A level Biology Preparation Work

Transcription

1 A level Biology Preparation Work Topic Completed Score 1. Cells /26 2. Mammalian circulatory system /16 3. Transport and Exchange /22 4. Genetics /20 5. Evolution /16 6. Enzymes /17

2 1. Cells Units of measurement When looking at cells and organelles, biologists need to use units that are smaller than cm or mm. This section gets you familiarised with them. 1) Complete the diagram below to show: names of the units of measurement, unit symbols, mathematical operations for converting between units. (4 marks) 2) Complete the table below to show the corresponding value nanometres, micrometres and millimetres for the measurements given in each row. The first row has been completed for you. Ensure that your answers use the correct unit symbols. Nanometre Micrometre Millimetre (8 marks)

3 3) Label the organelles of the cells below. (6 marks) 4) Describe the function of the organelles in the table below. Identify whether the organelles are found in animal, plant or bacteria cells. Organelle Function Cells found in Animal Plant Bacteria Nucleus X Chloroplast Ribosome Mitochondria Cell membrane Cell wall Permanent Vacuole Cytoplasm (8 marks)

4 2. Mammalian Circulatory System 1. Label the chambers of the heart and the blood vessels coming in and out of the heart (8 marks) 2. Label the blood vessels of the circulatory system below (3 marks) 3. What is the function of valves in a vein? Why are they required? (2marks) 4. Why do the artery walls have thicker elastic and muscle fibres? (1 mark) 5. How thick are capillaries? Why must they be this thick? (2 marks)

5 3. Transport and Exchange 1) Define the term diffusion. (1 mark) 2) Define the term osmosis. (3 marks) 3) Define the term active transport. (2 marks) 4) List 3 ways to increase the rate of diffusion (3 marks) 5) What are the functions of the xylem and phloem? (2 marks) 6) List 4 ways the alveoli are adapted to make gas exchange more efficient. (4 marks) i. ii. iii. iv. 7) List 4 ways the small intestines are adapted to make absorption of food more efficient. (4 marks) i. ii. iii. iv. 8) Describe how the method of glucose uptake changes from the beginning the small intestine to the end (3 marks)

6 4. Genetics 1. Define the following terms: Gene Allele Recessive allele Dominant allele Genotype Phenotype Homozygous Heterozygous (8 marks) 2. What is mitosis? When does mitosis occur in humans? (3 marks) 3. What is meiosis? When does mitosis occur in humans? (2 marks)

7 4. CRAM is an inherited condition which causes muscle breakdown. The breakdown products enter the urine, making it dark-coloured. The diagram below shows the inheritance of CRAM in one family. CRAM is caused by a recessive allele, n. The allele for normal health is N. 5. a) Give evidence from the diagram that CRAM is caused by a recessive allele (1 mark) b) None of person 2 s children have CRAM. Explain why (2 marks) c) Persons 7 and 8 want to have another child. What is the probability that this child will have CRAM? Draw a genetic diagram to explain your answer. Probability =... (4 marks)

8 5. Evolution 1. What causes variation? (1 mark) 2. Describe how natural selection occurs. (4 marks) 3. Why was Darwin s theory of natural selection not accepted at the time he proposed it? (2 marks) 4. What was Lamarck s theory for why organisms changed over time? (3 marks) 5. Give 2 examples of evidence scientists can use to support evolution? (2 marks) 6. Give 4 causes of extinction. i. ii. iii. iv. (4 marks)

9 6. Enzymes 1. What are enzymes? How do they work? (3 marks) 2. What is the optimum temperature or ph of an enzyme? (1 mark) 3. What does the term denaturing mean? What effect will this have on enzyme activity and why? (3 marks) 4. The graph shows the effect of ph on the activities of three enzymes, X, Y and Z. These enzymes help to digest food in the human digestive system. Each enzyme is produced by a different part of the digestive system. ph (i) What is the optimum (best) ph for the action of enzyme Z?... (1 mark) (ii) The stomach makes a substance that gives the correct ph for enzyme action in the human stomach. Name this substance.... (1 mark) (iii) Which enzyme, X, Y or Z, will work best in the human stomach?... (1 mark)

10 5. Fresh milk is a mixture of compounds including lipid, protein and about 5% lactose sugar. Lactose must be digested by the enzyme lactase, before the products can be absorbed. Lactase can be added to fresh milk to pre-digest the lactose. This makes lactose-free milk, which is suitable for people who do not produce enough lactase of their own. A student investigated the effect of changing ph and temperature on the digestion of lactose in milk. The results are shown in Tables 1 and 2. Table 1 Effect of ph Table 2 Effect of temperature ph Time taken to digest lactose in minutes Temperature in C Time taken to digest lactose in minutes No digestion (a) The label on a carton of lactose-free milk states: Lactase is normally produced in the stomach of mammals. The results in Table 1 suggest that this statement is not true. Explain how. (2 marks) (b) Explain, as fully as you can, the results shown in Table 2. (3 marks)

11 (c) Bile is produced in the liver and is released into the small intestine. Bile helps the digestion of lipid in the milk. Describe how. (2 marks)