Biology Homeostasis and Osmosis Quiz

Homeostasis and Recovery

• Homeostasis aims to maintain equilibrium around a set point, typically a resting state.
• Pulse rate is measured immediately after exercise, then monitored during the recovery period until it matches the resting rate.
• Recovery time refers to the duration it takes for the body to return to a resting state post-exercise, crucial for cardiovascular adaptations.
• Recovery of the cardiovascular system can occur within minutes to hours, with variations based on training status.

Osmosis and Osmotic Pressure

• Osmosis is the movement of water across a semipermeable membrane from areas of low solute concentration to high solute concentration.
• Osmotic pressure can be calculated using the formula: V = R⋅T⋅cs, where V is the osmotic pressure, R is the gas constant, T is temperature in Kelvin, and cs is solute concentration in mol/L.
• Cells can be isoosmotic, having equal osmotic pressure with their solution.

Photosynthesis Stages

• Photosynthesis consists of two phases: Light-Dependent and Light-Independent (Calvin Cycle).

Light-Dependent Phase

• Energy from sunlight is converted into ATP and NADPH; photon absorption causes pigment excitation, boosting electrons to higher energy levels.
• Key enzymes are NADP Reductase (for NADPH) and ATP Synthase (for ATP).
• Water is split to produce oxygen, with tasks divided among components like Photosystem II and plastoquinone.

Light-Independent Phase (Calvin Cycle)

• Does not require light and can occur anytime, involving CO₂ fixation through RuBisCO.
• The cycle starts with the combination of CO₂ and ribulose bisphosphate (RuBP), forming an unstable compound that breaks down into 3-phosphoglycerate (3-PGA).
• G3P, a product of the cycle, is a precursor to glucose, requiring two G3P molecules to form one glucose.

Pigments and Solubility

• Chlorophyll reflects green light while absorbing blue and red wavelengths, essential for photosynthesis.
• Various pigments exist: α-Carotene, xanthophylls, lutein, and zeaxanthin; they assist in maximizing energy absorption across wavelengths.
• Plant pigments, including chlorophyll, are lipids, with solubility varying across solvents, primarily extracted using acetone.

Plant Responses and Adaptations

• Photosynthetic organisms utilize specialized tissues (aerenchyma) for gas exchange, enabling buoyancy and diffusion of gases produced during photosynthesis.
• Light intensity directly influences the rate of photosynthesis, observed through oxygen bubble production in aquatic plants like Myriophyllum.
• The process of cavitation can occur when gas builds up in xylem, breaking vascular bundles if the stem is cut below water level.

Key Phases in the Calvin Cycle

• Carboxylation: CO₂ is fixed to RuBP with RuBisCO, forming 3-PGA.
• Reduction Phase: ATP and NADPH convert 3-PGA into G3P.
• Regeneration Phase: RuBP is regenerated to continue the cycle, allowing for ongoing CO₂ fixation.

This quiz covers key concepts in homeostasis, osmosis, and the stages of photosynthesis. You'll explore how the body maintains equilibrium during recovery after exercise and the principles of osmotic pressure in biological systems. Test your understanding of these essential biological processes.