LIFE SCIENCES. 1. The question paper consists of 8 pages (1 to 8) and an insert of 4 pages (i iv). Please check that your question paper is complete.

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1 GRADE 10 EXEMPLAR EXAMINATION NOVEMBER 2006 LIFE SCIENCES Time: 2 hours 150 marks PLEASE READ THE FOLLOWING INSTRUCTIONS CAREFULLY 1. The question paper consists of 8 pages (1 to 8) and an insert of 4 pages (i iv). Please check that your question paper is complete. 2. Write your name on the front page of the insert (Section A). 3. Section A: Write your answers on the question paper. Section B: Write your answers in your answer book. 4. Read the questions carefully. 5. Number your answers exactly as the questions are numbered. 6. Use the total marks which can be awarded for each question in sections A and B as an indication of the amount of detail required in your answer. 7. It is your own interest to write legibly and to present your work neatly. PLEASE TURN OVER

2 LIFE SCIENCES: GRADE 10 EXEMPLAR PAPER Page 2 of 8 SECTION A Answer ALL questions in this section in your Answer Book. QUESTION 1 2(a) The diagram below shows some cells which form the lining of your mouth cavity (i) Name the structure labelled 2. (1) (ii) Write down the number and name of the part which controls the cell's activities. (2) (iii) State three ways in the structure of a plant cell would be different from the cells shown above. (3) 2(b) (i) Write down the letter of the part that represents the position of the cell membrane in the cell drawn above. (1) (ii) Name two components of cell membranes. (2) (iii) What is the function of the cell membrane? (2) (iv) Name the process by which water molecules pass through the cell membrane. (1) 2(c) Your aunt has developed a lump in her throat which her doctor tells her is a malignant tumour (cancerous growth). The specialist recommends the following treatment: removal of the tumour by surgery followed by a course of chemotherapy. (During chemotherapy the patient is given one or more courses of drugs which target all rapidly dividing cells in the body (including the tumour). Unfortunately, chemotherapy has unpleasant side effects such as nausea, vomiting, loss of hair and the layer of cells that line the gut. Your aunt is scared of going through this treatment and would prefer to consult a traditional healer or homeopath. She asks you for your advice. Explain the advantages and disadvantages of the two types of treatment to help your aunt make a decision.

3 LIFE SCIENCES: GRADE 10 EXEMPLAR PAPER Page 3 of 8 QUESTION 2 3(a) (i) What is a tissue? (3) 3(b) The diagram below shows a section through an alveolus (air sac) of a human lung and its surrounding capillary. C D 1 B A (i) Name the type of tissue forming the wall of the alveolus (labelled 1). (1) (ii) Name the gases shown at A and B in the diagram. (2) (iii) For which process do the cells of the body need a constant supply of gas A? (1) (iv) State and explain three ways in which the alveolus is structurally suited to the process of gaseous exchange. (6) 3(c) The diagram below shows the nitrogen cycle. NITROGEN (in the air) lightening SOIL NITRATES taken up by plants NITRATES Plant protein Animal protein Dead organisms and faeces excretion AMMONIA PLEASE TURN OVER

4 LIFE SCIENCES: GRADE 10 EXEMPLAR PAPER Page 4 of 8 (i) Why is nitrogen essential for life? (1) (ii) How do plants and animals obtain the nitrogen they require? (3) (iii) Which type of micro-organism do the empty boxes represent? (1) (iv) Why is soil made more fertile by growing beans, peas and clover? (2) [20] QUESTION 3 4(a) The diagram below shows a section through part of a leaf of a plant. 1 palisade layer spongy layer (i) Name the organelle labelled 1. (1) (ii) Why are there more of these organelles in the palisade layer than in the spongy layer? (2) (iii) Explain three reasons why photosynthesis is important to plants and animals. (6) 4(b) The graph below shows the results of an investigation into the effect of temperature on the rate of photosynthesis o Temperature ( C)

5 LIFE SCIENCES: GRADE 10 EXEMPLAR PAPER Page 5 of 8 (i) What was the rate of photosynthesis at 10 O C? (1) (ii) Over what range of temperatures was photosynthesis the fastest? (2) (iii) If a farmer grew lettuces in a glass walled building (greenhouse) which substances would he need to supply to the plants for rapid growth to occur? (2) 4(c) In the past, maize (mealie) cobs were picked, the grain was stripped off the cobs and stored in a grain pit. Cool & Dark gas The pit was usually dug in a cattle kraal. The inside of the pit was coated with a mixture of cattle dung and clay and the base was covered with small stones and clay. The pit was left to dry in the sun. The cool, dry pit was then filled with grain and the top covered with sticks and sealed with a mixture of clay and dung. A large stone was placed over the pit to mark its position and prevent cattle from falling in. Some of the grain at the edges of the pit fermented and the gas given off suffocated the pests that eat grain. When people opened the grain pit, they waited for a few minutes before they climbed in to collect some grain to eat. (i) Why do you think the sides of the pit were coated with dung and clay and this was allowed to dry out? (2) (i) Name one of the 'suffocating' gases that the fermenting grain produced. (1) (ii) During which process was this gas released? (1) (iv) Why do you think that people wait for a while after they have opened the pit, to climb into it? (2) [20] PLEASE TURN OVER

6 LIFE SCIENCES: GRADE 10 EXEMPLAR PAPER Page 6 of 8 QUESTION 4 Read the information below and answer the questions that follow. CROHN'S DISEASE 1 Crohn's disease is a chronic (ongoing) disorder that causes inflammation of the digestive tract. It can affect any part of the gut but most commonly affects the small and large intestines. The disease tends to run in families (there is a genetic link) and affects mainly 5 people between 15 and 35, although older people can also get it. Researchers believe that, in people with Crohn's disease, the immune system (which normally protects the body from infection) reacts against bacteria that live in the intestine and attacks these using white corpuscles. These white corpuscles move into the intestine lining and produce inflammation. The inflamed cells release products that injure the 10 intestines. Substances in the environment are also believed to cause the disease. Crohn's disease is more common in the developed world, particularly in the United States of America and Europe Diagram showing the human digestive system The symptoms are urgent diarrhoea, abdominal cramps and pain, fever and rectal 15 bleeding. Sufferers may also lose weight and lack energy. The disease can affect joints, eyes, skin and liver. Children who develop the disease may suffer from delayed growth and sexual development. Symptoms range from mild to severe and patients can lead normal lives followed by periods in which the disease flares up. 20 There is 110 cure for the disease. Several groups of drugs are used control the disease. The drugs work by healing the intestine lining, reducing the symptoms and controlling the immune system so that it does not attack bacteria in the gut. In the past, the disease would not have been diagnosed and the patient would have died.

7 LIFE SCIENCES: GRADE 10 EXEMPLAR PAPER Page 7 of 8 25 Complications of the disease include blockages of the intestines where inflammation occurs and ulcers which may spread into surrounding parts of the body. People with the disease often suffer from malnutrition because essential nutrients are not absorbed from the gut in inflamed areas. Two thirds of patients with the disease will require surgery to 30 cut out damaged or blocked parts of their intestines. Unfortunately, the disease often develops at the point of surgery. In really severe cases, the patient may have most or all of their intestines removed. These people can eat food so that they lead as normal a life as possible but the food passes from the stomach into a 'bag' attached to a pouch on the outside of the body. The patient is 'fed' 35 intravenously from prepared solutions. This 'feeding' often takes place at night. The patient is trained to attach a bag of prepared nutrients into a valve on the outside of his body and allow the liquid to drip into his blood system while he sleeps. (Source = Questions 1. What is Crohn's disease? (1) 2. Researchers believe that there are three main causes of this disease. Name two of these. (2) 3. Look at the diagram of the human gut. Write down the numbers of the parts which are usually affected by the disease. (2) 4. List three of the symptoms that doctors use to diagnose the disease. (3) 5. Patients who suffer from Crohn's disease usually avoid eating spicy foods, foods high in fibre and drinking alcohol. Suggest a reason why these foods should be avoided. (2) 6. Suggest a reason why Crohn's disease occurs mostly in the 'developed world'. (Line 12) (2) 7. Crohn's disease patients who are 'fed' intravenously (lines 34-37) obtain their nutrients from specially prepared solutions. List six substances that you feel should be included in these solutions. (6) 8. Do you think a patient with Crohn's disease who is 'fed' intravenously could be supplied with sufficient bags of dissolved nutrients to provide him with nourishment for a year in advance? Give a reason to support your answer. (2) [20] PLEASE TURN OVER

8 LIFE SCIENCES: GRADE 10 EXEMPLAR PAPER Page 8 of 8 QUESTION 5 6 (a) (i) What is meant by the term 'biodiversity'? (2) (ii) Why is it important for us to conserve biodiversity? Give three reasons. (3) (b) Explain how two of the following have become threats to the biodiversity of our planet: In your answer give examples to explain how the threat has occurred and some of the organisms that are threatened. Suggest ways in which the threat could be reduced. habitat loss invasive species pollution over-consumption of natural resources (20) [25]