Refraction can be defined as the bending of a wave as it crosses the boundary between two medium. This takes place for all forms of waves including light.

Why refraction occurs?
Refraction occurs because there is a change in velocity between both medium.

Refractive index

Refractive index can be defined as a constant that gives the degree to which refraction or bending of a wave takes place between the two medium.
Here are the formulas associated with refractive index:

• Snell's Law

         n= sin i ÷ sin r

• n = incident velocity ÷ refractive velocity

• n= incident wavelength ÷ refractive wavelength

n => refractive index
i => angle of incidence
r => angle of refraction

• anb = 1 / bna

'a' and 'b' are the different mediums.


Where do waves bend with respect to the normal?

When waves are entering a denser medium they bend toward the normal but when entering a less dense medium they bend away from the normal.

What happens to light when it meets a boundary perpendicularly?

Refer to the diagrams below. When the wave meets the boundary perpendicularly it is not diffracted it just goes straight through.

Here are some free rate of reaction questions and answers.

1.  How does a catalyst speeds up a reaction?
2. Does increasing the concentration of a reaction Always increases the rate of the reaction?
3. Where would the Maxwell-Boltzmann Distribution shift if temperature increases, to the right or to the left?
4. Reactions occur in a series of steps called?
5. What is the overall order of a reaction?
6. Does catalyst increase speed of reactants?
7. A energy profile diagram shows the products have more energy than reactants. What kind of reaction is this?
8. In a zero order reaction what is the shape of the graph is it curved or straight?

Answers:

1. By lowering the activation energy.
2. No increasing the concentration of a reaction does not always increase the rate of the reaction.
3. To the right.
4.  Mechanism.
5. This is the sum  of the order of the reactants.
6. No.
7. Endothermic.
8. The shape of the graph is straight.

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Genes are the fundamental units of inheritance which have the function of transmitting information from generation to generation. They are found on the portion of DNA that codes for polypeptide. Similar to genes are alleles which are the alternative form of a gene. However an allele can exist in more than two pairs.

Dominant Gene:- Is one that shows its effect in the phenotype in both homozygous and heterozygous conditions.
Recessive Gene:- A  gene that only expresses itself when in homozygous conditions.

Homozygous Vs Heterozygous

Homozygous refers to two identical alleles found on the same chromosome  while heterozygous refers to alleles that are unidentical.

Mono-hybrid Inheritance:

This is inheritance involving only one pair of contrasting characteristics.

Types of mono-hybrid inheritance:

Complete Dominance

1. Complete Dominance:- This is where the dominant gene shows its effect more in the phenotype (75% in offsprings to be exact).

Characteristics of Complete Dominance:

• Phenotypic ratio->> 3:1

• Genotypic ratio->> 1:2:1

• Both parents possess the same genotype and are heterozygous.

Incomplete Dominance/Codominance

In incomplete dominance each allele has the ability of expressing itself to some extent when in the heterozygous condition.  This is because of intermediate alleles, which are alleles which lask dominant and recessive relationship.


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When a mRNA( messenger RNA) leaves the nucleus it enters the cytoplasm. A group of ribosomes attract the mRNA, an attachment can then be formed. This attachment is known as a polysome.
tRNA( transfer RNA) on the other hand binds with its respective amino acid. This is determined by the anti-codon on the CCA end of the tRNA. A tRNA-amino acid complex is then formed.
The tRNA-amino acid complex is attracted to the codon of the mRNA by its anti-codon using complementary base pairing.

In its simplest form when the mRNA attaches itself to the ribosome, the first tRNA-amino acid complex  will then be attracted to the first codon on the mRNA. Similarly a second tRNA-amino acid complex will arrive and will be attracted to the second codon on the mRNA. The ribosome will then hold the mRNA and tRNA complex together until the amino acids are joined by a peptide bond. The ribosome will continue along the codons of the mRNA for each respective amino acid that arrives. A peptide chain would be formed by these amino acids. However the chain need to stop at some point. At this point a termination code or nonsense code will be used. When the ribosome reaches this code the chain will be cut off. The polypeptide chain will then form its relevant protein structure

Vessels are very long, tubular looking structures and are the characteristic conducting units of angiosperm xylem. There are several cells that make up this structure and they are all connected end to end in a row. The vessel element represent each of the cells of a xylem vessel which is equivalent to a tracheid. How are vessels formed? well vessels are formed when vessel elements that are close bond as a result of the disintegration of their walls

Solving physics equations can be tormenting if you don't know what you are doing and some can be very disturbing seeing how complicated some can get. So here I'll be showing you some tips for understanding calculations in physics.

1. First you need to know your formulas and how a specific formula is related to the question you are doing. 
2. Write down the quantities that you are given. This way you will know what formula to use for the question.
3. Practise alot of physics questions this way you'll be able to solve more difficult questions easily.
4. Please ensure you know your math very well, seeing that both subjects are interrelated. You must be able to transpose and make one term the subject of a formula because in almost every physics question there is going to be some type of transposition.
5. Ask for help whether online or at school. When you are unable to answer a question don't be afraid to ask, you would be surprised at how well this could turn out.

A protein molecule can lose its specific three dimensional shape either temporarily or permanently this is referred to as Denaturation. This change in shape prevents the molecule from carrying out its normal function. These however can be caused by different agents namely:

1. Heat/Radiation
2. Heavy metals.
3. Detergents/organic solvents
4. Strong Acids.
5. Alkalis.

Although proteins denature some will again refold to their original structure, this is known as renaturation .

A wave is a means of transferring energy from one point to another without the transfer of particles.
Waves can come in two forms, they can either be vibrating perpendicular to the direction in which the energy is flowing(transverse waves), or they can move parallel to the direction of energy flow(longitudinal waves).

There are three states of matter:

1. Solid
2. Liquid
3. Gas

Solid

• The particles of solids are very tightly packed
• They posses a definite shape and volume
• Have unlimited number free space

Liquid

• Particles are slightly packed. They can move more freely than solids but not more than gases.
• They have define volume but indefinite shape
• They have one free space

Gas

• Particles are very far apart.
• They move freely
• They have indefinite shape and volume
• No free spaces present

The rate of a reaction is not how much of products are formed nor how much of reactants disappears but rather how fast the reaction takes place.

For a reaction to take place there are certain conditions that must occur:

• The particles must collide with enough energy for bonds to break.
• The particles must be properly orientated.

The speed of a reaction can be found in a number of ways:

1. By measuring the time a certain amount of product is formed
2. By measuring the time taken for a reactant to disappear.

Factors affecting the rate of a reaction:

• Concentration
• Particle size
• Pressure

Concentration:- Increasing the concentration of a reaction increases the rate of the reaction.

Particle size: - The smaller the particle the faster the rate of the reaction.

Pressure:- Like concentration increasing the pressure increases the rate of the reaction but its usually for gases.

Wondering which subjects to choose in school?
There are a number of things to consider before choosing your subjects. You should take into consideration whether or not you will enjoy this subject. You should thing about the long term effects of choosing this subjects, does this subject has anything to do with what you
want to become? Does this subject contrast all other subjects you're doing?. All these are things you should take into consideration.

One of the worst things a student can do is to choose a subject simply because his/ her friend chose that subject, this is total nonsense and can cause allot of problems in the late future. Lastly you should not chose a subject because someone else wants you to, you should be the one to decide who you want to become, but please chose wisely. All these and more are considerations you should meditate upon before choosing your subjects.

Arterioles are small vessels into which blood passes from the arteries. Arterioles can prevent blood from flowing into the capillaries, this can be done because they have sphincters just at the point where they enter the capillaries. These sphincters are circular muscle fibers which can contract and stop the flow of blood.

 Are your school notes killing you?, are you looking for ways to make studying easier? are you at that point of your life where you think you can't go on any further? well your at the right place here I'll be sharing with you ways to make your studying a little easier. Studying may seem stressing at times, but at the end of the day you will feel pleased with your self knowing how hard you have worked. And believe me when i say this the grades you will be receiving will be very pleasing. Studying isn't something you do over night but rather a daily ruitine which requires hard work and determination. But not to fret there are ways of easing this stress of studying:

Electric cells are those that convert chemical energy into electrical energy.


The Two Types of electric cells:

• Primary Cells
• Secondary Cells

Primary cells are those whose energy conversions are irreversible(cannot be recharged), while secondary cells  those whose energy conversions can be reversed(recharged).

Primary cells include:

• The Leclanche Cell

• Simple cell

• Dry Cell

Secondary Cells Include:

• Lead acid accumulator

Glucose is a hexose. The molecules shape is like that of a ring whose sides are formed by one oxygen atom and five carbon atoms. The side branches of the glucose molecule contains hydrogen atoms, OH groups and an alcohol group. These side groups and their positions are what determines the properties of a sugar and its nature.

Having the knowledge of the three dimensional structure of glucose can better help you in understanding the properties of carbohydrates.

Alpha and Beta Glucose

The two types of glucose molecules are alpha and beta glucose. The structures of alpha and beta glucose are shown below. As you can see both structures look the same but if you look closely you can see that Beta glucose is quite the opposite of alpha glucose, looking at the side groups you can see that beta glucose is formed by switching around the H and OH side groups of alpha glucose.

UPDATE

(Image taken from biology 11)

Forces of attraction which holds an individual molecule together is known as Intramolecular attractions while intermolecular forces of attractions are between neighboring molecules.


Please note: All molecules experience intermolecular attractions

At the center of an atom is the nucleus. The nucleus contains the nucleons which are the protons and neutrons. Because most of the weight of an atom comes from the nucleus, electrons can be said to weigh little.

The formula for finding out the number of protons and neutrons is:

Mass number (A) = Number of protons + number of neutrons


Some common comparisons:
Number of protons = Atomic number
Mass number = Nucleon Number