Digestion

In this chapter, we learnt about how the food we eat gets into our body to produce energy for our daily activities.

We need food to:

-Provide us with energy for our daily activities

-Maintain a healthy body

-Grow new cells

-Repair worn out cells

There are 3 main types of nutrients, Carbohydrates, Proteins and Fats.

Carbohydrates

-Our immediate source of energy

-Found in food like rice, bread and noodles

-Exist in different forms such as starch, sucrose, maltose and glucose

Proteins

-Large molecules made up of amino acids

-Makes enzymes

-Found in food like fish, meat and eggs

Fats

-Large insoluble molecules made up of glycerol and fatty acids

-Found in food like butter and cheese

-Stored under our skin and acts as an insulator

The nutrients in the food we eat has to pass through the gut walls and into the blood vessels, in order to be carried through the bloodstream to all parts of the body. However, the gut walls has small openings which only allow molecules small enough to pass through, hence, most nutrients has to be broken down into smaller molecules, as they are too big, in order to be able to pass through the gut walls, and this process is called Digestion.

Enzymes

Enzymes are complex proteins that speed up the rate of chemical reactions by breaking down large molecules into smaller molecules. Enzymes remains unchanged at the end of chemical reactions.

Type of Enzymes:

Enzymes                                       Acts on                                Digested products

Amylase                                       Starch                                    Maltose

Maltase                                        Maltose                                 Glucose

Protease                                       Proteins                                 Amino acids

Lipase                                          Fats                                       Fatty acids and glycerol

Particulate Model of Matter

In this chapter, i have learnt how the different physical properties of solid, liquid and gas can be explained by using the Particulate Model of Matter.

Particulate Model of Solids
The particles in the solid state are:

-Strongly attracted to each other

-Packed extremely closely to one another
-Arranged in a fixed and regular pattern
-Vibrating only in their fixed position


This tells that the particles in a solid are unable to move around freely, hence it has a definite shape and volume. It also explains that there is no space between the particles, hence the particles cannot be compressed any tighter.


Particulate Model of Liquids
The particles in the liquid state are:
-Attracted to one another
-Packed closely together
-Not arranged in fixed, regular pattern
-able to move over short distances


This explains why liquid has no definite shape, because its particles are not arranged in a fixed position. However, it is still unable to be compressed and has a fixed volume because the particles are still held closely together.


Particulate Model of Gases
The particles in the Gaseous state are:
-Weakly attracted to one another
-Far apart from one another
-Able to move freely in any direction


This explains why a gas can be compressed easily and has no definite shape or volume as the particles in a gas are spread far away from one another.

Acid and Alkali

I have learnt that Acids and Alkali have properties that differs from each other.

Acids
Acids are usually corrosive, sour in taste and turns moist blue litmus paper, red.
When acid reacts with reactive metal (Zinc, magnesium), hydrogen gas and chemical salt are produced. [Example, Zinc + Hydrochloric acid --> Hydrogen gas + Zinc Chloride]
Also, when acid reacts with metal carbonate ( Calcium carbonate, zinc carbonate), carbon dioxide, water and chemical salt will be produced. [Example, Zinc Carbonate + Hydrochloric acid --> Carbon Dioxide + Water + Zinc Chloride]

Alkali
Alkalis are also usually corrosive, have a soapy feel, taste bitter and it turns moist red litmus paper, blue.

Lesson on 30th August 2010

Headline- Making food using sunlight, carbon dioxide and water. Is that possible?

In fact, plants can make food with just sunlight, carbon dioxide and water. Green leaves of plants contains a green pigment called chlorophyll. This chlorophyll will then trap sunlight. Water will be absorbed through the roots, and carbon dioxide will be absorbed through tiny pores, mostly found on the underside of the leaves, called stomata. With all of these 3 products, the plants will then be able to photosynthesize and produce glucose.

Lesson on August 16 2010

Today we experimented on Chromatography and also, we were taught on distillation.
3-2-1

3thoughts/ideas:
-Distillation is a physical method used to separate a mixtures into its constituent elements/compounds. It is used to only separate a liquid mixture, or dissolved substances.
-Chromatography is another physical method to separate mixtures. Only a small drop of sample is needed to find out the constituent substances.
-There must be a solvent put into a boiling tube, then the filter paper that has the drop of sample will be put into the boiling tube, but the drop of sample has to be above the solvent, then a stopper will be used to prevent the solvent from evaporating. In a short while, the drop of sample will be separated into different colours.

2Questions:
-What will happened if a large amount of sample is used for just a small piece of filter paper?
-Can the round-bottomed flask originally used in a distillation experiment that contains the mixture be changed to a boiling tube?

1Useful Applications:
-Chromatography is used in a lab for forensics.

26th July 2010 Science lesson

I use to think that there is no much difference between the sugar content in Coke and Coke zero.
Now i learn that there is actually a very big difference between them. Coke zero has actually much much less sugar than coke.

I used to think that the amount of oil in different food is not significant/
Now i learn that the amount of oil in different food is really significant because the temperature of the water in the test tube increased quite much when the different burning food are placed under it

23th July 2010 Science Lesson

The headline would be ''Rubrics revealed''