B2.2 Cell Structure

Question 1

Imagine you are examining a specimen of blood under a microscope to look at red blood cells. Why might it be important to know the magnification of the lens you are using?

Answer 1

Because If you a not using a suitable magnification for the specimen you are looking at, you may not able to see what you want to do.

( it is most useful to start by focusing at a lower magnification and then moving up to the magnification you want to use).

Question 2

You are working at an object that measures 0.5 mm and the image you see is 10mm long. Your friend is looking at an object that is 0.1mm long using the same magnification. What size of image does your friend see?

Answer 2

2mm

Question 3

The image you are looking at is 2.5mm long and you are using a magnification of 100. Write down the calculation you would use to work out the actual size of the object.

Answer 3

. 2.5 mm
actual size = —————–
100

Question 4

Net movement means

Answer 4

more particles moving in one direction.

Question 5

Diffusion means

Answer 5

the sum of movement of PARTICLES from an area of HIGH concentration TO an area of LOWER concentration in a solution or across a partially permeable membrane.

Question 6

Explain why some particles can diffuse through cell membranes but not others.

Answer 6

Only SMALL particles that are small enough to pass through the membrane can diffuse.

Larger molecules cannot diffuse though the membrane.

Question 7

osmosis means

Answer 7

The net movement of WATER molecules from a region of their HIGH concentration to a region of their LOWER concentration.

Question 8

Explain how osmosis is similar to diffusion

Answer 8

It is a PASSIVE movement of molecules as the result of a CONCENTRATION GRADIENT.

Question 9

Explain how osmosis different from diffusion

Answer 9

Osmosis only considers the movement of the WATER molecules.

Diffusions considers the SALUTE molecules.