OCR 21st Century Science B5 C5 P5 Wed 18th

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I said 3 were unaffected, but I'm not sure I got it right either xD

Hey Guys I was revising C5 and found this stuff really helpful!!

Module C5 Summary

Atmosphere: Layer of gas surrounding the earth
Hydrosphere:Mostly made up of water and dissolved compounds
Biosphere: Made up of all the living things on earth
Lithosphere: Rigid Out layer of the earth , made up of the crus and mantle.

Chemical cycles -Movement of chemicals between different spheres

Chemical in the atmosphere

Chemical that make up the atmosphere are gases at 20 because they have low boiling points.
Gases have weak forces of attraction between molecules so only need small amounts of energy to break forces.
Covalent bonds: Strong eletrostatic attraction between positive nuclei and shared pair of negative electron

Chemical of the Hydrosphere

Ionic compouns - Ions are electrostatically attracted to each other to form a 3-d giant crystal lattice with high melting and boiling points.Conducts electricitywhen dissolved in water.

Salts-dissolved ionic compounds

Polar molecule - Wter molecule is bent because shared electrons are nearer the oxygen atom than hydrogen atoms. So, atoms have small charges.

Water molecule attracted to crystal lattice -> Ion breaks away - > Ion moves freely through water

Chemical of the lithosphere

-Oxygen
-Silicon
-Aluminium

Silicon dioxide

Compound made from Silicin and oxygen. Found in earth's crust. Forms GIANT COVALENT STRUCTURE.

Silicon diozide -> Quartz in granite - > Main constituent of sandstone

Properties of Silicon Dioxide = Hard,High melting and boiling point, electrical insulator and insolubre in water

Chemical of the biosphere

Carbohydrates - Carbon, oxygen,hydrogen
Proteins - Polymer made from amino acid monomers joined together
Dna - large,complex molecule

Extracting Useful Materials

Ores= rocks containing varying amounts of mineral from which metals can be extracted

Metal less reactive than carbon - > Extracted by heating with Carbon
Metal reduced -> Lost oxygen
Metal oxidised -> Gained Oxygen

Electrolysis - Breaking down of an electrolyte using an eletric current. Used to extract reactive metals from their ores.

Positive ions - negative electrode
Negative ions - positive electrode

Calculating a METAL's mass

If you are given its formula, you can calculate the mass of metal that can be extracted from a substance:

1. wRITE down the formula
2. Work out the relative formula mass
3. Work out the percentage mass of the metal
4. Work out the mass of the metal

Example:

Find the mass of Zn that can extracted from 100g og ZnO

1- ZnO
2-Relative formula mass = 65(Zn) + 16 (O) = 81
3-Percentage of Zinc present

65(Zn) / 81(Mr) x 100 = 80%

4- In 100g og ZnO , there will be 80/100 x 100 = 80g of Zn

Reply 82

Fiasco

Downward Spiral

I said 3 were unaffected, but I'm not sure I got it right either xD

After some more research - 1 was the corrent answer. :p:

Asked my brother, he agreed with my answer. I also found this that explains the mutation (frameshift):

"Because of the frameshift, all the amino acids downstream from the insertion are different to the original."

Reply 83

Downward Spiral

Fiasco

After some more research - 1 was the corrent answer. :p:

Ah, oh well =P I wasn't far off >.<

Do you remember how many marks that Q was worth by any chance?

Yea, 1 mark. :p:

Does anybody have any P5 notes?

Reply 86

Kameo

So you can only get two grades which are the same, like AA, BB, CC?

If that's so it's certainly cheered me up. But are you really sure?? I'm sure you can get AA*

Reply 87

RodrigoB

Dark Ace

Does anybody have any P5 notes?

Here u go!

Module p5 Summary

Static Electricity - is created when two objects are rubbed together.

Objects receiving electrons -> Negatively Charged
Objects giving up electrons -> Positively charged
Two materials with same charges -> Repel each other
Two materials with different charges -> Attract each other

Current and Pontential difference

Current= Flow of charge measured in amperes.

Direct current-> Flows in same direction
Alternating current-> Constantly changes direction
Metal conductors-> Lots of charges free to move
Potential difference = Voltage - > measured in Volts
Greater Potential difference across a component -> Greater Current through the component

Adding batteries in series -> Increase voltage and current
Adding Batteries in parallel -> P.D and Current stays the same and each baterry supplies less current.

Resistance
Components - resist flow of charge

Eletric current flows through component - Component heats up!
Greater resistance in a circuit -> Smaller current
Adding resistors in series -> Increases total resistance
Adding resistors in parallel -> Reduce total resistance and increases current through the battery.

Current-potential difference graphs- current through resistor is directly proportional to voltage across resistor.

Thermistor - Resistor depends on temperature.
LDR - Resistance dependes on light intensity

Resistance (Ohm) - Potential difference (Volts)/Current (Ampere)

Circuits

In series circuit...

Current Flowing through each component is the same
Potential difference across compnents add up to tha across the battery
Potential difference is largest across components with greater resistance.]

In parallel circuit...

Current flowing through each component depends on resistance
Current running to and from battery is equal to sum of current through each parallel component.
Current is smallest across components with greatest resistance.

Circuit symbols - are used to represent components in circuits.

Eletromagnetic Induction

When a magnet is moved into a coil of wire , a voltage is induced. If ends of coil are connected , a current is induced.

Current can be induced in opposite direction by...

Moving a magnet out of coil
Moving other pole of magnet into coul.

Electric generators - use electromagnetic induction. Produce mains electricity.

Generators produce alternating current as the directions of flow is reversded every half turn of the magnet.

Transformers - used to change the voltage of an alternating current.

Power and energy

Power - measure of the rate of energy transfer

Power ( W) = P.D(v) x Current (A)

Energy - measured in Joules. DOmestic energy is measured in kilowatt hours as joules are very small amounts of energy.

Energy tranfered (J)/(kWh)= power (W)/kW) x Time (s)/(H)

Efficiency - the proportion of energy that is usefully transfered by an appliance.

Efficiency ( %) = Energy usefully tranferred / Total energy supplied x 100

I hope this helps!!! :wink:

Reply 88

variusers

thanks rodrigo, how about posting b5 notes as well?

Reply 89

xxbah_boooxx

go0d luck everyone doing this exam 2moro!!!

>< I'm dreading this exam and the B6, C6 n P6 x_X

Reply 90

beachboi

Yeh, I'm sure it will be fine to be honest. People said todays was fairly easy (tuesdays). So...hope the good luck follows for tomorrow!

Need 38/50 to get an A supposedly!

Reply 91

xxbah_boooxx

beachboi

Yeh, I'm sure it will be fine to be honest. People said todays was fairly easy (tuesdays). So...hope the good luck follows for tomorrow!

Need 38/50 to get an A supposedly!

awww I hope so0... I didn't do that paper but anywho0 I hope this is easier than the ideas in context cos that was so0o0 blo0dy hard!! one of the hardest papers I've done yet x_X I think I failed that paper...
go0d luck everyone!!! =]

Reply 92

LW5x01

hehe good luck people =]

doing foundation so its relatively easy for me lol.

Reply 93

RodrigoB

Hey guys, I know it's bit late to post b5 notes but if u just read through it might help u to remember main keywords ....This is the easiest module in this exam i think isnt it ?

[U]Summary B5

Cells

Cells are the building blocks of all living things

Cells contains...
Dna
Organelles

DNA molecule are in the form of a double helix and contain the genetic code
Organelles different parts of the cell's structure
Animal and plant cells have cytoplasm , a nucleus,ribosomes and a cell membrane
Plant cells also have a cell wall, a permanent vacuole and chloroplasts.

Cell division

Mitosis - division of the body cells to produce new cells. Each new cell contains the same genetic information as the parent cell.

Organelles increase -> Chromosomes copied -> Copies of chromosomes separate -> Cells divide

Meiosis - division of cells in the testes and ovaries to produce gametes for sexual reproduction

Gametes - contain half number of chromosomes as the parent cell.

Fertilisation

During fertilisation , a male gamete and a female gamete fuse together to produce a zygote

Zygote - Has one whole set of chromosomes.

After fertilisation, the zygote divides by mitosis to produce an Embryo.

Genes

Genes present on the chromosomes in each cell nucleus.

Genes control...

-Growth and development in organism
-Development of characteristics

Meiosis and sexual reproduction produce VARIATIOn between offspring and parents as genetic information from two individuals is combined.

Genetic code - made up of four bases which hold the two strands of the DNA molecule together.

Bases always pair up in the same way

(A)denine + (T)hymine
(C)ytosiine + (G)uanine

mRNA - small molecule which leae the nucleus and carry genetic information into the cytoplasm

Ribosomes - Follow instruction from mRNA to make proteins

A group of THREE BASES PAIRS for ONE AMINO ACID in a PROTEIN CHAIN, called a Triplet code. There are 20 different amino acids that can be made.

Stem cells

Embryonic stem cells - unspecialised cells that can turn into any kind of cell.

After the eight cell stage, the cells in an embryo become specialised and can form different types of tissue.

Stem cells can be used to treat diseases and disorders and repair damage to various tissues. The three sources of stem cells are embryos,blood from the umbilical cord and adult stem cells.

Plant growth

New cells in plants specialise into cells of

Roots
Leaves
Flowers

Meristem - area of plasnt growth,where unspecialised cells diide repeatedly
Lateral Meristem- leads to increase girth
Apical Meristem - leads to increased height and longer roots
Xylem tubes - transport water from the roots to the stem and leaves and replace lost water
Phloem tubes - transport dissolved food to the whole plant for respiration or storage.

Plant cuttings
New plants develop when cuttings are taken from a plant and put in a rooting hormone. The new planets are clones of the parent plant.

Auxins mains plant hormones used in horticulture which cause cell growth and division.

Phototropism

Growth of plants towards a light source.

Light source oerhead -> Auxin spread evenly -> Shoots grow STRAIGHT UP
Light source at an angle - > Auxin on side furthest from light -> Shoots bends towards light.

WELL GUYS... EXAM in about 4 hours time... good luck EVERYONE!

Reply 94

Baller92

Help!
Doing a 2007 past paper on ocr website, but the bloody markscheme doesnt give the answer!

If any one can give me the answer to question 7a) it would be super helpful =]

http://www.ocr.org.uk/Data/publications/past_papers_2007_june/GCSE_TFC_Additional_Science_A_A216_02_June_2007_Question_Paper.pdf

Thanks! xxx

Reply 95

Dark Ace

many thanks for your notes RodrigoB i hope these notes will help me pass

Reply 96

oceanic815

those notes are great thanks alot RodrigoB!

Reply 97

LW5x01

35mins before the exam :smile:

hehe..

good luck people!!!

Reply 98

RodrigoB

THAT WAS A JOKE! haha...
how did u guys find it ?!? the only question I was confused was the one about maximum power supply from the plug. (230w) , ( 5 amps )... I selected 230/5 option. is that alright ?