Lab IB: Introduction to Microscopy

Question 1

Most eukaryotic cells range in size between WHAT? (in um)

Answer 1

between 10 and 100 micrometers (um)

Question 2

Name all 4 organelles/structures in all cells

Answer 2

plasma membrane
DNA (genetic material)
cytoplasm
ribosomes

Question 3

What does DNA stand for

Answer 3

Deoxyribonucleic acid

Question 4

Do all cells have a nucleus?

Answer 4

NO, just eukaryotes (not prokaryotes)

Question 5

What happens in the cytoplasm?

Answer 5

contains organelles and dissolved chemicals.

Question 6

What do plant cells have that other cells don’t have?

Answer 6

a cell wall

Question 7

Is a cell wall on the outside or inside region compared to the plasma membrane

Answer 7

OUTSIDE (so plasma membrane (in) & CW (outer))

Question 8

Do animal cells have a cell wall?

Answer 8

NO

Question 9

Viewing sub-cellular structures such as the nucleus requires optimization of contrast. What are TWO distinct ways you can optimize contrast to best observe these structures?

Answer 9

• Adjusting the height of the condenser
• Adjusting the diameter of the iris diaphragm

Question 10

Plant cells are circles, rectangles, or triangles shaped

Answer 10

RECTANGLE

Question 11

How do we name the long side of it:

Answer 11

the average length (long side)

Question 12

How do we name the short side of it:

Answer 12

width (short side)

Question 13

To measure the average length of these cells, view the specimen at WHAT total magnification

Answer 13

100X

Question 14

To measure the average width of these cells, view the specimen at WHAT total magnification

Answer 14

400X

Question 15

you may want to magnify a small organ during a dissection or examine an insect. In this situation, which microscope is best?

Answer 15

The stereoscopic (dissecting) microscope

Question 16

Name one disadvantage of a dissecting microscope

Answer 16

the overall magnification possible is low when compared to a compound light microscope

Question 17

What biological specimen is viewed with a stereoscopic microscope?

Answer 17

the species of flatworms (Planaria)

Question 18

Name all 5 species of flatworms (Planaria)

Answer 18

1) Dugesia (arrow-like)
2) Schmidtea
3) Dendrocoelum
4) Planaria
5) Polycelis

Question 19

What is the importance of staining a cell specimen?

Answer 19

to highlight certain parts of a cell’s structures

Question 20

Which cell components were stained by methylene blue in the plant cell?

Answer 20

the CW and nucleus

Question 21

Which cell components were stained by methylene blue in the animal cell?

Answer 21

• nucleus
• cytoplasm
• plasma membrane

Question 22

Plan cell, tot mag of 100X, what is the approximate LENGTH of onion cell?

Answer 22

between 360 - 450 um

Question 23

Plan cell, tot mag of 400X, what is the approximate WIDTH of onion cell?

Answer 23

40 - 55 um

Question 24

Human check cell, tot mag of 400X, what is the approximate diameter of cell? (assume FD 4.5 mm at 4X objective)

Answer 24

450 um

Question 25

Human check cell, tot mag of 400X, what is the approximate diameter of NUCLEUS? (assume FD 4.5 mm at 4X objective)

Answer 25

40 - 60 um

Question 26

Which component can be used to control the magnification level of a stereoscopic light microscope?

Answer 26

Zoom control knob

Question 27

What is the range of magnification for a stereoscopic light microscope?

Answer 27

8 -50X

Question 28

Main difference b/w Compound and Stereoscopic light microscope

Answer 28

Compound: moves stage toward objectives
Stereo: moves lens towards stage

Question 29

How does the image of a specimen viewed by the stereoscopic light microscope differ from a compound?

Answer 29

at all magnifications the image is 3D

Question 30

What are the 2 main key morphological features that allowed you to identify the flatworm genus (dugesia)?

Answer 30

• body shape (arrow-like)
• position of eyespots