Question

Imagine a container of glucose solution, divided into two compartments (A and B) by a membrane that is permeable to both water and glucose. If some glucose is added to compartment A, how will the contents of compartment B change? Explain.

Short answer

In conclusion, when glucose is added to compartment A, the contents of compartment B change, resulting in an increase in glucose concentration as glucose diffuses from compartment A to compartment B. Simultaneously, there is a decrease in water concentration in compartment B, as water moves from compartment B to compartment A through osmosis to reach an equilibrium of water and glucose concentrations in both compartments.

Step-by-step solution

Understand the concepts of diffusion and osmosis

Diffusion is the process where molecules move from an area of high concentration to an area of low concentration. In this case, glucose and water can both diffuse across the membrane. Osmosis, on the other hand, is the diffusion of water across a selectively permeable membrane.

Initial situation in compartments A and B

Initially, both compartments have an equal concentration of glucose and water. When we add glucose to compartment A, the concentration of glucose will be higher in A compared to B. The membrane allows both water and glucose to pass through.

Glucose diffusion

According to the concept of diffusion, glucose will move from compartment A (higher concentration) to compartment B (lower concentration) until the concentrations are equal on both sides. This movement occurs because the membrane is permeable to glucose.

Osmosis of water

Simultaneously, water molecules will also move across the membrane due to osmosis. Since the glucose concentration is higher in compartment A, the water concentration is relatively lower compared to compartment B. Water will move from compartment B (higher water concentration) to compartment A (lower water concentration) by osmosis. This movement will continue until there is an equilibrium of water and glucose concentrations in both compartments.

Final situation in compartments A and B

After some time, the glucose and water molecules will reach an equilibrium between the two compartments. This means that the glucose concentration in compartment B has increased due to the diffusion of glucose from compartment A. Additionally, the water concentration in compartment B will have decreased due to the osmosis of water to compartment A. In conclusion, when glucose is added to compartment A, the contents of compartment B change, resulting in an increase in glucose concentration and a decrease in water concentration as the molecules reach equilibrium through diffusion and osmosis.

Key concepts

Glucose Diffusion

When glucose is introduced into compartment A of our hypothetical container, it sets the stage for a natural process known as glucose diffusion. Diffusion is like the desire to spread out; imagine a crowd dispersing after a concert ends, moving from a cramped area to open spaces. Similarly, glucose molecules spread out from the crowded compartment A, where their concentration is high, into compartment B, where they have room to roam.

This movement is driven by the glucose molecules' inherent energy and persists until the concert-goers (glucose) are evenly spaced out across both compartments, A and B. This point, where there is no net movement of glucose, is known as the molecular concentration equilibrium. It's important because it highlights how substances move in the body and across cells, ensuring that every part gets its fair share of nutrients like glucose.

Selectively Permeable Membrane

Think of a selectively permeable membrane as the bouncer at the door of a club, deciding who gets in and who stays out. In our glucose solution scenario, this membrane's job is crucial because it can recognize and allow both glucose and water molecules to pass through.

It acts like a filter, selectively choosing substances based on size, charge, or solubility, which is key for maintaining the balance needed for our body's cells to function. Such membranes are fundamental components of biological systems, keeping the internal environment of cells constant while allowing essential materials to enter and exit.

Molecular Concentration Equilibrium

Reaching a molecular concentration equilibrium is like finding the perfect balance on a seesaw. Initially, when glucose is added to compartment A, the seesaw is tilted, with more glucose on one side. As glucose diffuses, it's like children moving from the heavier side of the seesaw to the lighter side, slowly balancing it out.

At molecular concentration equilibrium, the seesaw is level - the glucose concentration is the same in both compartments. The system now is at peace, with no net movement of glucose molecules. This concept is fundamental in understanding many biological and chemical processes where balance is key for stability.

Water Movement

Water, the essence of all living things, also follows its own set of rules. In our divided container, water movement occurs through osmosis, a specialized type of diffusion exclusive to water. It may seem counterintuitive, but water diffuses in the opposite direction to glucose - from compartment B, where there's less glucose and therefore more water, to compartment A, where introducing glucose has made water relatively scarce.

This dance of water molecules continues until equilibrium is achieved - not just for glucose, but for water too. Understanding osmosis is crucial, considering how our cells and organs rely on this process to maintain the right balance of fluids and nutrients.