lab 1

Question 1

what is a hypothesis?

Answer 1

explanations for an observation which are generated by gathering and examing prior knowledge to explain an event

Question 2

why are hypothesis important?

Question 3

how do you test a hypothesis

Answer 3

1) is the hypothesis testable
2) does the hypothesis include controls so the experiment can be replicated
3) does the hypothesis change one variable at a time
4) does the hypothesis minimize the confounding factors in the experiment
5) was the experiment ran more then once to provide confidence or reliability about the results
6) make sure that the experiment is able to be repeated by other researchers

Question 4

What is a dissecting microscope

Answer 4

• a microscope that has a low magnification (x2 and x4 lens)
• only has two or three lenses
• used on macroscopic specimans (things visible to the eye)

Question 5

what is a compound microscope

Answer 5

• has 4 different lenses all equal to or greater then x4 (x4, x10, x40, x100)
• used to examine specimans that are microscopic

Question 6

what is the care precedure (ie. how do you carry it and how do you clean it) for a microscope

Answer 6

• carry it with one hand under the base and one hand around the arm (dominant hand on the arm)
  -lenses are cleaned with dry lens paper that is gently rubbed on the lens

Question 7

What are the step to focus a microscope

Answer 7

• lower stage completely down
• switch to the x4 lens
• put slide on the stage with the clip
• raise the stage all the way up
• slowly lower the stage until you can see part of the sample
• use the adjustment knobs to focus the microscope
• if image is still blurry, switch the the next lens and adjust the definition with the adjustment knobs

Question 8

what are the different parts to a compound microscope (10)

Answer 8

• base: very bottom of the microscope that sits on a surface
• arm: attaches the base to the nose piece
• lamp or mirror: found on the top side of the base and points flat towards the stage
• stage: the flat part attached to the arm that is holds the sample being examined
• diaphragm: located directly under the stage that focus the lamp light
• objective lens: the lens that are connected to the nosepiece which are filtered through when looking at an image
• nosepiece: the place that holds the objective lens that is moved to change the magnification
• ocular lens: barrel at the top of the microscope that you look through to view the sample
• course focus knob: the knob that is used to focus images at the lower magnification
• fine focus knob: the knob that is used to focus images at higher magnification

Question 9

When would you use the x4 len

Question 10

when would you use the x100

Question 11

How do you calculate the total magnification

Answer 11

ocular lens (10x) x objective lens

Question 12

What is a dichotomous key

Answer 12

a way to identify the species of an unknown organism based on anatomical features
- is set up where you identify one characteristic and follow it to the next number provided

Question 13

What is the purpose of stain samples

Answer 13

we stain samples because it helps us identify the difference between the two main type of bacteria

Question 14

what is gram positive bacteria

Answer 14

indicated the exotoxins that are produced by a cell that tend to go to the outside of the cell
- indicated that a cell has a thick cell wall of peptidoglycan (will appear violet)

Question 15

what is gram negative bacteria

Answer 15

indicates the endotoxins that are produced by a cell that tend to go to the inside of the cell
- indicates that a cell has a thinner cell wall composed of peptidoglycan and has an outer layer (will appear pink)