I've got the same exam tomorrow aswell,
Revising for it is just reading all three articles thouroughlly and understanding every key word you don't know.
Also, my school gave me a document which had questions on it for each article and we have to be able to answer all those questions.
Also, we were told to look at the last year exam, and the link to it is here:
http://www.ocr.org.uk/Data/publications/past_papers_2007_june/GCSE_TFC_Science_A_A214_02_June_2007_Question_Paper.pdf
that is higher tier
also here are the questions we had to be able to answer:
Is PVC safe for our children?
1. Read the article and make sure you are able to write a full
answer to the title question.
2. Section : What is PVC?
- Be able to describe how PVC is made.
- From the named items, make a list of those which would contain no
phthalate plasticizer, 10% and 50% plasticizer. What properties would
the PVC in each of these groups have?
3. Section: What do Plasticizers do?
- Draw a diagram of polymer chains with and without plasticizers.
Explain how addition of a plasticizer makes the polymer less rigid.
Testing tensile strength- experiment
- What is the independent variable (i.e.What would the scientist
measure)?
- How would you make the test accurate and reliable?
- Which factors (variables) would be controlled (kept the same) to
ensure fair testing?
- Predict: If PVC with 50% phthalate plasticizer deflects (bends) 20
cms from the horizontal, the reading for PVC with 10% and no
placticizer.
- What is the correlation between amount of plasticizer and rigidity?
- Measuring how far the rod bends shows how flexible it is but PVC with
high amounts of plasticizers will also stretch ( elongate) How would you
measure this ?
4. Section: Are plasticizers safe?
- Which sentence suggests that when adults have long term exposure to
phthalates their bodies cannot get rid of the chemical? Which animal
experiment was used to test this?
- Is the monkey experiment a good model for long term exposure in
humans? Which group of people have regular blood transfusions?
- Predict the percentage amount of phthalate plasticizer in PVC bags
used for blood transfusions.
- Phthalates are not chemically bonded to PVC which means they can leach (move away from) into other things in contact with the plastic (example food wrapped in cling film) and they can evaporate into indoor air and the atmosphere. Humans are exposed through ingestion (sucking, eating), inhalation (breathing in) and by contact with the skin.
Why are babies and young children at greater risk of exposure through their toys? What do babies do with their toys?
- Toxic chemicals are usually broken down by the liver. Rats exposed to phthalates had damaged livers. Why did this finding indicate a greater risk to babies and young children?
- The European Union has banned the use of phthalates in toys for small
children, even though there is no strong scientific evidence to prove
that they are harmful to humans. Which principle has been applied?
Explain why?
- Why do toy manufacturers say there is no need to worry about the
plasticizers in children’s toys?
- Identify in the passage 1. all evidence 2. all explanations 3. all speculations and 4. An opinion
Herceptin: a new cancer treatment
1. What is a cancer and how do cancerous cells move around the body?
Section: Herceptin
- In these early trials why were two groups of women with advanced
breast cancer compared? Why did all the women receive
chemotherapy?
- Would it have been ethical to have included a third group who received
Herceptin only?
- How effective was the new drug Herceptin?
Section: Testing new cancer drugs
- Why are new drugs tested in the laboratory before being tested on
humans? How are new drugs tested in the laboratory?
Phase1 – Clinical trials
Phase 1 trials are done to find out:
A safe dose range
Possible side effects
How the human body copes with the drug
If the treatment shrinks the cancer
- Why are these first tests carried out on a small number of women?
Why would the women volunteer?
Phase 2
- In phase 1 doctors monitor the progress of the women. Why are
scientists needed in phase 2?
- It is important that the cancers are in early stages here. Do you know
why? (See first paragraph)
Phase 3
- Blind or double blind trials are usually carried out in phase 3 of clinical
trials. What does this mean?
- Sometimes healthy individuals (as a control group) are included in
clinical trials of new drugs. Why didn’t this happen in the case of
Herceptin? (read last page).
- Be sure you understand the advantages of monitoring over a long time.
Which drugs should be used?
- Even though results indicate that Herceptin stops cancer cells
dividing why is it not available to women with breast cancer at an early
stage?
- What long term economic benefits are there which would overcome the
cost of using Herceptin?
- Herceptin still needs more trials which monitor patients over a long
time. Is it likely that NICE would wait to recommend this drug for use
by women in advanced stages of cancer?
- Is it ethical to refuse beneficial drug treatment because the drug is
very expensive?
- From the passage identify 1. Evidence 2. Speculation 3. Facts
How did the Dinosaurs die?
Questions taken from text book (p81Higher)
1. What are the two explanations for dinosaur extinction? Make a list of
points for and against each explanation. Which do you think most
likely. Give your reasons.
2. How could scientists tell that the layer of iridium rich clay around the
world was all deposited at the same time? Iridium is present in very
small amounts in the Earth’s crust. Name two places where iridium is
found in higher amounts.
3. What might have happened to the theory that an asteroid caused
mass extinction of the dinosaurs if
a. The Chicxulub crater had not been found?
b. Iridium rich layers had been found to have different ages at
different places?
4. What is the difference between data and theory?
5. Both impact by an asteroid and large volcanic eruptions would produce
chemical changes in the Earth’s atmosphere(acid rain) and fill the
atmosphere with dust for months/ years. What effect would the dust
have on the temperature of the Earth? Why would the dust cause
major changes in food chains ?
6. What evidence is there in the Cretaceous –Tertiary clay layer that
huge forest fires swept across the Earth?
7. About 75% of all living species became extinct 65 million years ago.
However life was almost completely destroyed on Earth 250 million
years ago with 95% of all species wiped out. To add support to each
theory what evidence would scientists need?
8. Which theory provides the correlation with the mass extinction of the
Dinosaurs. Explain why.
9. Give reasons why scientists may disagree with the theories of other
Scientists (here there is the example of Earth scientists-Geologists and Physicists having different
views)
I hope this helps you =]