Biological Hierchary

Ecology 355 August 26th, 2024 Biological Hierchary Atoms Molecules Organelles Cells Tissues Organs Organ systems Organisms Populations Communities Ecosystems Biosphere Life and the Physical Environment - Aquatic - Terrestrial Properties of water that make it favorable for life - Thermal properties Water has a high specific heat and resists changing states - Density Liquid water is more dense (ice cubes float !) - Viscosity the thickness of a fluid that causes objects to encounter resistance as they move through it - Mineral solubility Water is a powerful solvent with an impressive capacity to dissolve substances, which makes them accessible to living systems - Acidity The concentration of hydrogen ions in a solution pH- a measure of acidity or alkalinity, defined as PH= -log[H+] Aquatic organisms face the challenge of exchanging gases (CO2 and O2) CO2 - Moves between the atmosphere and aquatic system ( through the water column) - The concentration in the water is the same as the concentration in the atmosphere - When carbon dioxide dissolves in water most of the molecules will combine with water and are quickly converted into carbonic acid Challenges of living in water - Gas exchange - Temperature Plant adaptations to limited CO2 - Plants can use both carbon dioxide and carbonic acid for photosynthesis - Aquatic plants in acidic habitats use only CO2 for photosynthesis - CO2 is limiting in habits at a high pH ● Calcareous fens are fed by carbonate-enriched groundwater ● Areas with more pH. Chara spp. - An algal plant that lives in basic environments - They can secrete hydrogen ions and manipulate the pH directly around its epidermis by secreting hydronium ions into the water Oxygen has a slow diffusion rate into the water - The maximum solubility of oxygen is 0.01 liter per water ( 1 percent) - Oxygens low solubility in water can limit the metabolism of organisms in aquatic habitats