This exam seems abit harder than BCP 4,5, and 6. Its supposed to be about the context of science rather than science itself, not many people have been given much revision material and i didnt really know what to do at first... Anyway i've been on OCR site looking over pastpapers to get an idea of what we are supposed to do,
Based on these questions i've come up with some which we could be asked. Appreciate anyone else posting revision material! I'll get round to Phy and Bio later.
Tufa Towers at Mono Lake, California
1. Give 2 reasons why it’s important to protect the towers at mono lake from acidic rain and global warming
2. How could park rangers go about protecting the towers?
3. The tufa towers are now sticking out of the lake, explain why this has happened.
4. Park rangers believe that over the coming years, when measured from the base, the towers will be shorter, yet when measured from the lakes meniscus, they will be the same height. Using your contextual knowledge of global issues, what basis do you believe they have to state this.
5. Give the formula of calcium carbonate
6. It wouldn’t be possible for a lake with the same features as mono lake to occur in Canada or South Africa. Explain why.
Re: OCR Additional Sci A, Ideas in Context material
1. This is the time to spout loads of rubbish about their unique nature and how important it is to preserve our natural heritage.
2. Here you can use the section where they explain how to recreate your own lake water... explain that they could counter the acidic rainfall by increasing the concentration of salts in the lake by adding artificialy created salts.
3. Really simple one, just to check you have read through the content properly, quote the article... 'the level of the lake has dropped oer the last 30 years, and these towers can be seen sticking up like fingers out of the water.'
4. Question papaer is likely to have some vague questions, here explain that although acidic rainfall is likely to errode the towers, an increase in temperatures will speed up the evaporation proccess. Thus, although the towers will be shorter, the decrease in water levels will mean aproximatly the same amount of tufa will be exposed from the lakes meniscus
5. Often have a simple formula question, CaCO3
6. Checking you understand the proccess, explain that the lack of hot sun in canada would mean a lake with no outlet would either overflow, or the tufa would remain underwater.
For SouthAfrica, explain that the lack of rain to refill the lake and boiling sun would mean evaporation was to fast.
Last edited by LearningMath : 21-05-2008 at 13:03.
Re: OCR Additional Sci A, Ideas in Context material
Hi, have you anymore reasons that you could put for an answer to your first question?
Plus can I ask you why does the hot temperatures in the area mean that the tufa towers will erode more quickly? (not related to your questions, just related to the texts).
And finally why does the salts make the water alkaline?
Re: OCR Additional Sci A, Ideas in Context material
Originally Posted by danhirons
Hi, have you anymore reasons that you could put for an answer to your first question?
Plus can I ask you why does the hot temperatures in the area mean that the tufa towers will erode more quickly? (not related to your questions, just related to the texts).
And finally why does the salts make the water alkaline?
Thanks
Dan
For the first question put atleast 3 vague reasons, stuff like 'they are a tourist attraction and hence important for the local economy etc'
I guess hot temperatures = faster reactions, hence they are eroded quicker
Not to sure about this one...Alkali metals (g1)... sodium, potassium etc have made salts, so the salts they make are alkali, or something about giving off HO- ions during reaction, i lost my notes on this... can anyone expand please?
Re: OCR Additional Sci A, Ideas in Context material
Thanks, your questions seem very realistic.
I'll post up the questions I have for C5;
1. What is the concentration of salts in the sea?
2. How would the concentration of salts in the lake have changed over the past 30 years? Explain your prediction.
3. Write down the formaula of salt formed from Sulphric Acid (Can someone help me on this question)
4. What gas will be released when the acid reacts with the tufa towers?
5. In the past the towers were broken up local farmers and spread onto thier land to improve its fertility. What affect would the addition of the powder have on the soil's pH?
6. Why is it likely that towers like this would ever form in England?
7. When salt crystals form at the edges of the lake, why are the ions attracted to echother?
8. how grams of salt will be in 1dm^3 of sea water?
9. If some acid was dropped onto some tufa what would you see?
10. Sulhuric acid is in acid rain. How is it made?
Re: OCR Additional Sci A, Ideas in Context material
hurray some feedback
1. 81/3 , but isnt this the same as Q3?
2. The concentration of salts in the lake is likely to have increased due to higher temperatures evaporating a larger volume of water.
3. Im not sure about this one aswel But wouldnt it depend on what the sulphuric acid reacted with?
4. Hydrogen?
5. EDIT: Increase the pH duh!
6. High rainfall combined with less sun means it would be likely the lake would overflow or the tufa remain underwater.
7.
8. 81/3
9. Not sure... but isnt calcium carbonate slightly acidic... eek EDIT: checked, no its alkali
10. I guess you mean how it is made in industry since its about acidic rain... im not sure... also do you want a literal answer or equation?
Re: OCR Additional Sci A, Ideas in Context material
Originally Posted by I Have No Imagination
Write down the formaula of salt formed from Sulphric Acid.
Is the answer to this sulphuric acid + calcium carbonate?
again i think this depends on the reactants? i would have thought the question would be more along the lines of... Give the equation for the reaction between X and Y, hmm
Re: OCR Additional Sci A, Ideas in Context material
Here's what I can get from the physics one at the moment - hope it helps!
The top bunch of writing is basically to do with momentum and change in momentum.
It suggests two new types of lampposts: flexible lampposts and breakable lampposts.
The point of the flexible lampposts are to reduce the time in which there is a change of momentum. By bending underneath the car they increase the time in which there is a change in momentum. Therefore, the car and the passengers experience and smaller force and so are less likely to be seriously injured.
The point of the breakable lampposts are to reduce the momentum. They only bend at lower speeds because a significant reduce in momentum isn’t needed at these lower speeds and the lampposts only need to bend slightly in order to increase the time of the change of momentum to reduce the force enough to prevent the risk of bad injuries. However, at greater speeds they break to reduce the momentum of the vehicle which will also reduce the force experienced by the vehicle and its passengers. However, these can’t be used in cities and urban areas as the lampposts flying off would hit shops, houses, people etc. and cause considerable damage.
Finally, the bottom section of text is all about gravitational potential energy and kinetic energy. The third type of lamppost are ones that are hinged and buckle over when hit. This raises the car into the air. Therefore, the cars GPE increases which decreases the cars KE. As a result this reduces the cars speed significantly and so reduces its momentum and the force applied to the car in the collision.
Key equations:
Momentum = mass x velocity
Change of momentum = force x time it is applied
GPE = weight x v height
KE = 0.5 x mass x velocity 2
Re: OCR Additional Sci A, Ideas in Context material
I have the answers for a couple of them.
7. They have opposite charges, opposite charges attract.
8. A third of 81 so 27g.
9. You would see bubbles of fizzing due to the production of carbon dioxide
10. Sulphur dioxide is made wen fossil fuels burn. Sulphur dioxide is made when coal is burnt at a power station. The sulphur dioxide dissolves in waster vapour in the atmosphere to make rain.
Re: OCR Additional Sci A, Ideas in Context material
Originally Posted by I Have No Imagination
Thanks, your questions seem very realistic.
I'll post up the questions I have for C5;
1. What is the concentration of salts in the sea?
81/3
2. How would the concentration of salts in the lake have changed over the past 30 years? Explain your prediction.
They would have increased due to increased evaporation of water.
3. Write down the formaula of salt formed from Sulphric Acid (Can someone help me on this question)
sulhpuric acid + what? Why do you need to know this?
4. What gas will be released when the acid reacts with the tufa towers?
Carbon dioxide.
5. In the past the towers were broken up local farmers and spread onto thier land to improve its fertility. What affect would the addition of the powder have on the soil's pH?
Make it more alkaline I suppose.
6. Why is it likely that towers like this would ever form in England?
Not many hot springs, not that hot - not much evaporation of water, lots of rain - make it overflow.
7. When salt crystals form at the edges of the lake, why are the ions attracted to echother?
I guess it's because the opposite charges of the ions are attracted to one another.
8. how grams of salt will be in 1dm^3 of sea water?
81/3
9. If some acid was dropped onto some tufa what would you see?
Depends on concentration - strong acid would cause a reaction in which there would be lots of fizzing, some tufa would obviousily be dissolved and you CO2 would be given off.
10. Sulhuric acid is in acid rain. How is it made?
Acid rain is formed by pollutants such as sulphuric dioxide, nitrogen dioxide and carbon dioxide. They mix with water vapour and are transported in clouds and then the water vapour condenses into rain and contains the pollutants which turn this rain slightly acidic.
Re: OCR Additional Sci A, Ideas in Context material
1) Sudden Infant Death Syndrome (if we get asked this i will be laughing!)
2) across synapses - diffuse across the gap.
3) Serotonin allows the nerve impulse to travel across the synapse and into the motor neuron.
4) use tests on more babies and on the same number of babies from each group
5) because you can't tell whether they have SIDS or not - only when they die
6) less neurons able to stimulate gasping for air when babies are asleep and stop breathing
7) 41 babies
8) a gap that links two different neurons
9) medulla?????????
10) They might think it was a contradiction because of the fact that they would think that the baby should be able to gasp for air if they have SIDS because they have lots of serotonin which triggers gasping for air. However, reading it closely makes the reader realise that the babies with SIDS have fewer receptors so it doesn't make much difference whether or not they have more serotonin.
Re: OCR Additional Sci A, Ideas in Context material
Ok here's my take on the biology - hope this helps!
The article is all about two scientists trying to link the chemical serotonin and its receptors across synapses in the brain to cot deaths - in order to find a possible future cure.
First thing to notice is that the groups they have tested their theory on are very small - which indicates these are only early findings. You need much larger sample of groups to be sure of your correlation. Plus the groups are not even - so it makes it harder to compare them. The 10 babies that died from other causes are the control group.
Also you should look at the word "may" - shows that it hasn't been proven yet that this theory of serotonin and the lack of receptors may be the causes of SIDS.
The 55% that they found had more serotonin and fewer receptors of the 31 babies who died from SIDS is not conclusive at all as this means 45% didn't. This doesn't really prove that well their theory.
In this you need to know all about synpases and serotonin.
A synapse is the gap across two neurons - sensory and motor. The sensory neuron carries nerve impulses from the receptor to the central nervous system and the motor neurons carry impulses from the CNS to the effector. The synapse is the gap between these two types of neurons which connects them. When a nerve impulse passes along the sensory neuron it then sends out a neurtransmitter (serotonin). This diffuses across the gap and fits into the receptors on the other side. The neurotransmitters carry the impulse across the gap and then as they fit into the receptors pass the impulse and its signal along the motor neuron. The serotonin is then brought back through re-uptake tunnels into the sensory neuron.
In this case the medulla would be the receptor and the effector would be the lungs to gasp for air.
However, what this statement is saying is that the babies with SIDS had fewer receptors for the serotonin to pass the nerve impulses for the baby to start breathing and gasping for air. As a result, it is suggesting when these babies died it was because of the lack of receptors meaning that time an impulse to be taken to the lungs couldn't get their in time to stop them from suffocating. The babies who had SIDS had more serotonin either because of a coincidence - as only 55% had more, or because of the fact that the medulla realised the messages were struggling to get across the synapses and so produced more serotonin to try to help - even though this didn't.
I know this is long but it will help - at least I hope it does!
Re: OCR Additional Sci A, Ideas in Context material
Thanks! Us 3 are really posting some valuable content here! I've gota revise for that god aweful subject media now . Reckon il be back to this thread tomorow afternoon, thanks!
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OCR Additional Sci A, Ideas in Context material
But wouldnt it depend on what the sulphuric acid reacted with?
. Reckon il be back to this thread tomorow afternoon, thanks!
