MCQ
Essay 1
Essay 2
Essay 3
100

Why is water a good solvent for ionic substances?
A. Positive ions are attracted to the hydrogen atom in water.
B. Negative and positive ions are attracted to the oxygen atom in water.
C. Negative ions are attracted to the covalent bonds in water.
D. Negative and positive ions are attracted to polar water molecules

D. Negative and positive ions are attracted to polar water molecules

100

State what is meant by the term isotonic solution.    

An isotonic solution is a solution that has the same tonicity as the cytoplasm of a cell

100

Define solute and solvent.

Solute:
- The solute is the substance that is dissolved in the solution.
- It is typically present in a smaller amount compared to the solvent.
- The physical state of the solute can be solid, liquid, or gas.

Solvent:
- The solvent is the substance in which the solute dissolves to form a solution.
- It is usually the component present in larger quantities.
- The solvent can also be in any physical state - solid, liquid, or gas.

100

Draw a diagram of a plant cell before and after plasmolysis. Explain how osmosis causes plasmolysis.

In a hypertonic medium, cells with a cell wall undergo plasmolysis, where the cytoplasm shrinks away from the cell wall due to water loss.

200

In which conditions will there be a net movement of water molecules by osmosis from cell X to cell Y?

     Cell X condition                                        Cell Y condition
A.    Hypertonic                                                  Hypotonic
B.      Isotonic                                                      Isotonic
C.    Hypotonic                                                   Hypertonic
D.  More concentrated solutes                     Less concentrated solutes

     Cell X condition                                        Cell Y condition

C.    Hypotonic                                                  Hypertonic

200

Distinguish how animal and plant cells are affected by being placed in hypotonic solutions and hypertonic solutions.    

In hypotonic solutions, plant cells become turgid, whereas animal cells may lyse

In hypertonic solutions, in animal cells, the cell will shrivel or become crenated, whereas in plant cells, the cell will become plasmolysed or flaccid     



 

200

Explain the role of electrolytes in maintaining proper cell function. Relate this to the concepts of hypertonic, hypotonic, and isotonic solutions.

  1. Electrolytes play a crucial role in maintaining cell function by influencing osmotic balance and tonicity. 

  2. Imbalances can lead to hypertonic or hypotonic conditions affecting cell integrity.

200

Draw the effects of a hypotonic medium on cells with a cell wall. Discuss the development of turgor pressure and its significance for plant cells.

In a hypotonic medium, cells with a cell wall develop turgor pressure, which provides structural support to plant cells and prevents cell collapse.

300

Predict what would happen if a eukaryotic animal cell was bathed in a hypertonic solution.
A. It will shrink.
B. It will expand.
C. It will burst.
D. It will remain the same.

A. It will shrink.

300

Explain why the water molecule is polar. Refer to electrons and covalent bonding in your answer.

  1. The water molecule is polar because of the unequal sharing of electrons in the covalent bonds between oxygen and hydrogen. 

  2. A water molecule (H₂O) consists of one oxygen atom and two hydrogen atoms.
    Oxygen is more electronegative than hydrogen, meaning it has a greater ability to attract electrons toward itself.

  3. As a result, the electrons in the O-H bonds spend more time around the oxygen atom, creating a partial negative charge (δ-) on the oxygen atom and partial positive charges (δ+) on the hydrogen atoms. 

  4. This uneven distribution of charges results in a dipole moment, making the water molecule polar.

300

You are in the hospital and need intravenous fluids. You read the label on the IV bag, which lists all of the solutes in the water.

Why is it important for an IV solution to have salts in it? 

  1. Salts (electrolytes) in an IV solution are important for maintaining the balance of ions in the body's cells and tissues. 

  2. Electrolytes, such as sodium, potassium, chloride, and others, play crucial roles in nerve function, muscle contraction, and maintaining proper fluid balance.

400

An organ for transplant is bathed in a cooled liquid to be transported to the operating theatre patient. What should be a property of this liquid?
A. It is hypotonic to body fluids.
B. It is isotonic to body fluids in glucose concentration.
C. It is hypertonic to body fluids.
D. It is isotonic to body fluids in solute concentration.

D. It is isotonic to body fluids in solute concentration.

400

Explain the effects of a hypotonic medium on cells lacking a cell wall. Provide examples and discuss the consequences of excessive water intake.

  1. In a hypotonic medium, cells without a cell wall will take in excess water, leading to swelling and potential bursting (lysis). 

  2. An example is a red blood cell in pure water.

400

Why is it essential for freshwater unicellular organisms to have mechanisms, such as contractile vacuoles, for removing excess water? How do contractile vacuoles function?

  1. Freshwater unicellular organisms face hypotonic environments, and contractile vacuoles actively pump out excess water to prevent cell swelling and bursting. 

  2. They maintain osmotic balance.

500

Osmosis is the movement of water molecules across a membrane. It requires a membrane in order to:
A. Maintain the water potential across the membrane.
B. Provide protein pumps for water movement.
C. Allow solute movement out of the cell.
D. Provide energy to drive osmosis.

A. Maintain the water potential across the membrane.

500

Describe the consequences of placing a cell without a cell wall in a hypertonic medium. Include terms such as shrinkage and crenation in your explanation.

  1. In a hypertonic medium, cells without a cell wall will lose water, causing shrinkage and crenation. 

  2. An example is a red blood cell in a concentrated salt solution.

500

If a cell is isotonic with a 0.88% NaCl solution, how would an extracellular fluid with 1% NaCl effect the cell?

  1. If a cell is isotonic with a 0.88% NaCl solution, it means that the cell and the solution have the same concentration of solutes, and there is no net movement of water. 

  2. If the extracellular fluid has a higher concentration (1% NaCl), it becomes hypertonic relative to the cell. In this case, water would move out of the cell, causing it to shrink or crenate.

500

What would happen if you were given pure water in an IV?

  1. If pure water were given in an IV without salts, it would create a hypotonic environment in the bloodstream. 

  2. This could lead to the influx of water into red blood cells, causing them to swell and potentially burst (hemolysis). 

  3. Additionally, the imbalance of electrolytes could disrupt normal cellular functions.

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