Question

How does size affect the rate of diffusion?

Size doesn't matter.

Large molecules diffuse faster.

Small molecules diffuse faster.

The first step taken when looking through the oculars of a microscope is to adjust the oculars until only one circle of light can be viewed.

T/F

A serial dilution is conducted in order to create a solution of higher concentration.

True

False

Glucose has a molecular weight of 180 g/mol. Starch has a molecular weight that varies, but is at least 342 g/mol. Which substance is less likely to cross a dialysis membrane?

		glucose
		starch

Answer 1

1) How does size affect the rate of diffusion?

A: Small molecules diffuse faster.

As the molecular size decreases and if the substance can be dissolved into the membrane then, smaller molecules require less energy to diffuse and cross across the membrane compared to the energy requirement of a larger molecule because of its larger mass. The diffusivity of a molecule is inversely proportional to its mass.

2)The first step taken when looking through the oculars of a microscope is to adjust the oculars until only one circle of light can be viewed.

A): T

For binocular microscopes, the first step after placing the specimen on the lowest possible magnification and to adjust the interpupillary distance so that only one circle of light is seen with both the eyes open.

3) False.

Serial dilutions are done to obtain a solution of lesser concentration than the given concentration of the solution. This can be done by taking 1 ml of liquid from the main solution and mixing it with a known volume, for example, 9 ml of distilled water to obtain a 10 ml diluted concentration of the original solution.

4) Starch is less likely to cross the dialysis membrane due to its larger molecular weight but glucose is more likely to pass through. Larger molecules like proteins and starch do not likely pass through the dialysis membrane due to the large sizes of these molecules.