BIOLOGY 103
FALL, 2003
LAB 4
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| BIOLOGY 103 | |
The activity falls into three parts. The first we will do and discuss together. From it will emerge an hypothesis that groups will attempt to test with relevant observations. A summary of your observations and the conclusions you draw from them should be the first part of your lab report. Your group will then be asked to make an additional set of observations, and try and come up with an hypothesis to account for it that draws from the first two activities in the lab. The second part of your lab report should include a summary of your observations, the resulting hypothesis, and a suggestion of a set of new observations that could be used to test it.
Observations:
8 Micron Microsphere (measured at 4):
-Quick jiggling movements, all in similar directions
-Beads are small and circular shaped
-Microns moved in 2-3 degree distances*
4 Micron Microsphere (measured at 10):
-Quick jiggling/jutting movements
-Outside force is causing them to move in similar directions
-Microns moved in 2 degree distances*
2 Micron Microsphere (measured at 10):
-Faster movement than any other group
-Microns moved in 1 degree distances*
*measured using micron ruler
Conclusion:
We couldn't really draw an absolute conclusion because the microspheres kept vibrating, and we couldn't differentiate between their movement and outside movement.
Hypothesis: Larger microbeads will move father distances (randomly) than smaller microbeads during a constant period of time.
Our period of time was 10 seconds for each size of microbead. After establishing what movement could be attributed to bulk movement, currents, table shaking, and other outside forces, we came up with the following observations:
2 Micron-sized beads:
moved 30 ums
4 Micron-sized beads
moved 2.6-4.8 ums
8 Micron-sized beads
moved 50 ums
we realize the discrepancies in our accounts of the observations, and these errors could be attributed to any number of sources. the flawed measurements were wrong, but we did resist the urge to change our data and observations to match our expectations. since we learned this valuable lesson, we believe our erroneous data collection should be discarded.
8um-- 3 tics, 4, 5
4um-- 5 tics,7,10
2um-- 9 tics, n/a, n/a
Observations and conclusions: Given that the results are inconclusive, from those which we were able to gather, we found that the smaller the sphere size, the greater the movement. There was a visible difference between the 8um ad 2um spheres, in that the latter would migrate further from their origin point, whereas the former would circulate around their origin area ,moreso.
We recorded movement in a given amount of time in units of micron, under a magnification of 40.
8 micron spheres: Moved 5 microns in 5 seconds
4 micron spheres: Moved 9 microns in 5 seconds
2 micron spheres: Moved 9 microns in 3 seconds
Conclusion: Observations support our hypothesis.
We looked high and low, nearer and farther for these moving microspheres, and got nothing, what is this? why can't these storming malestroms be seen? What is science? who are we? Oh, where are you beadies...? The conclusion is we were duped, hoodwinked, bamboozled , but Ah we found some with help from Professor Grobstein. Part two better be an improvement or else what is the point of these futile efforts on the part of people who are born to die and get three hours of sleep while living anyway?!!!!!!!!!!
We discovered four moving "beadies" that moved pretty slowly, but were cool nonetheless. However, many of the surrounding beads were still, which sucked. We were unable to measure the size and speed due to lack of time, but from our very general observations, we saw a bead move 1 milimeter in about 1.5 seconds, this is for the largest bead, but we have yet to measure the others.
Further observations to support or not support the implication:
The smaller microspheres will move faster and have more movement in comparison to larger microspheres; compared to each other, 2nm will move the most and the fastest, 4 nm will move a little less, and 8 un will move the least and the slowest.
Observations:
8 nm:
30 un --> 35 sec
30 un --> 31 sec
30 un --> 19 sec
avg = 28.33 sec
4 nm:
30 un --> 9 sec
30 un --> 9 sec
30 un --> 8 sec
avg = 8.66 sec
Conclusion:
As we had predicted, the movement of the 4 un microspheres was more eradic than the 8 un microspheres. This fact made it more difficult to collect the data. However, the information that we did collect supports the implication made previously with the class.
Observations:
8 Micron Microsphere (measured at 4):
-Quick jiggling movements, all in similar directions
-Beads are small and circular shaped
-Microns moved in 2-3 degree distances*
4 Micron Microsphere (measured at 10):
-Quick jiggling/jutting movements
-Outside force is causing them to move in similar directions
-Microns moved in 2 degree distances*
2 Micron Microsphere (measured at 10):
-Faster movement than any other group
-Microns moved in 1 degree distances*
*measured using micron ruler
Conclusion:
We couldn't really draw an absolute conclusion because the microspheres kept vibrating, and we couldn't differentiate between their movement and outside movement.
We recorded movement in a given amount of time in units of micron, under a magnification of 40.
8 micron spheres: Moved 50 microns in 5 seconds
4 micron spheres: Moved 90 microns in 5 seconds
2 micron spheres: Moved 90 microns in 3 seconds
Conclusion: Observations support our hypothesis.
Observation:
1% Salt Water
- Long, thin cells
- Stationary
25% Salt Water
- Little bubble like things are forming within the cell walls. The cell membrane is shrinking.
- Keep getting smaller, i.e. cell membrane keeps shrinking.
- Not necessarily all pulling away in a circle or uniform shape.
Distilled Water
- Begins to return to normal shape, but does not return entirely.
Story: The cell is made up of water. The presence of salt begins to eliminate the presence of water, or pushes out/extracts water from the cell. The presence of distilled water refloods the cell, causing it to return to its normal shape.
WATER ONE(1% salt concentration) observations:
well-defined cells with cell walls; can see organelles inside cells. Nothing appears to be moving at this magnification (4x) or at a higher magnification (10x).
WATER TWO (25% salt concentration) observations:
cell walls got darker, smaller. and seem to be more condensed. They appear to have lost water content as a result of adding the salt water.
WATER THREE (distilled water- 0% salt concentration) observations:
upon addition of the distilled water, we observed the un-doing of the salt water addition: the cells appeared condensed like before, at first, but were more transparent than with the salt . Over a longer period of time, the cells were even more transparent, but now the "pockets" of space created by salt water filled back up. evantually things looked "back to normal".
OBSERVATIONS:
Salt water removed the water from the cell membrane, and left the wall intact. It took a longer period of time for the cell wall to retain its original appearance as distilled water is added.
HYPOTHESIS:
during the addition of the different waters, the cell wall remains intact, however the cell membrane contracts (as more salt is added) and water is drawn out and expands (as less salt is present).
CONCLUSION:
Salt affects the movement of water across the cell membrane.
Are water molecules in constant random motion? YES.
Conclusion:
Obviously, water is crucial in maintaining the structure of cell walls in plants. The movement of water molecules pushes the NaCl or the distilled water through the semi-permeable cell walls, resulting in the destruction and restoration of the cells.
New Hypothesis:
Water molecules are in constant motion.
Implications of hypothesis ("test"-able observations): When smaller objects are placed in water, they will "jiggle" around more than larger objects in water. This will happen because the moving molecules will push them around more.
Group: Su-Lyn, Brittany
Observations:
The 8 micrometer beads didn't appear to move at all at a magnification of 10x, but we used a coverslip, so that could have affected the outcome. The second time we tried, however, the 8 micrometer beads rocketed across the screen in circular patterns at very fast speeds; however, some of them were moving faster, others slower, and some didn't move at all. The 4 micrometer beads, however, moved quite a lot a magnification 10x.
8 m: 0, 30, 40, and 100 microns/second
2 m: 0, 200, 250, and 300, 2740 microns/second
Our conclusions support the idea that larger objects, on average, "jiggle" or move less in water than smaller objects, which in turn would support the greater hypothesis that liquids such as water are not static at the molecular level. However, discrepancies in our experiment---for example, the different particles moving at different speeds and the fact that some didn't move at all---indicate that more observations will be necessary to formulate a new less wrong hypothesis. However, we did notice that the particles seemed to be moving in the same direction, so we hypothesize that the movement of the particles is not totally random. New observations will be necessary to determine the order (if, in fact, any) of the particles' movement.
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Plant Cell Experiment
Regular plant cells
Plant cells w/distilled water
Plant cells w/salt water
Plant cells w/distilled water again
What happens when we put in the 25% salt: the yellow areas swell up.
What happens when we put in distilled water: the yellow areas shrink.
1% Solution of NaCl-- Distinguishable pattern of the cell walls and membrane with nuclei
25% Solution of NaCl-- The NaCl absorbed the moisture from the cells, thereby causing the cell membrane to contract
Distilled H20-- The solution restored moisture to the cell, therefore returning the cell wall and membrane to its original shape
Story:
The NaCl properties cause the membrane to contract as it absorbs the moisture. Once the distilled water replaces the salt water, the cells return to their original state.
Hypothesis: Water molecules are constantly in motion.
Observations:
1% NaCl
-The observations started at lens 4. The different cells are visible. They are long and rectangular. We cn see the outline of the cell walls and when we magnified to 10, there was a clearer picture of the cell walls and we were able to observe the nuclei in some of the cells. We were not able to differentiate the cell wall from the cell membrane.
25%
-We were able to see both the cell wall and the cell membrane. The membrane appears to have shrunk with the salt water. We could now see the nucleus in all of the cells.
Distilled Water
The cell membranes appear to have gone back to their original position, pressed up against the cell wall. The nuclei was visible.
Conclusion:
We know that a cell membrane is permeable. Thus when the salt water enters the cell it shrivels up the cell membrane, pushing the water out and thus making it easier to observe. We can assume that the salt in the water dehydrates the cell membrane. Then when we put distilled water back onto the cell, the membrane becomes hydrated and it is harder to see.
Hypothesis: The smaller the object, the faster it moves.
Observations:
At 8 microspheres, the beads jiggled individually and moved in one direction simultaneously.
At 4 microspheres, the beads also jiggled individually and moved in more random directions at a faster speed than the 8 microsphere beads.10s.-->2
At 2 microspheres, the beads jiggled, moved in random directions at a higher speed. 10 s. -->4
Conclusion: The observations are consistent with the hypothesis.
Hypothesis:
Water makes things move.
Observations:
1%: we can observe long thin cells, cell walls, membranes and mnucleus are visible.
Salt Water(25%): salts eats up the cell and diminishes its size.
Distilled Water: the cell takes its initial form within the cell wall.
Our Story: When salt water is added, the size of the cells diminish. But when distilled water replaces the salt water, the sizes of the cells take their initial form. It seems that water allows the mobility of cells, whereas salt inhibits them from moving, therefore the cells contract.
We can come to the conclusion that water is essential for cell function.
Part II
Original hypothesis: Water molecules are constantly in motion
Observations: When using the 1% salt water, the plant cell is considered to be at the natural state, where the cell walls are rectangular shaped and seem uniformly position in the area. When adding the 25% salt water, we observed that the cell membrane shrunk and the cell walls lost it's rectangular shape. The high concentation of salt shriveled the cell walls. When distilled water was added, the cells took their rectangular shape. However, they were wider and seemingly bigger with small circular pockets(cell membrane) within the cell wall. With these observations we can state that the concetration of salt greatly affects the plant cells by either making them bigger or smaller; salt molecules affect the rate of motion of the water molecules.
8um-- 3 tics, 4, 5
4um-- 5 tics,7,10
2um-- 9 tics, n/a, n/a
Observations and conclusions: Given that the results are inconclusive, from those which we were able to gather, we found that the smaller the sphere size, the greater the movement. There was a visible difference between the 8um ad 2um spheres, in that the latter would migrate further from their origin point, whereas the former would circulate around their origin area ,moreso.
The 4 micron object, over a time period of one minute, traveled within a range of 50 micrometers, but traveled back and forth multiple times so that the total distance it moved was unclear.
Although it would be helpful to gather more data, the data we have so far is consistent with the original hypothesis.
Now we are testing a small sample of onion to see what effect water has on the cells.
When adding salt water: the cells (perhaps the cell membranes) changed from straight and even to shriveled and bubbly-looking. They look destroyed.
When adding Distilled water: there are water pockets inside the cell walls.
We have two possible explanations/ new hypotheses:
1) that the salt molecules might be moving faster than the regular water molecules, causing more damage/ change to the plant cells.
2) that water molecules might be smaller and move faster than the salt molecules, and so when there is salt in the solution, there is a longer time for change to occur.
With more time and funding, we could ake more observations and see which of these hypotheses we want to keep.
Obsevations:
In ten seconds, the spheres moved the following distances:
2 um spheres -- 10.4 um
4 um spheres -- 7.8 um
8 um spheres -- 3.9 um
We observed that as the size of the particles decreased, the speed of the movement increased.
Our hypothesis was that the smaller particles would move further distances.
However, in the short time that we had to make observations, our evidence did not support that.
2-micron particle traveled 15 tics in 30 seconds
4-micron particle traveled 30 tics in 30 seconds
8-micron particle traveled 100 tics in 30 seconds
We suspect that there is a large percentage of error due to movement of the slide, movement of the table, etc.
Ammendment to our posting:
We measured it under the 40X lense.
so the 2 micron particle moved 39 um
the 4 micron particle moved 78 um
and the 8 micron particle moved 260 um
Hypothesis:
Smaller particles move faster in water than larger particles do.
Observations:
All observations were made in 30 seconds span.
8um -- moved 16.1um , 10.4um
4um -- moved 44.2um, 39um
2um -- moved 52um, 49.4um, 52um
Conclusion:
Our observations are consistent with our hypothesis. The smaller particles have a larger diameter of motion than the larger particles, therefore the smaller particles move faster than the larger particles. We anticipate some measurement error due to random movement of particles (the precise distance they travel is hard to measure).
we were only able to collect data for the smallest size of bead. the beads were obviously moving at what seemed to be a rather fast rate. however, we were unable to find any movement in the other sizes. but may be inclined to say that the large beads would have moved less than the smaller beads.
Hypothesis: Smaller microbeads will move faster than larger microbeads in water.
We looked at three different sizes of microbeads, but only got measurements for two sizes. What we observed did not support our hypothesis but instead implied that smaller microbeads moved more slowly.
Size four microbeads moved 50 micrometers in 30 seconds, or 100 a minute.
Size two microbeads moved 25 micrometers in 30 seconds, or 50 a minute. Most of these actually vibrated in place, even though we examined them at multiple depths.
Before we began our observations, we predicted that the larger beads would move slower and be less affected by the collisions, because they had a larger body and that the smaller beads would move faster because they had less mass and more affected by the collisions.
Our results were as follows:
8 in 5 seconds approx. 52 emds
4 in 5 seconds approx. 30-40 emds
2 in 5 seconds approx. 8-12 emds
We believe that the quicker/ further travel of the smaller beads, and the less distance the beads traveled within 5 seconds as they got larger, supports our hypothesis.
Hypothesis: We beleive that the smaller particles move at faster rate due to the fact that they possess less mass, in conjuntion with the idea that these particles contain less energy in proportion to the energy emitted by the water.
Observations:
8 microspheres- particles moved approximately 6um in 10 seconds
4 microspheres- particles moved approximately 15 um in 10 seconds
2 microspheres- partcles moved approximately 23 um in 10 seconds
These observations were obtained using the 40x lens.
We proved our hypothesis to be true as the larger microspheres moved at a slower rate than each of the smaller ones.
Hypothesis: Smaller particles move around more than bigger particles.
Observations:
8 microns: beads moved 5.2 ums in a time span of about 30 seconds. The beads were vibrating.
4 microns: beads moved 26 ums in a time span of 30 seconds. The beads were vibrating quickly, but drifting slowly.
Our observations supported our hypothesis that smaller particles moved more than larger beads.
We think that the cells will look more shriveled up in the 25% salt solution because the salt removes the water from the cell, but when the cells are in the distilled water, we feel it was return back to its regular shape and plumpness.
Observations:
1% salt - cell walls are stable, not deteriorating, thick
2% salt - the membrane is shrinking, the inside of the cell is shriveling up, the cell wall appears to be thinner
distilled water (0% salt) - returning to original shape, cell wall thicker, membrane plump
We felt that this happened because the salt could have broken down the particles of the cells and therefore resulted in a shriveling effect.
Observations--
1% NaCl-- cell walls and membranes appear to be intact and stable, not moving
25% NaCl-- cells have shrunken, cell membranes have been destroyed, looks collasped. still able to see cell walls intact. little circles that appear to be smaller cells are smaller as well.
Distilled water-- cells have returned to normal size, initial conditions
Due to our observations, we would hypothesis that 25% salt solution causes water to move out of a cell membrane which makes the cell shrink. Pure water moves back into the cell membrane and returns the cell to its original size.
After adding 1% NaCl, we noticed a very small change in the size of the cells.
After extracting the 1% and adding 25% we saw a very pronounced change in the appearance of the cells. The cells had contracted, and were obviously darker, almost filled with solution.
In the presence of distilled water, the cells were wide and clear.
We have hypothesized that, salt decreases the size of the cells.
Observation: The cell nuclii grow with salt.
Hypothesis as to why this occures: The water particles move the salt inside the cell nucleus, and this pushes the outside of the nuclues in all directions, stretching it.
Well, through observing the onion cell and cooperating the knowledge we observed through phase one of our explanation we are able to assert that:
NaCl @ 1% we observed no movement of the cells, however we were able to note the rectangular shape of the cells, which is very different from the organism we observed prior to this experiment.
NaCl @ 25% we were able to detect slight movement in the cells, we noted the rectangular shape of the cells observed at 1% we now perceived to be ovular.
Distilled Water we did not notice much difference from NaCl 1%.
Observations:
Onion cells in 1% salt solution: clearly visible cell walls and cell membranes, transparent cells
Onion cells in 25% salt solution: the cell walls stay the same, while the membrane shrinks significantly, cells get more clouded
Onion cells in 0% salt solution: the membrane expands back to its regular size, cells look the same as the cells in the 1% solution (perhaps a bit more transparent). The cell walls stay the same throughout.
Hypothesis: The 25% salt solution draws water out of the cell through the cell membrane. Because there is less water left in the cell, the membrane shrinks. When we add pure distilled water, its constantly moving particles enter into the cell through the membrane, filling it again to the size observed in the first instance.
Original hypothesis: water molecules are constantly in motion.
Observations:
onion skin + 1% NaCl solution: cells are in "normal" state. long, thin cells with very distinct cell walls. cell membrane not remarkably visible.
onion skin + 25% NaCl solution: cell walls remain completely intact; however, cell membranes are now distinctly shriveled or shrunken.
onion skin + DI H20: cells return to "normal" state - looked identical (if not even clearer) to original set of observations.
Conclusions:
It seems that salt affects the motion of water molecules by slowing them down: we can infer from our observations that the salt molecules caused water to move more slowly inside the cell membrane, which would have caused it to lose its shape and shrink or shrivel.
Hypothesis: The 25% salt would leave a residue on the cells of the onion membrane and that the water would move across the onion faster than salt.
N.Cl on Onion- You can see cells clearly. Can see small amount of motion. Nothing to compare the motion to yet.
25% Salt on Onion- Can see what we feel are salt particles moving rapidly and randomly across the onion membrane. The salt seems to spread itself out over the membrane, eventually causing a film over the membrane. The 1% N.Cl and the 25% salt, we assume, have appeared to mix over the membrane. while causing the walls of the individual cells to appear thicker.
0% distilled water- Seemed to rinse off some of the residue. Allow the walls of each individual cell to appear sharper and thinner. The cells also looked lighter under what remained the same magnification and light the entire observational period.