe if there is any change in the colour of the food item.

Did it turn blue-black?

A blue-black colour indicates that it contains starch.

b) Test for Protein

If the food you want to test is a solid, you first need to make a paste of it or

powder it.

Put some of this in a clean test tube, add 10 drops of water to it and shake the

test tube.

Now, using a dropper, add two drops of solution of copper sulphate and ten

drops of solution of caustic soda to the test tube.

Shake well and let the test tube stand for a few minutes.

A violet colour indicates presence of proteins in the food item.

c) Test for Fats

Take a small quantity of a food item.

Wrap it in a piece of paper and crush it. Take care that the paper does not

tear.

Now, straighten the paper and observe it carefully.

Does it have an oily patch?

Hold the paper against light.

Are you able to see the light faintly, through this patch?

An oily patch on paper shows that the food item contains fat.

4. With the help of give pictures make a table of food sources

containing different nutrients.

Sources of Carbohydrate

Sources of Protein

Sources of Fats

Rice Plant Sources – Moong Gram Tuar dal Beans

Plants Source – Groundnuts Nuts Til

Wheat Bazra

Sweet potato

Potato Soyabeans Peas

Animal Sources – Meat Fish Paneer Eggs Milk

Animal Source –

Meat Fish Eggs Milk Ghee Butter cream

Sugarcane

Papaya Mango Maize

Melon

Unit – 1 Knowing our Numbers

➢ Estimation(Approximation)

Where do we approximate? Imagine a big celebration at your home. The

first thing you do is to find out roughly how many guests may visit you.

Can you get an idea of the exact number of visitors? It is practically

impossible.

➢ Estimation by Rounding of Numbers We round off a number to gets it approximate estimation. We round off numbers to the nearest ten, nearest hundred, nearest thousand and so on.

1. Round off to the nearest 10.

In this we need to focus on the digit at ones place. Case 1 – If the digit at ones place is 4 or less than 4 – Put 0(zero) at ones place and remaining digits will be same.

For eg. Round off 453 to the nearest ten H T O 4 5 3 LESS THAN 4 Therefore, round off to the nearest ten

= 450 Case 2 – If the digit at ones place is 5 or more than 5 – Put 0(zero) at ones place and add 1 to the digit at tens place.

For eg. Round off 456 to the nearest ten H T O 4 5 6 MORE THAN 5(add 1 to digit at tens place) Therefore, round off to the nearest ten

= 460

2. Round off to the nearest 100.

In this we need to focus on the digit at tens place.

Case 1 – If the digit at tens place is 4 or less than 4 – Put 0(zero) at both tens and ones place and remaining digits will be same.

For eg. Round off 443 to the nearest hundred H T O 4 4 3 LESS THAN or EQUAL TO 4 Therefore, round off to the nearest hundred

= 400 Case 2 – If the digit at tens place is 5 or more than 5 – Put 0(zero) at both ones and tens place and add 1 to the digit at hundreds place.

For eg. Round off 466 to the nearest hundred H T O 4 6 6 MORE THAN or EQUAL TO 5 (add 1 to the digit at hundred place) Therefore, round off to the nearest hundred

= 500 2. Round off to the nearest 1000.

In this we need to focus on the digit at hundred place. Case 1 – If the digit at hundred place is 4 or less than 4 – Put 0(zero) at hundred, tens and ones place and remaining digits will be same.

For eg. Round off 45378 to the nearest thousand

TH TH H T O 4 5 3 7 8 LESS THAN or EQUAL TO 4 Therefore, round off to the nearest thousand

= 45000 Case 2 – If the digit at hundred place is 5 or more than 5 – Put 0(zero) at hundred, tens and ones place and add 1 to the digit at thousands place.

For eg. Round off 45780 to the nearest thousand TH TH H T O 4 5 7 7 8 MORE THAN or EQUAL TO 5 Therefore, round off to the nearest thousand

= 46000 ➢ To estimate sum or difference

You can round off to any nearest value. There are no any fixed rules Example 5 : Estimate: 5,290 + 17,986. Solution : You find 17,986 > 5,290. Round off to thousands. 17,986 rounds off to 18,000 +5,290 rounds off to + 5,000 Estimated sum = 23,000 Does the method work? You may attempt to find the actual answer and verify if the estimate is reasonable.

Example 6 : Estimate: 5,673 – 436. Solution : To begin with we round off to thousands. (Why?) 5,673 rounds off to 6,000 – 436 rounds off to – 0 Estimated difference = 6,000 This is not a reasonable estimate. Why is this not reasonable? To get a closer estimate, let us try rounding each number to hundreds. 5,673 rounds off to 5,700 – 436 rounds off to – 400 Estimated difference = 5,300 This is a better and more meaningful estimate.

To estimate products

What is the estimate for 19 × 78? to nearest tens, we get 80 and 20 × 80 = 1600

➢ Exercise

28 = 30 32 = 30 52 = 50 41 = 40 39 = 40 48 = 50

64 = 60 59 = 60 99 = 100 215 = 220 1453 = 1450 2936 = 2940

75847 nearest tens = 75850 75847 nearest hundreds = 75800 75847 nearest thousands = 76000 75847 nearest ten thousands = 80000

a) 87 x 313

after rounding off = 90 x 300

= 27000

b) 9 x 795


= 8000

c) 898 x 785


711000

d) 958 x 387

after rounding off

960 x 390 = 374400

Solutions

English

Computer

B

A.1.

2

3

Civics

1. Ladakh is known as ‘Little Tibet’.

2.Goats produce pashmina wool and the shawls made of this wool fetch a lot

of money.

3. Ibn Battuta wrote a travelogue describing the lives of Muslims.

4. Cheena-vala are the fishing nets in Kerala.

Hindi

1

2

Subject Science(solution) Chapter 1 Food Where does it ...

Documents

Transcript of Subject Science(solution) Chapter 1 Food Where does it ...