Biology Chapter 3 Flashcards

Properties of Water

• Water is a polar molecule, with one side having a slight positive charge and the other side a slight negative charge.
• Cohesion results from hydrogen bonds between water molecules, enabling the upward movement of water through plants as it evaporates from leaves.
• Adhesion is the tendency of water to cling to other substances, assisting in counteracting gravity as water travels from roots to leaves.
• Surface tension quantifies the difficulty of stretching or breaking a liquid's surface; water's surface tension is enhanced by hydrogen bonds, allowing some organisms to walk on water.

Thermal Properties

• Water has a high specific heat, requiring 1 calorie per gram per degree Celsius to change temperature, which helps regulate environmental temperatures beneficial for marine life.
• The heat of vaporization for water is substantial; about 580 calories are required to convert 1g of water at 25°C from liquid to gas, owing to the strength of hydrogen bonds.
• Evaporative cooling stabilizes temperatures in bodies of water, providing a protective thermal environment for aquatic organisms.

Solutions and Concentrations

• A solute is any substance that dissolves in a solution, while a solvent is the medium (often water) in which a solute dissolves.
• An aqueous solution specifically refers to a solution where water serves as the solvent.
• Molarity measures the concentration of solute in a solution, expressed as moles of solute per liter of solution.

Molecular Properties

• Hydrophilic molecules exhibit an attraction to water, while hydrophobic molecules do not interact with water.
• A colloid consists of small particles dispersed throughout another substance, such as smoke in air.
• The hydration shell forms around dissolved ions, facilitating their interaction in solution.

Acids and Bases

• An acid increases the concentration of hydrogen ions in a solution, while a base decreases it.
• Small changes in pH are critical in biology due to the logarithmic scale of pH measurement; a one-unit change corresponds to a tenfold variation in hydrogen ion concentration, potentially disrupting cellular processes and causing cell death.

Explore key concepts in Biology Chapter 3 with these flashcards. This quiz focuses on understanding water as a polar molecule and the concept of cohesion in water molecules. Test your knowledge and reinforce your learning in biology!