6132/01Edexcel GCEBiology (Salters Nuffield)Advanced SubsidiaryUnit Test 2Monday 1 June 2009 – AfternoonTime: 1 hour 30 minutes
Materials required for examination Items included with question papersRuler Nil
Instructions to CandidatesIn the boxes above, write your centre number, candidate number, your surname, initials and signature. Check that you have the correct question paper. The paper reference is shown above.Answer ALL NINE questions. Write your answers in the spaces provided in this question paper.Some questions must be answered with a cross in a box ( ).If you change your mind about an answer, put a line through the box ( ) and then indicate your new question with a cross ( ).If you need to use additional answer sheets, attach them loosely but securely inside this booklet.Show all the steps in any calculations and state the units. Calculators may be used.Include diagrams in your answers where these are helpful.
Information for CandidatesThe marks for individual questions and the parts of questions are shown in round brackets: e.g. (2).There are 9 questions in this question paper. The total mark for this paper is 70.There are 16 pages in this question paper. Any blank pages are indicated.
Advice to CandidatesYou will be assessed on your ability to organise and present information, ideas, descriptions and arguments clearly and logically, including your use of grammar, punctuation and spelling.
1. Give the name of the structure found in plant cells which most closely fits the description given in the table. The first row has been done for you.
Description Structure
A thick elastic layer of cellulose microfibrils outside the cell membrane Cell wall
A double membrane-bound organelle containing chlorophyll and where photosynthesis takes place
A strand of cytoplasm passing through a pit in a cell wall allowing substances to pass from one cell to another
The membrane enclosing the large central vacuole which regulates the movement of substances between the vacuole and the cytoplasm
A double membrane-bound organelle, without chlorophyll, where starch grains are stored
A layer of calcium pectate sticking the cell wall of one cell to that of another cell
Q1
(Total 5 marks)
Leave blank
3
Turn over*N34137A0316*
2. Water travels through the stem of a plant in the xylem. Adhesion and cohesion are important in this process.
(a) Explain the difference between adhesion and cohesion.
(c) When the flow of water through the xylem increases, the diameter of the stem is slightly reduced. When the flow is reduced, the stem returns to its original size. Suggest why these changes take place.
4. (a) Which one of the following statements most accurately describes the greenhouse effect. Put a cross ( ) in the correct box.
An alternative term for climate change
The only cause of climate change during the past 100 years
A process which causes the Earth to be warm enough to support life
A process which makes it easier for infra-red radiation to leave the Earth’s atmosphere than for it to enter
(1)
(b) Global warming is likely to have a serious effect on the biodiversity of the UK. Suggest why some plants and animals might survive in a garden or a zoo, but no longer be able to survive in the wild.
(ii) Tree rings shown in the diagram could support the theory that increasing temperatures (caused by global warming) is one factor causing increased tree growth. Suggest an alternative factor which may be the cause of increased growth.
(iii) Name the two types of dead cell that are the main components of wood.
............................................................ and ............................................................(2)
(c) The concentration of nitrates dissolved in rain has increased over the past fifty years. Explain how this increase in concentration could lead to a faster growth rate in trees.
(d) Planting more trees is a common kind of ‘carbon offsetting’. Instead of reducing their carbon emissions a company pays for trees to be planted to remove carbon dioxide from the air.
(i) Name the process by which trees remove carbon dioxide from the air.
(ii) Suggest why many scientists believe that planting more trees is only a short term solution to the problem of rising carbon dioxide concentrations.
(b) P. haloplanktis is a species of bacterium which produces β-galactosidase in a similar way to E. coli. The graph below shows the rate at which β-galactosidase from each species causes ONPG to break down to (yellow) ONP, at a range of temperatures.
(i) Suggest and explain a conclusion from the data shown in the graph.
(ii) β-galactosidase is used to break down lactose in cheese manufacture. Suggest why using β-galactosidase from P. haloplanktis, rather than from E. coli, might lead to increased efficiency.
7. Mesenchymal stem cells (MSC), normally found in bone marrow, can be implanted into damaged liver tissue enabling it to produce new cells and thus heal itself.
8. Rapid advances in medical research mean that more women are surviving breast cancer, especially when it is diagnosed early. In breast cancer, a tumour develops inside the tissues of the breast. In some, but not all cases, cancerous cells may break off and travel through the blood and lymph to different parts of the body where each cell may develop into another tumour.
Nobody knows why a particular woman may be unfortunate enough to get breast cancer although it is most common in women over 55. Risk factors appear to include HRT (hormone replacement therapy), obesity after the menopause and too much alcohol. In some cases, there seems to be something wrong with certain genes such as BRCA 1 and 2, which normally repair damaged DNA, and TP53 which normally controls cell division.
(a) Describe how a tumour is formed in the tissues of someone who has never had cancer before.
(b) (i) Name the international project which began in 1990 and which aimed to sequence as many human genes as possible, including BRCA1, BRCA2 and TP53.
(ii) Breast cancer is often treated by an operation to remove the tumour from the breast and by the use of drugs which suppress the multiplication of cancerous cells. Explain why it is important to remove the tumour as soon as possible.
(iii) Docetaxel is a drug which can be used to treat breast cancer. It is effective for some patients but not for others. Scientists at Aberdeen University identified two genes which can be used to predict whether docetaxel is likely to be effective for a particular patient.
Suggest two reasons why the identification of these genes could be an advantage for patients whose cancer would not be cured by docetaxel.
(ii) Suggest reasons why a patient might prefer not to know that she has genes which make her more at risk of developing breast cancer than the majority of women.
9. Cotton plants are used to produce the cotton from which cloth is made. They are grown in certain parts of the world, such as India and the USA, where cotton farming is an important way in which people earn their living. Normally, cotton plants need to be sprayed with chemical insecticides to kill insect pests. Recently, genetically-modified (GM) cotton plants have been developed which produce a natural insecticide of their own. This insecticide kills the insect pests but is harmless to humans.
A field of cotton plants showing the ‘bolls’ of cotton fibres which are collected to make cloth. The bolls are the fruit of the plant and contain seeds.
(a) Suggest advantages to cotton farmers and to the environment of growing genetically-modified cotton.
(c) For many people, genetic modification of plants remains controversial. In 2007, the European Union once again decided not to lift the ban on GM crops in Europe although they are widely grown in the USA and India.
State whether you are for or against the growing of GM crops. .................................
Explain why you hold this view. Use scientific knowledge and make reference to social or ethical issues to support your explanation.
