Tonicity and Osmoregulation

Read the following passage to help answer: Red blood cells have an internal concentration of 0.9% NaCl. When placed in solutions with varying NaCl concentrations, determine whether each solution is isotonic, hypertonic, or hypotonic relative to the red blood cells. Then, predict the effect on the red blood cells and the net flow of water. Solution: 0.5% NaCl. Choose the combination that correctly identifies the solution’s tonicity, prediction for the cells, and net water movement.

• Hypotonic; cells swell and may lyse; water moves into cells

• Isotonic; no change in cell volume; no net water movement

• Hypertonic; cells shrivel; water moves out of cells

• Hypertonic; cells swell; water moves into cells

Tags

NGSS.HS-LS1-3

NGSS.HS-PS1-5

Read the following passage to help answer: Red blood cells have an internal concentration of 0.9% NaCl. When placed in solutions with varying NaCl concentrations, determine whether each solution is isotonic, hypertonic, or hypotonic relative to the red blood cells. Then, predict the effect on the red blood cells and the net flow of water. Solution: 1.5% NaCl. Choose the combination that correctly identifies the solution’s tonicity, prediction for the cells, and net water movement.

• Hypertonic; cells shrivel (crenate); water moves out of cells

• Hypotonic; cells swell and lyse; water moves into cells

• Isotonic; no change; no net water movement

• Hypotonic; cells become turgid; water moves out of cells

Tags

NGSS.HS-LS1-3

A normal saline IV is 0.9% NaCl, making it isotonic to the patient’s blood cells. Distilled water is 100% water. What physiological problem would administering distilled water create in the patient’s bloodstream?

• Administering distilled water can result in increased blood pressure.
• Administering distilled water may cause blood clotting issues.
• Administering distilled water can cause cytolysis of red blood cells.

• Administering distilled water can lead to dehydration of cells.

Explain how the patient’s red blood cells would react to the introduction of distilled water. Why would this reaction occur?

• The red blood cells will swell and may burst due to the influx of water from the hypotonic distilled water.
• The red blood cells will shrink and become rigid due to water loss and the hypertonic distilled water.

• The red blood cells will remain unchanged as they are isotonic to distilled water.
• The red blood cells will absorb water and become denser without bursting because the water is isotonic to the bloodstream.

A U-tube is divided into side A and side B by a semipermeable membrane. The membrane is freely permeable to water, but not to glucose. Side A contains a 5% glucose solution, while side B contains a 9% glucose solution.

In terms of tonicity, side B is ______ to side A.

• Hypertonic

• Hypotonic

• Isotonic

A U-tube is divided into side A (5% glucose) and side B (9% glucose) by a semipermeable membrane that is permeable to water but not glucose.

Identify which molecule(s) can move across the membrane and describe the net direction of movement.

• Water moves from side A to side B; glucose does not cross

• Glucose moves from side B to side A; water does not cross

• Both water and glucose move equally; no net movement

• Water moves from side B to side A; glucose crosses to equalize concentrations

Tags

NGSS.MS-PS1-5

Observe that the water levels on both sides of the U-tube are currently equal. Will the water levels remain equal over time? Explain your reasoning based on the principles of osmosis and tonicity.

• No; water will rise on side A and fall on side B because A is hypertonic

• Yes; levels will remain equal because the membrane prevents any movement

• No; water will rise on side B and fall on side A because B is hypertonic

• Yes; glucose will diffuse to equalize concentrations

The solution is: ​ (a)  

Prediction: ​ (b)  

Net flow of water: ​ (c)  

• hypotonic
• increase turgor pressure
• into the plant cell
• hypertonic
• isotonic
• decrease turgor pressure
• out of the plant cell

Tags

NGSS.MS-LS1-2

The solution is: ​ (a)  

Prediction: ​ (b)  

Net flow of water: ​ (c)  

• hypertonic
• decrease turgor pressure
• out of the cell
• hypotonic
• isotonic
• increase turgor pressure
• into the cell

Why do grocery stores spray their produce with water before selling them?

• To increase turgor pressure inside plant cells and keep produce crisp

• To dilute sugars so fruit tastes less sweet

• To prevent osmosis by blocking water movement

• To add salt to the surface so cells lose water and firm up

Tags

NGSS.MS-LS1-5