Biology

Lab 7 worksheet: Microscopes and Mitosis

5 points

Part 1: Microscopes (2.5 points)

For this part of the lab, follow the video link below to the virtual microscope. Work through all of the parts of the guide, learn and explore sections. When you are finished, answer the questions below.

https://www.ncbionetwork.org/iet/microscope/

· You go to the lab to view a sample of Elodea under the microscope. You are using the 10x objective lens. What is the total magnification of your sample? Show your work.

· Describe the proper way to care for and clean microscope lenses.

· Using the information provided in the PowerPoint of this lab, calculate the diameter of the field of view when using the high power objective lens. Show your work.

· List the function of each part of the light microscope in the table below.

Part	Function
Iris diaphragm
Course adjustment knob
Fine adjustment knob
Nosepiece
Objective lenses

Part 2: Mitosis (2.5 points)

For this part of the lab, you will classify cells in an onion root tip based upon the phase of mitosis they are in. There are 2 sample areas (2 images below). To do this, first go up and down the rows of cells to count all of the cells in interphase. Then go up and down all of the rows of cells to count all of the cells that you see in prophase. Do this for all 5 phases. Be sure to count ALL of the cells in that sample area and record your data in the table below. You will need to be able to identify theses phases on your own on the exam, so this is good practice.

Next, add up the cells in each phase of the 2 sample areas and put this in the table under total cells. Add up all of the cells you counted in all phases to get the grand total of cells. Find the fraction of cells in each phase by dividing the number of cells in that phase by the grand total. Assuming the total time between cell divisions in an onion root tip is 12 hours (720 minutes), determine the time in minutes spent in each of the phases based on the fraction of time spent in each phase (fraction of cells in the stage × 720 minutes = number of minutes in the stage).

	Sample Area 1	Sample Area 2	Total cells in each phase in both sample areas	Fraction of cells in each phase	Time in minutes spent in each phase
Interphase
Prophase
Metaphase
Anaphase
Telophase		Grand total of cells: Total minutes per cycle: 720

Sample area 1: Sample area 2:

· Based on your data above, which phase was longest? Which phase was shortest? Explain why you think that is based upon what you know is happening during those phases.

· List the major events that occur during each of the following phases of the cell cycle:

Interphase:

Prophase:

Metaphase:

Anaphase:

Telophase