Plant Biology

Basics

Origin of Ecology

The study of relationships between living organisms and their physical environment, Studied at different levels (e.g., ecosystems, biome).,

Ecosystems

Communities of biotic (living) organisms and abiotic (non-living) components in a shared environment, Interactions linked through nutrient cycles and energy flows.,

Importance of Plants

Constitute ~80% of Earth's biomass, Provide oxygen, Primary producers sustaining life, More plants than animals (except arthropods).,

Earth's Energy Budget

Sunlight provides energy, Some absorbed, some reflected, Greenhouse effect vital but excessive levels are harmful.,

Photosynthesis

Converts CO2 and H2O into sugar and oxygen using light energy, Takes place in chloroplasts.,

Photosynthesis Reactions

Light reaction: converts light energy into ATP, Light-independent reaction: uses ATP & NADPH with CO2 to produce carbohydrates.,

Energy Flow

Energy is lost as heat and must be replenished, Matter is recycled and reused.,

Photosynthesis Inefficiency

Chloroplasts absorb only certain light wavelengths, Energy losses occur inside the leaf, Net gain after losses.,

C3 Pathway

Uses RuBisCo to capture CO2, Works well in high CO2, Suffers from photorespiration in low CO2, Most plants use this pathway.,

C4 Pathway

Extra step concentrates CO2, Higher energy cost but beneficial in hot, dry environments with intense sunlight.,

CAM Pathway

Crassulacean Acid Metabolism, Alternative photosynthetic pathway.,

Primary Production

Gross primary production: total chemical energy produced by plants, Net primary production: stored plant biomass passed through the food web.,

Ecosystem Components

Producers: autotrophs converting solar energy, Consumers: heterotrophs consuming plant material, Decomposers: fungi reducing organic matter to simpler forms.,

Trophic Levels

Position of an organism in the food chain, Represented in pyramids showing biomass distribution.,

Ecological Efficiency

~10% of biomass transferred to the next trophic level, Energy lost via respiration, defecation, heat, and non-predatory death.