Write a statement to explain the molecular composition | Homework Helpers

Lab 1: Introduction to Science

Exercise 1: Data Interpretation

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Dissolved oxygen is oxygen that is trapped in a fluid, such as water. Since many living organism requires oxygen to survive, it is a necessary component of water systems such as streams, lakes and rivers in order to support aquatic life. The dissolved oxygen is measured in units of ppm (parts per million). Examine the data in Table 4 showing the amount of dissolved oxygen present and the number of fish observed in the body of water the sample was taken from; finally, answer the questions below.

Table 4: Water Quality vs. Fish Population

Dissolved Oxygen (ppm)

0

2

4

6

8

10

12

14

16

18

Number of Fish Observed

0

1

3

10

12

13

15

10

12

13

Post-Lab Questions

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

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.

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

4. What would be the independent and dependent variables?

5. What would be your control?

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

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

8. 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 (1-6) are testable. For those that are testable answer the following questions:

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 miIDle 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, her blood pressure is 10 points lower than when she eats unhealthy 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

 Conversion Chart-

Temperature – oC = 5/9 (oF – 32)

Time – 60 seconds equals one minute

60 minutes equal to one hour

Mass- 1000 milligrams equals one gram

1000 grams equals one kilogram

Length –

2.54 centimeter equals one inch

Lab 2: The Chemistry of Life

Pre-Lab Questions-

1. Nitrogen fixation is a natural process by which inert or unreactive forms of nitrogen are transformed into usable nitrogen. Why is this process important to life?

2. Given what you have learned about the hydrogen bonding shared between nucleic acids in DNA, which pair is more stable under increasing heat: adenine and thymine, or cytosine and guanine? Explain why.

3. Which of the following is not an organic molecule; Methane (CH4), Fructose (C6H12O6), Rosane (C20H36), or Ammonia (NH3)? How do you know?

Experiment 1: Testing for Proteins

Data Tables and Post-Lab Assessment

Table 1: A Priori Predictions

Sample Initial Color Final Color Is Protein Present?
1. Albumin Solution
2. Gelatin Solution
3. Glucose
4. Water
5. Unknown

Table 2: Testing for Proteins Results

Sample Initial Color Final Color Is Protein Present?
1. Albumin Solution
2. Gelatin Solution
3. Glucose
4. Water
5. Unknown

Take a picture of your results. Include a note with your name and date on an index card in the picture. Insert picture here:

Post-Lab Questions

1. Write a statement to explain the molecular composition of the unknown solution based on the results obtained during testing with each reagent.

2. How did your a priori predictions from Table 1 compare to your actual results in Table 2? If there were any inconsistencies, explain why this occurred.

3. Identify the positive and negative controls used in this experiment. Explain how each of these controls are used, and why they are necessary to validate the experimental results.

4. Identify two regions which proteins are vital components in the human body. Why are they important to these regions?

5. Diet and nutrition are closely linked to the study of biomolecules. Describe one method by which you could monitor your food intake to ensure the cells in your body have the materials necessary to function.

Experiment 2: Testing for Reducing Sugars

Data Tables and Post-Lab Assessment

Table 3: Testing for Reducing Sugars Results

Sample

Initial Color

Final Color

 

Reducing Sugar Present

1 – Potato

 

 

 

2 – Onion

 

 

 

3 – Glucose Solution

 

 

 

4 – Water

 

 

 

5 – Unknown

 

 

 

Take a picture of your results. Include a note with your name and date on an index card in the picture. Insert picture here:

Post-Lab Questions-

1. What can you conclude about the molecular make-up of potatoes and onions based on the two tests you performed? Why might these foods contain these substance(s)?

2. What results would you expect if you tested ribose, a monosaccharide, with Benedict’s solution? Biuret solution?

Experiment 3: What Household Substances are Acidic or Basic?

Data Tables and Post-Lab Assessment

Table 4: pH Values of Common Household Substances

 

Substance

 

pH Prediction

 

Test Strip Color and pH

Acetic Acid (Vinegar)

 

 

Sodium Bicarbonate Solution (Baking Soda)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Take a picture of your results. Include a note with your name and date on an index card in the picture. Insert picture here:

Post-Lab Questions

1. What is the purpose of determining the pH of the acetic acid and the sodium bicarbonate solution before testing the other household substances?

2. Compare and contrast acids and bases in terms of their H+ ion and OH- ion concentrations.

3. Name two acids and two bases you often use.

Lab 3: Cell Structure and Function

Pre-Lab Questions

1. Identify the major similarities and differences between prokaryotic and eukaryotic cells.

2. Where is the DNA housed in a prokaryotic cell? Where is it housed in a eukaryotic cell?

3. Identify three structures which provide support and protection in a eukaryotic cell.

Experiment 1: Cell Structure and Function

Post-Lab Questions

1. Label each of the arrows in the following slide image:

2382_Figure.png

2. What is the difference between the rough and smooth endoplasmic reticulum?

3. Would an animal cell be able to survive without a mitochondria? Why or why not?

4. What could you determine about a specimen if you observed a slide image showing the specimen with a cell wall, but no nucleus or mitochondria?

5. Hypothesize why parts of a plant, such as the leaves, are green, but other parts, such as the roots, are not. Use scientific reasoning to support your hypothesis.

Experiment 2: Osmosis – Direction and Concentration Gradients

Data Tables and Post-Lab Assessment

Table 3: Sucrose Concentration vs. Tubing Permeability

Band Color

Sucrose %

Initial Volume (mL)

Final Volume (mL)

Net Displacement (mL)

Yellow

 

 

 

 

Red

 

 

 

 

Blue

 

 

 

 

Green

 

 

 

 

Hypothesis:

Take a picture of your results. Include a note with your name and date on an index card in the picture. Insert picture here:

Post-Lab Questions

1. For each of the tubing pieces, identify whether the solution inside was hypotonic, hypertonic, or isotonic in comparison to the beaker solution in which it was placed.

2. Which tubing increased the most in volume? Explain why this happened.

3. What do the results of this experiment this tell you about the relative tonicity between the contents of the tubing and the solution in the beaker?

4. What would happen if the tubing with the yellow band was placed in a beaker of distilled water?

5. How are excess salts that accumulate in cells transferred to the blood stream so they can be removed from the body? Be sure to explain how this process works in terms of tonicity.

6. If you wanted water to flow out of a tubing piece filled with a 50% solution, what would the minimum concentration of the beaker solution need to be? Explain your answer using scientific evidence.

7. How is this experiment similar to the way a cell membrane works in the body? How is it different? Be specific with your response.

Lab 5: Meiosis

Pre-Lab Questions

1. Compare and contrast mitosis and meiosis.

2. What major event occurs during interphase?

Experiment 1: Following Chromosomal DNA Movement through Meiosis

Data Tables and Post-Lab Assessment

Trial 1 – Meiotic Division Without Crossing Over Beads Diagram:

Take pictures of your beads for each phase of meiosis I and II without crossing over. Include notes with your name, date and meiotic stage on index cards in the pictures. Insert pictures here:

Prophase I

Metaphase I

Anaphase I

Telophase I

Prophase II

Metaphase II

Anaphase II

Telophase I

Cytokinesis

Trial 2 – Meiotic Division Beads Diagram:

Take a picture of your results for Trial one. Include a note with your name and date and meiotic stage on an index card in the picture. Insert pictures here:

Prophase I

Metaphase I

Anaphase I

Telophase I

Prophase II

Metaphase II

Anaphase II

Telophase I

Cytokinesis

Post-Lab Questions

1. What is the ploidy of the DNA at the end of meiosis I? What about at the end of meiosis II?

2. How are meiosis I and meiosis II different?

3. Why do you use non-sister chromatids to demonstrate crossing over?

4. What combinations of alleles could result from a crossover between BD and bd chromosomes?

5. How many chromosomes were present when meiosis I started?

6. How many nuclei are present at the end of meiosis II? How many chromosomes are in each?

7. Identify two ways that meiosis contributes to genetic recombination.

8. Why is it necessary to reduce the number of chromosomes in gametes, but not in other cells?

9. Blue whales have 44 chromosomes in every cell. Determine how many chromosomes you would expect to find in the following:

i. Sperm Cell:

ii. Egg Cell:

iii. Daughter Cell from Mitosis:

iv. Daughter Cell from Meiosis II:

10. Research and find a disease that is caused by chromosomal mutations. When does the mutation occur? What chromosomes are affected? What are the consequences?

11. Diagram what would happen if sexual reproduction took place for four generations using diploid (2n) cells.

Experiment 2: The Importance of Cell Cycle Control

Post-Lab Questions

1. Record your hypothesis from Step 1 in the Procedure section here.

2. What do your results indicate about cell cycle control?

3. Suppose a person developed a mutation in a somatic cell which diminishes the performance of the body’s natural cell cycle control proteins. This mutation resulted in cancer, but was effectively treated with a cocktail of cancer-fighting techniques. Is it possible for this person’s future children to inherit this cancer-causing mutation? Be specific when you explain why or why not.

4. Why do cells which lack cell cycle control exhibit karyotypes which look physically different than cells with normal cell cycle.

5. What are HeLa cells? Why are HeLa cells appropriate for this experiment?

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