Question

Internal fluid pressure against a cell wall or membrane is called ___________. a. osmosis b. turgor pressure c. diffusion d. osmotic pressure

Short answer

The correct answer is b. turgor pressure.

Step-by-step solution

Understanding the Term

Before picking the correct answer, let's focus on the term 'internal fluid pressure against a cell wall or membrane'. Internal fluid pressure is exerted when a fluid within a cell presses against the cell wall or membrane. It's crucial to understand which term specifically refers to this pressure.

Defining the Options

Examine the given options to understand what each term means: - Osmosis is a process by which water molecules move from a higher concentration to a lower concentration through a semi-permeable membrane. - Turgor Pressure is the pressure of the cell contents against the cell wall in plant cells, causing the wall to expand and maintain rigidity. - Diffusion is the movement of particles from a region of higher concentration to one of lower concentration. - Osmotic Pressure is the pressure required to prevent the inward flow of water across a semi-permeable membrane.

Matching the Definition

Compare the defined terms with the term from the question ('internal fluid pressure against a cell wall or membrane'). Among the definitions, 'Turgor Pressure' specifically relates to the pressure exerted by the fluid inside a plant cell against its cell wall.

Concluding the Answer

Since 'Turgor Pressure' uniquely relates to internal fluid pressure against a cell wall or membrane, it matches the description provided in the question.

Key concepts

Osmosis

Osmosis is a crucial biological process that involves the movement of water molecules across a semi-permeable membrane. This movement depends on the concentration gradient, where water travels from a region of higher water potential to lower water potential. This spontaneous movement continues until equilibrium is reached.

This concept is vital for maintaining cell turgidity and overall cellular function. For instance, in plants, osmosis regulates water intake, ensuring that cells remain firm and functional. This process contributes to turgor pressure, which keeps plants upright and supports their structural integrity.

Key aspects to remember about osmosis include:

• It only involves the movement of water molecules.
• The presence of a semi-permeable membrane is necessary.
• Osmosis is a passive process that doesn't require energy input from the cell.

Understanding osmosis is fundamental to grasping how cells maintain their environment and function effectively in both plant and animal systems.

Diffusion

Diffusion is a natural process where molecules spread from areas of high concentration to areas of low concentration, driven by the random motion of particles. This process occurs both in living organisms and the non-living environment.

In biological contexts, diffusion is essential for the movement of substances like oxygen, carbon dioxide, and small nutrients across cell membranes. It ensures cells receive the necessary materials for energy production and other metabolic activities.

Key characteristics of diffusion include:

• It can occur in gases, liquids, and even solids.
• Diffusion is another passive process, requiring no energy from the cell.
• It continues until a uniform concentration is reached.

Through diffusion, cells manage their internal environments, enabling efficient operation and survival in varying conditions.

Osmotic Pressure

Osmotic pressure is a critical concept in understanding how cells interact with their environment through osmosis. It refers to the pressure required to prevent the inward flow of water across a semi-permeable membrane.

This pressure arises due to differences in solute concentrations on either side of the membrane. When a solution has a high solute concentration, it exerts higher osmotic pressure, attracting water more strongly from areas of lower solute concentration.

Important points about osmotic pressure include:

• It is directly proportional to solute concentration.
• Osmotic pressure is a colligative property, depending on solute particles present, not their identity.
• It plays a vital role in maintaining cell shape and preventing cells from bursting in hypotonic surroundings.

Understanding osmotic pressure is central to comprehending how cells regulate their water content and manage their interactions with their environment, maintaining homeostasis.