Lab Exercise 3A Student\'s Name Instructor Pre-lab Homework: Read the Introducti
ID: 189112 • Letter: L
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Lab Exercise 3A Student's Name Instructor Pre-lab Homework: Read the Introduction to Diffusion above and then complete the following questions before coming to lab. 1. Define the term selectively permeable. 2. A. Name 3 types of passive transport B. Does passive transport require cellular energy (e.g. ATP) in order to occur? 3. Define diffusion. 4. A. Why does the cell require substances to diffuse across the plasma membrane? B. Give 2 examples of substances that must diffuse across the plasma membrane. [Hint: Think about the substances you need to survive.] 5. A. Name 5 factors that can affect diffusion across the plasma membrane. B. Think about what you have learned in class about chemical bonds and how that affects the charge or lack of charge of molecules. The plasma membrane has a hydrophobic or uncharged region that molecules must cross in order to get into or out of the cell. Based on this information, which molecule would cross the cell membrane more easily-O2 (molecular oxygen) or sodium ions? Why? Read over Part II of the lab and the outline of procedure: 6. What do the agar blocks represent in this lab? 7. A. What color is the pH indicator phenol red at neutral pH? B. What color is the pH indicator phenol red at acidic pH?Explanation / Answer
1.Selectively permeable is a term used for membranes that allows only certain and specific substances to pass through it either by passive or active transport.
2.
A.Three types of passive transport are:
B.No, passive transport does not require cellular energy input.
3.Diffusion can be defined as the process of movement of atoms or molecules from a region of higher consnetration to a region of lower concentration.
4.A.The cells require substances to diffuse across the plasma membrane so that homeostasis is maintained .
B.The two substances are oxygen and carbon dioxide.
5.
A.Five factors are:
B.Oxygen would cross the cell membrane more easily as it is small and non polar.Sodium ion being large when dissolved in water cannot diffuse freely across the cell membrane as there are presence of hydrophobic fatty acid tails of the phospholipids that make up the lipid bilayer.
6.Agar blocks represent the cell with cytoplasm and cell membrane.
7.A.At neutral pH, phenol red is red color.
B.At acidic phH, phenol red is yellow color.
8.Hydrogen ions present in vinegar.
9.
A.It is neutral
C.No diffusion of hydrogen ions would occur.
D.Color of agar block will be yellow.
10.The purpose of trial in an experiment is the anticipation of a result.
11 & 12 .lab related answers to be given.
13.
7 min 15 sec = 435 sec
60 sec = 1 minute
435 sec = 7.25 minutes
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