Microscope Review

Give the name and function of each structure labeled.

A – Ocular: eyepiece used to look at specimen

B – Fine adjustment: to focus specimen under high power

C – Arm: used to hold microscope

D – Objective lens: used to magnify image

E – Coarse adjustment: Used to focus specimen under low power

F – Diaphragm – adjust amount of light reaching specimen

E

F

What was the highest possible magnification that can be obtained when using this microscope?

Objective - Ocular 40 x 10 =

400x

E

F

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)

E

F

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

Which structure can only be used to focus the specimen under high power? Support your answer.

The fine adjustmentbecause using the

coarse adjustment under high power can break the objective lens or the slide.

E

F

What are two possible adjustments that need to be made when switching to high power?

Adjust the diaphragm to make the filed of view brighter.

Focus with the fine adjustment.

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.

What must be done to the microscope before switching from low power to high power?

Center the specimen

Focus with the coarse adjustment

Which laboratory technique is illustrated in the diagram?

Preparing a wet mount.

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.

Why must the cover slip be placed at an angle when preparing a wet mount?

To avoid air bubbles.

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

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?

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?

The total magnification of an image is the result of the combined magnifications of the

1) eyepiece and diaphragm 2) objective and eyepiece

3) objective and mirror 4) low-power and high-power

objectives

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

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.

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

A student is using a compound light microscope to observe a wet mount of unstained human cheek cells. Which cell organelle will most likely become more visible after she adds iodine solution to the slide?

(1) nucleus (2) ribosome (3) cell wall (4) mitochondrion

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

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) methylene blue (2) dilute acid (3) Benedict's solution (4) bromthymol blue

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

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?

A cover slip should be used for preparing a

(1) frog for dissection (2) solution of iodine for food testing (3) wet mount of elodea (a simple

plant) (4) test to determine the pH of a

solution

Which part of a microscope should be used with the low power objective, but not with the high-power objective?

a. fine adjustmentb. diaphragm

c. coarse adjustment d. eyepiece

A prepared slide was placed on the stage of a microscope so that the slide faced the student, as shown in the diagram below.

Which image will the student most likely see?

Convert:1.6.23mm = ______ um2.5678um = ______ mm3..093mm = ______ um4.48.2um = ______ mm

5.678

6230

93

.0482

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

This organism could be centered in the field of view by moving the microscope slide towards

(1) A (2) B (3) C (4) D

The diameter is 1mm. What is the length of the cell in um?

500um250um

125um

375um

3.5mm

3500um

1750um

The length of the cell is approximately 1750um.

Field of view = 1.5mm

There are 3 cells across the field of view.

= 1500um

1500/3 = 500um