Microscope Review

1. Give the name and function of each structure labeled. A – Ocular lens/eyepiece: used to look at specimen B – Fine adjustment: to focus specimen under high power C – Arm: to hold microscope D – Objective lens: used to magnify image E – Coarse adjustment: to focus specimen under low power F – Diaphragm – adjust amount of light E F

2. What was the highest possible magnification that can be obtained when using this microscope? 40 x 10 = 400x Lowest: 10 x 10 = 100x E F

The amount of light decreases (so the field of view gets darker) 3. What happens to the amount of light in the field of view when switching from low to high power? The amount of light decreases (so the field of view gets darker) 4. What happens to the field of view when switching from low to high power? The field of view decreases ( so you see less of the slide). E F

5. Which structure can only be used to focus the specimen under high power? Support your answer. The fine adjustment can only be used because using the coarse adjustment under high power can break the objective lens or the slide. E F

6. What are two possible adjustments that need to be made before switching to high power? Focus specimen Center specimen 7. What happens to the number of cells that are visible in the field of view when switching to high power? The number of cells that are visible in the field of view decreases.

8. Which laboratory technique is illustrated in the diagram? Preparing a wet mount.

9.Describe the steps to follow when preparing a wet mount. 1. Place a drop of water on slide. 2. Place specimen on slide. 3. Place the cover slip at an angle. 4. Slowly lower the cover slip on to the specimen. 10. Why must the cover slip be placed at an angle when preparing a wet mount? To avoid air bubbles.

11. The diagram represents a cell in the field of view of a compound light microscope. In which direction should the slide be moved on the microscope stage to center the cell in the field of view? Towards C

12. The image to the left is placed on the slide 12. The image to the left is placed on the slide. A student then views the letter “f” under low power. Which diagram below most closely resembles the image under low power? 2

13. A student sees the image to the left when observing the letter "f" with the low-power objective lens of a microscope. Which diagram below most closely resembles the image the student will see after switching to high power? 1

14. The total magnification of an image is the result of the combined magnifications of the eyepiece and diaphragm objective and eyepiece objective and mirror low-power and high-power objectives 2 15. A student views some cheek cells under low power. Before switching to high power, the student should (1) adjust the eyepiece (2) center the image being viewed (3) remove the slide from the stage (4) remove the coverslip 2

16. A student changes the objective of a microscope from 10x to 50x 16. A student changes the objective of a microscope from 10x to 50x. If this is the only change made, what will happen to the field of view? (1) Its diameter will decrease. (2) Its diameter will increase. (3) Its brightness will increase. (4) Its brightness will remain the same. 1 17. A student determined that exactly 10 pollen grains could fit along the diameter of the field of view of a microscope. If each pollen grain has a diameter of 200 micrometers, what is the diameter in millimeters of this microscope's field of view? (1) 2,000 mm (2) 2 mm (3) 5 mm (4) 500 mm 1

18. To locate a specimen on a prepared slide with a compound microscope, a student should begin with the low-power objective rather than the high-power objective because the (1) field of vision is smaller under low power than under high power (2) field of vision is larger under low power than under high power (3) specimen does not need to be stained for observation under low power but must be stained for observation under high power (4) amount of the specimen that can be observed under low power is less than the amount that can be observed under high power 2 19. An unstained wet mount preparation of cheek cells shows few details. Which substance could be added to the slides to make the details more visible? (1) stain (2) water (3) Nothing should be added 1

20. After switching from the high-power to the low-power objective lens of a compound light microscope, the area of the low-power field will appear (1) larger and brighter (2) smaller and brighter (3) larger and darker (4) smaller and darker 1 21. Which part of a microscope should be used with the low power objective, but not with the high-power objective? a. fine adjustment b. diaphragm c. coarse adjustment d. eyepiece C

22. The diagram represents a hydra as viewed with a compound light microscope. If the hydra moves to the right of the slide preparation, which diagram below best represents what will be viewed through the microscope? 2

23. Which of the following describes proper microscope care and technique. a. Be sure to carry the microscope upright, with one hand on the arm and the other under the base. b. To protect the lenses of the microscope, place it down gently and don't drag it across the tabletop. c. Always begin focusing with the lowest power objective lens available. d. Only use the coarse focus knob with the low power objective lenses. e. All the above are examples of correct microscope care and technique. E 24. Which of the following regulates the amount of light passing through the slide specimen on the microscope stage? a. nosepiece b. objective lens c. diaphragm d. fine adjustment knob C

25. An increase in magnification causes a 25. An increase in magnification causes a. a decrease in the field of view. b. a decrease in the working distance. c. a decrease in the depth of field. d. all of the above. 1 26. When the letter e slide is viewed with the microscope, it appears a. right side up. b. right side up and backwards. c. upside down. d. upside down and backwards. D

27. Which part holds the two or three objective lenses, and rotates around in a circle, allowing you to choose which objective lens you want to use? nosepiece 28. What holds the upper portion of the microscope above the stage and is also where you grab the microscope anytime you decide to take it for a walk? arm 29. This part allows you to focus while using the high power objective. fine adjustment knob

30. What holds the slide in place? stage clips 31. What's the long, skinny tube that holds the eyepiece above the microscope, and allows light to travel up from the objective lenses to the eyepiece? body tube 32. What parts are attached to the nosepiece and vary in size? Objective lenses 33. On what part of the microscope do you place your specimen? stage

34. A prepared slide was placed on the stage of a microscope so that the slide faced the student, as shown in the diagram below. hg What image will the student most likely see? hg

35. How is the total magnification of a microscope calculated? Eyepiece magnifications x objective lens magnification 36. What is the total magnification produced by a microscope, using a 10X ocular lens and a 10X objective lens? 10 x 10 100x

37. Convert: ) 6.23mm = ______ um ) 5678um = ______ mm 6230 5.678 93 .0482

2 38. The diagram represents the field of view of a compound light microscope. Three unicellular organisms are located across the diameter of the field. What is the approximate length of each unicellular organism? 1) 250 um 2) 500 um 3) 1,000 um 4) 1,500 um

2 39. This organism could be centered in the field of view by moving the microscope slide towards (1) A (2) B (3) C (4) D

40. Determine the diameter of the field of view below in millimeters and micrometers. 3.5 mm 3500 um

41. Determine the diameter of the field of view below in millimeters and micrometers. 3.8 mm 3800 um

42. Determine the diameter of the field of view below in millimeters and micrometers. 5 mm 5000 um

43. Determine the diameter of the field of view below in millimeters and micrometers. 10 mm 10,000 um

44. Determine the diameter of the field of view below in millimeters and micrometers. 3.8 mm 3800 um

45. Determine: Diameter = 7.5 mm , 7500 um Length of specimen = the diameter of the field of view below in millimeters and micrometers The length of the specimen in the field of view Diameter = 7.5 mm , 7500 um Length of specimen = 4 mm , 4000 um

46. Determine the diameter of the field of view below in millimeters and micrometers. 5 mm , 5000 um

47. Determine the diameter of the field of view below in millimeters and micrometers. 2 mm , 2000 um

48. The diameter is 1mm. What is the length of the cell? 0.25 mm, 250 um

49. The diameter is 3.5 mm. What is the length of the cell? 1.75um 3.5mm The length of the cell is approximately 1.75 mm, 1750um.

50. The diameter is 2000 um. What is the length of the cell? The length of the cell is approximately 500 um, 0.5 mm.

51. The diameter is 1800 um. What is the length of the letter? 900 um, 0.9 mm

Diameter = 6 mm 52. What is the length of 1 cell? 6/3 = 2 mm

53. What is the length of one cell? 400/4 = 100 um 0.1 mm

54.