Fluid Movement in Cells and Osmosis

Fluid Movement in Cells

• Cell membranes selectively allow substances to cross.
• Impermeable membranes prevent any substance from passing through.
• Permeable membranes allow all substances to pass through.
• Selectively permeable membranes allow certain substances to pass through.
• Particles constantly move in all liquids.
• Diffusion is the movement of particles from a high concentration to a low concentration.
• Concentration influences the direction of substance movement through cell membranes.
• Particles move from higher concentration areas to lower concentration areas.
• Movement continues until equilibrium (balance) is achieved.
• Diffusion allows evenly spread out movement of particles in and out of cells.
• Diffusion plays a role in transporting substances into and out of cells.

Osmosis

• Water's critical role in living organisms stems from its ability to dissolve many substances involved in cellular processes.
• When water moves out of a cell, dissolved substances become more concentrated.
• When water moves into a cell, dissolved substances become more diluted.
• Water always moves from a dilute solution to a more concentrated solution.
• Osmosis is the diffusion of water across a selectively permeable membrane.
• Osmosis occurs due to the diffusion of a solvent, primarily water.

Osmosis in Different Solutions (Animal and Plant Cells)

• Hypotonic solution: Water enters the cell, causing animal cells to swell and potentially burst (cytolysis) and plant cells to become turgid (firm).
• Hypertonic solution: Water leaves the cell, causing animal cells to shrink (crenation) and plant cells to become plasmolysed (the cell membrane shrinks away from the cell wall).
• Isotonic solution: Water moves in and out of the cell at an equal rate, maintaining the cell's normal shape in both animal and plant cells.

Fluid Movement in Plants

• Plants have vascular tissues connecting root systems to shoot systems.
• Xylem tissue transports water and minerals absorbed by root cells to all other plant cells.
• Phloem tissue transports sugars manufactured in leaves to all parts of the plant.
• Root hairs increase the surface area for water absorption.
• Water moves from high to low pressure (root hairs to leaves) via osmosis and pressure differences.
• Transpiration is the process of water loss from plants primarily through evaporation from stomata.
• Water pressure in root hairs causes water movement up the xylem.

Plant Systems

• Plants have shoot, root, and reproductive systems.
• The root system absorbs nutrients and water.
• The shoot system produces stems and leaves and is the site of photosynthesis.
• The reproductive system produces flowers, fruits, and seeds.

Cell Specialization and Organization

• Unicellular organisms have a single cell performing all functions.
• Multicellular organisms have a hierarchy of organization: cells, tissues, organs, organ systems, and organisms.
• Cells specialize in performing specific tasks.
• Specialized cells are crucial for the functioning of complex multicellular organisms.
• Different cell types have different structures and roles.

Levels of Organization

• Cells with similar structure and function form tissues.
• Tissues combine to form organs.
• Organs working together form organ systems.
• Organ systems ensure the organism's functions.

Examples of Specialized Cells

• Nerve cells (neurons) transmit signals.
• Red blood cells (erythrocytes) carry oxygen.
• Onion skin cells form a protective layer.