Biology 12 Name: Cell Structure and Function Practice Exam - KEY Cell parts and Function 1. Identify each part of the cell indicated and give one role for each structure in the secretion and/or synthesis of a protein. (6 marks) NOTE: A points to the nucleolus Structure A B Function in protein synthesis and/or secretion Nucleolus produces rrna which forms part of the ribosome OR Chromatin has recipe for production of primary structure of protein ribosome - where protein synthesis occurs C Endoplasmic reticulum passageway for protein forms transport vesicles D Vesicle transports protein from ER to Golgi Body and from Golgi body to cell membrane E Golgi Body modifies and checks protein before secretion forms secretory vesicles F Cell membrane fuses with secretory vesicle to release (secrete) protein by exocytosis
2. Explain why a cell membrane is described as selectively permeable. (1 mark) Some substances can enter or exit cell but other substances can t 3. State one function of the following: (6 marks) a) mitochondria Produce ATP (C 6 H 12 O 6 + O 2 38 ATP + CO 2 + H 2 O) b) lysosomes Have hydrolytic enzymes to digest wastes and can destroy cell if damaged c) endoplasmic reticulum Rough ER helps transport protein made at ribosome + produce transport vesicles Where protein folding can occur d) Golgi apparatus Modifies protein before it is secreted and repackages it into secretory vesicle e) ribosomes Site of protein synthesis f) smooth endoplasmic reticulum Smooth ER detoxifies (has enzymes to break down) drugs and alcohol Also, produces steroid hormones (lipids) 4. Draw and label the parts of the fluid mosaic model of a cell membrane. Describe the role of each of these components. (6 marks) 1. Phospholipid bilayer - keeps membrane flexible - gives membrane its selectively permeable properties. 2. Embedded proteins - embedded within phospholipid bilayer, give structure 3. Carrier proteins a. form protein pores, these allow small charged ions (H+, Na+, Cl-) and large polar molecules (glucose, amino acids) to diffuse in/out of cell. b. act as pumps actively transporting molecules in/out of cell. (glucose, amino acids, Na+ and K+) 4. glycolipids - carbohydrate attached to phospholipid. glycoproteins - carbohydrate attached to embedded protein *both serve in cell recognition (antigens) and receptor (docking) sites on cell membrane.
Use the following diagram to answer questions 5-7 5. Molecule W functions to a) provide cell movement b) transport ions into the cell c) package cell products for export d) provide a selectively permeable membrane 6. Which molecule allows glucose to enter and exit the cell? a) W b) X c) Y d) Z 7. The structure labeled X is called a) lipoprotein b) glycolipid c) glycoprotein d) phospholipids 8. Glycolipids and glycoproteins can function as? a) Passageways into the cell b) Antigens and receptor sites c) Structural components of the cell membrane d) Help keep the cell membrane flexible 9. When insulin attaches to a glycoprotein it a) Opens the carrier protein for glucose to enter the cell b) Closes the carrier protein to prevent glucose from entering the cell c) Marks the cell for phagocytosis d) Causes the cell to take in glucose by pinocytosis 10. Explain why the following phrases are true: (1 mark each) a) Cells that secrete proteins have many Golgi bodies. Golgi modifies protein and makes secretory vesicles so that proteins can be secreted b) Larger organisms are made of more cells, NOT bigger cells. Large cells have low surface area to volume ratio and so are unable to diffuse enough nutrients into cell
Osmosis and Diffusion (Passive Transport) 11. A 0.9% NaCl solution is isotonic to red blood cells. Which statement describes the results if red blood cells are placed in a 9% solution of NaCl? a) they will burst b) they will shrink c) nothing will happen d) they will expand but not burst 12. Which term below refers to the bursting of an animal cell? a) plasmolysis b) crenation c) lysis d) turgor pressure 13. An animal cell will always take in water when placed in a a) hypertonic solution b) osmotic solution c) isotonic solution d) hypotonic solution 14. Uptake of solutes by a cell from an isotonic medium will be followed by osmosis. a) true b) false 15. Describe how the structure of the cell membrane permits molecules to enter the cell by the following processes. (1 mark each) a) Osmosis: Diffusion of water (from high conc to low conc) through the phospholipid bilayer. b) Facilitated Transport (Facilitated diffusion): Diffusion of small polar substances (eg. glucose and amino acids) through a carrier protein. 16. Describe two ways to increase the rate of diffusion across the membrane (2 marks) *increase temperature *increase concentration gradient
17. Use the following experimental setup to answer question 16. a. Describe what happens to the concentration of glucose solution on side B. Explain Water diffuses out of side B to side A (side A is hypertonic - high [solute] low [water]) Glucose concentration in side B goes up as water diffuses out-membrane impermeable to glucose b. Describe what happens to the concentration of copper sulphate solution on side A. Explain. (2 marks) Water diffuses out of side B to side A (side A is hypertonic - high [solute] low [water]) Copper sulphate concentration in side A goes down as water diffuses into side A Copper sulphate will diffuse from side B to side A until it is isotonic 18. An experiment was designed to measure the effect of tonicity on potato cells. Six potato sections, all identical in size and mass and cut from the same potato, were placed in varying concentrations of sucrose and distilled water solutions. The mass of the sections was taken before the experiment and 24 hours after the experiment began. The percentage change in the mass of the cells was recorded as follows. Section Sucrose concentration Change in the Mass due to water loss in mol/l or gain (expressed as a percent) 1 1.0-20 2 0.8-15 3 0.6-12 4 0.4 +2 5 0.2 +5 6 0.0 +8 a. Explain why some potato sections lost mass and why some gained mass. (2 marks) Gained mass because water diffuses into cells because environment is hypotonic Lost mass because water diffuses out of cells because environment is hypertonic b. Approximate a sucrose concentration that would be isotonic to the potato cell. (1 mark) Any approximation between 0.4 and 0.5 mol/l c. Why was distilled water used as the solvent for this experiment? (1) Distilled water has no other solutes that would affect the concentration of the solutions
19. Plant tissue was placed in a starch solution. The following data were gathered over an 80 minute period. a. Plot the data on the graph provided. (1 mark) b. Explain the process occurring in the plant tissue between 0 and 60 minutes. (2 marks) Water diffuses out of cells because the environment is hypertonic c. Name the substance that was added to the solution at 60 minutes and explain how this substance caused the change illustrated on the graph. (2 marks) Water was added to make the solution hypotonic and water diffuses into cells
Active vs. Passive Transport 20. A small lipid soluble molecule passes easily through the cell membrane. Which of these is most likely the explanation? a) a protein carrier must be at work b) cell membrane is composed of lipids c) the cell is expending energy for this d) phagocytosis has enclosed the molecule 21. Which of these does not require an expenditure of energy? a) diffusion b) osmosis c) facilitated transport d) all of these 22. The thyroid gland contains a high concentration of iodine. This is an example of a) passive transport b) active transport c) facilitated transport d) endocytosis 23. Cell drinking is synonymous with a) cell eating b) endocytosis c) phagocytosis d) pinocytosis 24. Which of the following is actively transported across cell membranes? a) carbon dioxide (CO2) b) oxygen (O2) c) water (H2O) d) sodium (Na+) 25. Describe the differences between active and passive transport. (4 marks) Passive Transport Active Transport Place the following in the correct box: osmosis, diffusion, phagocytosis, pinocytosis, carrier protein pumps, carrier protein pores Differences Diffusion, osmosis, facilitated transport (facilitated diffusion), carrier protein pores No ATP (energy) required Molecules diffuse from high to low concentration Enocytosis (phagocytosis + pinocytosis) Exocytosis (secretion) Carrier protein pumps ATP (energy) required Molecules moved from low to high concentration
26. Describe the differences between the following types of active transport. (3 marks) Type of active transport Carrier protein pumps Active transport of ions through a carrier protein pump Requires ATP Pinocytosis Active transport when cell engulfs large macromolecules like protein. These macromolecules are smaller in size than materials engulfed by phagocytosis Phagocytosis Active transport when cell engulfs larger materials like bacteria Exocytosis (secretion) Active transport of protein and other molecules. Secretory vesicle fuses with cell membrane to release protein. 27. Describe what would happen in a white cell after bacteria are engulfed by phagocytosis. (How would these bacteria be destroyed?) (2 marks) Lysosomes would fuse with vacuole and release hydrolytic enzymes into vacuole. Hydrolytic enzymes would digest bacteria.