KULLEĠĠ SAN BENEDITTU Secondary School, Kirkop

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1 KULLEĠĠ SAN BENEDITTU Secondary School, Kirkop Mark HALF YEARLY EXAMINATION 2014/2015 Trk 3 FORM 4 BIOLOGY TIME: 1h 30min 4 5 Global Question Mark Max. Mark Mark Instructions to students: Answer ALL questions. Calculators are allowed; Good English and orderly presentation are important. Read each question carefully. DO NOT WRITE ABOVE THIS LINE Name: Class: Section A: Answer all questions in this section on the exam paper. This section carries 55 marks. 1. Explain the biological significance of the following posters. (2) Kulleġġ San Benedittu Secondary School Kirkop Page 1 of 11

2 (2) (2) [6 marks] 2. The table below shows the energy used by a typical 25-year-old woman doing various activities. She has a mass of 62 kg. Activity Energy used in kj per minute Dancing 19 Running 27 Sitting 5 Standing 9 Walking Slowly 11 Walking up and down stairs 28 a. i. Which activity uses the most energy per minute? (1) ii. Calculate the percentage increase in energy used per minute when the person has been sitting, then walks up and down stairs. Show your working. Answer: (2) Kulleġġ San Benedittu Secondary School Kirkop Page 2 of 11

3 b. Explain why dancing uses more energy than walking slowly. (2) c. Suggest what difference there would be if the woman weighed 75 kg. Give a reason for your answer. (2) [7 marks] 3. Lemna (also known as duckweed) is a small floating plant, which grows in fresh water. An experiment was set up to investigate the role of mineral ions on the growth of Lemna. Five dishes (labelled A to E) were set up as shown in the diagram below. Each dish contained the same number of Lemna plants. A complete solution, includes all the mineral ions required by Lemna for normal growth. The dishes were placed by a window in the classroom and observed over a period of three weeks. Growth of the Lemna plants was estimated from the changes in leaf size and number of leaves. Kulleġġ San Benedittu Secondary School Kirkop Page 3 of 11

4 a. Compared with dish A, Lemna plants in dish B showed less growth and their leaves turned yellow. Suggest an explanation for this result b. In this experiment, why is a comparison made with dish A rather than dish E? c. Explain why all the dishes were placed by a window in the classroom. [5 marks] 4. The table below shows the mass of certain food components in 100 g of liquid milk and in 100 g of dry powdered milk. a. i. How much carbohydrate would be in 50 g of liquid milk? (1) ii. How much more fat is contained in 100 g of powdered milk than in 100 g liquid milk? iii. List the elements making up carbohydrates. (3) b. The food components in the table are all needed in a balanced diet. Name TWO other food components, not listed in the table, that are needed in a balanced diet. Kulleġġ San Benedittu Secondary School Kirkop Page 4 of 11

5 c. Describe a simple test you could carry out to test a food sample for fats (lipid). d. Mothers feed their babies on milk. Describe the process of digestion of fat present in milk, in the gut of a baby. (3) [12 marks] 5. The diagram below shows the apparatus used by a student to measure the heat produced by germinating seeds. a. The table below shows the steps used to set up the apparatus and the reason for each step. Complete the table by writing reasons in each empty box. One has been done for you. (3) Step 1. Soak one set of seeds in water for 24 hours Reason for Step 2. Boil second set of seeds 3. Wash both set of seeds in disinfectant 4. Place each set of seeds in a different vacuum flask and leave for 3 days Compare heat production Kulleġġ San Benedittu Secondary School Kirkop Page 5 of 11

6 b. Why is a vacuum flask used to contain the seeds? c. Suggest why cotton wool is used to plug the vacuum flasks rather than a rubber bung d. Describe and explain the results you would expect after several days. [8 marks] 6. The following graph shows the level of lactic acid in the blood before, during and after a period of exercise. a. By how much did the level of lactic acid increase during exercise? Kulleġġ San Benedittu Secondary School Kirkop Page 6 of 11

7 b. How long after the period of exercise did it take for the lactic acid concentration to return to normal? c. Name the process which produces lactic acid d. Write the word equation representing the process which is producing lactic acid. e. After exercise the amount of oxygen taken in is approximately double the normal intake. Account for this difference. [7 marks] 7. This question is about the digestive system a. What is the purpose of digestion? b. The rate at which enzymes digest nutrients in the digestive system depends upon the conditions they are working in. i. Name the part labelled A (1) ii. Name the enzyme produced in structure A. (1) iii. Explain the function of the enzyme mentioned in ii. (1) Kulleġġ San Benedittu Secondary School Kirkop Page 7 of 11

8 iv. Name TWO conditions present in structure A which are needed for the action of the enzyme released there. (2) c. i. Name the part labelled B (1) ii. List TWO enzymes produced by structure B. (2) [10 marks] Section B: Answer all questions on a separate foolscap. Answer Question 1 and choose any other two questions. This section carries 45 marks. 1. Sucrose can be digested to give glucose and fructose. This reaction is speeded up by the enzyme sucrase. Sucrase Sucrose Glucose + Fructose a. A student carried out an investigation to study the effect of increasing the concentration of the enzyme sucrase on the rate of this reaction. He kept the concentration of sucrose constant. He used six different concentrations of the enzyme (sucrase) and for each of these he measured the time taken for the sucrose to be completely digested. He carried out all the reactions at 40 C. The student s results are shown in the table below. Kulleġġ San Benedittu Secondary School Kirkop Page 8 of 11

9 i. Plot a line graph of these results on the graph paper provided. Plot enzyme concentration on the x-axis and time taken to digest sucrose on the y-axis. Join the points with straight lines. (5) ii. Define the term enzyme. (2) iii. Describe how increasing the concentration of the enzyme (sucrase) affected the time taken for the sucrose to be digested. (2) b. i. Suggest why he carried out all of the reactions at 40 C. (1) ii. Describe one way how he could keep the temperature constant (at 40 C). (1) c. The student then repeated this experiment, first at 20 C and then at 80 C. Suggest what would happen to the time taken for the sucrose to be digested at 20 C and 80 C. In each case give a reason for your answer. (4) [15 marks] 2. Explain the biological significance of the following statements. a. Smaller mammals often have a higher respiration rate than larger mammals. (3) b. The stomach has means to prevent self-digestion. (1) c. Aerobic and anaerobic respiration in mammals varies considerably. (4) d. Fat is necessary in slowing down heat loss. (2) e. High roughage foods and are recommended by nutritionist worldwide. (2) f. Water is the basis of life. (3) [15 marks] 3. This question is about digestion. a. Name a part of the digestive system where: i. Most absorption of digested food takes place. ii. Most absorption of water takes place. iii. Egestion takes place. (3) b. Name the process by which food is moved through the digestive tract. (1) c. i. Draw a clear well-labelled diagram of a villus. (3) ii. Name two ways in which a villus is adapted to speed up absorption. (2) Kulleġġ San Benedittu Secondary School Kirkop Page 9 of 11

10 iii. Name one process by which digested food may be absorbed. (1) d. Distinguish between absorption and assimilation (2) e. Describe what happens to food which is not digested and absorbed. (3) [15 marks] 4. A biology student wants to investigate the effect of the enzyme amylase on starch. Explain how you would design an experiment of the sort. In your description include: a. Aim of the investigation (1) b. Apparatus needed (2) c. Materials needed (2) d. A detailed method including a suitable control (you may include a diagram) (6) e. Results expected (2) f. Interpretation of result expected (2) [15 marks] 5. Mycobacterium avium causes chronic infection in ruminants, which is one of the most widespread bacterial diseases of domestic animals, causing enormous economic losses worldwide. Though the disease was first described more than a century ago, the biology of the infecting organism and the mechanisms of its interactions with the host still remain a mystery. a i. Define the term ruminants. (2) ii. Give one reason why chronic infection in ruminants may cause enormous economic losses worldwide. (1) iii. Explain how fermentation of plant material in a ruminant happens. Use the term biogas in your explanation. (3) iv. Give TWO differences between the dentition of a herbivore and a carnivore. (2) Calves in a cattle population were found to be suffering from Milk Fever Syndrome. This disease results due to lack of calcium in milk they are fed on. On the same farm, several pigs were found to be suffering from anemia. After veterinary investigation, it was found that farm owners were not providing their animals with nutritious food, hence legal action was taken to prevent further deficiency diseases in the animals. Kulleġġ San Benedittu Secondary School Kirkop Page 10 of 11

11 b. i. Name the deficiency disease resulting from lack of calcium in the diet and explain the effect of this disease on the body of the mammal. (2) ii. Name the mineral which is lacking in the food fed to pigs on this farm and explain the effect of anemia on the body of the mammal. (2) iii. Cattle on the same farm were milked and milk was stored into vats and sent to a dairy products factory. Briefly explain how yoghurt is produced. (3) [15 marks] END OF EXAM Kulleġġ San Benedittu Secondary School Kirkop Page 11 of 11