Bio Exam 2 Study Guide

Signaling Pathway

A process through which cells communicate and respond to their environment, involving signal reception, transduction, and response.

Signal Reception

The initial step in a signaling pathway where receptors on the cell surface bind to specific molecules, such as hormones or environmental stimuli.

Signal Transduction

The process of spreading the signal within the cell, leading to the activation of proteins and enzymes that relay the signal.

Phototropism

The growth of a plant toward light, controlled by auxin distribution leading to cell elongation on the shaded side.

Phytochromes

Photoreceptors in plants that absorb light and undergo conformational changes to activate plant responses.

De-etiolation

The process triggered by light that causes seedlings to stop elongating, develop chlorophyll, and prepare for photosynthesis.

Auxin

A plant hormone produced in the apical meristem and young leaves that promotes elongation, root formation, and phototropism.

Gravitropism

The directional growth of plant roots toward gravity (positive gravitropism) or shoots against gravity (negative gravitropism).

Cytokinins

Plant hormones produced in roots, seeds, and growing tissues that stimulate cell division and promote lateral bud growth.

Gibberellin (GA)

A plant hormone that stimulates stem elongation, seed germination, flowering, and fruit development.

Abscisic Acid (ABA)

A plant hormone that inhibits growth, promotes seed dormancy, and induces stomatal closure during drought.

Ethylene

A plant hormone involved in regulating fruit ripening, leaf abscission, and stress responses.

Mobile Nutrients

Nutrients that can be moved within the plant from older tissues to newer growth, deficiencies appear in older leaves.

Immobile Nutrients

Nutrients that cannot be moved within the plant, deficiencies appear in younger leaves.

Water Potential

The potential energy of water in a system, determined by solute potential and pressure potential.

Bulk Flow

Pressure-driven movement of water and solutes together, occurring in the xylem and phloem of plants.

Cohesion-Tension Hypothesis

Describes how water is pulled upward through the xylem due to transpiration and the cohesion between water molecules.

Transpiration

The process by which water evaporates from the plant leaves, creating a negative pressure that moves water from the roots.

Calvin Cycle

A series of biochemical reactions in plants that convert carbon dioxide into glucose, occurring in the stroma of chloroplasts.

Rubisco

An enzyme that incorporates carbon dioxide into organic molecules; produced in high abundance due to its inefficiency.

Photorespiration

A metabolic process in plants where oxygen is consumed, and carbon dioxide is released, typically occurring under low carbon dioxide conditions.

C4 Photosynthesis

A type of photosynthesis that improves efficiency by fixing CO2 in mesophyll cells and transporting it to bundle-sheath cells.

CAM Photosynthesis

A type of photosynthesis that fixes CO2 at night and stores it for use during the day, reducing photorespiration and water loss.