# Umuc Biology 102103 Lab 1 Introduction 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 pm.

**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:

- The amount of dissolved oxygen affects the number of fish that can live in a body of water.
- As dissolved oxygen concentration increases, more fish can live in the body of water.
- 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?**

I would have different bodies of water all with the same amount of oxygen, and I would add different amounts of oxygen to the oxygen that is already there. After that, I would observe how many fish are in each body of water.

**2. What would be the independent and dependent variables?**

The independent variable would be the amount of oxygen in the water and the dependent variables would be the increase or decrease in the number of fish.

**3. What would be your control?**

My control would be one body of water that I added no extra oxygen to.

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

A bar graph would best represent the data set because bar graphs compare results that are independent of each other, and that is the case with this data set.

**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.**

The bar graph in question 7 shows that as the oxygen level increased, so did the number of fish observed.

**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:

**Answer; **

**Independent variable: ** The size of aquarium

**Dependent variable:** Goldfish survival rate

**Controlled variables:** Temperature of water, type & amount of food, clean water

**Experimental controls/control groups:** Putting 6 Goldfish in different sizes of aquarium.

Positive result is the 6 Goldfish most likely to survived in a larger size aquarium. Negative result is less survival rate in smaller sizes aquarium.

**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:**

A. One with nutrient agar and E. coli

B. One with mannitol-salt agar and E. coli

C. One with MacConkey agar and E. coli

D. One with LB agar and E. coli

E. 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:

**Answer; **

**Independent:** The bacteria E. Coli

**Dependent:** The amount of bacterial growth in agar

**Controlled:** The temperature and quality of air

**Experimental controls/ control groups:** Adding E. Coli bacteria in four different types of agar and 1 without.

Positive result is presence of bacterial growth measured in agar and negative result in agar without E. Coli bacteria.

New perspectives on Html5 and Css3 7th Edition tutorial 4 case problem 1.

**Exercise 3: Testable Observations**

### 1. 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**

**Question 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.**

**Answer; **

**Hypothesis:**Plants in the window sill grow faster due to increased light.**Null hypothesis:**Increased light does not make plants grow faster.**Approach:**Place two plants in the window. Leave one in the window and take the second plant and let it spend different amounts of time in the light (decreased light exposure).**Dependent variable:**Height of the plant.**Independent variable:**Amount of time spent in the sunlightby each plant.**Control:**A plant remaining out of direct sunlight (but not in total darkness), like on the table.**Data collection:**Measure the height of each plant every day for a week and record the total growthafter one week.**Data presentation:**Use a bar graph to show the results. Each of the three plants will have its ownbar representing the height it grew in one week**Analyze:**Look for an increase in growth with increased time on window sill

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

**Answer; **

**No testable hypothesis**– This is an observation, but it is a statement with no testable component.

**Question 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.**

**Answer;**

**Hypothesis:**A healthy diet leads to lower blood pressure.**Null hypothesis:**A healthy diet doesn’t lead to lower blood pressure.**Approach:**Collect blood pressure data over time for groups eating healthy foods and a group eatingfatty foods.**Independent variable:**Healthy or Unhealthy Diet.**Dependent variable:**Blood pressure (would be affected by the change in diet).**Controls:**All groups should be exposed to similar amounts of exercise and stress.**Data collection:**Test the blood pressure of your study subjects at fixed intervals over time – alwaysat the same time of day, under similar diet conditions.**Presentation:**Use a line graph for individual evaluation over time. Use a bar graph to show the averageblood pressure for each of your study groups.**Analyze:**Look at data gathered over time to see whether diet lowered blood pressure.

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

**Answer; **

**No testable hypothesis –**This is a statement with no testable relationship.

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

**Answer**;

For this particular, specific observation, you could not create a controlled experiment, so you

could have said it’s an observation only, and that would have been acceptable for the information

given. If you did propose an experiment, since the the time appears to be the independent

variable that the dependent variable (clouds) depends on, but that is not the case, you’d have to

go further and propose what variables you’re going to look at–what atmospheric conditions (that

aren’t observed in this case) are the variables related to the cloud formation? (So, you’d need

additional observation before you could actually come up with a hypothesis. If you did make

some assumptions about cloud formation and proposed a hypothesis, it might look something

like this:

**Hypothesis:**As temperatures rise throughout the day, it increases the rate of evaporation, increasing the amount of moisture in the air. Temperatures and atmospheric water concentrations reach their maximum at mid-afternoon. Then, when temperatures begin to lower at about 3:00, clouds form and the evaporated moisture in the air condenses and it rains. This experiment could be recreated in a microclimate, under lab conditions, or observed using daily weather station instruments to see if the pattern holds up. Meteorologists can gather data about the atmospheric conditions to determine what variables are related to this and then develop experiments to see if their models work—looking for a correlation between those conditions and similar weather. Each observation would be a replication. Meteorologists gather a lot of data FIRST, then use it to make predictions– hypotheses–that they test by making more observations in the real world to compare with.

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

**Answer;**

**Testable**– Yes**Hypothesis**– Heat melts ice-cream faster.**Null Hypothesis**– Heat does not melt ice-cream faster.**Experimental Approach**– Keep two ice -cream cones at two different temperatures**Dependent Variable**– Temperature , amount of ice-cream and type of holder**Independent Variable**– Flavor of ice cream**Positive Control**– Ice cream kept in 35 degree Celsius.**Negative Control**– Ice cream kept in 10 degree Celsius.

**Exercise 4: Conversion**

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

1. 46,756,790 mg = _______ kg

46756790 mg / 1000000

= **46.75679 kg**

2. 5.6 hours = ________ seconds

=**20160secs** (1hr=60mins || 60mins=60secs) 5.6hrs*60mins= 336*60secs= 20160

3. 13.5 cm = ________ inches

**5.315 inches** (1cm=0.394inch)

13.5cm/2.54= 5.3149 round off 4 to 5.

4. 47 °C = _______ °F

(47°C times 9 then divide 5)+32= **116.6 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.

**Answer;** *Results are accurate. All students achieved their result*.

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.

**Answer; ***The results are precise. The 5 students results average 90 which is similar to the average of 89.5*

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

**Answer; ***These results are neither. They are not similar to the average* of 75.

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

**Answer; ***Accurate., I count 4 horseshoes which means 4 people played in teams of two. In that setting you would have 4 horseshoes.*

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.

**Answer; ***Neither. The criteria is closely guessed* hence this cannot be replicated.

**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.**

**405000**– 3 significant numbers. 4,0, & 5.**0.0098**– 2 significant numbers. 9 & 8.**39.999999**– 8 significant numbers. 3, & all 9’s.**13.00**– 4 significant numbers. 1,3, & both 0’s.**80,000,089**– 8 significant numbers. 9, all 0’s, & both 8’s.**55,430.00**– 6 significant numbers. Both 5’s, 4, 3, and two 0’s or right of decimal.**0.000033**– 2 significant figures. Both 3’s.**620.03080**– 5 significant figures. 6, 2, 3, the 0 following, & 8.

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

1. ** 70,000,000,000** – 7.0 * 10^10.

**2. ** **0.000000048** – 4.8 * 10^-8

**3. 67,890,000** – 67.9 * 10^7

**4. 70,500** – 7.05 * 10^4

**5. 450,900,800** – 4.51 * 10^8

**6. 0.009045** – 9.05 * 10^-3

**7. 0.023** – 2.3 * 10^-2

Explore more about the rules of determining significant digits.

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