Christopher Mr. Snyder Biology 1 August, 2008
Lab Report Sheet Part A: Observations
Pupae: Description ●
The pupae are small, tubular organisms, reddish brown in color, with spiral markings that lead across the body, to air holes on each side. They are entirely still.
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Nasonia: Description ●
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The Nasonia are almost unobservably small flies, yellowish of appearance, with various white splotches showing. They do not appear multi—segmental from my viewpoint, and their heads are roughly a fourth the size of their bodies.
Behavior: ●
Immediately after being introduced to the pupae, the Nasonia attacked them viscously, stinging and stabbing from above.
Part B: Hypothesis
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The Nasonia, when introduced to the pupae, will quickly become vicious, stinging and stabbing at the pupae, in an attempt to eat them. This will probably be caused due hunger from their long hibernation.
Part C: Experimental Design
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In order to test my hypothesis, I will designate one pair of pupae my control group, and place them in the controlled environment of a test tube. The other group I will designate as my experimental group, and place in a test tube alongside Nasonia. After 14 days of observation, I will end my experiment.
Part D: Data Collection â—?
â—?
Part E: Conclusion After Collecting data, you should make a conclusion about the relationship between the pupae and the Nasonia
Analysis 1. Was you original hypothesis correct or incorrect? Your teacher may have made a class list of hypotheses from each team. if so, have you truly disproven any of the hypotheses that differ from yours? ●
My original hypothesis was incorrect— but the results proved that several of the other hypotheses were also incorrect.
2. Parasitism is defined as follows: One organism (the host) receives no benefits and is often injured while supplying nutrients and/or shelter for the other organism (the parasite). Based on what you observed throughout this activity, explain why Nasonia are called parasites. ●
Nasonia are called parasites because they kill their host giving it nothing in return, and inject their young into further hosts.
3. The pupae in this activity are from the organism know as Sarcophoga. What do you think the Sarcophoga do after they emerge as adults. ●
They lay their own eggs, beginning the Sarcophoga life cycle all over again…
4. Before the Sarcophoga formed a pupae, it was a wormlike creature called a larvae. You probably call them maggots. Can you think of another insect that has a life cycle like the Sarcophoga? ●
The butterfly has a life cycle like the Sarcophoga.
5. How do you think that the young Nasonia got into the Sarcophoga pupae? ●
Through the air holes at each end of the Sarcophoga.
6. Reflecting on this activity, you should now be familiar with the steps that scientists take when performing research. What are the steps of the scientific method that you employ in this activity? ●
Some of the steps are: forming a hypothesis, devising an experiment, making observations, and formating data.
7. Throughout this activity, you were able to observe the Nasonia at varying developmental stages. Describe the Nasonia life cycle. ●
The nasonia goes from egg, to larvae, to pupae, to adult, and then lays eggs.
Christopher Mr. Snyder Biology 1 August, 2008
Activity One
Constructing a Water Lens Microscope For Centuries scientists have used transparent materials, having at least one curved surface, to make lenses to form magnified or reduced images, or to concentrate or spread light rays. In this activity you will construct such a lens— out of water—and mount it on a card to function as a simple, single-lens microscope. What you need per group: ● ● ● ● ●
Four paper card with center holes One cup containing water One Pipet Printed magazine images; color and black/white transparent tape
What to do… 1. Carefully place a piece of transparent tape so that it covers the center hole on the card provided. 2. Carefully place a drop of water onto the transparent tape covering the hole on the card. Keep adding small drops of water until the enlarging drop fills the hole. 3. Describe, draw, and label the created lens through this process below: ●
4. Now use this water lens to view the type of this page. Record you your observations below: ●
Text viewed under the water lens is magnified approximately twice it's size, but becomes extremely blurry.
5. Use your water lens microscope to view printed black/white and color images supplied by your teacher. Can you determine how these images are made? Describe your observations below: ●
Text viewed under the water lens is magnified approximately twice it's size, but becomes extremely blurry.
6. What is your definition of a lens and a microscope? Definition of a lens: ●
A lens is something which bends light to magnify an object
Definition of a microscope ●
A microscope is an object intended to view things to small for, or invisible to, the naked eye.
Christopher Mr. Snyder Biology 1 August, 2008
Activity Two
Using the Compound Microscope What you need per group: ● ● ● ● ● ● ●
Compound Microscope Coverslip Forceps glass microscope slide Newsprint Scissors Student Information Sheet #1 Visual Guide to the Microscope
What to Do… Making a new newsprint: 1. Use scissors to carefully cut out a short newsprint word (not a headline word) containing the letters “e”, or “r”. 2. Place a single drop of water in the center of a clear microscope slide. 3. Carefully lower a coverslip at an angle onto the wetted paper being careful not to trap air bubbles. Observing a Wet Mount of Newsprint 1. Place the slice on the stage of the compound microscope, with the center of the upright coverslip area centered over the hole in the stage. Position the slide using stage clips so that the newsprint is facing you and can be read right side up. Record what you observe below: Image Orientation: ●
Image appearance to the naked eye on the microscope stage
2. Adjust the light source (flat mirror surface or illuminator) and diaphragm (disk or iris) so that light passes up through the paper. You should be able to see a circle of light when you look into the eyepiece. 3. Position the lowest power objective into the optical path by rotating the nosepiece. You will feel a “click” when the objective is correctly positioned. Use the coarse adjustment knob to lower the objective to approximately 1 inch (2.5 cm) above the stage. 4. Look through the eyepiece and slowly raise the objective by turning the coarse adjustment knob counter–clock–wise (i.e towards you) until the image is in focus. Then use the fine adjustment knob to bring the image into sharp focus. Image Description: ●
The image resembles a picture from outer space; swirls of color and vibrancy radiate from orange to green, in every shape and size. Some are spiral, others are flat, some tall, some short. Regardless, in every way a stunning sight.
Image appearance: ●
5. In the newsprint image formed by the microscope oriented the same as when you observe it with your naked eye? Move the slide downward. Which way does the image move? Move the slide to the right and then the left. Which way does the image move? â—?
Christopher Mr. Snyder Biology 1 August, 2008
Activity Three
Determining Magnification and size In Activity One, you made observations using a single–lens microscope of your own construction. A basic compound microscope has two lens systems: an “Objective” lens (i.e. closest to the thing being viewed), and an “ocular” lens (i.e. closest to the eye). Magnification is the ratio of the apparent size of a magnified object to its true size. If a lens produces an image of a viewed object that is four times its real size, its magnification is capability of power is “4x” In a compound magnifying system, magnification takes place in two stages. The objective lens first projects a magnified image of the object to a fixed position about 1 cm below the top of the viewing tube in the microscope. The eyepiece, positioned in the body tube above this projected image, re–magnifies into a second image that the eye observes. Thus the total magnification of the microscope is found by multiplying the power of the objective by that of the eyepiece.
What you need per group: ● ● ● ●
Compound microscope Prepared wetmount of newsprint (from Activity Two) Ruled 1mm graph paper (1 cm, square) Ruler, metric
Determining Magnification 1. Record the total magnification of the lowest power objective of your microscope used to view newsprint in Activity Two below: Lowest power magnification: ●
40x
2. Change to a higher power objective. Exercise care when rotating any high– power objective into the optical path. Make sure that the higher objective will not touch the coverslip. With most newer microscopes, you should be able to rotate the higher power objective into place and observe an image that will only need sharpening using the fine adjustment knob. If not, turn the coarse adjustment knob clockwise to “rack down” the objective until it is no closer than 1–2 mm from the coverslip surface. Then use the fine–adjustment knob, to sharpen the focus. Do not use the coarse adjustment knob to focus any high–power objective. Is the light brighter or darker? After changing objective lenses, readjust the diaphragm for best lighting. You will need more light. (i.e. a wiser diaphragm opening )at higher objective lens magnifications. 3. Below, draw comparative drawings of the newsprint image at both lowest and next highest magnification of your compound microscope. Also record total magnification for each. ●
Determining Field Diameter and Object Size
4. To determine the diameter of a particular field–of–view, place a piece of 1mm ruled graph paper over the hole in the stage. Focus using a low power objective (i.e. 4X or 10x) to obtain a clear image of the divisions of the ruler or the rules of the graph paper. You should observe an image like the one below. ●
5. For Each object,, draw the observed field of view and determine its field size below: ●
6. Knowing the field diameter for a particular objective lens can aid in measuring length. If an organism is about one–quarter the length of the field diameter at 100x it is approximately 400qm in length. Using the field diameter as an aid in estimating the width of the newsprint letter you are observing and record it below: ●
7. Use a ruler to measure the the true size, in millimeters (mm), of the width of the actual newsprint letter and record it below. They should also take eyepiece measurements of the apparent image of the letter “e” ● ● ●
Actual (true) size = 1 mm Apparent Size— lowest magnification = 4 mm Apparent Size— next highest magnification = 400 mm
8. Next, Calculate the magnification ration for both eyepiece magnification views of the newsprint letter measure based upon your previously recorded measurements. For example What is the magnification ratio of an apparent image at the lowest power total magnification (40x) is 4 mm if it measures 4mm? Magnification = 160 mm (Tube Length) divided by Apparent Size. 160 mm divided by 4 mm = 40 :1 ratio. Tube length is the distance between the objective and eyepiece lenses. â—?
Christopher Mr. Snyder Biology 1 August, 2008
Agar Experiment
Objectives: • Determine the extent and rate of diffusion into three different sized agar cubes • Calculate the surface area to volume ratio for each ager cubes • Observe the relationship between cell size and extent of diffusion in the ager cubes • Understand the necessity for microscopic cell sizes
Materials: • 1 3 cm x 3 cm x 6 cm phenolphthalein agar block • 1 Plastic knife • 1 Plastic cup • Diffusion medium
Procedure: 1. Obtain a 3 cm x 3 cm x 6 cm agar block from your teacher. Using a plastic knife, trim this piece to a cube 3 cm³. Repeat this procedure to make a 2cm³ cube and a 1cm³ cube 2. Place the three cubes carefully into a plastic cup. Add diffusion medium until
the cup is approximately half full. Be sure the cubes are completely submerged. Using a plastic spoon, keep the cubes submerged for 10 minutes, turning them occasionally. Be careful not to scratch any surface of the cubes 3. As the cubes soak, calculate the surface area, volume, and surface area to volume ratio for each cube. Record these values in Data Table 1. Use the following formulas:
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surface area = length x width x number of sides
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volume = length x width
4. After 10 minutes, use a spoon to remove the agar cubes and carefully blot them dry on a paper towel. Then, cut the cubes in half. Not the color change from red or pink to clear that indicates the diffusion of diffusion medium into the cube. 5. Using a metric ruler, measure the distance in centimeters that the diffusion medium diffused into each cube. Record the data in Data Table 2. Next, record the total time of diffusion. Finally, calculate and record the rate of diffusion for each cube as centimeters per minute. 6. Examine the extent of diffusion for reach cube. Visually estimate the percentage of diffusion into the cube. Record your estimate in Data Table 3 7. Calculate the volume of the portion of each cube that has not changed color. Record your results in Data Table 3. 8. Calculate the extent of actual diffusion into each cube as a percent of the total volume.
Graphs:
Date Table 1: Ager Cubes Cube Size
Surface Area(cm)
Volume (cm²)
Surface Area/Volume
3cm³
54
27
2:1
2cm³
24
8
3:1
1cm³
06
1
6:1
Date Table 2: Rate of Diffusion
Cube Size
Depth of Diffusion
Time (min.)
Rate of Diffusion (per min.)
3cm³
0.1
10
.01
2cm³
0.5
10
.05
1cm³
1.0
10
.10
Data Table 3: Extent of Diffusion
Cube Size
Estimation of Total Volume Cube Which of Cube has changed Color
Volume of Cube Which has not Changed Color
Percent Volume of Cube Which Changed Color (Extent of Diffusion)
3cm³
27 cm³
10%
24.3
10%
2cm³
8 cm³
50%
4.0
50%
1cm³
1 cm³
100%
0
100%
Assessment: The agar you used to make your cubes contained phenolphthalein and had a pH of greater than 9. Explain how the use of a pH indicator allowed you to visualize the extent of diffusion into the cubes ● The acidic diffusion medium causes the pH's color to change from pink to clear. 2. According to Data Table 2, into which cube did the diffusion medium diffuse the deepest? ● The 1cm³ cube Into what cube did the medium diffuse the most by volume? ● The 1cm³ cube Examine your data in Data Table 2 for a relationship between cube size and the rate of diffusion into the cube. Make a generalized statement about the relationship between cell size and the rate of diffusion. ● The larger the cell size, the slower the rate of diffusion 5. Examine your data in Data Table 1. Describe what happens to the surface area , the volume, and the ration between the two values. ● The volume cubes, the surface area squares, and the ratio increases toward the the volume. 6. If each cube represents a living cell and the diffusion medium a substance needed within the cell, what problem might exist for the largest cell? ● The timely moving of substances across its cell membrane, the amount of substances which could enters, and (in some cases) the capacity for photosynthesis. 7. According to the results of your investigation, describe the characteristics of cell size, surface area, and surface are to volume ration which best meet the diffusion needs of living cells ● Cell size would be small, surface area would be wold be large, and surface area to volume ratio would be large.
8. The size of some human human cells is 0.1 mm. Using the formulas in this activity, calculate the surface area to volume ration of such a cell (assume the cell is a 0.1 mm cube). Describe the extent and rate of diffusion into this living cell as compared to the small ager cube. ● The surface area to volume ratio is 600 to 1. ●
The rate of diffusion for the living cell would be much faster than that of the ager cube, due the latter's lesser surface–area–to–volume ratio.
9. Is diffusion the only method in which substances enter a cell? If not, what factors are not accounted for in the simulation. ● Active transport, and any type of facilitated diffusion. 10. Osmosis is a specialized form of diffusion. Research Osmosis and create a venn diagram comparing osmosis to diffusion. ●