Key Area CELL STRUCTURE

Transcription

1 Key Area. - CELL STRUCTURE Exercise Research task on unicellular organisms After doing some research, choose one example of a unicellular organism (single celled organism). Make a labelled drawing of the organism. Write a paragraph describing where it lives and how it obtains its food. Write a list of references you used at the end. Exercise 2. Name THREE structural features that a typical plant cell and a typical animal cell have in common. (3) 2. Name THREE structural features present in an Elodea leaf cell but absent from a cheek cell. (3) 3. Give the function of each of the following structures: cell membrane, cell wall, nucleus. (3) Total (9)

2 Exercise 3 a) Identify FOUR structural features that a yeast cell has in common with an Elodea leaf cell. (4) b) Name ONE structure absent from a yeast cell but present in Elodea. () 2 A yeast cell can divide to form 2 cells in 30 minutes. 0 yeast cells are placed in a sugar solution. a) How many yeast cells will be present after 2 hours? () b) How long will it take for there to be over 000 yeast cells? () c) Name the process by which yeast cells reproduce. () 3 Give the function of these cell structures. a) Mitochondria b) Ribosomes c) Chromosomes (3) 4 Bacterial cells have a main coil of DNA and other smaller rings of DNA. a) What name is given to the smaller rings of DNA? () b) What is their function in bacterial cells? () c) What type of microscope is needed to see details of cell structures in small cells? () Total (4) 2

3 Exercise 4 Research task on yeast Research the uses of yeast in industry. Describe the ways in which yeast is used in two different industrial processes. Write your information in two separate paragraphs. Write a list of references you used at the end. Exercise 5 Exam style questions. The diagram below represents a plant cell. Which of the labelled parts of the cell are also found in an animal cell? A B C D M and N N and O M and P M, N, O and P 2. The diagram below represents a unicellular organism. Which part indicates this is a plant cell? 3

4 3. Which line in the table below correctly matches the plant cell structure to its function? A Cytoplasm Plant cell structure Function Controls the chemical activities B Cell wall Keeps the cells turgid C D Vacuole Cell membrane Prevents the cell from bursting in a hypotonic solution Controls which molecules enter or leave the cell 4. Which structural feature is common to both plant and animal cells? A B C D Cell wall Chloroplast Nucleus Large central vacuole 5. Which of the following prevents bursting of plant cells? A B C D Nucleus Cytoplasm Cell wall Cell membrane 4

5 6. Which plant cell structure is made of cellulose? A Cell wall B C D Cell membrane Chloroplast Nucleus 7. The diagram below shows onion cells as observed under a microscope at a magnification of 00 X. 300 micrometres The diameter of the field of view is 300 micrometres. The average width of each cell in micrometres is A 0.38 B 0.75 C 37.5 D

6 Question 8 and 9 refer to the diagrams of cells below. 8. Which cells are plant cells? A B C D P only P and Q P and R R only 9. The function of structure X is to A B C D control all cell activities keep the cell turgid produce glucose using light energy release energy from glucose 6

7 0. Which line in the table below describes correctly the functions of the cell wall and chloroplasts in plant cells? A B C D Function of cell wall prevents cell bursting controls entry of substances prevents cell bursting controls entry of substances respiration respiration Function of chloroplast photosynthesis photosynthesis. The diagram below shows a plant cell and an animal cell. (a) Identify structure X. (b) Give a function of the nucleus. (2) 7

8 2. The diagrams below show sections of three different cell types. They are not drawn to the same scale. (a) (i) Copy and complete the table below to show the name and function of the parts labelled, X, Y and Z. Part of cell Name Function X Y Z (ii) Cells A and B are plant cells and cell C is an animal cell. Describe two features, shown in the diagrams, that support this statement. (5) 3. Copy and complete the table. Cell Structure Function Site of aerobic respiration Ribosomes Small rings of DNA in bacterial cells for reproduction (3) Total (20) 8

9 Exercise 6 Research task on bacteria Choose one of the following research tasks: A Research the uses of bacteria in the dairy industries. Describe how bacteria are used in the production of two different foods. Write your information in two separate paragraphs. Write a list of references used at the end. OR B Research diseases caused by bacteria Describe two bacterial diseases, their symptoms and treatment. Write your information in two separate paragraphs. Write a list of references used at the end. 9

10 Key Area.2 TRANSPORT ACROSS MEMBRANES Exercise 7. Name the two types of molecule present in the cell membrane. (2) 2. The cell membrane is sometimes described as a fluid mosaic structure. a) Why is it described as fluid? b) Why is it described as a mosaic? (2) 3. Cell membranes are selectively permeable. a) What does this mean? b) Name one substance which can pass through a cell membrane easily. c) Name one substance which cannot pass through cell membranes. d) Why is this substance unable to get through the membrane? (4) 4. a) Name an artificial material used in experiments which is selectively permeable. b) Describe the test for starch. c) What colour change would indicate a positive result for glucose with Benedicts solution? (3) Total () 0

11 Exercise 8 Make a 3D cell membrane model Your task is to make a 3D model of the cell membrane. You can use any materials you can find at home, especially recycling materials. Your model should show the proteins and the phospholipids with their head and tail ends. The component parts should be labelled or there should be a key a identify them. Examples of materials you could use include paper, cardboard, plastic bottle lids, plasticene, playdoh, straws, cotton buds, cocktail sticks, buttons, ribbons, fabric, lolly sticks, dry pasta, Lego, stickle bricks, k nex. THE POSSIBILITIES ARE ENDLESS SO HAVE FUN Exercise 9. Name the two types of passive transport. (2) 2 a) Name TWO essential substances that enter an animal cell by diffusion. (2) b) Name a waste material that diffuses out of an animal cell. () c) What structure controls the passage of substances into and out of a cell? () 3 a) Explain why diffusion is important to human beings. (2) b) Predict what would happen to the rate of diffusion of oxygen into muscle cells if a person exercised vigorously. Explain your answer. (2) Total (0)

12 Exercise 0 Research task on diffusion in the lungs Do some research on diffusion in the lungs. Make sure you find out about both of the main gases involved. Write a paragraph about this diffusion. Draw a diagram to show what happens, or print and stick in a diagram. Make a list of the references you used at the end. Exercise. Define the term diffusion. () 2. a) Describe the change in mass undergone by a cylinder of fresh beetroot when it is immersed for 24 hours in (i) water (ii) concentrated sucrose solution (2) b) What name is given to the special type of diffusion that causes these changes? () c) What substance is gained or lost by the beetroot cells during this process? () 3. a) Define osmosis using these terms: Lower water concentration, net movement, membrane, water molecules, higher water concentration. (3) b) Using the terms selectively permeable membrane and concentration gradient of water, explain how the process of osmosis occurs. (2) 2

13 4. The diagram below shows four plant cells, P, Q, R and S. If the plant cells remained in contact as shown, then water would pass by osmosis from BOTH: A R to Q and Q to P B Q to S and R to Q C P to Q and R to S D Q to P and Q to R (Choose ONE answer only) () 5. Three identical cylinders of fresh turnip were immersed in the liquids as shown below for 24 hours. Each was then removed and held between forefinger and thumb as shown in the second diagram. a) Match numbers, 2, and 3 with letters A, B and C. () b) Explain your choice in each case. (3) Total (5) 3

14 Exercise 2 Research task on paramecium Paramecium is a single celled animal that lives in fresh water. Find out why it does not burst due to osmosis. Make a labelled drawing of paramecium. Describe how paramecium copes with the intake of water by osmosis. Make a list of the references you need at the end. Exercise 3 a) Explain why red blood cells burst when placed in water yet onion epidermal cells do not. (2) b) Why do red blood cells shrink when placed in concentrated salt solution? () 2 a) Describe the effect of very concentrated salt solution on onion epidermal cells. () b) Explain why this happens. () c) What name is given to cells in this state? () d) How could these cells be restored to their turgid condition? () 3 Make a labelled drawing of a plasmolysed cell. (3) Total (0) 4

15 Exercise 4 a) Define the terms active transport. () b) State two ways in which active transport is different from diffusion. (2) c) Give an example of active transport in living cells. () d) What molecules in the cell membrane are involved in active transport? () 2 The diagram below shows the direction of movement of two different substances through the cell membrane of an animal cell. cell membrane a) Name processes X and Y. () b) Which of these processes requires energy? () c) Which of these processes does not occur in dead cells? () Total (8) 5

16 Exercise 5 Exam style questions. The following diagram shows the fluid-mosaic model of the structure of a cell membrane. Which pair of structures numbered in the diagram are correctly identified in the following table? PROTEIN PHOSPHOLIPID A 7 B 2 4 C 3 7 D Diffusion is the movement of molecules of a substance from a region of: A high concentration to a region of low concentration of the same substance B low concentration to a region of high concentration of the same substance. C high concentration to a region of low concentration of a different substance. D low concentration to a region of high concentration of a different substance. 6

17 3. Diffusion is important to the unicellular animal Amoeba because it is the means by which A B C D oxygen, a useful substance, enters and CO 2, a waste product, leaves. CO 2, a useful substance, enters and oxygen, a waste product, leaves. oxygen, a waste product, enters and CO 2, a useful substance, leaves. CO 2, a waste product, enters and oxygen, a useful substance, leaves. 4. The movement of water through a selectively permeable membrane from an area of high water concentration to an area of low water concentration is called A B C D absorption osmosis plasmolysis active transport 5. A piece of potato weighs 20 g fresh and 5 g dry. What is the percentage water content of the potato? A 5% B 5% C 25% D 75% 7

18 6. When animal cells are placed in water they A remain unchanged B burst C plasmolysed D become turgid Question 7 and 8 refer to the accompanying diagram. It shows the results of an experiment where turnip cylinders, initially measuring 5 cm in length, were immersed in three different liquids for 24 hours. The test tubes were kept in a thermostatically controlled water-bath during this time. 7. Which line in the following table correctly identifies liquids X, Y and Z? Bathing liquid X Y Z A % sucrose 0.3 % sucrose Pure water B % sucrose Pure water 0.3 % sucrose C 0.3 % sucrose % sucrose Pure water D 0.3 % sucrose Pure water % sucrose 8. The factor that was varied in this experiment was A B C D temperature of bathing liquid length of turnip cylinder concentration of sucrose solution diameter of turnip cylinder 8

19 9. The accompanying diagram shows four red onion cells immersed in four different solutions P, Q, R and S. If the bathing solutions were arranged in order of increasing water concentration, the sequence would be: A B C D R, Q, S, P R, S, Q, P P, Q, S, R P, S, Q, R 0. Three plant cells, P, Q, R are shown below. a) Water is moving from cell P to cell Q and from cell Q to cell R. Which cell has the highest water concentration? () b) If all three cells were placed in pure water for one hour, what term would be used to describe the resulting appearance of the cells? () 9

20 . Three similar cylinders were cut from the same potato, dried and weighed. Each cylinder was placed in a different solution as shown in the diagram below. 0.5% Salt solution % salt solution water After one hour, the cylinders were removed from the solutions, dried and reweighed. (i) Copy and complete the table below by using the information in the diagrams. Solution Initial weight (g) Final weight (g) () (ii) Which process has caused these changes in weight? () (iii) The diagram below shows a cell from one on the potato cylinders. What term would be used to describe the condition of this cell? () 20

21 2. The diagram below shows the unicellular organism Paramecium which lives in fresh water. a) Name the process by which oxygen moves from the water into the organism. () b) Name a substance that moves from the organism into the water. () d) Name the cell structure which controls the entry and exit of materials. () Total (6) 2

22 Key Area.3 - MAKING NEW CELLS Exercise 6. What name is given to the type of cell division that produces two cells that are identical to the parent cell? () 2. State the main events that occur during this cell division in an animal cell. (2) 3. Which cell structure controls cell activities including cell division? () 4. Arrange the stages of mitosis (shown below) in the correct sequence beginning with (b.) (5) 5. Describe the process of mitosis (nuclear division) in a cell including the terms equator and spindle fibres in your answer. (4) 6. Why is it important that the chromosome number of new daughter cells in a multicellular organism is maintained? () 7. What process maintains this continuity? () Total (5) 22

23 Exercise 7 Part : Using piece of A4 paper produce a cartoon strip/storyboard to explain the stages involved in the process of mitosis. Use the following steps to help you: The original cell contains single-stranded chromosomes. When the cell is preparing to divide, each of the chromosomes is copied to form a double-stranded X-shaped chromosome. A spindle forms in the cell. The chromosomes line up along the centre (equator) of the cell. The spindles pull the chromosomes apart. The single-stranded chromosomes reach opposite ends of the cell. The cell splits into two, producing two genetically identical daughter cells. Extension Try to include the word diploid in your explanation. Total (7) Part 2: Answer the following questions in full sentences:. What is mitosis? () 2. Why is mitosis important? (2) 3. What would happen if mitosis didn t take place? () 4. What is meant by a diploid cell? () 5. What cells in the body do you think are not diploid? () Total (6) Exercise 2 total (3) 23

24 Exercise 8: Culturing Bacterial Cells Instruction Manual Your task is to create an instruction leaflet on how to safely culture bacterial cells. You must include: What cell culturing is and why bacteria can be used. You should include: A step by step guide to explain how to safely culture (grow) bacterial cells, you may include diagrams. You could include: A detailed description about the health and safety involved in culturing bacterial cells (aseptic technique) This work will be graded A, B or C. Exercise 9: Answer each of the Learning Outcomes for Unit Topic 3: Making New Cells as full sentences. You may present this information in any way you wish; you may produce a mind-map, a poster, a pamphlet, use diagrams or pictures etc Total: 4 Marks Exercise 20 Make a poster on Aseptic Techniques You must include; At least five different techniques with diagrams - used to ensure conditions are sterile in a lab. Total (0) 24

25 Exercise 2 Answer the following questions in full sentences:. What does the word optimum mean? () 2. Name the two types of medium that are used to grow cells in Biology? () 3. Name three conditions that are required for cells to grow (3) 4. Give the name of the large vessels in which bacteria or fungi are grown. () 5. Give three conditions that are required for growth in these vessels. (3) Total (9) Exercise 22 Exam Style questions. The diagrams below show six stages of a cell process. The stages are shown in pairs. The diagrams in each pair are in the correct order. The three pairs of diagrams are NOT in the correct order. (a) (b) (c) (a) Name the process shown in the diagrams. () (b) Write the letters of each pair in the order in which they occur in this process () (c) Name the cell structure which controls this process () 25

26 2. A cell can divide to produce two daughter cells. Each daughter cell grows and then divides. The beginning of these divisions is shown in the diagram below. st division st generation Calculate the number of cells in the 4th generation. Space for calculation 2nd division 2nd generation Answer: cells () 3. The diagram below shows some of the stages in cell division occurring in the cells of a plant root. Describe the stages of cells division (mitosis) shown in the cells labelled X, Y, and Z. 26

27 X: () Y: () Z: () 4. Describe the meaning of the term diploid cell () 5. Typical timings of the stages of mitosis are shown in the table below. Stage A B C D Time (minutes) What percentage of the total time for mitosis is taken by stage C? Space for calculation Answer: % () 6. Name the structure within a cell which controls cell division. () 7. Below is a diagram of a human cell. Name the structure labelled X. () X 27

28 8. Complete the following sentences by deleting the incorrect word from each pair to create a correct sentence. Write out in full. The number of chromosomes in the new cells produced by cell division will be the same as/half that of the parent cell. During cell division each parent cell produces two/four new cells. The cells produced by cell division will be different/identical to each other. (3) 9. Cell division can be described as a controlled cycle. What might occur if cell division is uncontrolled? () 0. An onion cell contains 6 chromosomes. It divides to form two new cells, which then divide again. How many chromosomes will these new cells have? () Total (6) 28

29 Key Area.4 DNA AND THE PRODUCTION OF PROTEINS STRUCTURE OF DNA Exercise 23 Research Task on DNA Structure Research one of the following scientists and write a short report on how their work has helped us to understand the structure of DNA. Provide a list of references at the end. Francis Crick James Watson Rosalind Franklin Maurice Wilkins Erwin Chargaff Exercise 24. What are chromosomes and where are they located in a cell? () 2. a) What do the letters DNA stand for? () b) The DNA molecule is described as a double helix. What does this mean? () c) i) How may different types of base molecule are found in DNA? () ii) Name the four base molecules. (4) iii) Describe the base pair rule. () Total (9) 29

30 Exercise 25 The diagram below shows a yeast cell. (i) (ii) Name the structure shown in the yeast cell which contains the genetic information. () A molecule consisting of chains of bases is contained in chromosomes. (a) Name this molecule. () (b) Explain how this molecule controls cell activities. () Total (3) Exercise 26 Complete the following in full sentences in your homework jotter. are units of inheritance which make up chromosomes. Chromosomes are made up of longs strands of which consists of two backbones each containing a chain of molecules. There are four types of base molecule, adenine,, thymine and. The of the bases determines the sequence of in a protein. Three molecules form the code for one amino acid. The protein produced controls the characteristics of the organism. Chromosomes exist in pairs, and each normal body cell of an organism has matching sets of these. (In humans, 2 sets of making in total). Total () 30

31 Exercise 27 Research report on genetic disorders Cystic fibrosis is a medical condition that is passed from parents to their children. This condition is caused by an error in one of the genes found in the nucleus of the parent s cells. a) What are genes made of? b) What effect might inheriting a damaged gene have on the production of a protein? c) Research one of the following genetic disorders. Describe how the disorder is inherited, the symptoms and treatments. Provide a list of references at the end. Cystic Fibrosis Tay-Sachs Down s Syndrome Duchenne Muscular Dystrophy (DMD) Huntington s Disease Exercise 28 Exam Style Questions. Which part of a cell controls cell division? A Membrane B Nucleus C Cell wall D Cytoplasm 2. DNA is found in which part of the cell? A Cytoplasm B Ribosomes C Nucleus D Cell membrane 3

32 3. The DNA of a chromosome carries information which determines the structure and function of A B C D fats bases carbohydrates proteins 4. Which of the following is a correct description of a chromosome? A B C D a chain of DNA bases a chain of RNA bases a chain of amino acids a chain of sugar molecules 5. The DNA base, (A) adenine, pairs with what other base? A (A) Adenine B (T) Thymine C (C) Cytosine D (G) Guanine 32

33 6. The diagram shows DNA during replication. Base H represents thymine (T) and base M represents guanine (G). Which letters represent the base cytosine (C)? A B C D J and K J and L N and P N and R 7. A DNA molecule consists of 4000 bases of which 20% are adenine (A). How many guanine (G) bases will be present in the DNA molecule? A 800 B 000 C 200 D Decide if each of the following statements about DNA and the 33

34 Key Area.5 - Proteins and Enzymes Exercise 29. All enzymes are composed of A B C D carbohydrates protein glycerol fatty acids 2. The enzyme phosphorylase was added to a 2% glucose--phosphate solution. After one hour, the concentration of glucose--phosphate had fallen to 0.05%. How many times lower was the concentration after one hour than at the start? A 0. B.95 C 40 D Two grams of fresh liver was added to hydrogen peroxide The time taken to collect 0cm 3 of oxygen foam was 2 minutes. The rate of oxygen production was A 2.5 cm 3 /g/min B 5.0 cm 3 /g/min C 0.0 cm 3 /g/min D 20.0 cm 3 /g/min 34

35 4. Two grams of fresh liver was added to hydrogen peroxide at different ph values. The time taken to collect 0 cm 3 of oxygen foam was noted for each ph. ph of hydrogen peroxide solution Time to collect 0 cm 3 of oxygen foam (s) At ph 7, the enzyme which breaks down hydrogen peroxide is A at its optimum activity B at its minimum activity C denatured D digested 35

36 5. The graphs below show the effects of temperature and ph on the activity of enzyme. Which line in the table identifies correctly the conditions at which the enzyme is most active? Temperature ph A 40 2 B 40 4 C 50 2 D

37 6. Which of the graphs below shows the effect of increasing temperature on enzyme activity? A B C D 37

38 Questions 7, 8 and 9 refer to the information below. An investigation into the effect of ph on the digestion of milk by an enzyme was carried out. Five identical dishes were set up with wells cut out of the agar. To each well was added 5 cm 3 of the enzyme kept at a different ph as shown in the diagram below. The dishes were kept at 35 C. The diameter of the area cleared by the action of the enzyme was measured. Diameter of clear zone (mm) ph Dish Dish 2 Dish 3 Dish 4 Dish

39 7. The average diameter cleared at ph 5 was A 3mm B 4mm C 5mm D 6mm 8. The variable altered in this investigation was A temperature B diameter of the well C ph D milk concentration 9. The ph at which the enzyme was most active was A 3 B 5 C 7 D 9 39

40 0. Potatoes store carbohydrate in the form of starch. An enzyme found in potato cells converts glucose--phosphate into starch. glucose--phosphate Enzyme starch The following description outlines how an investigation into the time taken for the synthesis of starch to occur was carried out.. A starch-free potato extract was prepared. This potato extract contained the enzyme. 2. Two rows of a spotting tile were set up as shown in the diagram. A glucose--phosphate + potato extract B B glucose--phosphate + water 3. A stop clock was started. 4. Iodine was added to each column at 5 minute intervals. Iodine turns black when starch is present. The results A B The dimples in row A gradually turned blue/black All dimples in row B stayed orange Time (minutes) (a) Name the enzyme present in the potato extract. (b) Explain why all the starch was removed from the potato extract before it was used in the investigation. 40

41 (c) What evidence is there to show that the enzyme is necessary for the synthesis of starch? (d) What conclusion can be drawn from the results in row A?. Yeast cells contain the enzyme catalase which breaks down hydrogen peroxide into oxygen and water. hydrogen peroxide catalase oxygen + water The following diagram and description outlines how an investigation was set up and carried out. After ten minutes in the water bath at 25 o C, the yeast suspension was mixed with the hydrogen peroxide by shaking the test tube. The volume of oxygen released from the hydrogen peroxide in one minute was measured. The procedure was then repeated at 25 o C. The same apparatus was then used to investigate the effect of a range of temperatures. 4

42 (a) In this investigation temperature is the only variable which should be changed. State two variables which should be constant. (b) (i) Explain why the procedure was repeated at each temperature and an average calculated. before (ii) Explain why the yeast and hydrogen peroxide were not mixed they were placed in the water bath. (c) The results are shown in the table below. Temperature ( o C) Volume of oxygen collected (cm 3 /minute) First run Second run Average Present the results in an appropriate format on a graph. 3 (9) 42

43 Exercise 30. An experiment was set up to investigate the effect of ph on the action of the enzyme salivary amylase. After 30 minutes a sample from each test tube was tested for the presence of simple sugars. (a) Other than temperature, state two variables that must be kept constant in the experiment. (b) The results obtained are shown in the table below. ph Simple sugars test negative 4 negative 7 positive 0 negative (i) What conclusions can be drawn from these results? 43

44 (ii) Predict the results if the enzyme had been boiled before use. Give an explanation for your answer. (c) Explain why food containing starch must be digested before it can be used in the human body. 2. (a) Four groups of students investigated the catalase concentration of different tissues. Each group set up a test tube containing 5 cm 3 of hydrogen peroxide and a cube of potato. The oxygen was collected over a 3 minute period and the volume was measured as shown in the diagram below. This procedure was repeated by each group using cubes of liver, apple and carrot. Volume of oxygen collected in 3 minutes (cm 3 ) Tissue Group Group 2 Group 3 Group 4 Average Potato Liver Apple Carrot

45 (i) Copy and complete the table to show the average volume of oxygen collected for potato tissue. (ii) The volume of hydrogen peroxide and time to collect the oxygen were kept constant in this investigation. State two other variables that must be kept constant. (iii) What was done in this investigation to make the results reliable? (iv) What conclusion can be drawn from these results? 3. (b) The diagram below shows the action of the enzyme phosphorylase in a potato. (i) Copy the following sentence and select the option to make the sentence correct. The action of the enzyme phosphorylase catalyses the syntheses / degradation of starch. (ii) State the effect of phosphorylase on the rate of this reaction. (iii) Explain why lipase could not produce starch in this reaction. 45

46 4. The leaves of black walnut trees produce a chemical which is released into the soil when the leaves fall. This chemical prevents the germination (growth) of other plant seeds. The chemical can be extracted from the leaves. (a) A student carried out an investigation into the effect of this chemical on mung bean seeds. Leaf extracts containing different concentrations of the chemical were prepared. The student was supplied with:- 30 mung bean seeds a bottle of 0.% leaf extract chemical 3 identical petri dishes a bottle of % leaf extract chemical cotton wool a bottle of 0% leaf extract chemical (i) (ii) Copy and complete the diagrams below to show how the investigation should have been set up. Label the contents of each petri dish. 2 cotton wool cotton wool cotton wool Petri dish Petri dish 2 Petri dish 3 (iii) What observations and measurements should be taken to obtain results for this investigation? (iv) A control Petri dish should also have been set up to show that it was the leaf extract preventing the growth of the mung bean seeds. Copy and complete the diagram below to show the contents of the control Petri dish. cotton wool Control Petri dish 46

47 (b) Explain why producing this chemical is an advantage to the blackwalnut trees. 5. (a) Enzymes are involved in synthesis or degradation chemical reactions. The diagram below represents an example of one of these types of reactions. (i) Name the type of chemical reaction and the enzyme shown in the diagram. (ii) Copy the diagram and place an X to show the position of an active site. (b) What type of molecule are all enzymes made of? (c) What happens to the active site when an enzyme is denatured? (d) State the effect of an enzyme on the energy input needed for chemical reaction. (2) 47

48 Exercise 3. Albumin is a protein that can be broken down by the enzyme trypsin. When albumin is added to agar the agar becomes cloudy. When the albumin is broken down by trypsin the agar becomes clear. albumin tryp sin amino acids Groups of students carried out an investigation to find the effect on ph on the activity of the enzyme trypsin. Each group carried out the following procedure.. A petri dish containing cloudy albumin agar was collected. 2. Three wells were cut out of the agar. 3. Drops of trypsin and buffer solution of different ph were added to the wells as shown in the diagram below. ph4 cloudy albumin agar trypsin and buffer at ph7 trypsin and buffer at ph9 trypsin and buffer at 4. The dishes were incubated at 37 o C for 24 hours. 5. The diameter of the clear zone around each well was measured. 48

49 (a) State one variable that should have been kept constant when the dishes were set up. (b) The results from each group are given in the table below. Diameter of the clear area (mm) ph Group Group 2 Group 3 Group 4 Average (i) Copy and complete the table by calculating the average diameter of the clear area for ph7. (ii) Explain why the results for all groups were collected and averages calculated. (iii) From the results describe the effect of ph on the activity of trypsin. (c) The group suggested setting up a control to show that the enzyme caused the observed effects. Copy and complete the labels on the diagram below to show the content of the wells for the control. cloudy albumin agar 49

50 2. (a) Amylase is produced in the salivary glands. The substrate of amylase is starch. Amylase was added to a starch suspension and a sugar was produced. (i) Name the sugar produced by the action of amylase on starch. (ii) State the optimum o C temperature for the action of amylase. (b) An enzyme has a shape which is complementary to its substrate. (i) What term describes this property of an enzyme? (v) Name the part of the enzyme that is complementary to its substrate. 3. The diagram below represents an amylase molecule. 50

51 Describe and explain the events that take place when the enzyme is added to a starch suspension. 3 (2) Key Area 8 - Photosynthesis Exercise 9. Groups of students carried out an investigation into the effects of competition. Trays containing seeds were set up as shown below. place. The trays were watered regularly to allow germination to take After several days the seedlings were observed and the number with healthy green leaves was noted. The results are shown in the table below. Number of seeds in Number of seedlings with Percentage of seedlings with 5

52 each tray healthy green leaves healthy green leaves (i) (ii) Predict the percentage of seedlings with healthy green leaves if 75 seeds were sown in a seed tray. State two factors for which the seedlings could be competing in this investigation. 2. (a) An experiment was set up to measure the effect of light intensity on the rate of photosynthesis in the water plant. Elodea. The light intensity was varied using a dimmer switch on the bulb. The rate of photosynthesis was measured by counting the number of bubbles released per minute. 52

53 (i) Name the gas collected. below. (ii) The results of the experiment are shown in the table Light intensity (units) Rate of photosynthesis (number of bubbles per minute) (a) On a grid, plot a line graph to show rate of photosynthesis against light intensity. 2 (b) Using the data in the table, explain the results obtained at light intensities greater than 8 units. 3. (a) There are two reactions in photosynthesis. The first reaction is photolysis. (i) are Name the two substances produced by photolysis that required for the second reaction. 53

54 (ii) Name the second reaction. (b) Plant cells convert glucose into other carbohydrates. Copy and complete the table below by naming two of these carbohydrates. 2 Role of carbohydrate in plant cells Name of carbohydrate Storage as an insoluble material Forms cell walls 4. The rate of photosynthesis is limited by certain environmental factors. Name two limiting factors and describe how the growth of greenhouse plants in winter can be increased. Items 5 and 6 refer to the accompanying diagram which shows some of the steps carried out to test a leaf for the presence of starch The correct sequence of the steps is A Y, W, Z, X B Z, W, Y, X C Y, W, X, Z D Z, Y, W, X 6. The reason for carrying out step W is to A kill the leaf cells B soften the leaf discs C remove chlorophyll from the leaf cells 54

55 D extract oxygen bubbles from the leaf discs Items 7 and 8 refer to the accompanying diagram. The plant was left in sunlight for two days and then leaf discs W, X, Y and Z were tested for the presence of starch. 7. The leaf disc found to contain starch was A W B X C Y D Z 8. This experiment proves that in order to photosynthesise, a plant must have A sunlight and carbon dioxide B carbon dioxide and water C chlorophyll and sunlight D carbon dioxide and chlorophyll 55

56 9. A variegated leaf on a destarched ivy plant was treated as shown in the accompanying diagram. Which of the following shows the appearance of the leaf after testing it for starch? 0. The total volume of carbon dioxide daily entering the plant shown in the accompanying diagram is mm 3. The daily rate of diffusion of carbon dioxide into the plant in mm 3 CO 2 per mm 2 of leaf is 56

57 A 0.6 B 6.00 C D Questions and 2 refer to the accompanying diagram which shows the process of photolysis. The two questions also refer to the following possible answers. A water B oxygen C hydrogen D carbon dioxide. What is the correct identity of chemical substance X? 2. What is the correct identity of chemical substance Y? 3. Which of the following CANNOT be used to measure rate of photosynthesis? A volume of oxygen released per unit time B volume of carbon dioxide taken up per unit time C mass of carbohydrate produce per unit time D volume of water vapour released per unit time 57

58 4. The graph in the accompanying diagram shows the results from a photosynthesis experiment. Which of the following pairs of environmental factors must be kept constant during this experiment to make it valid? A light intensity and temperature B Temperature and carbon dioxide concentration C water content and oxygen concentration D light intensity and carbon dioxide concentration (24) Exercise 0. Products of the photolysis stage of photosynthesis are A B glucose and hydrogen carbon dioxide and hydrogen C water and oxygen D hydrogen and oxygen 2. Which of the following are all limiting factors in photosynthesis? A intensity. B Carbon dioxide concentration, temperature and light Carbon dioxide concentration, oxygen concentration and light intensity. C Oxygen concentration, temperature and light intensity. D Oxygen concentration, carbon dioxide concentration and temperature. 58

59 3. Which line in the table below identifies the best conditions for the production of early crops? 4. What must be present in leaf cells for photosynthesis to take place? A B C carbon dioxide and water oxygen and water carbon dioxide and oxygen D oxygen and hydrogen 5. The Added factor Light intensity word equation for A oxygen high B oxygen medium C carbon dioxide medium D carbon dioxide high photosynthesis is A carbon dioxide + water glucose + oxygen B oxygen + water glucose + carbon dioxide C D glucose + oxygen carbon dioxide + water carbon dioxide + oxygen glucose + water 59

60 6. Plants compete mainly for A water, light and soil nutrients B water, food and soil nutrients C D light, water and food light, food and soil nutrients 7. ATP synthesised during photolysis provides the carbon fixation stage of photosynthesis with A B C glucose carbon dioxide energy D hydrogen 8. Photolysis is the A B combining of water with carbon dioxide use of water by chlorophyll to split light C release of energy from water using light energy D splitting of water using light energy 9. The table below shows the rate of photosynthesis by a plant measured at different light intensities. Light intensity (kilolux) Rate of photosynthesis (units)

61 What change in light intensity produces the greatest increase in the rate of photosynthesis? An increase in light intensity from A 0 to 20 kilolux B C D 20 to 30 kilolux 30 to 40 kilolux 40 to 50 kilolux 6

62 0. The bar chart below shows the number of cells of different lengths in a sample of onion epidermis. Number of cells Length of cell (micrometres) is The percentage of cells with a length greater than 55 micrometres A 0% B 5% C 20% D 30%.. The diagram below shows an investigation into photosynthesis. 62

63 Which of the following statements is correct? A B P, Q and R make food only P and Q make food C only P makes D only R makes food 2. The diagram below shows the carbon fixation stage of photosynthesis. ATP X carbon dioxide X glucose Y Y A hydrogen starch B starch ADP Which line in the table correctly identifies X and Y? 63

64 C starch oxygen D water starch 3. The graph below shows the effect of increasing light intensity on the rate of photosynthesis. Rate of photosynthesis (bubbles of oxygen released per minute) Light intensity (units) the Which factor is limiting the rate of photosynthesis at point X on graph? A B carbon dioxide concentration temperature C light intensity D oxygen concentration 64

65 4. The graph below shows the effect of temperature on the rate of photosynthesis in a plant. Rate of photosynthesis 0 5 Temperature ( o C) A correct conclusion would be that A B C as the temperature increases, the rate of photosynthesis increases as the temperature increases, the rate of photosynthesis decreases as the temperature increases, the rate of photosynthesis remains constant D as the temperature decreases, the rate of photosynthesis increases 5. The following stages occur during photosynthesis. W X Y Z glucose is formed water is broken down to produce hydrogen glucose is converted to starch hydrogen is combined with carbon dioxide The correct order for these stages is A B W Z X Y Z Y X W 65

66 C X Z W Y D Y X Z W 66

67 6. An experiment was carried out to investigate the growth of pea plants kept in a high light intensity following germination. The graph shows the average shoot length of the pea plants. During which 5 day period is there the greatest increase in average shoot length? A Day 0 5 B Day 5 20 C Day D Day

68 7. The diagram below shows the internal structure of a leaf. During the hours of daylight, the concentration of carbon dioxide in the air spaces is higher than in the cells of layer X. Explain why this difference in concentration is important to the leaf cells. 3 68

69 8. The rates of photosynthesis and respiration in a green plant were measured over a period of 24 hours. The results are shown in the graph below. Key photosynthesis respiration (a) (b) (c) (d) At what time was the production of glucose at its maximum? Between what two times was the plant producing more oxygen than it was using? What substance traps the light energy required for photosynthesis? The diagram below represents a summary of part of the process of photosynthesis. ATP + hydrogen Substance Y Reaction X glucose Substance Z (structural component of cell walls? Name the following: 69

70 Reaction X; Substance Y; Substance Z (24) 2 Exercise. a) Lettuces may be grown in tunnels covered in clear polythene as shown in the diagram below. 2 Air rich in carbon dioxide can be passed through these tunnels. Explain how this would make lettuces grow faster. b) The graph below shows how the rate of photosynthesis is affected by light intensity at different concentrations of carbon dioxide. 70

71 (i) What factor was limiting Sugar the rate concentration of photosynthesis at points and 2? (percentage of dry mass) 2 Time of day (ii) Name one other Sample factor that may Sample limit 2 the rate Average of photosynthesis. (hours) 2. a) A scientist 0400 grew some 0.42 cereal plants in 0.48 a field During the course of the day, she removed 2 plants every 4 hours and measured the concentrations of sugar in the leaves of the plants. The results are shown in the table below. 7

72 Present the results in an appropriate format on a grid. (3) (b) The following word equation shows the first stage of photosynthesis. light energy water oxygen + hydrogen + ATP (i) Name this stage of photosynthesis. products. (ii) Describe what happens to each of the following (a) (b) (c) Oxygen Hydrogen ATP 3. (a) Some students were asked to design an investigation to compare the rate of production of oxygen gas by two different species of water plant. The diagrams below show the proposed procedure. 72

73 Identify two changes to the procedure that should be made to ensure that a valid conclusion can be made. 2 (b) When changes were made to ensure validity, the following results were obtained. Plant Total volume of oxygen produced in8 minutes (cm 3 ) Rate of oxygen production (cm 3 /minute) P 64 8 Q 96 (i) Calculate the rate of oxygen production for Plant Q. (ii) that Calculate the ratio of oxygen produced by Plant P to produced by Plant Q. (c) The volume of oxygen produced was measured at time intervals of one minute. The results for Plant Q are shown in the line graph below. 73

74 Describe what happens to the volume of oxygen produced per minute as the investigation proceeds. (d) The diagram below shows the first stage of photosynthesis. light energy Stage water hydrogen oxygen (i) (ii) Name the substance which captures the light energy needed at Stage. The energy is used to split water molecules. What name is given to this process? 74

75 (iii) glucose. The hydrogen the combines with carbon dioxide to form Name this second stage in photosynthesis. 4. (a) A horticulturist grew a crop of peas in a polythene tunnel. State two conditions that could limit the rate of photosynthesis in the pea plants. (b) The graph below shows the mass of sugar in the leaves and the concentration of carbon dioxide just above the pea plants at different times of the day. concentration of carbon dioxide above the leaves mass of sugar in the leaves (i) decrease For how many hours did the carbon dioxide concentration 75

76 2 (ii) Explain this decrease in carbon dioxide concentration. (iii) Explain why the mass of sugar in the leaves is as its maximum at 600. (iv) Calculate the percentage increase in sugar in the leaves between 0400 and 600. (v) Give two reasons why the mass of sugar decreases between 2000 and Groups of students carried out an investigation into the effects of competition. Trays containing seeds were set up as shown below. place. The trays were watered regularly to allow germination to take After several days the seedlings were observed and the number with healthy green leaves was noted. The results are shown in the table below. Number of seeds in each tray Number of seedlings with healthy green leaves Percentage of seedlings with healthy green leaves

77 (i) (ii) Predict the percentage of seedlings with healthy green leaves if 75 seeds were sown in a seed tray. State two factors for which the seedlings could be competing in this investigation. 6. Groups of students carried out an investigation into the effects of competition. Trays containing seeds were set up as shown below. place. The trays were watered regularly to allow germination to take After several days the seedlings were observed and the number with healthy green leaves was noted. The results are shown in the table below. 77

78 Number of seeds in each tray Number of seedlings with healthy green leaves Percentage of seedlings with healthy green leaves (i) (ii) Predict the percentage of seedlings with healthy green leaves if 75 seeds were sown in a seed tray. State two factors for which the seedlings could be competing in this investigation. (30) Key Area 7 - Respiration Exercise 7. Which of the following shows the use of energy released from the breakdown of glucose? A B ATP + Pi ADP ADP + Pi ATP C ATP ADP + Pi 78

79 D ADP ATP + Pi 2. The energy values of different food materials are shown on the table. How much energy is contained in a food sample consisting of 3 grams of glucose and 2 grams of fat? A 7 kj B 2 kj C 30 Food Energy value (kj per gram) kj D 35 Glucose 4 kj Protein 4 Fat 9 3. The diagram below shows energy transfer within a cell. 79

80 and Y? Which line of the table below identifies correctly compounds X X Y A glucose ATP B glucose ADP C ADP ATP D ATP glucose 4. (a) The diagram below shows part of an investigation into the effect of adding three different concentrations of ATP solution to three pieces of muscle. 80

81 muscle. Equal volumes of the ATP solutions were added to the pieces of The results are shown in the following table. Concentration of ATP solution (g per litre) At start (mm) After 0 minutes (mm) Length of muscle Decrease (mm) Percentage decrease muscle (i) Calculate the percentage decrease in length of the with 0 g per litre ATP solution. Copy and complete the table. percentage (ii) In this experiment why is it necessary to use 8

82 decrease in length in the comparison of the results? this (iii) Explain why three different syringes should be used in investigation. 5. The diagram below shows the apparatus used to investigate the energy content of different foods. One gram of each food was burned under a beaker containing 00 cm 3 of water. Food Energy value (joules/g) The temperature rise for each food was recorded. The energy content of the foods was calculated using the following equation. energy content = temperature rise x 420 (joules/g) The table below shows the results for the investigation. 82

83 butter 0500 chicken 4200 bread 3400 margarine 0500 (a) of (b) 2 (c) 7.5 o C. Calculate the simple whole number ratio of the energy content chicken to that of butter. Construct a bar graph of the results in the table. One gram of fish was also burned. The temperature rise was Calculate the energy content for fish using the equation above. (d) Slimmers may be advised to use margarine instead of butter. Use the data in the table to suggest why this would not aid weight loss. 6. The diagram below shows the main stages of aerobic respiration. Stage Glucose ATP Pyruvate Stage 2 X Hydrogen 83

84 Water ATP Y (a) Name Stage. (b) Name substances X and Y. 2 (c) (d) Which substance shown in the diagram is the source of the energy used to synthesis ATP? Copy and complete the following word equation which represents the syntheses of ATP. + + energy ATP (e) (f) How many molecules of ATP are produced per glucose molecule during each of Stage and Stage 2. During aerobic respiration some energy is lost from the cell. In what form is this energy? 7. The diagram below represents an animal cell that is respiring aerobically. aerobic respiration occurs in the cell raw materials enter the cell wastes leave the cell 84

85 Describe the two stages of aerobic respiration. Include the name of the raw materials and the products of the two stages. 3 (2) Exercise 8 85

86 . The fermentation pathway of one molecule of glucose results in the net gain of A B 2 molecules of ATP 2 molecules of ADP C 38 molecules of ATP D 38 molecules of ADP 2. The bar chart shows the volume of blood supplied per minute to the skeletal muscles and to other parts of the body of a healthy male at rest and during strenuous exercise. Key blood to muscles blood to other parts of the body During exercise, the ratio of blood supplied to the muscles to blood supplied to other parts of the body is A : 4 B 4 : 86

87 C 0 : 8 D 0 : 9 87

88 3. An investigation was carried out into the concentration of lactic acid in the blood before, during and after a two minute period of strenuous exercise. The results are shown in the graph below. (a) What was the concentration in mg/00 cm 3 of lactic acid in the blood ten minutes after the start of the exercise? (b) Explain why the concentration of lactic acid in the blood increased during 88

89 (c) after and immediately after the strenuous exercise. What caused the lactic acid concentration to decrease 5 minutes the start of the exercise? 4. As part of an investigation into the effect of different solutions on fresh muscle tissue, 2 drops of ATP were added to a strand of fresh muscle of initial length 50 mm. After a few minutes it length was found to be 42 mm. Which line in the table correctly summarises the experiment? % difference in length Reason for change of muscle strand A 8 contraction of muscle fibres B 8 relaxation of muscle fibres C 6 contraction of muscle fibres D 6 relaxation of muscle fibres 5. The rise in level of coloured liquid indicates that the A grasshopper is taking in oxygen B sodium hydroxide is absorbing oxygen C grasshopper is giving out carbon dioxide D sodium hydroxide is releasing carbon dioxide 6. From this experiment it can be concluded that the grasshopper s rate of A carbon dioxide output is 0.2 ml/hour 89

90 B carbon dioxide output is 4.0 ml/hour C oxygen consumption is 2.0 ml/hour D oxygen consumption is 0.4 ml/hour Items 7 and 8 refer to the accompanying diagram which represents the process of the fermentation pathway in plant cells. 7. The number of molecules of ATP formed at position X following the breakdown of one molecule of glucose is A 2 B 8 C 36 D The substance released at position Y is A water B oxygen C hydrogen D carbon dioxide Questions 9, 0, refer to the accompanying graph which shows the effect of a period of exercise followed by a period of rest on the lactic acid concentration of the blood of a healthy fit teenager. 9. For how many minutes did the period of exercise last? A 6 B 0 C 2 D 4 0. How many minutes did it take for the concentration of lactic acid to drop from its highest level to 50% of its highest 90

91 level? A 9 B 20 C 38 D 40. If the trend at X continues, at what time will the initial level of lactic acid in the blood be reached? A 5.56 B 6.02 C 6.08 D 6.20 Items 2 and 3 refer to the data in the following table which were obtained from a series of experiments involving a group of 8 year olds. Activity Average rate of oxygen consumption (cm 3 /s) Average rate of energy consumption (kj/min) Cycling 2 26 Swimming Skiing Brick-laying From the data it can be concluded that the average rate of oxygen consumption is A inversely related to CO 2 output B greatest for sporting activities C directly related to energy consumption D inversely related to energy released as heat 3. Which pair of bars in the accompanying graph 9

92 represents skiing? 4. During jogging, a 6 year old was found to use 40 kj per minute. The energy for 5 minutes of this activity could be supplied by consuming 50g of one of the foods in the accompanying table. Which one? Food Energy content (kj/g) A honey 2 B sucrose 9 C biscuit 2 D chocolate Which of the following would NOT affect the daily energy requirement of a 5 year old child? A the climate in which the child lives 92