Investigation 1

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Overview of the investigation                                                            click image for video

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Student will use gummy bears placed in solutions of varying concentrations as a model of a cell to see the effects of osmosis, and observe how the size of the cell can change.  They will form hypotheses about what happened to the cell and why. Once they have concluded that water either moves one way or the other (into or out of the cell) they will then speculate about how that is possible, reaching the conclusion that the membrane of the gummy bear allows water to pass through, but not the other things inside the gummy bear.  This is a Level w structured inquiry, intended to introduce concepts and construct them in the students mind as ‘a hands on’ alternative to a lecture.

 

Objectives

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Students will be able to:

• Visualize the flow of water in osmosis

• Describe a membrane that is permeable to water and not salt

• Identify that as a semi-permeable membrane

• Describe that there is some force that causes the water to move, and asvribe that force to a concentration gradient.

 

More advanced lab using dialysis tubing 

                                              (click image)

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Alignment with Texas Essential Knowledge and Skills (TEKS)

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This investigation addresses the following TEKS:

§112.35. Chemistry The student understands and can apply the factors that influence the behavior of solutions. The student is expected to: (A) describe the unique role of water in chemical and biological systems;

§112.38. Integrated Physics and Chemistry (5) Science concepts. The student recognizes multiple forms of energy and knows the impact of energy transfer and energy conservation in everyday life. (E)  relate the structure of water to its function as a solvent and investigate the properties of solutions and factors including nature of solute, concentration, 

 

 

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Investigation 2

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Overview of the investigation

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Students will conduct a thought investigation to consider what happens when their either is or is not a concentration gradient and there is or is not a membrane permeability of certain ions. By examining all four cases, they will conclude that a force equilibrium and a concentration gradient across a semi-permeable membrane can support a resting membrane potential. This is a level 1 inquiry.

 

Objectives

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Students will be able to:

• Describe the balance of forces that lead to a resting membrane potential in animal cells.

• Identify the ions of sodium and potassium as key to this potential

• Identify the sodium pump on the membrane as key to establishing the relatively high concentration of sodium ions  outside the cell, and relatively low concentration inside the cell.

• Describe the source of the energy to power the sodium pump.

 

Alignment with Texas Essential Knowledge and Skills (TEKS)

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This investigation addresses the following TEKS:

§112.34. Biology (9) Science concepts. The student knows the significance of various molecules involved in metabolic processes and energy conversions that occur in living organisms. The student is expected to: (A) compare the structures and functions of different types of biomolecules, including lipids, proteins,

§112.38. Integrated Physics and Chemistry (5) Science concepts. The student is expected to: (E)relate the structure of water to its function as a solvent and investigate the properties of solutions and factors including nature of solute, concentration,

 

Investigation 3

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Overview of the investigation

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Safety considerations rule out a live experiment for this investigation. Instead, students will watch a video showing the electric fields generated by certain eels and fishes. Based on their observations, they will form hypotheses about how these fields are generated, in context of their knowledge of resting membrane potential from the previous experiments. This is a level 1 inquiry.

 

Objectives

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Students will be able to:

• Understand how animal cells can generate resting membrane potentials

• Visualize that multiple cells could some their potentials to great a large electrical potential.

• Explain the way that electric eels and fishes make electric fields.

 

Alignment with Texas Essential Knowledge and Skills (TEKS)

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This investigation addresses the following TEKS:

§112.34. Biology (5) Science concepts. (B) examine specialized cells (9) Science concepts. The student knows the significance of various molecules involved in metabolic processes and energy conversions that occur in living organisms.

§112.35. Chemistry The student understands and can apply the factors that influence the behavior of solutions. The student is expected to: (A) describe the unique role of water in chemical and biological systems;

§112.38. Integrated Physics and Chemistry (5) Science concepts. The student is expected to: (E)  relate the structure of water to its function as a solvent and investigate the properties of solutions and factors including nature of solute, temperature, pressure, pH, and concentration,  (F) evaluate the transfer of electrical energy in series and parallel circuits and conductive materials;