Mid Term Exam October th Year Biology. Name: Result:

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1 Mid Term Exam October th Year Biology Name: Result: Teacher Feedback: STAR STAR WISH Question 1- Food and Scientific Method 20m a) Name a reagent used to test for reducing sugar. b) Name the elements always present in Proteins. c) An education guess to explain an observation is called a. d) An example of a carbohydrate that has a structural role is. e) Name the vitamin involved in the prevention of rickets. f) The role that an organism plays in an ecosystem is called. Question 2 Metabolism and Characteristics of Life 20m a) What is meant by the term metabolism? b) Life is very difficult to define. There are characteristics which all living things share. What are they? c) Which characteristics are shown by the following: i. a plant bends to grow towards a light source ii. the production of seeds by a plant

2 Question 3 Cell structure and the scientific method 20m (a) Interpretation: (b) Hypothesis: (c) Label the organelle in the image below: (d) State the contents of this organelle: (e) Name the organelle in the image above.

3 (f) Outline a function of this organelle: Name the organelle in the image above. Name: (g)outline a function of this organelle: (h) Identify the type of cell in the diagram above: State a reason for your answer: Label the cell: Question 4 Cell structure 20m Each of the following sentences is false. Re-write each sentence by replacing the word in italics. (a) The nucleus is a structure that surrounds a cell and helps control what enters and exits the cell. (b) A(n) prokaryotic has membrane bound organelles.

4 (c) Organelles are basic units of all organisms. (d) (e) Compare and contrast eukaryotic and prokaryotic cells. (f) Why might a microscopist, who specializes in the use of microscopes to examine specimens, use a light microscope instead of an electron microscope? (g) A material is found in an asteroid that might be a cell. What criteria must the material meet to be considered a cell?

5 Question 5 20m Fill the gaps: (a) (b) (c) How does the orientation of the phospholipids in the bilayer allow a cell to interact with its internal and external environments? (d) Write a hypothesis for how a cell would be affected if it lost the ability to be selectively permeable. (e) Fill the gaps: 1. stores sap. 2. produces proteins. 3. generates energy for a cell.

6 Question 6 Cell Structure (a) (b) (c) (d) (e) Where is the genetic material of a cell located? -

7 (f) Answer: What is the function of a selectively permeable membrane? (g)

8 (h) (i) (j)

9 (K) (L) To test for starch Question 7 Experiments 1. Name the three chemical elements present in starch. 2. To what food group does starch belong? 3. Name three foods that contain starch. (i) (ii) (i) 4. What is the function of starch in the diet?

10 5. Draw a labeled diagram of the apparatus you will use in this experiment. To test for reducing sugar 1. What reagent did you use? 2. Did you need to use heat and if so, how did you heat the solution? 3. When Benedict s reagent is added to a reducing sugar and heated, what colour change occurs? 4. Suggest a control for this experiment. 5. Was there a colour change in the control? 6. If you used a mortar and pestle in this experiment what was its function?

11 To test for Protein 1. State one reason that your body needs protein. 2. What chemical(s) is used to test for protein? 3. When this chemical(s) is added to protein, what colour change is observed? 4. Suggest a control for this experiment? To test for fat 1. What are the products of the digestion of fats? 2. Where is fat stored in animals? 3. What will you use to test for the presence of fat? 4. What result will indicate the presence of fat? Examining plant cells 1. Why are stains often used when examining cells under the microscope? 2. State one precaution you should consider before carrying out this experiment: (i) 3. What was the source of the plant cells used in this experiment?

12 4. Draw a labelled diagram of what you saw under the microscope: Unstained Plant Cell Under Low Power Unstained Plant Cell Under High Power Examining animal cells 1. In the space provided, draw a typical animal cell, and label the following parts: -Cell membrane -Cytoplasm -Nucleus -Ribosome -Nuclear pores -Mitochondrion -DNA

13 2. Describe briefly how you will obtain a sample of human cheek cells 2. Why is a mounted needle used? 3. Outline how you applied the stain to the slide 4. Why is a cover slip placed on the slide? Questions on the effect of ph on enzyme activity: 1. What is an enzyme? 2. Name the enzyme you used and give its source 3. Name the substrate for this enzyme _ 4. List 3 factors that affect enzyme activity _ 5. Sketch a graph to show the effect of ph on enzyme activity 6. How would the graph differ for a stomach enzyme?

14 7. What factors are kept constant during this experiment? 8. How each factor is is kept constant? _ 9. How is the rate of enzyme activity measured? 10. How did you know at which ph the enzyme worked best? 11. What is the optimum ph for the enzyme you used? 12. Enzymes are specific. What is meant by specificity of an enzyme? 13. Outline the Induced Fit Theory (Lock and Key Model) Outline Labelled Diagram