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BIOL 1000 Lecture Notes - Lecture 17: Cell Membrane, Plant Cell, Osmoregulation

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School
University of Manitoba
Department
Biological Sciences
Course
BIOL 1000
Professor
Kevin G.Scott

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Document Summary

Polar water molecules cluster around hydrophilic solute molecules . Water balance between cells and their surroundings is crucial to organisms. Tonicity = ability of a surrounding solution to cause a cell to gain/lose water . Mainly depends on its concentration of solutes that cannot cross the plasma membrane, relative to the concentration of solutes inside the cell. When an animal cell is immersed in an isotonic solution (to the cell), the cell"s volume remains constant . Solute concentration of cell & isotonic environment are equal . Cell gains water at the same rate that it loses water . Rbcs are transported in isotonic plasma of blood . Iv fluids must be isotonic to blood cells . Seawater is isotonic to many marine animals (sea stars, crabs, etc. Hypotonic = a solution with a solute concentration lower than that of the cell . Hypertonic = a solution with a higher solute concentration than that of the cell .

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Related Questions

1,Match the descriptions to the type of transport.

- A. B. C.

Water enters a cell because it is hypertonic compared to the extracellular environment, increasing its turgor pressure
- A. B. C.

Water enters guard cells because the guard cells are hypertonic compared to the surrounding cells
- A. B. C.

Potassium ions are pumped into guard cells
- A. B. C.

The motor cells of a Venus fly trap are hypotonic compared to surrounding cells, causing water to leave the motor cells
- A. B. C.

Sugar is loaded into the phloem
A.

Both active and passive transport
B.

Passive Transport
C.

Active transport

2,Describe what is wrong with the following statement and explain why:

All prokaryotic and eukaryotic cells contain plasma membrane, nucleus, ribosomes, organelles, cytoplasm, and cell walls.

What is short-distance transport?

a,

The movement of solutes from a region of low concentration to a region of high concentration

b,The movement of water, nutrients, and other substances between cells
c,

The movement of substances from a region of high concentration to a region of low concentration
d,

The movement of water across a semipermeable membrane from a region of low solute concentration to a region of high solute concentration.

What terms describe the movement of water across a semipermeable membrane from a region of high water concentration towards a region of low water concentration (and high solute concentration.)

What is found in the proptoplasm?

Cell wall, cytoplasm, plasma membrane, nucleus, and other cell organelles

Plasmodesmata, cell wall, and plasma membrane

Cell wall, cytoplasm, and plasma membrane

Cytoplasm, nucleus, and other cell organelles

The channels that allow nutrients and protoplasm to pass between plant cells are called _________________.

What happens when a plant cell is placed in a hypotonic solution?

Water will enter the plant cell and the plasma membrane will swell and cell lysis will occur

Water will leave the plant cell and the plasma membrane will pull away from the cell and plasmolysis will occur

Water will enter the plant cell and the plasma membrane will swell and push against the cell wall

Water will leave the plant cell and the plant cell will lose turgor pressure, causing the plant to wilt

________________ transport uses cellular energy.

What molecules make plasma cell membranes hydrophilic on the outside and hydrophobic on the inside?

What type of cells do plants have?

Bacterial

Archaeic

Eukaryotic

Prokaryotic

Cell Membranes Lab Report

  1. Diffusion

  1. Compare the following terms: solvent, solute, andsolution.

  1. Go to Lab, Section I, Exercise 1 to explore the factorsinfluencing the rate of diffusion and complete the following:

  1. Predict how molecular mass and temperature may affect theoutcome of this experiment.

  1. Record the data from information in the Lab in the tablebelow.

Time

(min)

Diameter (mm)

5°C MB

5°C PP

23°CMB

23°C PP

0

15

30

45
  1. Construct a line graph of the data from the table above. Yourgraph should include labeled axes, units, and a legend indicatingwhich treatment is presented. Sign, date and prepare an image ofyour graph and include it with this lab report.
  1. Osmosis

  1. Go to Lab, Section II, Exercise 2 to view a demonstration ofosmosis and answer the following questions:

  1. Describe the net movement of water in osmometer 1.
  1. How is the movement of water molecules related to theconcentration gradient of the solution?

  1. Go to Lab, Section II, Exercise 3 to observe the effect ofsolute concentration on the rate of osmosis. Answer the followingquestions:

  1. Was the net movement of water in bags 1 to 4 into or out of thebags?
  1. Explain the results from bags 4 and 5.
  1. Selective Permeability of Membranes

  1. Go to Lab, Section III, Exercise 4 to learn about theimportance of selectively permeable membranes, then complete thetable and answer the following questions:

Contents of Beaker

0 Min

30 Min

Starch

Chloride ion
  1. Which substances diffused through the dialysis membrane?

  1. How does dialysis tubing model the selective permeability of aplasma membrane?
  1. Tonicity

  1. Go to Lab, Section IV, Exercise 5 and 6 to observe plasmolysisin Elodea cells and tonicity in red blood cells. Summarizethe concept of tonicity using blood and Elodea cells asexamples. Your description should incorporate these terms: turgid,plasmolysis, hemolysis, and crenation.

Cells

Isotonic Solution

Hypertonic Solution

Hypotonic Solution

Elodea

RBC

  1. Based on your previous work, reproduce the table below and drawan illustration of a single cell in each box. Include arrows toshow the direction of water flow relative to each cell and dots tosymbolize solutes. Sign, date and prepare an image of your drawingand include it with this lab report.

Cells

Isotonic Solution

Hypertonic Solution

Hypotonic Solution

Elodea

RBC

Summary Questions

  1. Compare diffusion and osmosis. Give an example of each.

2. In which direction will osmosisoccur if a 15% sugar solution is separated from a 25% sugarsolution by a selectively permeable membrane?

3. Why did osmosis, but not diffusionof sucrose molecules, occur across the dialysis membrane containing20% sucrose solution?

4. You are having a party and thecelery is limp. What might you do to make the celery crisp (turgid)again? What will occur in the cells?

5. A small amount of fertilizer(mineral salts) will stimulate plant growth, but over fertilizationcan kill plants? Why?

6. Michael adds sugar to his coffee.Explain what in this drink is the solvent, solute, and solution.

7. You add a cube of sugar to yourdrink. How could you speed up the diffusion of sugar moleculeswithout stirring?

8. How is dynamic equilibriumestablished within a solution?