Grade 10 science chapter 1 simple notes in english ,grade 10 science notes in English ,science English notes pdf free download

The chemicals of life

-wondering what makes you come to life ?there are four important chemicals made majorly from 

-carbon hydrogen and oxygen that are known as the chemicals of life.

The four chemicals

carbohydrates - carbohydrates are the body's main source of energy

-They contain the elements carbon hydrogen and oxygen 

They come in two kinds 

-simple sugars [ monosaccharides ] are the simplest form of carbohydrates complex sugars[ disaccharide and polysaccharide ] simple sugar


-Monosaccharide - simple sugars can provide
a lot of energy for immediate usage.
however they contain no other useful nutrients [ Example-glucose ]

complex sugar disaccharide and polysaccharide

-these are good sources of energy.

-the body can easily store this form of energy for rapid use in the future.

-plant cells store complex sugars in the form of starch.
-Animal cells store complex sugars in the form of glycogen.
-Animal cells store complex sugars in the form of glycogen.

Examples

-disaccharide maltose 

-polysaccharide starch or glycogen 

Foods containing carbohydrates are

-bread 

-root vegetables

-potatoes 

-pasta 

-milk 

-As mentioned before energy from carbohydrates is converted into glycogen and is stored in the liver and in our muscles

-when energy is needed. the body changes that glycogen into glucose which is then used by the body during aerobic respiration 

-if a lot of carbohydrates is eaten it will be stored as fat

Fat's 

-fats are used for energy but only when carbohydrate supplies run low.

-they contain the elements carbon,hydrogen and oxygen 

-their simplest forms are fatty acids and glycerol.

There are two types of fat

-saturated fat 

-these are usually found in foods such as   -milk 

-butter

-cheese 

-meat 

-unsaturated fat

-these are usually found in foods such as

-fish oils 

-cooking oils 

-vegetable oils 

Saturated fats are converted to cholesterol by the liver 

There are two types of cholesterol

-HDL [ high density lipids ] 

-must be in greater amounts as it is beneficial and good  

-LDL [ low density lipids ]

-Must be controlled amount or else the person may get infected with coronary heart
disease

-for this reason no more than 10 percent of your energy should come from eating saturated fats

-if the percentage level of saturated fats in your diet increases fat deposits begin to build up inside of the blood arteries making them stiffer, less elastic and narrower.

-when this particularly happens in the
coronary artery that supplies oxygen to
the heart.

-very less oxygen is supplied
to it.

-decreasing its performance andincreasing the risk of coronary heart disease.

-this usually results in blood clot and a heart attack.

-Eating too much fat leads to obesity coronary heart disease and diabetes 

The functions of fats.

-they are needed to keep us warm

-they are stored in the adipose tissue.
which can break down the fats if the body's carbohydrate stores get exhausted.

-The adipose tissue is needed to insulate our body 

PROTEINS

-proteins are used to generate energy only when thevbody has exhausted its store of fat and carbohydrates.

-proteins are very important for the body our muscles and other tissues hemoglobin, fibrin,keratin,collagen,DNA and Enymes
etc.are all made up of proteins 

-the proteins you eat are broken down into amino acids and are used by the body to build and repair cells and to make blood

cells.

-proteins are made by the synthesis of amino acids in the ribosomes of cells carbon,hydrogen,oxygen and nitrogen and a bit of sulfur is what amino acid molecules contain

-food containing proteins are eggs fish etc 

-kwashiorkor is characterized by a protruding abdomen due to a lack of proteins 

water

-the body is majorly composed of water approximately 60% of an adult's weight
is composed of water 80% of the child's.
-it is vitally important that you drink
enough water.

-dehydration can seriously damage performance of the body.

utilization of water 

-water is used in our bodies for a vast number of reasons here are some of them 

-it is an important solvent 

-it is needed for carrying and metabolic processes 

-it is beneficial in excreting wastes body products such as urea 

-it can cool down our bodies significantly by releasing sweat 

-it is needed for enzymes to dissolve in it 

-it is the major part of blood plasma the

Tests

-this section focuses particularly on the tests to detect the presence ofthe chemicals of life 

Testing for carbohydrates

-there is a simple test for carbohydrates just add Benedict's solution to the food and heat it up

however to give you a detailed description here we go

1.cut or grind a piece of the food to be tested.
2.add some water to the food and try to
dissolve it in a test tube.

3.add some Benedict's solution to the test tubewhich is blue as it contains copper
salts.

4.heat the test tube until it is 80 degrees Celsius observe the color change from blue to brick red blue to green to yellow to orange and automatically brick red.

-safety precaution however use a water bath to eat the test tube.

Test for starch 

1.put a small piece of food on a white tile so that color change can be noticed.

2.add a drop of iodine solution to the food.

3.notice the color change to blue-black 

Testing for fats

fats don't dissolve in water and thus ethanol needs to be added use the.

1.chop and grind small amounts of food.

2.be tested to added the food into a clean test tube.

3.pour some pure ethanol into it.

4.shake it to dissolve.

5.take another test tube and add some distilled water into it.

6.pour the liquid part into the second test tube a milky appearance proves that the food contains fat.

Testing for proteins 

1.put the food into a test tube 

2.added water

3.add some potassium hydroxide solution

4.add two drops of copper sulfate solution 5.shake the tube gently an appearance of a purple color proves that protein is present