PHYSICAL ENVIRONMENT ECOL 1

Common definitions

  • Plant: 

  • Autotrophic

  • Eukaryotic

  • Multicellular

  • Generally adapted to a terrestrial existence

  • Have a cell wall

  • Take in carbon dioxide

  • Autotroph: an organism that makes its own food from inorganic molecules

    • From the greek auto meaning self and trophe meaning nourishing

  • Animal:

  • Heterotrophic

  • Eukaryotic

  • Multicellular

  • Take in oxygen with few exceptions

  • Theory: an explanation of a natural phenomenon supported by many observations

    • Same results occur over and over using scientific method

    • Example: gravity is a theory


Physical environment

  • Water makes all life possible

  • Fresh water is vital to life but also a finite resource

  • Most of earth's surface is water (71%)

  • 97% is saline

  • 3% is freshwater mostly in ice snow or groundwater

  • 0.9% of freshwater is from lakes and rivers

Properties of water

  • Polarity

    • In a water molecule hydrogen and oxygen have an unequal sharing of electrons

    • Hydrogen is partially positive, oxygen is partially negative, bent molecular shape at poles

    • Partial charge attracts other polar molecules, often dissolving them

  • Universal solvent

    • Water dissolves more substances than any other liquid

  • Cohesion

    • Sticks to itself

    • Creates surface tension

  • Adhesive

    • Sticks to other things

    • Helps draw water up the plant (i.e., capillary action)

Properties of water in plants

  • Water absorbed by roots and root hairs

  • Water molecules pull each other up against gravity (cohesion + adhesion + water potential)

  • Water molecules exposed to air and evaporation through pores (stomata) in leaf (process is transpiration)

  • Water and nutrients passively absorbed through roots

  • Water moves up stem in xylem tissue system and adhesion + cohesion “stickiness”

  • Water evaporates through stomata


Transportation of water through tall trees

  • Through fog 

  • Epiphyte: plant or plant-like organism that grows on another plant, but is not parasitic


Nutrients = essential compounds 

  • availability varies by biome

    • Bedrock: underlying geology (i.e., limestone has different minerals than granite)

    • Water: movement of nutrients and weathering of rock

    • Soil type: different types/sizes of soil retain nutrients better

  • 3 classes

    • Clay, silt, sand

    • Properties of sand

      • Largest particle size

      • Greatest “room in between particles (pore size)

      • Warm up faster since more air can circulate

  • Different biomes

    • Desert soils are mostly sandy

    • Little precipitation

    • little/no weathering processes

    • Release of nutrients from bedrock very slow

    • Low amounts of organic material

    • Very nutrient poor

  • Tropical

    • Soils are variable (clay loam and sand)

    • Abundant precipitation

    • Fast weathering process

    • High organic materia, quickly reused

    • Pacific soils do not trap nutrients

    • Very nutrient poor

  • Adaptation to nutrient availability

    • Plants

      • Succulent, waxy leaves

      • Root allocation

      • Spines and hairs

      • Carnivory

    • Animals

      • Structural adaptation (seabirds secrete excess nutrients through nasal cavity

      • Resource adaptation (adapting to foods where there is less competition)

      • Metabolic adaptations (freshwater fish produce lots of dilute urine, marine produce little urine that is concentrated


Light and energy

  • Happens above ground

  • All living things need energy

  • Carbon dioxide + water + light energy = glucose + oxygen

  • CO2 + H2O + sunlight = C6H12O2

  • Simplified photosynthesis definition:

    • Conversion of inorganic carbon dioxide into organic compounds using water and light energy

  • Light is energy

  • Pigments that absorb energy

    • Chlorophyll a

    • Chlorophyll b

    • Carotenoids

    • Action spectrum (most effective)

  • Wavelengths outside of the action spectrum reflect (absorb red and blue, reflects green) (why plants are green)