Biology Diffusion and Osmosis Quiz

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Questions and Answers

What happens to an animal cell when placed in a solution with high water potential?

The cell stays the same size.

The cell swells and may burst. (correct)

The cell shrinks and forms spikes.

There is no net movement of water.

What describes a hypotonic solution in relation to a cell?

It has a lower water potential than the cell.

It has the same water potential as the cell.

It has a higher concentration of solutes than the cell.

It has a higher water potential than the cell. (correct)

What occurs when an animal cell is placed in an isotonic solution?

There is no net movement of water. (correct)

The cell bursts.

The cell swells.

The cell shrinks.

What term is used to describe the process when an animal cell shrinks and forms spikes?

Crenation Signup and view all the answers

Which solution has a lower water potential when compared to an animal cell's cytoplasm?

Hypertonic solution Signup and view all the answers

Which scenario best represents osmosis in animal cells?

Water moves into the cell when it is in a higher water potential solution. Signup and view all the answers

What is the effect of placing an animal cell in a solution with lower water potential compared to the cytoplasm?

Water leaves the cell. Signup and view all the answers

Why do the terms isotonic, hypotonic, and hypertonic specifically apply to animal systems?

They are not applicable to plant cells. Signup and view all the answers

What is the definition of osmosis?

Net movement of water molecules from a solution of higher water potential to a solution of lower water potential through a partially permeable membrane Signup and view all the answers

What happens to the liquid level in the thistle funnel when water moves into it?

The liquid level inside the thistle funnel rises Signup and view all the answers

Which statement is true about water potential?

Water potential measures the tendency of water to move from high potential to low potential Signup and view all the answers

What effect does a partially permeable membrane have on osmosis?

It allows only water molecules to pass while restricting solute molecules Signup and view all the answers

What happens when two solutions of different water potential are separated by a partially permeable membrane?

Water moves from the solution with higher water potential to the one with lower water potential Signup and view all the answers

Which of the following statements about a dilute solution is correct?

It has more water molecules per unit volume than a concentrated solution Signup and view all the answers

What is primarily measured by water potential?

The tendency of water to move from one solution to another Signup and view all the answers

Why does the level of solution in one arm of a U-tube fall while it rises in the other arm during osmosis?

Water molecules move to equilibrate the concentration of solutes Signup and view all the answers

What happens to a plant cell when it is placed in a solution with low water potential?

The cell becomes plasmolysed. Signup and view all the answers

Why is turgor pressure important for plants?

It maintains the shape and firmness of plant tissues. Signup and view all the answers

What is a consequence of prolonged plasmolysis in plant cells?

The cells will be killed. Signup and view all the answers

What causes certain plant movements, such as leaves folding in response to touch?

Changes in turgor pressure within the cells. Signup and view all the answers

How can the evaporation of water affect a plant?

It can cause the plant to wilt due to loss of turgor pressure. Signup and view all the answers

What is the significance of the surface area to volume ratio in cells?

It determines the cell's ability to exchange materials effectively. Signup and view all the answers

Which of the following substances typically enters a cell?

Oxygen and nutrients Signup and view all the answers

What can happen if cells fail to exchange materials quickly enough?

They will eventually die. Signup and view all the answers

How does the surface area to volume ratio change as a cell grows larger?

It decreases with size. Signup and view all the answers

What is a characteristic of actively metabolizing cells?

They have a large surface area to volume ratio. Signup and view all the answers

What makes root hair cells effective for absorption?

Their long protrusions. Signup and view all the answers

Which type of cell structure helps increase the rate of oxygen uptake in red blood cells?

A flattened biconcave shape. Signup and view all the answers

What is the primary requirement for active transport to occur in cells?

Energy is needed to move particles. Signup and view all the answers

How do epithelial cells in the small intestine enhance nutrient absorption?

By increasing their surface area with microvilli. Signup and view all the answers

Why do cells stop growing after reaching a maximum size?

To prevent metabolic slowdown. Signup and view all the answers

Which factor is most crucial for the faster rate of diffusion across a cell surface?

Surface area to volume ratio. Signup and view all the answers

What best defines diffusion?

The net movement of particles from a region of higher concentration to a region of lower concentration. Signup and view all the answers

When does diffusion stop?

When the particles reach dynamic equilibrium. Signup and view all the answers

What is the primary factor that drives diffusion?

Concentration gradient. Signup and view all the answers

In the experiment with potassium permanganate, what is observed over time?

The solution becomes homogeneous. Signup and view all the answers

What does dynamic equilibrium indicate in terms of particle movement?

Particles are evenly distributed with no net movement. Signup and view all the answers

How do molecules from food get detected by the nose?

By diffusion of molecules through the air. Signup and view all the answers

What is NOT a characteristic of diffusion?

It requires energy expenditure. Signup and view all the answers

What process explains the distribution of pheromones released by moths?

Diffusion. Signup and view all the answers

Study Notes

Diffusion

Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient.
It stops when particles reach dynamic equilibrium; a state of constant random motion with no net movement.
Potassium permanganate diffusing in water demonstrates this; particles move from high to low concentration, resulting in a homogenous solution.
The process responsible for the smell of food reaching the nose is diffusion of food molecules.
Moths use diffusion to distribute pheromones in the air to attract mates.

Osmosis

Osmosis is the net movement of water molecules from a solution of higher water potential to a solution of lower water potential across a partially permeable membrane.
Water potential is the tendency of water to move; dilute solutions have higher water potential than concentrated solutions.
Water always moves down a water potential gradient.
An experiment using a thistle funnel with a sucrose solution demonstrates osmosis; the liquid level inside the funnel rises due to water entering.

Types of Solutions

Solutions with the same water potential are isotonic.
A hypotonic solution has higher water potential, a hypertonic solution has lower water potential.
These terms mainly apply to animal, not plant systems.

Osmosis in Living Organisms

Animal and plant cells are surrounded by partially permeable membranes.
Osmosis occurs across the cell surface membrane.

Osmosis in Animal Cells

In a hypotonic solution (high water potential), water enters the cell causing it to swell and potentially burst.
In an isotonic solution (same water potential), there's no net water movement, cell size remains unchanged.
In a hypertonic solution (low water potential), water leaves the cell, causing it to shrink (crenation).

Osmosis in Plant Cells

Plant cells in a hypertonic solution lose water, becoming plasmolysed (cell membrane shrinks from the cell wall).
This causes flaccidity, and prolonged plasmolysis kills cells. Excess fertilizer can cause this.
Turgor pressure due to osmosis maintains the shape of plant tissues. Changes in turgor cause movement in some plant parts (e.g., flower opening/closing, mimosa leaves).

Surface Area to Volume Ratio

Cells exchange materials (oxygen, nutrients in; carbon dioxide, waste out) across their surface membranes.
The surface area to volume ratio affects the efficiency of this exchange; a large ratio enables faster diffusion.
As cell size increases, the surface area to volume ratio decreases. Smaller cells have larger ratios and more efficient exchange.
Actively metabolizing cells are usually small to maintain a high surface area to volume ratio.

Cells for Absorption

Root hair cells have long projections to increase surface area for water and mineral absorption.
Red blood cells have a biconcave shape to increase surface area for oxygen uptake.
Epithelial cells in the small intestine have microvilli to enhance the absorption of digested food.

Active Transport

Active transport uses energy to move substances against a concentration gradient (from a lower to a higher concentration).

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Description

Test your knowledge of diffusion and osmosis with this quiz. Explore key concepts such as concentration gradients, dynamic equilibrium, and water potential. Understand how these processes impact living organisms and their environments.