Microscopes: parts, types and total magnification
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
Read this first
Field of view (example data)
total magnification field diameter (mm) 100× 1.8 400× 0.45 At 100× Ari counts 128 evenly spread cells in the field. About how many cells will the 400× field show?
- About 32 cells, since the field is 4 times narrower
- About 8 cells
- About 2,048 cells, since 400× shows 16 times more
- About 512 cells, since 400× is 4 times more
Two slides (example data)
slide magnification field diameter (mm) cells counted 1 100× 1.8 40 2 400× 0.45 6 Bo counts cells on two slides. Which slide has more cells per mm², and by how much?
- Slide 1, since it shows 40 cells against 6
- Slide 1, about 1.7 times denser
- Slide 2, about 4 times denser
- Slide 2, about 2.4 times denser
Use π ≈ 3.14. Esme estimates the cells on the whole cover slip. About how many are there?
- About 23,000 cells
- About 3,600 cells, from 9 × 400
- About 8,000 cells, from 9 ÷ 0.45 per mm
- About 5,700 cells, using 0.45 as the radius
Photo magnification 500×. The cell measures 8 mm on the photo. Note: 8 mm × 500 = 4,000 mm. Jun checks a classmate's note. Which fix is right?
- Keep the multiplying, but convert: 4,000 mm is 4 m long
- Divide, but keep the unit: the cell is 16 mm
- Ignore the magnification: the cell is 8 mm long
- Divide, not multiply: 8 mm ÷ 500 = 0.016 mm = 16 µm
“Example data:” Kira sized a cell on a poster copy using the original photo's bar. Which result is right?
- 216 µm, multiplying 36 by 6
- 1.8 µm, halving the answer for the enlargement too
- 7.2 µm, using the original 30 mm bar
- 3.6 µm, using the poster copy's own 60 mm bar
1 nm = 1,000 pm. A headline says a new light microscope at 20,000× shows single atoms, about 0.1 nm wide. Milo checks the table. Which reply is best?
- Possible: 0.1 is smaller than 200, so atoms are easy to separate with enough light
- Possible: 20,000× is far more than the 400× in the table, so atoms would show
- Not possible: light microscopes cannot go above 400×, whatever lens is used
- Not possible: light microscopes cannot separate points closer than about 200 nm
Published width: about 8 µm. 1 mm = 1,000 µm. Noah finds the real width of red blood cells from the photo. Which statement is best supported?
- The real width is about 1,296 µm, the mean photo width times the 400× power
- The real width is 3.24 µm, the mean width as measured on the photo itself
- The real width is about 0.0081 µm, since 3.24 ÷ 400 is 0.0081 and the unit is µm
- The mean photo width is 3.24 mm, so the real width is about 8.1 µm, close to 8 µm
Counting yeast (example data)
measure value field diameter at 400× (mm) 0.45 Pia wants the density of yeast cells (cells per mm²) on a slide. Which plan is best?
- Count five fields at 400×, find one field's area from 0.45 mm, and average the counts per mm²
- Count the clearest field at 400× and report that count as the density of the whole slide, as is
- Count one field at 400× and multiply that count by 400, the power used on the slide
- Count five fields, each at a different power, and then average the five counts together
Two electron microscopes (facts from OpenStax Biology 2e)
kind how the beam works what it shows scanning moves back and forth across the surface surface details transmission passes through a thin slice internal structures A caption says a scanning electron micrograph shows the mitochondria inside a cell. Ren checks the card. Which reply is best?
- Doubtful: electron microscopes cannot show organelles in a cell, just whole cells in total, at most
- Right: scanning means the beam scans through the whole cell from top to bottom
- Right: electron microscopes show the inside of any cell they are used on
- Doubtful: scanning images show surface details; insides need a transmission image of a slice
1 mm = 1,000 µm. Zee reads a cell as 20 mm long, with a ruler good to ±1 mm. What range of real lengths is fair?
- 38 to 42 mm
- 38 to 42 µm
- 9,500 to 10,500 µm
- 39.9 to 40.1 µm