MORE REVISION INFO FOR 10 a1 AND 11 SCIENCE

Remember 10 a1 (and 11 Science) the Standards needed for NCEA External Exams which will be in the Mock Senior Exams:

• Science 1.3 Describe Aspects of Biology
• Science 1.4 Describe Aspects of Chemistry
• Science 1.6 Describe Aspects of Physics

This post will be a quick recap / revision for:

MICRO-ORGANISMS

• All micro-organisms are CONSUMERS, whereas Green Plants for example are producers, meaning they produce there own food. We are also consumers, like all animals, as we cannot produce our own food, instead we eat other organisms. Fungi do not contain chlorophyll so cannot produce their own food
• Micro-organisms are either SAPROPHYTES or PARASITES 
• Saprophytes live and feed on dead matter and can be called decomposers
• Parasites live on living organisms
• Microorganisms are divided into: BACTERIA, FUNGI and VIRUS

Below is a 'simple' flash animation from the BBC Bitesize Science Website..

CLICK HERE FOR ALL YOU NEED TO KNOW FOR SCIENCE NCEA LEVEL 1

Here are some questions you may want to try:
1. When investigating whether microorganisms are present in air and soil

a) Why must the original petri dishes be sterile
b) Why is the lid left off one dish
c) Why the petri dishes are labelled on the bottom
d) Why are the dishes left in a warm place
e) How can you tell the difference between the different microorganisms growing on the plate
f) What types of microorganisms are growing on the plate and what are the reasons
g) Why was there no growth on the control plate

2. a) Name a way in which fungi are different to green plants
b) Why can fungi never act as producers in a food chain
c) Fungi are used to make bread. What conditions during bread making allow fungi to grow and help in he bread making process

3. a) Name 3 conditions needed for bacteria to grow
b) Give two benefits of bacteria
c) Name 3 diseases caused by bacteria

4. a) Discuss why viruses only exist as parasites
b) Why can viruses not be cultivated on an agar plate
c) How do viruses reproduce and what is this method called

ClICK HERE for Sample Answers....TRY AND GIVE THE Q'S A GO FIRST!!

Revision LInks for Year 10 A1: upcoming NCEA Exams

Guys...check the links below for some practice revision exams from the NCEA...these will be good to go over yourselves both for the upcoming Mock Exams and also the NCEA Exams in Term 4...

BIOLOGY
Describe Aspects of Biology 2007 Exam


Describe Aspects of Biology 2006 Exam

You can check your answers with these examplars links...aim for Excellence!

Excellence answers 2006
Merit answers 2006
Achievement answers 2006

CHEMISTRY
Describe Aspects of Chemistry 2007 Exam



Describe Aspects of Chemistry 2006 Exam

PHYSICS
Describe Aspects of Physics 2007 Exam


Describe Aspects of Physics 2006 Exam

There are also a few useful Revision Posts aand links on the blog if you search for them..

DC CIRCUITS REVISION

Check out this link and play around with it and have a go at contructing circuits...

DC CIRCUIT SIMULATION

There are plenty of other good educational (and FUN) simulations to play around with...

SCIENCE SIMULATIONS FROM THE UNIVERSITY OF COLORADO

Forces and Mechanics for Year 10 Sia1 and 11 PY

At it's simplest a Force, symbol F can be seen as a push or a pull in a given direction. From this we can see that Force must be a Vector Quantity as it has a direction and also has a magnitude.

The Net Force, Fnet is the resultant sum of all the vector forces acting on a body and if these are balanced then Fnet is zero and the body is subject to Newton's First Law of Motion, ie it has inertia and remains in equilibrium:

• if it is at rest it will continue to remain at rest (be stationary) and if it is moving it will continue to move at a constant speed
• all the force vectors must add up to zero

If the forces become unbalanced the Fnet no longer add to zero and the the object starts to accelerate or decelerate, according to Newton's Second Law of Motion (Force = Mass x Acceleration) and the sum of all the vector forces must produce a resultant Force Vector in the direction of the acceleration.

Newton's third law can help us with understanding some of the other forces in play and how to represent them on a Force Diagram: "every action has an equal and opposite reaction." So for example if a box is sitting on the ground stationary there is a force, due to gravity, acting in a downward direction. From Newton's 3rd Law there must be an equal and opposite reaction: in this case a force acting upwards that is equal to the gravitational force: the two forces balance out with the resultant Fnett = 0, so the box remains stationary and will only move if another force acts on the box making the Fnett grater than zero. Now the forces are no longer in balance or equilibrium!

HAVE A GO YOURSELVES HERE WITH THE PHYSICS CLASSROOM

simple overview of forces with some easy questions...CHECK IT OUT!!

Excellent link for forces and mechanics

MOTION

A quick post to go over some of the main points of motion and the graphs associated with them. The first thing to get our heads around is the difference between scalar and vector quantities.

A Scalar quantity only has a magnitude whereas a Vector quantity has a direction as well as a magnitude.

For example time and distance are scalar quantities as they only have a magnitude, whereas displacement and velocity are vector quantities as they have both a magnitude and a direction:

Quantity         Scalar or Vector       Magnitude and Direction   Unit

Time                Scalar                      Just a magnitude                    Seconds

Distance          Scalar                      Just a magnitude                    Metres

Displacement  Vector                     Magnitiude and Direction       Metres

Velocity           Vector                     Magnitude and Direction        Metres per Second

Displacement, as opposed to just distance, is the shortest distance form the start point and comprises a distance along with an angle or bearing, and Velocity is speed in a given direction.

On the displacement time graph, to the side, the displacment is shown by the orange arrow, which shows the shortest distance from the origin. This displacement should be given with a distance in metres as well as a direction, with an angle or bearing.

On the velocity time graph the minus figure does not indicate a minus speed; instead it indicates a direction relative to the start direction which is shown from the origin. In this example if we assume the the y axis corresponds to a direction angle of 90 degrees or East, then the initial velocity is around 45 degrees, or North East, which then changes to approximately 135 degrees and returns to a direction / angle that is the same as the origin at 30 seconds. The velocity continues on this same angle / heading for another 7 seconds or so then changes angle back to a direction of approximately 45 degrees, or North East to return to the same direction / angle / bearing as the start direction / angle / bearing at 50 sec.

Finally to reiterate a number of final points:

• 
  
  The gradient of a distance time graph equals the speed
• The gradient of a velocity time graph equals the acceleration
• The area under a velocity time graph equals the distance travelled

FACTORS AFFECTING THE RATE OF CHEMICAL REACTION

From previous classes we know that: Reactants------------------> Products, or a number of reactants combine to form a product / products. We can also say that the particles in the products collide in order for a reactant to be formed.

Depending on the types of reactant the time taken for a reaction to occur can vary considerably.

For example, the chemical reactions that occur in the formation of crude oil occur over huge periods of time whereas the chemical reactions betwen Sodium and Acid occur very quickly. So how do we determine / measure the rate of a reaction? We can say:

Rate of Reaction = amount of reactant(s) used or product(s) formed / Time Taken

We can look at either how much reactant is used up in the chemical reaction or the amount of product formed. Below is a simplified graph to show this relationship:

It can be seen that with higher temperatures and higher concentration and smaller pieces the line of the graph showing the relationship between the total amount of products used and the time taken is steeper, thus indicating the reaction is happening more quickly.

Equally if this graph was showing the total amount of reactants being used against time then the steeper line would, again, indicate, a faster rate of reaction.


What this graph tells us then is that there are a number of factors that determine the rate of the reaction. These are listed below:

• The temperature at which the reaction takes place
• The concentration of reactants being used
• The pressure at which the reaction is occuring
• The size of the pieces of reactants being used in the reaction
• The addition of a catalyst

In simple terms:

•  the higher the temperature the faster the rate of reaction
• the greater the concentration of dissolved reactants the faster the rate of reaction
• The higher the pressure of a reactsnt gas the faster the rate of reaction
• the smaller the pieces of a solid reactant the faster the rate of reaction
• if a catalyst is added the faster the rate of reaction

Again, keeping it simple:

• with higher temperatures the greater the energy of the particles in the products and the more likely they are to react when they collide with other particles
• with greater concentrations of particles or pressure in gases the greater number of particles there are thereby increasing the chances of collisions at high enough energy levels to create a reaction
• with smaller pieces of solids both the surface area and the number of pieces are increased, thereby increasing the number of collisions which will speed up the chemical reaction
• if a catalyst is added the activation energy needed to result in a reaction when particles collide is lowered, thereby increasing the rate of the reaction. Catalysts are added to a reaction but are not used up

The slide show below gives a greater depth of detail if you are interested:

Reaction Rates

View more presentations from wsautter.

an excellent site with more on this as well as lots of other science topics

GRAPHING TUTORIAL

When having to draw graphs and interpret data the starting point is making sure the correct axes are used. The independent variable goes on the X axis (horizontal axis) and the dependent variable goes on the y axis (vertical axis).

From designing our Fair Tests we know that the Independent Variable is the variable that we, as Scientists, change, making sure that we only use the 1 independent variable. As we change the value of the independent variable we observe what happens to the Dependent Variable. If we have designed a good Fair Test then there should be a relationship between the two; this is what we are testing. Time is often an Independent variable that is used with observations being observed for any changes in the chosen dependent variable over time.

For example we could look at changes in rate of growth of microorganisms on an agar plate over time. With all other variables being controlled, such as temperature, nutrient source, sterilisation etc then time which is obviously measurable is the independent variable and changes in growth is the dependent variable. If we changed the fair test to study the effects of different concentrations of disinfectant  on microorganism growth then the concentrations of disinfectant we have chosen, and measured, would be the independent variable.

Returning to graphs there are a number of types of graphs we can draw depending upon the type of data being analysed. Some of the most common include:

• Line Graphs
• Bar Charts
• Pie Charts

Generally the most common type of graph we will be concerned with plotting is a line graph which are particularly good for plotting data that changes over time, with time often being the independent variable, plotted on the x axis.For further information on different types of graphs press here.

The science buddies website has more useful information:
this page gives a good overview and lists key points when drawing up graphs!