Size Scales - Cells and Organisms

Several investigative teams were assigned the task of testing the idea that the sizes of organisms related to the sizes of the cells of which they were made up, i.e. that bigger organisms were bigger because they had bigger cells. To explore this idea, the teams used compound microscopes with ocular micrometers to measure cell size in samples they collected from organisms of different sizes. Papers were presented at brief scientific meetings at the end of each laboratory, and the findings were questioned, discussed, and debated in an effort to arrive at the best available summary of the observations.

Sujatha Sebastian and Caroline Dyar

Hypothesis: Cell size is dependent on organism size.

We collected three specimens of plant life: moss, a bush leaf, and a tree leaf. We then measured the cell size in each specimen.

Specimen: Estimated Organism Size: Cell Size in Micrometers:

Moss 2 mm 52 micrometers

Bush Leaf 6 ft 26 micrometers

Tree Leaf 50 ft 39 micrometers

Analysis: After examining our results we conclude that the hypothesis is untrue. Cell size is not dependent on organism size. This can be clearly seen by looking at the numerical data. By looking at the correlation of cell size to organism size one can see that there is not a clear relationship between the two. If the hypothesis were to be true one might assume that the moss is the largest organism because it has the largest cell size.

Does the size of the organizm depend on the size of the cell? Someone thought so, albeit I am questioning what they were thinking, yet out of respect for my collegues I generally accepted it until I went out with my partner to prove otherwise.

We collected four different plant organisms, ranging in size from 35'+ to 3" tall. The samples consisted of a leaf from a maple tree, a leaf from a 6' tall bush, a blade of grass measuring 5", and a little three leaf clover measuring in at 3".

After converting our samples into slides where we could observe the size and structure of the cell, we collected the following data: Tree cells averaged in size 41.6 micrometers; Bush cells 23.4 micrometers; Grass cells 55.9 mircrometers; Clover cells 26.87 micrometers.

Due to the variety of sizes ranging, there is no solid evidence present to proove that cell size determines organizm size. First off, the largest organism obviously did not display the largest cell size, the organism which did so measured only 5", the second smallest organism in the sample series. The Bush and Clover, two organisms varying greatly in size did not do so with their cell size, since at average measurements of 23.4 and 26.87, the sizes were relatively close.

From our general observations, we noted that the structure and shape of the cell was relatively similar to the overall structure of the organism or the large sample we collected. The cells which came from leaves which were jagged and pointy around the edges had cells with ridged and pointy edges; the grass had long, retangular shaped cells and the clover had small, round cells.

Even though our evidence somewhat disproves that cell size is not relative to organism size, we cannot make a general conclusion that it definitely does not determine size, since we feel that for the larger organisms our samples were not fully adequate. It is possible that the cell structure in the bark, branches, trunks, roots, etc. differ. So it seems this experiment of ours has left us hanging at a cross road.

Katie Gallagher and Susy Jones

The hypothesis was that the size of an organism is directly proportional to the size of its cells (the bigger the organism, the bigger its cells and vice versa).

We took samples from the leaves of a clover (smallest, 4 cm), bush (medium, 1.5 m), and tree (largest, 15 m). We looked at the cells of each organism under the microscope and observed that the average size of the clover cell was 28.6 um, the average size of the bush cell was 24.6 um, and the average size of the tree cell was 52.0 um. The shapes of all the organisms’ cells were irregular: asymmetrical, interlocking, and roughly circular.

Our observations do not support the hypothesis because the average clover cell was larger than the bush cell, even though the clover is a smaller organism than the bush. In the case of this experiment, size of the cell does not necessarily dictate the size of the organism. Cell size varies from organism to organism.

Katie Kaczmarek and Rachel Hochberg

Lab Report #2

We tested the hypothesis that organismal size is determined by the size of the cells (ie. Large organisms are made up of large cells and small organisms are made up of small cells.) In order to test this hypothesis we collected a sample from three different-sized organisms: a 5 cm clover, a 1.83 m bush, and a 15.12m tree. Our last two measurements were approximated in feet and converted to the metric system. We then took cell samples from each of the organisms and found the average cell length and width for each. The average cell size of the clover was 39 micrometers long and 22.53 micrometers wide; the average bush cell was 35.53 micrometers long and 29.47 micrometers wide; and the average tree cell was 43.33 micrometers long and 18.2 micrometers wide. This would seem to disprove the hypothesis because the length of the clover is greater than the length of the bush and the width of the tree is smaller than the other two.

But the best comparison is between the average lengths of the cells and the heights of the objects. Under the original hypothesis, the ratios of the lengths of the cells and the heights of the organisms should be equal, because the tree cell should be as many times bigger as the clover cell as the tree is bigger than the clover. We calculated the ratio of the tree's height and the clover's height and found that the tree was 302 times bigger than the clover. However, the ratio of the tree's cell length and the clover's cell length was 1.11. Clearly these ratios are not equal or approximately equal as they would be if the original hypothesis was correct. Therefore, the size of an organism is not determined by the size of its cells; all cells are similar in size.

Lab Report # 2

We collected three samples from 3 different organisms: a tree, a bush and grass. The size of the organism was taken into consideration and we carefully chose samples from three very differently sized organisms; small- grass, medium-bush, and large-tree. Then, we examined the cells of each organism to see if the size of the cells is related to the size of the organism. We collected the following results:

#1 GRASS SAMPLE:

Avg cell size: 46.8m m length, 13 m m width

#2 BUSH SAMPLE:

Avg cell size: 40m m length, 30m m width

#3 TREE SAMPLE:

Avg cell size: 84.5m m length, 18.2m m width

Melissa Donimirski and Jill McCain

Lab #2 – Scale

In order to investigate claims that cell size is relative to organism size, we measured cell sizes of three different samples of three different sized organisms: tree leaf, bush leaf, blade of grass.

Estimated size of the tree was 10 meters tall. Bush size was estimated at 1.5 meters, and grass blade was approximately 10 centimeters in length.

Three cells of each organism were measured and the average was found. The average cell size of the blade of grass was 13.9 micrometers by 19.9 m m. The average cell size of the bush leaf was 26 m m by 17.3 m m. The average cell size of the tree leaf was 20 m m by 20 m m.

These measurements would tend to suggest that there is no direct relation between the size of the organism and the cell size.

Robin Reineke, Debbie Plotnick, and Jakki Rowlett

Biology Lab Two 9/20/00

Hypothesis: There is a correlation between constituent cell size and the overall size of the organism, i.e. the smaller the cell size the smaller the organism, and likewise, the larger the cell the larger the overall size of the organism. Furthermore, this relationship is a proportionate one bearing out a ratio correspondent to size.

Methods: (4) Samples of species from the kingdom plantae were collected, scored and thin cross-sections were extracted from each sample were placed on a slide to be viewed under a microscope. Two cells from each specimen were examined. The samples were as follows:

1. (Slide # 2) A ripe red berry from Bush A -
2. (Slide #1) A dried berry from Bush B
3. (Slide 4) A leaf from Bush C
4. (Slide 3) Lichen found growing at the base of tree A

Observations:

Cell Size Organism Size

Slide 1 — Cell 1 — 2080 um approx. 4’ 6"

Cell 2 — 2808 um

Slide 2 — Cell 1 —500 um approx. 5’ 6"

Cell 2 — 1000 um

Slide 3 - Cell 1 — 48.984 um approx 1/32 in

Cell 2- 16.328 um

Slide 4 — Cell 1 — 260 um approx. 7’8"

Cell 2 — 163.28 um

Conclusion: According to our observations there is no correlation proportionate or otherwise between the size of constituent cells and overall size of an organism. In addition, our observations show that constituent cell size can vary greatly.

Nimia Barrera and Trudell Smith

Lab #2

Jeff's Hypothesis: Large organisms have larger cells, which determines the size of the organism.

Organism: Ground Level

Bush Level

Tree Level

Data:

 Organism's leaf Size of leaf cells um/ space (Width X Length) Average (um) Ground Level (10 cm.) 46.8 x 182 70.2 x 91 59.8 x 109.2 122.2 x 91 52 x 114.4 70.2 x 99.32 Bush Level (2.5 meters) 65 x 20.8 26 x 26 18.2 x 28.6 33.8 x 23.4 26 x 20.8 33.8 x 18.72 Tree Level (14 meters) 13 x 10.4 15.6 x 18.2 13 x 10.4 20.8 x 18.2 18.2 x 15.6 16.2 x 14.56

Conclusion:

Based on this experiment, we proved Jeff''s Hypothesis incorrect. We measured five different cells of each organism's leaf and concluded that the smaller the organism's leaf, the larger the cells. The size of the organism is not obviously determined by the size of the cells. Therefore, the smaller the cells the larger the organism and the larger the cells the smaller the organism.

Leila Ghaznavi and Jenny Wilson

Lab #2

Sept. 20, 2000

Introduction

Today in lab we were presented with the hypothesis that organism size is directly proportional to cell size and/or frequency. To test out this hypothesis we collected 3 samples from as diverse sources as possible. One was a human cheek cell from a 5’2 specimen, the second was from a tree leaf from a specimen approximately 20 ft in length, and the third was from a flower 4 1/2 inches in length. The following observations were obtained.

Observations

The average cell size for the leaf was 18.2 um x 29.12 um. The cells were sans nuclei and circular in shape with simplistic membranes. There were several hundred cells within our sample.

The average cell size for the flower was 31.2 um x 20.8um. The cells were oblong in shape with thinner cell walls than the leaf. There were fewer cells in this sample in comparison to the leaf sample.

The average cell size for the human cheek sample was 57.72 um x 58.24 um. The cells were cuboidal and above average in beauty, with the thickest membranes and most complex structures relative to the other cells we examined. In addition, they had a prominent nucleic structure. They created an extreme reaction in the TA for the class. We were all frightened. The cells were few and far between but I think in an actual human they would be a lot more common than what was represented on our slide…. I hope.

Conclusions

Our observations led us to the conclusion that neither cell size, nor cell frequency are directly proportional to the size of the organism. All in favor of the original hypothesis say aye <crickets chirp>. All opposed say nay-- NAY NAY NAY NAY! The hypothesis is rejected and propose that another experiment be done that would examine in more detail the complexity of the cells in relation to size.

Allison Hayes-Conroy and Jessica Hayes-Conroy

Lab # 2 Summary

The Relationship between Cell Size and Organism Size

The hypothesis that we were testing, created by Jeff, was that cell size increases proportionally with organism size. In order to test this, we collected samples from four different specimen. These included three plant species as well as cell samples taken from a human cheek. All four of the specimen we used were of differing sizes. The smallest was a blade of grass, about 9 cm long. The next sample was from the leaf of a medium sized bush, approximately 1 meter tall. The third plant sample was taken from the leaf of a maple tree, approximately 15 meters tall. The human from whom the cheek sample was taken is approximately 1.5 meters tall.

We measured all of the cell samples in micrometers using a 400x magnification. We measured five cells from each of the samples and then took averages from these numbers. The results are as follows:

Grass cell: 26.0 x 31.7 micrometers

Bush cell: 29.6 x 29.6 micrometers

Tree cell: 23.4 x 21.8 micrometers

Human cell: 62.4 x 69.2 micrometers

The conclusion that we drew from these observations is that organism size has no bearing on the size of its individual cells. The largest organism, the tree, actually had the smallest average cell size. (in other words, Jeff is wrong) Also, in doing this experiment, we should probably disregard the human cell since animal cells and plant cells differ greatly. Finally, another problem we invisioned is that the cell samples were taken from only one part of the highly complex organisms. Cell size may differ greatly within each singular organism.

Jeanne Braha and Meghan McCabe

Wednesday Lab 2

The hypothesis posed to us by Jeff was that there is a direct correlation between cell size and organism size. To test this, we took 3 samples of plants from the area just outside the PSB, then measured the length and width of 5 cells in each sample.

The samples we used were the leaf from a tree (15m high), the leaf of a bush (2m high) and a piece of grass (0.2m long). Our data is listed below.

The averages for the specimens were:

Tree cell length -- 53 micrometers tree height - 15 m

Tree cell width --- 40

Bush cell length -- 40 bush height - 2 m

Bush cell width --- 40

Grass cell length - 61 grass height - 0.2 m

Grass cell width -- 13

We assumed that the tree and bush were about the same width as height, because the bush looks that wide and the tree has wide roots and branches, though is noticeably narrower in the trunk. For the purposes of making the correlations of cell size: organism size, we'll just use height. The grass is much skinnier than it is tall, but we'll disregard this as well.

Just from a quick glance, the data do not seem to support Jeff's hypothesis. The grass cells are much longer than the tree cells, even though the tree is much taller than the grass. However, we will take pity on Jeff and show the ratios, just as one last test.

53:15::40:2::61:0.2

Or, 3.5:1::20:1::305:1

Clearly, the data do not support Jeff's hypothesis. There is no direct correlation seen between cell size and organism size evidenced in the cells of the different organism we observed in lab today.

Srabonti Ali and Jabeen Obaray

Biology 103- Lab #2

Hypothesis: There is correlation between the size of an organism and the size of it’s cells (i.e. The larger the organism, the larger the size of its cells)

Cells from a leaf of a tree:

40x lens

cell 1 — 4 spaces x 4 spaces

cell 2 - 7 spaces x 6 spaces

cell 3 — 10 spaces x 8 spaces

conversion:

cell 1 —16.40 um x 16.40 um

cell 2 — 18.20 um x 15.60 um

cell 3 — 26 um x 20.8 um

average cell size: 20.2 um x 17.6 um

Cells from bush leaf:

40x lens

cell 1 — 12 spaces x 10 spaces

cell 2 — 9 spaces x 6 spaces

cell 3 - 13 spaces x 9 spaces

conversion:

cell 1 — 31.2 um x 26 um

cell 2 — 23.4 um x 15.60 um

cell 3 — 33.8 um x 23.4 um

average cell size: 29.5 um x 21.6 um

Cells from the clover leaf:

40x lens

Cell 1 — 3 spaces x 4 spaces

Cell 2 — 3 spaces x 6 spaces

Cell 3 — 6 spaces x 8 spaces

Conversion:

Cell 1 — 7.8 um x 10.4 um

Cell 2 —7.8 um x 15.6 um

Cell 3 — 15.6 um x 20.8 um

Average cell size: 10.4 um x 15.6 um

Conclusion:

There is apparently no correlation between organism size and cell size. We found that the cells from the bush leaf were larger than the cells from both the tree leaf and clover leaf; despite the fact that the bush is a smaller organism than the tree. According to our initial hypothesis, the cells from the tree should’ve been larger than the cells from the bush, which in turn should have been larger than the cells from the clover.

Mary Rochelle and Promise Partner

20 September 2000

Lab 2

Our adept lab instructor Jeff presented us with an intriguing hypothesis: The size of an organism’s cells is directly proportional with the size of the organism itself. Though we do not doubt his extensive research, we decided to test his hypothesis by collecting and observing sample specimens from three organisms differing in size. We gathered a leaf from a tree approximately 25 meters tall, a clover approximately 5.5 centimeters tall (.055 meters), and a red berry from a bush about 2.25 meters tall.

Inside the lab we then used a razor blade to scrape cells from each organism onto a slide and we added a drop of water and covered it with a cover slip. With the microscope we observed and measured six cells from both the tree and the clover, using the ocular reticle and the scale of 2.6 micrometers per one reticle space. We had difficulty finding recognizable and measurable cells from the berry specimen and yet again with Mary’s cheek cells, so we then collected a third specimen of moss about 2 centimeter (.02 meters) tall.

Our results were as follows:

Tree cells

26 um

36.4

23.4

31.2

39.0

28.6

Average=30.77 um

Clover cells

28.6 um

33.8

13.0

39.0

26.0

33.8

Average=29.03 um

Moss cells

13.0 um

13.0

10.4

20.8

15.6

13.0

Average=14.30

According to these observations, we find it difficult to ascertain the correlation between an organism’s size in relation to its actual size. Because the difference in average cell size between tree and clover was less than one micrometer, we presumed the hypothesis to be incorrect and that the third specimen would follow suit. The size of the moss cells surprised us, for they were only half the size of both the clover and the tree cells. Therefore the given hypothesis does not hold true as our three samples’ cell sizes did not vary proportional to their actual sizes.

What is the relationship between organism size and cell size.

Cells looked at

Bush-average size 1.5 meters

Large Clover- average size-60 centimeters

Small Clover average size- 10 centimeters

Average Cell Sizes

We looked at 5 cells from each leaf taken from each organism

 Bush Big Clover Small Clover 2.6 13 6.5 1 2.6 26 10.4 3.9 18.2 13 5.2 20.8 10.4 2.6 15.6 7.8 Average 3.38 Average 18.8 Average 9.62

Conclusion

1. That size of the cell is not dependant of the size of the organism.

2. The size of the cells within an organism vary in size.

Julie Kwon and Naomi Lim

Biology 103 / Wednesday

Lab # 2 – Biology & Scale

Introduction:

What affects the size of an organism? The hypothesis that we explored was whether the size of the cells of an organism would determine the size of the organism. We wanted to know if there exists a correlation between the size of an organism and the size of its cells (the bigger the cells, the bigger the organism?).

Methods:

1. We went outside and collected the samples of three different-sized plants. We collected (from smallest to largest) moss, a clover, and a tree leaf.
2. We then scraped portions of each organism onto a cleaned glass slide, added a drop of water and mounted it.
3. Finally we proceeded to use the microscope to measure the size of the cells.

Results / Observations:

 Plant (length) Moss (0.5 cm) Clover (3 cm) Tree Leaf (15 meters) # reticle spaces 5 Reticle Spaces 6 Reticle Spaces 9 Reticle Spaces 4 Reticle Spaces 5 Reticle Spaces 8 Reticle Spaces 3 Reticle Spaces 7 Reticle Spaces 7 Reticle Spaces 4 Reticle Spaces 6 Reticle Spaces 8 Reticle Spaces 4 Reticle Spaces 7 Reticle Spaces 9 Reticle Spaces Average Ocular Reticle 4 Reticle Spaces 6.2 Reticle Spaces 8.2 Reticle Spaces Average Cell Size in Micrometers 10.4 16.12 21.32

Discussions:

Our results / observations seem to agree with the hypothesis stated. In our experiment, there seemed to be a correlation between cell size and plant size – the bigger the cells, the bigger the organism. However, these results are not completely reliable in any sense, given measurement error, errors in scraping samples onto the slides, and trouble using the microscope. We also need to take into consideration a larger sample of plants and other organisms to see if this hypothesis really holds true. With our given knowledge that there are other factors that can affect the size of organisms, such as the number of cells and the environment of the plants, there is a need to investigate further. It seems logical that cell size correlates with plant size.

Furthermore, we had a little trouble determining which was smaller, the clover or the moss, because we were not sure whether to measure the moss in pieces or as in the whole. Thus, we decided to measure the organisms by height and obtained the results stated above.