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IGCSE EDEXCEL BIOLOGY PAPER 1 12TTH MAY...are you ready?!

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It's cool man, in the pressure of exams you just don't think of these things. I suppose you could use garlic dough-balls at a push although they have a smaller surface area.

Yeh the pressure really got to me. I also put thought process as a system because they weren't shown on the diagram. Is this right???

Reply 161

Greg Lewis

Original post by Lokesh Jain

Yeh the pressure really got to me. I also put thought process as a system because they weren't shown on the diagram. Is this right???

Nah I don't think so mate lol. How can you see a thought man?? Nah I wrote urine process, thinking process and egestion process

Reply 162

olliefinch

Was the second last question, % change or % yield?

Reply 163

Lokesh Jain

Original post by Greg Lewis

Nah I don't think so mate lol. How can you see a thought man?? Nah I wrote urine process, thinking process and egestion process

I put none of those,I wasn't sure what it meant by systems as the diagram only showed organs. I think I failed. My parent s will slap me with a belt because I'm Asian

Reply 164

TastyPinkHair

Original post by Lokesh Jain

I put none of those,I wasn't sure what it meant by systems as the diagram only showed organs. I think I failed. My parent s will slap me with a belt because I'm Asian

And I'm Danish :smile:

No, please don't think that :smile:

Why would you think such a thing? Stereotypes are horrible :smile:

And I'm sure you didn't fail. :biggrin:

(edited 8 years ago)

Reply 165

Greg Lewis

Original post by Lokesh Jain

I put none of those,I wasn't sure what it meant by systems as the diagram only showed organs. I think I failed. My parent s will slap me with a belt because I'm Asian

Nah, I'm sure you've got a C. Anyway if you pass whats the difference between a C and A*

Reply 166

Pagarani Neelesh

Original post by Deano1

I can't believe it...
I drew a line graph/frequency polygon sort of thing when it said in the question draw a bar chart...

SIX MARKS.

THAT'S 5%...

Someone please please help me...

Don't worry yo ell still get atleast 3 marks for labeling and choosing the write scale

Reply 167

Pagarani Neelesh

Original post by Deano1

I can't believe it...
I drew a line graph/frequency polygon sort of thing when it said in the question draw a bar chart...

SIX MARKS.

THAT'S 5%...

Someone please please help me...

Don't worry you will still get atleast 3 marks for labeling and choosing the write scale

Reply 168

Strangerdanger

If you do single science then chill, you still have the chance to bring ur grade up
If not, dont worry 5% seems like alot but it isnt really, besides u'll get atleast half the marks for that question
Oh and tbh stop worrying about this, whats done is done, you cant change it so why worry?
Just focus on your upcoming exams :smile:

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Reply 169

Greg Lewis

Hey, how many marks do you need for a C? Really need this C cuz a D isn't good enough. Think I've probably got 45-55 on this paper....

Reply 170

Mujahidul Islam

Original post by reelsalah

I didn't write in such a detail but i just wrote place it in a fermenter so that bacteria produces the growth hormone.

i think u have misunderstood.it was not about fermentar.

the previous subdivision said that the growth harmone was a protein.

Proteins are amino acids joined together. DNA codes for amino acids therefor i think we have to use genetic engineering by using plasmid.

Reply 171

Mujahidul Islam

Original post by ChloexCharlotte

Yeah don't worry... I put immunity system haha :') which doesn't even exist

****

Reply 172

Mujahidul Islam

Solids
As the picture shows, all the particles in a solid are touching. Another feature of a solid is that the particles aren't moving, the particles have no energy.

Liquids
Liquid particles are, like solids, all touching. The difference is that liquid particles are moving- they flow to fit the space- this means that they have some energy.

Gas
In gasses the particles aren't all touching; they are far apart. They move freely and have a high energy level.

Reply 173

Mujahidul Islam

Spoiler

When ionic compounds are molten or in solution, the positive and negative ions separate this means that there are ions free to flow, and so they can conduct electricity.
Posted by Hannah A at 08:50 No comments: Email This BlogThis!Share to Twitter Share to Facebook Share to Pinterest

Labels: 1.50, Electrolysis, Section 1

1.49 understand why covalent compounds do not conduct electricity

In covalent compounds there are no electrons free to move, this means there can be no transfer of electricity through a covalent compound
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Labels: 1.49, Electrolysis, Section 1

1.48 understand that an electric current is a flow of electrons or ions

An electric current is a flow of electrons, although it can also be a flow of ions (as they have a charge.)
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Labels: 1.48, Electrolysis, Section 1

1.47 explain the electrical conductivity and malleability of a metal in terms of its structure and bonding.

Metals have delocalised electrons, electrons carry electricity; so because there are free electrons charge can pass easily through a metal.

The structure of a metal is with rows of atoms on top of one another, in pure metals as all the atoms will be the same size, the layers can slide easily over one another making them easy to bend.
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Labels: 1.47, Metallic crystals, Section 1

1.46 understand that a metal can be described as a giant structure of positive ions surrounded by a sea of delocalised electrons

In a metal atoms come together into a lattice, the electrons become detached from their atoms- delocalised- making the atoms positive ions.

(edited 8 years ago)

Reply 174

Mujahidul Islam

2.39 describe tests for the gases

i hydrogen

•

burns with a 'squeaky pop' sound

ii oxygen

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will relight a glowing splint

iii carbon dioxide

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Turns lime water cloudy

iv ammonia

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Damp red litmus paper blue

•

Damp universal indicator purple

v chlorine

•

bleaches damp litmus paper white

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Labels: 2.39, Section 2, Tests for ions and gasses

2.38 describe tests for the anions

i) Cl-, Br-and I-, using dilute nitric acid and silver nitrate solution

•

Chloride ions + nitric acid + silver nitrate > white precipitate (silver chloride)

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Bromide ions + nitric acid + silver nitrate > cream precipitate (silver bromide)

•

Iodide ions + nitric acid + silver nitrate > yellow precipitate (silver iodide)

ii) SO4 2- (sulphate ions) using dilute hydrochloric acid and barium chloride solution

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SO4(2-) + HCl + Ba(2+) > white precipitate (barium sulphate)

iii) CO3 2-, using dilute hydrochloric acid and identifying the carbon dioxide evolved

•

Carbonate + acid > salt + water + carbon dioxide

•

Carbon dioxide produced will turn lime water cloudy

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Labels: 2.38, Section 2, Tests for ions and gasses

2.37 describe tests for the cations

i) Li+, Na+, K+, Ca2+ using flame tests

•

Lithum: red

•

Sodium: orange (so strong can mask other colours)

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Potassium: lilac

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Calcium: brick red

ii) NH4+, using sodium hydroxide solution and identifying the ammonia evolved

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NH4 + OH > NH3 + H2O

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ammonium ions + hydroxide ions > ammonia + water

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ammonia (pungent smelling gas) turns red litmus paper blue

iii) Cu2+, Fe2+ and Fe3+, using sodium hydroxide solution

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Copper(ii) sulphate + sodium hydroxide > blue precipitate

•

Iron(ii) sulphate + sodium hydroxide > green precipitate

•

Iron(iii) sulphate + sodium hydroxide > brown precipitate

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Labels: 2.37, Section 2, Tests for ions and gasses

Wednesday, 15 May 2013

2.36 understand the sacrificial protection of iron in terms of the reactivity series.

Sacrificial is covering a metal with a more reactive metal. What this means is water and/or air will react with the more reactive metal instead of the one underneath.
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Labels: 2.36, Reactivity series, Section 2

2.35 describe how the rusting of iron may be prevented by grease, oil, paint, plastic and galvanising

Grease, oil, paint and plastic prevent air and/or water from coming into contact with iron. This means the reaction that rusts iron can't occur.

Galvanising is coating in zinc. This Zinc react in the air to form ZnCO3 which prevents air and/or water from coming into contact with the iron.
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Labels: 2.35, Reactivity series, Section 2

2.34 describe the conditions under which iron rusts

Water and oxygen are needed to rust iron: iron that reacts with these becomes hydrated iron(iii) oxide.
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Labels: 2.34, Reactivity series, Section 2

2.33 understand the terms redox, oxidising agent, reducing agent

In a redox reaction, a more reactive metal gains an oxygen from a less reactive metal which looses it.
i.e. a more reactive metal is oxidised and a less reactive metal is reduced.

The reducing agent is the more reactive metal which reduces the other metal.
The oxidising agent is the less reactive metal which allows the other metal to be oxidised.
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Labels: 2.33, Reactivity series, Section 2

2.32 understand oxidation and reduction as the addition and removal of oxygen respectively

oxidation is the gain of oxygen,
reduction is the loss of oxygen.
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Labels: 2.23, Reactivity series, Section 2

2.31 deduce the position of a metal within the reactivity series using displacement reactions between metals and their oxides, and between metals and their salts in aqueous solutions

A metal oxide or a metal salt dissolved in water:

•

introduce a more reactive metal and it will displace the current one

•

introduce a less reactive metal and no displacement will take place

From this you can deduce which metals are more and less reactive.
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Labels: 2.31, Reactivity series, Section 2

2.30 describe how reactions with water and dilute acids can be used to deduce the following order of reactivity: potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper

potassium, sodium, lithium and calcium all react with water and acids
magnesium, zinc and iron all react with acids (and very slowly with water.)
copper doesn't react with either.

The more vigorous the reaction the more reactive the metal. The more things a metal will react with, the more reactive the metal.
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Labels: 2.30, Reactivity series, Section 2

2.29 understand that metals can be arranged in a reactivity series based on the reactions of the metals and their compounds

docstoc

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Labels: 2.29, Reactivity series, Section 2

Tuesday, 7 May 2013

2.28 describe a physical test to show whether water is pure.

If water is pure it will boil at exactly 100° and freeze at exactly 0°
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Labels: 2.28, Hydrogen and water, Section 2

2.27 describe the use of anhydrous copper(II) sulfate in the chemical test for water

anhydrous copper sulphate will become hydrous copper sulphate when it is reacted with water.
So if anhydrous copper sulphate goes from white to blue in the presence of a liquid it will be water.
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Labels: 2.27, Hydrogen and water, Section 2

2.25 describe the reactions of dilute hydrochloric and dilute sulfuric acids with magnesium, aluminium, zinc and iron

acid + metal > salt + hydrogen

For example:
magnesium + hydrochloric acid > magnesium chloride + Hydrogen
Mg + 2HCl > MgCl2 + H2
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Labels: 2.25, Hydrogen and water, Section 2

2.26 describe the combustion of hydrogen

The combustion of hydrogen is its reaction with oxygen.
Water is created. and a lot of energy.
2H2 + O2 > 2H2O
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Labels: 2.26, Hydrogen and water, Section 2

2.24 understand that carbon dioxide is a greenhouse gas and may contribute to climate change

Carbon dioxide prevents heat leaving the earth's atmosphere in rays that the earth emits.
Significant amounts of green house gasses will warm up the earth, changing the climate.
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Labels: 2.24, Oxygen and oxides, Section 2

2.23 explain the use of carbon dioxide in carbonating drinks and in fire extinguishers, in terms of its solubility and density

Carbon dioxide is dissolved into drinks at a high pressure, this makes CO2 bubbles in fizzy drinks.

Some fire extinguishers have CO2 in, because it is denser than air it will fall over the fire creating a barrier between the air and fire: the fire can't burn with out the oxygen in the air.
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Labels: 2.23, Oxygen and oxides, Section 2

2.22 describe the properties of carbon dioxide, limited to its solubility and density

It is denser than air.
It is soluble in water at a high pressure.
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Labels: 2.22, Oxygen and oxides, Section 2

2.21 describe the formation of carbon dioxide from the thermal decomposition of metal carbonates such as copper(II) carbonate

When metal carbonates are heated they become carbon dioxide and a metal.
For example:
copper carbonate > copper oxide + carbon dioxide
CuCO3 > CuO + CO2
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Labels: 2.21, Oxygen and oxides, Section 2

2.20 describe the laboratory preparation of carbon dioxide from calcium carbonate and dilute hydrochloric acid

calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide

CaCO3 + 2HCl → CaCl2 + H2O + CO2

(edited 8 years ago)

Reply 175

Mujahidul Islam

Spoiler

(edited 8 years ago)

Reply 176

Braineater79

what was the answer about heart attacks and why they occur when there is less oxygen in the body?

Reply 177

.a.r.j.

essentially the cardiac muscles need oxygen to respire, if they don't get it they can't really respire, so they have no energy and can't contract anymore

Reply 178

Braineater79

Original post by .a.r.j.

essentially the cardiac muscles need oxygen to respire, if they don't get it they can't really respire, so they have no energy and can't contract anymore

Heart attacks are caused by the heart pumping against a block and therefore how can them not having enough energy lead to a heart attack. Shouldn't you have talked about coronary heart disease.

Reply 179

Electrify

What about the question with pollution of water by phosphate? It was something like why this conclusion may not be accurate with two answers. Also the question about why it's more common to cut tube B instead of oviduct.