To determine if the type of agar affects bacterial growth

UMUC Biology 102/103 Lab 1: Introduction To Science Answer Key

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Exercise 1: Data Interpretation (2 pts each)

1. What patterns do you observe based on the information in Table 4?

No fish are present when the dissolved oxygen is zero. When there is more dissolved oxygen in the water, more fish are present. However, the number of fish tends to drop or level off when the dissolved oxygen is higher than 12 ppm.

2. Develop a hypothesis relating to the amount of dissolved oxygen measured in the water sample and the number of fish observed in the body of water.

Possible Hypotheses:

1. The amount of dissolved oxygen affects the number of fish that can live in a body of water.

2. As dissolved oxygen concentration increases, more fish can live in the body of water.

3. There is an ideal dissolved oxygen concentration for fish to live in.

The rest of the questions are answered in full version:

1. What would your experimental approach be to test this hypothesis?

2. What would be the independent and dependent variables?

3. What would be your control?

4. What type of graph would be appropriate for this data set? Why?

5. Graph the data from Table 4: Water Quality vs. Fish Population (found at the beginning of this exercise).

6. Interpret the data from the graph made in Question 7.

Exercise 2: Experimental Variables

Determine the variables tested in the each of the following experiments. If applicable, determine and identify any positive or negative controls.

Observations

1. A study is being done to test the effects of habitat space on the size of fish populations. Different sized aquariums are set up with six goldfish in each one. Over a period of six months, the fish are fed the same type and amount of food. The aquariums are equally maintained and cleaned throughout the experiment. The temperature of the water is kept constant. At the end of the experiment the number of surviving fish is surveyed.

A. Independent Variable:

B. Dependent Variable:

C. Controlled Variables/Constants:

D. Experimental Controls/Control Groups:

2. To determine if the type of agar affects bacterial growth, a scientist cultures E. coli on four different types of agar. Five petri dishes are set up to collect results:

§ One with nutrient agar and E. coli

§ One with mannitol-salt agar and E. coli

§ One with MacConkey agar and E. coli

§ One with LB agar and E. coli

§ One with nutrient agar but NO E. coli

All of the petri dishes received the same volume of agar, and were the same shape and size. During the experiment, the temperature at which the petri dishes were stored, and at the air quality remained the same. After one week the amount of bacterial growth was measured.

A. Independent Variable:

B. Dependent Variable:

C. Controlled Variables/Constants:

D. Experimental Controls/Control Groups:

Exercise 3: Testable Observations

Determine which of the following observations are testable. For those that are testable:

Determine if the observation is qualitative or quantitative

Write a hypothesis and null hypothesis

What would be your experimental approach?

What are the dependent and independent variables?

What are your controls - both positive and negative?

How will you collect your data?

How will you present your data (charts, graphs, types)?

How will you analyze your data?

Observations

1. A plant grows three inches faster per day when placed on a window sill than it does when placed on a on a coffee table in the middle of the living room.

2. The teller at the bank with brown hair and brown eyes is taller than the other tellers.

3. When Sally eats healthy foods and exercises regularly, her blood pressure is 10 points lower than when she does not exercise and eats fatty foods.

4. The Italian restaurant across the street closes at 9 pm but the one two blocks away closes at 10 pm.

5. For the past two days, the clouds have come out at 3 pm and it has started raining at 3:15 pm.

6. George did not sleep at all the night following the start of daylight savings.

Exercise 4: Conversion

For each of the following, convert each value into the designated units.

1. 46,756,790 mg = _______ kg

2. 5.6 hours = ________ seconds

3. 13.5 cm = ________ inches

4. 47 °C = _______ °F

Exercise 5: Accuracy vs. Precision

For the following, determine whether the information is accurate, precise, both or neither.

1. During gym class, four students decided to see if they could beat the norm of 45 sit-ups in a minute. The first student did 64 sit-ups, the second did 69, the third did 65, and the fourth did 67.

2. The average score for the 5th grade math test is 89.5. The top 5th graders took the test and scored 89, 93, 91 and 87.

3. Yesterday the temperature was 89 °F, tomorrow it’s supposed to be 88 °F and the next day it’s supposed to be 90 °F, even though the average for September is only 75 °F degrees!

4. Four friends decided to go out and play horseshoes. They took a picture of their results shown to the right:

5. A local grocery store was holding a contest to see who could most closely guess the number of pennies that they had inside a large jar. The first six people guessed the numbers 735, 209, 390, 300, 1005 and 689. The grocery clerk said the jar actually contains 568 pennies.

Exercise 6: Significant Digits and Scientific Notation

Part 1: Determine the number of significant digits in each number and write out the specific significant digits.

1. 405000

2. 0.0098

3. 39.999999

4. 13.00

5. 80,000,089

6. 55,430.00

7. 0.000033

8. 620.03080

Part 2: Write the numbers below in scientific notation, incorporating what you know about significant digits.

1. 70,000,000,000

2. 0.000000048

3. 67,890,000

4. 70,500

5. 450,900,800

6. 0.009045

7. 0.023