Biology Cell HW Packet



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 |

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|Focus TEST | |0 1 2 3 4 5 |

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|HW |Due: | |

| |Questions 1-6 |0 1 2 3 |

| |Questions 7-10 |0 1 2 3 |

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| |READ CHAPTER 4 in Textbook | |

| |Questions on page 114 | |

| |#2, #5, #8 & #20 |0 1 2 3 4 |

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| | |_______ / 25 possible points |

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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 very small, convert your answers to micrometers.

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 believe your hypothesis is correct. Include that reason in your hypothesis 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 your answer in Table 1.

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.

Record your answer in Table 2.

[pic]

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 micrometers. Record your answers in Table 2.

Data and Observations:

TABLE 1. Measuring the field of view

|Setting |Eyepiece magnification|Objective magnification |Overall magnification |Field of View Diameter|Field of View |

| | | | |(mm) |Diameter ((m) |

|SUPER LOW |10x |2x | |5 mm | |

|LOW | | | | | |

|MEDIUM | | | | | |

|HIGH | | | | | |

TABLE 2. Estimating the size of cells

|Cell Type |Microscope Setting |# of cells |Estimated Cell Size ((m) |

|Mosquito wing |Super Low |500 | |

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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.

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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.

Answer the following questions on Page 114 in your Biology Textbook

#2

#5

#8

#20

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