Lab 1: Biology Tools and Techniques

Question 1

What is aseptic (sterile) technique

Answer 1

they are techniques used to avoid contamination like using the bunsen burner to kill bacteria, or roccalling the benches before and after use and washing hands

Question 2

What is a body tube?

Answer 2

its in a compound microscope and it contains a prism that passes light through

Question 3

what is a compound light microscope?

Answer 3

it uses light sources to magnify

Question 4

what is the condenser?

Answer 4

it focuses light

Question 5

What is the coarse focus?

Answer 5

it raises and lowers the stage

Question 6

what are dissecting microscopes?

Answer 6

they contain 2 eyepieces and 2 objective lenses and each eye gets a slightly different image of whats being viewed, therefore it shows the image in 3D.

Question 7

what are eye piece units?

Answer 7

they are the unit of measurement in an eyepiece of a compound microscope (the units of the built in ruler inside)

Question 8

What is the eyepiece (ocular lens)

Answer 8

it magnifies an image

Question 9

What is the fine focus knob?

Answer 9

it fine tunes the focus on a specimen being viewed

Question 10

What is the iris diaphragm?

Answer 10

it controls the contrast and amount of light that passes through specimen

Question 11

what are objective lenses?

Answer 11

they magnify an image and project it through the body tube

Question 12

what is an ocular micrometer?

Answer 12

its the small ruler you see in the ocular lens that measures in eyepiece unit

Question 13

what are parfocal microscopes?

Answer 13

present in most compound microscopes, where the image stays focused as you move your lenses I.e. from 10x to 40x

Question 14

what is serial dilution?

Answer 14

dilution (adding of water to solute) in each step to change the solute: water ratio

Question 15

what is the ‘stage’?

Answer 15

its the area where the wet mount slide gets placed on

Question 16

what is a wet mount?

Answer 16

its a preparation used to look at organisms live while they are preserved in liquids

Question 17

Why is it important to centre the object in the field of view before switching to high power?

Answer 17

it is easier to locate the area of the specimen under lower magnification so that you can see it better and find it when you switch to high power magnification.

Question 18

In switching from low power to high power, what did you notice about the brightness of the field of view?

Answer 18

higher power allows less light in, therefore the image appears dimmer as you go from low power to high. Therefore, you must adjust the brightness when doing so

Question 19

Did adjusting the iris diaphragm improve the contrast when you switched to high power?

Answer 19

Yes. The iris diaphragm controls the amount of light that gets passed through the stage and specimen.

Question 20

What are 4 distinct advantages to using the dissecting microscope?

Answer 20

1. produces 3D image
2. lower magnification limit than compound microscope (too high of a magnification can ruin the image you see)
3. Favourable depth of field
4. can be fitted with fluorescent lamp (cheaper)

Question 21

Which organisms were worked with in the first lab?

Answer 21

Pleurotus sp. was growing to attempt to grow a fruiting body of mushroom for the fungi lab (we grew this in mason jars)

The ceratopteris sp. (C-fern) was diluted and put into agar plates, we studied these in lab 4 to quantify the densities between the number of males and hermaphrodites at different densities of spores

Finally, the arabidopsis thaliana seedlings were put in agar plates that had low potassium and control potassium. They were then explored in lab 3 where we saw which one they favoured the most in their root structure.

We also worked with wet mounts on various cyanobacteria like the Gleocapsa colony

Question 22

What are 4 reasons why the a.thalania is important for research?

Answer 22

1. its tiny and requires very little space
2. it is easy to grow in culture
3. it self fertilizes
4. it has a short generation time and will produce thousands of seeds in only 4-6 weeks

Question 23

What is the micrometers of 1 epu under 4x objective lens?

Answer 23

1 epu = 25 micrometers

Question 24

What is the micrometers of 1 epu under 10x objective lens?

Answer 24

1 epu = 10 micrometers

Question 25

what is the micrometers of 1 epu under 40x objective lens

Answer 25

1 epu = 2.5 micrometers

Question 26

An algae viewed at 40x power is 16 epu in length. How long is the cell in micrometers?

Answer 26

16 epu X 2.5 micrometers = 40 micrometers

Question 27

What is the formula for obtaining magnification?

Answer 27

M = size of drawing / size of object (epu)

• you measure size of drawing by measuring it with a ruler and you get the size of object from calculating the epu

Question 28

how do you convert mm to micrometers?

Answer 28

you multiply it by 1000

Question 29

how do you convert micrometers into mm?

Answer 29

you divide it by 1000