Question

If you remove the cell wall from a plant cell and place it into a drop of water (a) the cell would begin to grow (b) the cell would shrink (c) the cell would burst (d) nothing would happen.

Short answer

The cell would burst due to the osmotic influx of water.

Step-by-step solution

Understanding Osmotic Pressure

When a plant cell's cell wall is removed, the remaining structure, known as a protoplast, is subject to osmotic pressure. Osmosis is the diffusion of water across a semipermeable membrane from a region of low solute concentration to a region of high solute concentration.

Predicting the Effect of Water

Placing the protoplast into a drop of water exposes it to an environment where there is a higher water concentration outside than inside. This means water will move into the cell due to osmosis.

Understanding the Plant Cell's Reaction

Without a cell wall to prevent expansion, the influx of water into the protoplast will continue to the point where the cell can no longer contain the internal pressure, resulting in the cell bursting.

Key concepts

Osmosis in Biology

Osmosis is a fundamental concept in biology that describes the movement of water across a semipermeable membrane. This spontaneous process occurs in various biological systems, including plant cells, where osmosis plays a critical role in maintaining cell structure and function.

In osmosis, water moves from an area of lower solute concentration to an area of higher solute concentration until equilibrium is reached. This is because water has a tendency to dilute concentrations to balance solute levels on either side of the membrane. For plants, this means water can enter or exit cells, depending on the osmotic pressure, which is crucial for many physiological processes such as nutrient uptake and turgor pressure maintenance.

Plant Cell Structure

The plant cell is a marvel of nature's design, encapsulated by a rigid cell wall that provides structural integrity and shape. This cell wall is primarily composed of cellulose, a sturdy carbohydrate polymer that makes plant cells distinct from animal cells, which lack such a protective barrier.

Inside the cell wall lies the cell membrane, a semi-permeable boundary controlling the passage of substances into and out of the cell. The interior of the plant cell, known as the cytoplasm, contains various organelles like chloroplasts for photosynthesis, mitochondria for energy production, and a vacuole that stores water and nutrients. The structured nature of the plant cell, especially the cell wall and vacuole, enables it to withstand osmotic pressure without collapsing or bursting.

Protoplast

A protoplast is the living part of a plant cell that includes the plasma membrane and all the contents within it, but notably excludes the rigid cell wall. This cell state can be experimentally achieved by using enzymes that digest the cell wall, such as cellulase.

Protoplasts are highly valuable in plant research and biotechnology for several reasons. They allow scientists to fuse cells from different species, create genetically modified cells, and study cellular processes without the interference of the cell wall.However, without the cell wall, protoplasts are delicate and susceptible to changes in their environment, such as osmotic pressure. In a hypotonic solution, where the external solute concentration is lower than the internal concentration of the protoplast, water can rush into the protoplast, swelling it, and potentially leading to cell lysis if the osmotic pressure becomes too great.