Question

part b: compare the size of a plant cell and paramecium cell. draw your observation on a separate sheet of paper with proper labeling technique.

1. examine a prepared slide of a plant stem or root at low power and at high power. the small compartments you see are cells. decide whether to estimate the size of a plant cell at low power or at high power. using the diameter of the fov you choose, estimate and record the size of a typical plant cell (use μm).
2. repeat step 7 with a prepared slide of paramecium. estimate and record the size of a typical paramecium cell (in μm).

cell length calculation practice:

1. formula:

field diameter / # of cells that fit across field diameter = cell length
10.to estimate the length of a cell, use the following steps:
step 1. estimate how many cells could be lined up end to end across the field diameter.
step 2. divide the field diameter by the number of cells that could fit across the field diameter.
10b. twenty cells fit across the high - power field of 455 μm. calculate the length of the cell.
10c. fifteen plant cells stretch across the medium - power field of 2000μm.
10d. five protozoan fit across the low - power field of 4100 μm.
analyze and conclude:

1. infer: why didnt you use the ruler to measure the fov of the medium - power and high - power lens?
2. classify: are paramecium unicellular organisms or multicellular organisms? provide evidence for your answer (you may also use a drawing with labels).
3. control variables: how did you decide which lens to use to estimate the size of the plant cell? the size of the paramecium cell?
4. predict: some plant diseases are caused by bacteria. could bacteria injure plant cells by surrounding and eating them? could bacteria injure plant cells by entering them? explain your thinking.
5. a microscope has a 20 x ocular (eyepiece) and two objectives of 20 x and 45 x respectively:

a.) calculate the low power magnification of this microscope. show your formula and all work.
b.) calculate the high power magnification of this microscope. show your formula and all work.

1. explain why as magnification increases, field of view decreases.
2. what is the advantage of using high power? what is the advantage of using low power?
3. which group of measurement units is correctly arranged in order of increasing size?

a. micrometer, millimeter, centimeter, meter
b. meter, micrometer, centimeter, millimeter

Explanation:

Step1: Determine magnification formula

Total magnification = Ocular magnification × Objective magnification

Step2: Calculate low - power magnification (a)

Given ocular magnification = 20X and low - power objective magnification = 20X.
Total low - power magnification = 20×20 = 400X

Step3: Calculate high - power magnification (b)

Given ocular magnification = 20X and high - power objective magnification = 45X.
Total high - power magnification = 20×45 = 900X

Step4: Answer question 10B

Given field diameter = 455 um and number of cells = 20.
Cell length = $\frac{455}{20}=22.75$ um

Step5: Answer question 10C

Given field diameter = 2000 um and number of cells = 15.
Cell length = $\frac{2000}{15}\approx133.33$ um

Step6: Answer question 10D

Given field diameter = 4100 um and number of cells = 5.
Cell length = $\frac{4100}{5}=820$ um

Step7: Answer question 1

A ruler is too large to measure the small FOV of medium - power and high - power lenses accurately as the FOV is in micrometers and a ruler measures in centimeters or millimeters.

Step8: Answer question 2

Paramecium are unicellular organisms. They are single - celled organisms that can perform all life functions within one cell. Evidence: They are microscopic and have a single - celled structure visible under a microscope.

Step9: Answer question 3

To estimate the size of the plant cell and paramecium cell, one might choose the lens based on the clarity and the ability to see the whole cell. For a larger view of the sample to get an initial idea, low - power lens can be used. For more detailed size measurement of a single cell, high - power lens can be used.

Step10: Answer question 4

Bacteria can injure plant cells both by surrounding and eating them (some bacteria are pathogenic and can secrete enzymes to break down plant cell walls and consume the cell contents) and by entering them (some bacteria can penetrate plant cells through natural openings or wounds and cause infection from inside).

Step11: Answer question 6

As magnification increases, the field of view decreases because the lens is focusing on a smaller area of the sample to make it appear larger.

Step12: Answer question 7

Advantage of high - power: Allows for detailed view of small structures within the cell. Advantage of low - power: Gives a wider view of the sample, useful for finding the area of interest and getting an overall view of the sample.

Step13: Answer question 8

The correct order of increasing size is micrometer, millimeter, centimeter, meter. So the answer is a.

Answer:

a. Calculate the low - power magnification: 400X
b. Calculate the high - power magnification: 900X
10B. Cell length: 22.75 um
10C. Cell length: 133.33 um
10D. Cell length: 820 um

1. A ruler is too large for accurate measurement of small FOV.
2. Paramecium are unicellular organisms. Evidence: Single - celled structure visible under microscope.
3. Choose lens based on clarity and whole - cell viewability.
4. Bacteria can injure plant cells by surrounding/eating and entering them.
5. As magnification increases, field of view decreases due to focusing on a smaller area.
6. High - power: detailed view of small structures. Low - power: wider view of sample.
7. a. micrometer, millimeter, centimeter, meter