Flashcards: Module 1 – Water & Inorganic Ions (CCEA AS Biology, Unit 1)

Q: What are the key properties of water that make it vital for biological systems?

A: Cohesion, adhesion, high specific heat capacity, high latent heat of vaporization, solvent properties, density anomaly (less dense as solid) — these support transport, temperature regulation, reaction medium, habitat stability.

Q: Why is water described as a polar molecule?

A: Oxygen is more electronegative than hydrogen, creating partial negative charge on O and partial positive on H—this polar nature enables hydrogen bonding and solubility of polar substances.

Q: How does cohesion contribute to water’s behavior in plants?

A: Cohesion causes water molecules to stick together, enabling the column of water to be pulled up through xylem (transpiration pull).

Q: Explain high specific heat capacity of water and its biological importance.

A: It takes lots of energy to change water’s temperature, helping organisms maintain stable internal and environmental temperatures.

Q: What are inorganic ions and why are they important in biology?

A: Inorganic ions are charged atoms or molecules (e.g., Ca²⁺, K⁺, Cl⁻) that are dissolved in bodily fluids—vital roles include nerve transmission, osmoregulation, enzyme activation, structural support.

Q: Role of Calcium ions (Ca²⁺)?

A: Involved in muscle contraction, blood clotting, bone and cartilage formation, acting as cellular messengers.

Q: Function of Potassium ions (K⁺)?

A: Key for nerve impulse transmission and maintenance of resting potential in cells; also essential in plant stomatal function.

Q: What about Chloride ions (Cl⁻)?

A: Important in chloride shift in respiration and maintain osmotic balance.

Q: Role of Hydrogen ions (H⁺)?

A: Central to pH regulation; proton gradient across membranes drives ATP synthesis.

Q: Why are phosphate ions (PO₄³⁻) biologically significant?

A: Integral for ATP, nucleic acids (DNA/RNA), and act as buffers in cellular pH.