BioNow:CellSize

BioNow Student Study Guide: Cell Size

Part I: Pre-Video Questions

1. Provide a brief definition of the following terms to gain familiarity before watching the video.

a. Cell:

b. Surface area:

c. Volume:

d. Surface-area-to-volume ratio:

e. Chemical reaction:

f. Cellular respiration:

g. Cell membrane:

h. Membrane transport:

i. Prokaryote:

j. Eukaryote:

Please read the video summary below and answer the questions that follow in detail.

Your body consists of 37 trillion cells! Each is so small; it cannot be seen with the naked eye. When together, however, you look as if you are a single piece, not 37 trillion. Why are you made of so many small cells instead of fewer, larger cells?

Cell size is a challenging concept, but it can be made easier using an analogy, or comparing two things in order to gain understanding. This is especially effective when one part of the analogy is something you already understand. For example, you may remember the function of the nucleus because you remember it as the “brain” of the cell. Cells are the basic unit of structure and function for all life. Some organisms are only made of one cell, and others of many cells. No matter the size of the organism, their cells are all pretty much the same size.

Can you think of an analogy to explain why all cells are a certain size, but can build many different sizes of organisms? They could be compared to a child’s building blocks that can be arranged into imaginary castles of different sizes and shapes. The purpose of this experiment is to create an analogy explaining why cells are so small by comparing the concept to fire.

1) Describe a unique analogy to explain how cells can create so many different organisms.

2) Describe how you would start a campfire.

3) Why can shopping at a mall with many smaller stores be easier and more convenient than visiting a giant chain store?

Part II: Video Questions

4) Describe the concept of surface-area-to-volume ratio.

5) Calculate the surface area, the volume, and the surface-area-to-volume ratio of this cube.

SA = height width number of sides

V = width length height

Ratio = SA V: 1 (ex. 6:1)

6) Which cube has a higher surface-area-to-volume ratio?

7) What is the overall goal of the experiment?

8) Describe the experimental procedure used to answer the question.

9) Which wood size has the highest surface-area-to-volume ratio?

10) How is combustion related to cellular respiration?

11) Describe the results of the experiment.

12) How do the results explain why cells are very small?

13) If cells were very large, what problems would result?

14) Describe how the scientific method was applied during this experiment and what occurred at each step.

15) What is the mathematical relationship between surface area and volume based on these results?

Part III: Video Evaluation

16) Do you think the analogy in this experiment was accurate to explain cell size?

17) What would you have done differently in the experiment?

18) Finish this analogy: Cells are very small because it creates a very large surface area for substances needed for chemical reactions to quickly move in and out of the cell. This is much like…(explain using wood and fire)

Part IV: Video Reflection

19) What was the most interesting part of the video?

20) What was something new you learned?

21) What are you confused about from the video?

22) Do you see any relationships to your life? Why or why not?

23) Which part would you like to learn more about?

24) What follow-up experiment would you like to do and how would you relate it to your life?