# Biology Cell HW Packet

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```					                              Biology Cell Packet

Name __________________________________Hour _____

HW Packet due September 11

Due:_______________
Cell Size    Data Table                                         0 1 2
Questions                                    0 1 2 3 4 5
Graph                                            0 1 2 3

Focus TEST                                                0 1 2 3 4 5

HW           Due:
Questions 1-6                                       0 1 23
Questions 7-10                                     0 1 2 3

Textbook
Questions on page 114
#2, #5, #8 & #20                                0 1 2 3 4

_______ / 25 possible points
Cell Size Lab 2
(from Biology: Living Systems, pg. 120-121)

Introduction: Cells are limited in how large they can be. This is because the surface
area and volume ratio does not stay the same as their size increases. Because of this, it
is harder for a large cell to pass materials in and out of the membrane, and to move
materials through the cell.

In this lab, you will determine the size of plant and animal cells. Your teacher will
supply a millimeter ruler and a variety of plant and animal cells. You can measure the
diameter of the field of view under low power with your millimeter ruler. It will be
easier for you to make your measurements in millimeters. However, because cells are

Hint:      1000 micrometers (m)= 1 millimeter (mm).

Problem: How big are cells?

Hypothesis: What is your group’s hypothesis?

(Remember, a hypothesis isn’t just a guess – you should have a reason for you
statement.)

Materials: Microscope
Ruler
Slides of plant and animal cells
Calculator

Procedure:
1. Take out your microscope and properly set it up as we did in the previous labs.
2. Set your microscope to LOW power.
3. Record the Eyepiece and Objective magnification in Table 1.
4. Mathematically, determine the Overall magnification.
5. Use your ruler to measure the diameter of the field of view in millimeters. Record
6. Convert the diameter in millimeters to micrometers. Record your answer in Table 1.
7. Repeat steps 2 and 3 for MEDIUM and HIGH power.
8. Obtain a slide and estimate the number of cells in the field of view.
1             2             3

9. The size of each cell can be determined using the following equation:

(field of View diameter) /(# of cells)

10. Use your math skills to determine the estimated cells of each individual cell in

Data and Observations:

TABLE 1. Measuring the field of view

Setting      Eyepiece         Objective         Overall          Field of       Field of
magnificat      magnificatio     magnificatio        View           View
ion               n               n             Diameter       Diameter
(mm)           (m)
SUPER            10x              2x                              5 mm
LOW
LOW
MEDIUM
HIGH
TABLE 2. Estimating the size of cells

Cell Type             Microscope               # of cells          Estimated Cell
Setting                                       Size (m)
Mosquito wing               Super Low                  500

Analysis and Conclusions:

Prepare a graph that shows the relationship of cell type (X-axis) to cell size (Y-axis). Be
sure to include a title, key, and labeled axis (X and Y) on your graph. Neatness counts.

Answer the following questions using complete sentences. I will be really
impressed if you use what you know about cells and cell parts to answer
them.

1. What was the average size of the animal cells you measured? What was the average
size of the plant cells you measured?
2. Which are larger, plant or animal cells? Does the data support your hypothesis?
Make some educated guesses about why this type of cell would be the largest.

3. Which specific cell type was smallest? Speculate about why it is an advantage for
that species of cell to be so small.

4. Which specific cell type was largest? Speculate about why it is an advantage for the
cell of that species to be larger.

5. Why do you think cells are different sizes?
Biology Homework: Cell
Transport
Transport is the life processes by which needed materials are brought to the cells of an
organism and wastes are carried away form the cells. Transport may be described in
two parts. One involves the passage of materials through the cell membrane, both into
and out of the cell. The second is the circulation of materials to and from the cells.

1. What is accomplished by the life process of transport?

Diffusion
The particles of every substance (atoms, molecules, or ions) are in constant, random
motion. In liquids and gases, this random motion results in frequent collisions. AS the
particles rebound from these collisions, they tend to move apart. Where a substance is
highly concentrated, collisions of its particles are more frequent than where the
substance is less concentrated. As a result, its particles tend to spread away from
regions of higher concentration toward regions of lower concentration. This spread
substance from region of higher concentration to a region of lower concentration is
called diffusion. The difference in concentration from one region to another is called
the concentration gradient of the substance.

2. What is a concentration gradient?

Osmosis
Osmosis is the diffusion of water through a membrane. The concentration of water is
highest in pure water. When other substances are dissolved in the water, the
concentration of the water decreases and the concentration of the dissolved substances
increases. Water will therefore diffuse from a solution that has a higher concentration
of water to one that has a lower concentration of water.
3. Would a cell lose or gain water when placed in a solution with a salt
concentration greater than that of the cell cytoplasm?

4. Would a cell lose of gain water when placed in a solution with a salt
concentration less that that of the cell cytoplasm?

Passive Transport
The cell membrane is semi-permeable – that is, some substances pass through freely,
while others cannot. The movement of substances that can pass freely through the
membrane depends only on the concentration gradient for that substance. Thus, the
movement of such as substance requires no expenditure of energy by the cell. This is
called passive transport.
Active Transport
Living cells have the capacity to move certain molecules and ions through the cell
membrane against the normal direction of diffusion. That is, these substances can be
moved form an area of lower concentration to an area of higher concentration. This
process is called active transport; require the expenditure of energy by the cell.
5. What factor determines the direction of net movement of molecules in passive
transport?

6. Where does the energy from active transport come from?

7. Create a drawing below; using a sugar cube in a beaker of water to illustrate the
movement of the granules of sugar before, during and after diffusion has been
completed in the space below.

8. Which way would the water molecules move in the following situations(in or
out)?
a. Cucumber slice is placed in salt water.
b. Salt is poured onto a snail.
c. Vegetables are sprinkled with water
d. Potato slice is placed in pure water

9. Water will move from high to low or low to high concentrations. (Circle one)

10. Describe in detail the function of the ribosome’s, ER, Golgi, and Cell Membrane.
Include some information on how they work together.
#2

#5

#8

#20

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