Jeddah Knowledge International School

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1 Jeddah Knowledge International School Biochemistry Revision Pack Quarter 2 Grade 9 Name: Section: Q2 G9 SCIENCE REVISION PACK

2 Q2 G9 Science Revision Pack Section A: Rates of Reaction 1. Using data from the table, when did the reaction stop? Using data from the table, what was the average rate of reaction? Why does reaction rate increase as the temperature increases?. 4. Which line represents the fastest reaction?.. 2 Q2 G9 SCIENCE REVISION PACK

3 5. Which curve represents the lowest concentration of acid for a certain reaction?.. 6. Which curve represents the highest pressure of two reacting gases?. 7. Why does reaction rate increase as the concentration increases? Which of the following statements about collisions is correct? (a) All colliding particles have the same amount of energy (b) Only fast moving particles collide with each other (c) Reactions can happen if the colliding particles have enough energy 9. A successful collision is one in which: The red curve represents the 'uncatalysed reaction' but which curve (A, B or C) represents the same reaction but with the catalyst added? 3 Q2 G9 SCIENCE REVISION PACK

4 Enzymes: 11. The monomers in proteins are: 12. What type of substances do lipases break down? 13. Amylase catalyses the breakdown of starch into:. 14. Proteases are used in some baby foods to: What are enzymes?. 16. What is the optimum temperature for an enzyme?. 17. What happens to enzymes at very high temperatures? Stomach enzymes work best around ph level:. DNA and Inheritance 19. Which of these is the smallest? (a) Gene (b) Chromosome (c) Cell 4 Q2 G9 SCIENCE REVISION PACK

5 20. Where are chromosomes found? (a) In the cytoplasm (b) In the nucleus (c) In the membrane 21. What shape is DNA? (a) Double helix (b) X shaped (c) Spherical 22. How many chromosomes do normal body cells have? (a) 46 pairs (b) 23 (c) 23 pairs 23. How many chromosomes do sperm and egg cells have? (a) 46 (b) 23 pairs (c) What is the definition of a gene? (a) One copy of all our DNA (b) A section of DNA that gives a characteristic (c) A coiled up, x shaped section of DNA Q2 G9 SCIENCE REVISION PACK

6 25. How many genes do we have? (a) 23 pairs (b) 23 (c) Around 20, The diploid number of chromosomes in humans is 46. The haploid number is (a) 92 (b) 46 (c) 23 Section B 1. 6 Q2 G9 SCIENCE REVISION PACK

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8 2. Babies find it difficult to digest proteins in their food. Baby food manufacturers use enzymes to pre digest the protein in baby food. (a) Use words from the box to complete the following sentences. amino acids amylases fatty acids proteases glucose lipases Proteins are pre digested using enzymes called... The pre digestion of protein produces... (b) A baby food manufacturer uses enzyme V to pre digest protein. He tries four new enzymes, W, X, Y and Z, to see if he can reduce the time taken to pre digest the protein. The graph shows the time taken for the enzymes to completely pre digest the protein. 8 Q2 G9 SCIENCE REVISION PACK

9 The manufacturer uses the same concentration of enzyme and the same mass of protein in each experiment. (i) How long did it take enzyme V to pre digest the protein?... minutes (ii) Which enzyme, V, W, X, Y or Z, would you advise the baby food manufacturer to use? Enzyme 3. The diagram shows the apparatus used to investigate the digestion of milk fat by an enzyme. The reaction mixture contained milk and the enzyme. In Experiment 1, bile was also added. In Experiment 2, an equal volume of water replaced the bile. In each experiment, the ph was recorded at 2 minute intervals. 9 Q2 G9 SCIENCE REVISION PACK

10 The results of the two experiments are given in the table. Time in minutes Experiment 1: with bile ph Experiment 2: without bile (a) Milk fat is a type of lipid. Explain why the ph changed in experiment (b) (i) For Experiment 1, calculate the average rate of fall in ph per minute, between 4 minutes and 8 minutes. Show clearly how you work out your final answer ph units per minute (ii) The average rate of fall in ph per minute for Experiment 2 was 0.1 units of ph per minute. Explain the difference in the rate of fall in ph when bile is present Q2 G9 SCIENCE REVISION PACK

11 4. Cells in a human body can be haploid or diploid. When an egg cell combines with a sperm cell a fertilised egg, known as a zygote, is formed. (i) Which row of the table gives correct information about the egg cell, the sperm cell and the zygote? Put a cross ( ) in the box next to your answer. %%% egg cell sperm cell zygote A diploid diploid haploid B diploid haploid diploid C haploid diploid haploid D haploid haploid diploid (ii) The single cell of the zygote divides into two cells in 15 hours. These cells continue to divide in this way to form an embryo. The diagram shows an embryo with 32 cells. Calculate the length of time it takes the single cell of the zygote to form an embryo with 32 cells. answer =... hours (iii) The cells of this embryo are genetically identical. Explain how these genetically identical cells are produced. 11 Q2 G9 SCIENCE REVISION PACK

12 5. Use words from the box to complete the sentences. Each of the cells produced contain identical sets of in their (b) Complete the sentence by putting a cross ( ) in the box next to your answer. Mitosis occurs during A digestion B fertilisation C growth D respiration (c) Embryonic stem cells divide by mitosis. (i) Explain why embryonic stem cells are useful in medical research. 12 Q2 G9 SCIENCE REVISION PACK

13 (ii) Each stem cell divides once every 30 minutes. Calculate how many minutes it would take one stem cell to form sixteen cells. (d) Complete the sentence by putting a cross ( ) in the box next to your answer. Organisms that are genetically identical to each other are called A cells B clones C gametes D zygotes 13 Q2 G9 SCIENCE REVISION PACK