Question

18. One factor that affects the rate of diffusion is_________________________ this factor is

DIRECTLY/ INDERCETLY/ (Circle one) proportional to the rate of diffusion.

19. Listed below are data from osmosis experiment, similar to the one toy conducted in lab a few weeks ago…. Different concentrations were tested and the percent weigh change was measured. Unfortunately, your partner forgot to label the sucrose beakers!

   Percent weight change Data (Mixed up!) +5.3% ; -27.8 ; -7% ; +11.2% ; and -17.5 %

A. Based on what you know about osmosis, match each percent Wt. change with the appropriate / correct OAS concentration.

       Concentration                                    % Wt. change

       .5 M               _________________              

.4 M               _________________               

.3 M               _________________             

.2 M               _________________             

.1 M               _________________                

O M               _________________          

B) Which concentration(s) was/were hypertonic to the potatoes cells?

Experimental design & the scientific method

20. You and your lab partner have decided to address the following question: what is the effect of a high protein diet on the growth of Guinea pigs?

A) What would be an appropriate hypothesis to address the following question?

B) You have decided to do an experiment in which you give four groups of guinea pigs of different amounts of proteins in their diet for four week-period.

What is your independent variable for this experiment? ________________________________

What is your dependent variable for this experiment?   _________________________________

Write an appropriate prediction if your hypothesis is to be supported by the data

21. You carry an experiment in which different batches of seeds are soaked in 5 different salt solutions of decreasing concentration and the percent germination is determined for each batch after 14 days.

Answer 1

18. Diffusion rate is determined by the particle size. When the particle size increases, it becomes harder for the particle to cross the membrane, thus resulting in lower diffusion rate. Similarly, when the particle size is smaller, the particle cross the membrane easily, resulting in higher diffusion rate.

ANSWER: One factor that affects the rate of diffusion is the size of diffusing particle. this factor is INDERCETLY proportional to the rate of diffusion.

19. A) During osmosis, the solutes moves from the higher concentration soultion to lower concentration solution. So the highest concentration solution (0.5M) loses more weight and the Least concentrated solution (0M) gains more weight. So the weight change of the solutions are as below:

• 0.5M: -27.8%
• 0.4M: -17.5%
• 0.3M: -7%
• 0.2M: 0%
• 0.1M:5.3%
• 0M:11.2%

B) In hypertonic solution, weight change is weight is lost. So 0.5M, 0.4M and 0.3M are hypertonic solutions.

20. A) Hypothesis: high protein diet increases the growth of Guinea pigs.

B) Independent variable (Factor changed by the researchers): Amount of protein given to the guinea pigs.

Dependent variabe (variable affected by the independent variable): Growth of guinea pig.

If the data supports the above mentioned hypothesis, then the results is that high protein diet increases the growth of the guinea pigs.

(Note: Question 21 is incomplete).