Lab Practical Review 1

Question 1

What is a hypothesis?

Answer 1

a testable prediction

Question 2

List a good charactersitic for a sound scientific hypothesis

Answer 2

predictable, testable, if-then statement

Question 3

If a hypothesis is not testable should it be used in science?

Answer 3

no

Question 4

Can a hypothesis be proven?

Answer 4

no

Question 5

What is a null hypothesis

Answer 5

A hypothesis that determines that there is no relationship between two or more variables

Question 6

Know the difference between an observation and an inference

Answer 6

Observation - What we see directly
Inference - A conclusion made from an observation based on reasoning

Question 7

Know the steps of the scientific method

Answer 7

1. Observation
2. Formulation of a question
3. Formulation of a hypothesis
4. Hypothesis Testing (experimentation)
5. Collection of data, analysis, presentation of results, and interpretation
6. Hypothesis Rejection (or not) or Revision

Question 8

List a logical hypothesis about Stanleya smithii

Answer 8

If stanleya smithii is selenium tolerant then it will grow in soil that is rich in selenium

Question 9

What were the independent and dependent variables for the experiment with stanleya smithii? List two nuisance variables.

Answer 9

Independent - the soil (selenium concentration)
Dependent - Plant growth
Nuisance - Genetic Variability

Question 10

A scientist is testing the effects of temperature on enzyme activity. The enzymes are incubated at each of 3 different temperatures. What is a good negative control for this experiment?

Answer 10

0 Celsius because enzyme activity is zero at that temperature

Question 11

A scientist is testing the effect of light intensity on photosynthetic rate. The rate is measured as a function of oxygen evolution at 3 different light intensities. What is a good negative control for this experiment?

Answer 11

Zero light is an appropriate negative control

Question 12

A scientist is testing the effect selenium on a possibly selenium tolerant plant. What is a good negative control for this experiment?

Answer 12

A selenium intolerant plant in 0 ppm (part per million) selenium soil

Question 13

Be able to identify independent and dependent variables using a graph only

Answer 13

Independent Variables - X-Axis
Dependent Variables - Y-Axis

Question 14

Be able to identify the parts of a compound light microscope from lab

Answer 14

…

Question 15

Know the objective and ocular magnifications of the color bands on a microscope.

Answer 15

Ocular- 10x for all bands
Objective - Red 4x, Yellow 10x, Blue 40x

Question 16

Know the techniques for finding and viewing specimens

Answer 16

1. Place the slide on the stage with the coverslip side up. Position the sample such that the specimen is directly over the lens (hole) in the stage so that light can pass through the specimen from below.
2. Rotate the revolving nosepiece until the lowest power objective (usually 4X = scan) clicks into place.
3. Next, while looking directly at the specimen (DO NOT look through the ocular), turn the coarse adjustment knob so that the objective lens is as close as possible to the surface of the cover slip. The objective lens should NOT at any time actually touch the slide.
4. Turn on the light source and adjust the intensity so that you can see light passing through the specimen. Next, while looking through the ocular, slowly turn the coarse adjustment knob in the opposite direction as before such that the objective lens moves slowly away from the slide. Continue until the specimen comes into view. Adjust the clarity of the image using the fine adjustment knob. Adjust the light intensity as needed.

Question 17

Know what happens to the field of view and light as the magnification increases (inversely proportional relationship)

Answer 17

As magnification increases, the field of view decreases

Question 18

Know when to use a compound light microscope versus a stereoscopic microscope and what the advantages and disadvantages are for each

Answer 18

Stereo microscopes are used for viewing larger objects while compound microscopes are used for smaller objects

Question 19

What does an electron microscope use for energy vs a compound microscope? Which of these has a much higher magnification potential? Be able to recognize a picture of something magnified using an electron microscope

Answer 19

Compound - Uses visible light for energy, has lower magnification power
Electron - Uses beam of electrons for energy, has higher magnification power