ECOL 182R Lecture Notes Flashcards

Physical Environment

• Common definitions in science.

• Topics include Water Budget, Properties of Water, Nutrients, Light & Energy.

Definitions

• Plant: Autotrophic, eukaryotic, multicellular, generally adapted to a terrestrial existence, has a cell wall, takes in carbon dioxide (CO_2).

• Autotroph: An organism that makes its own food (i.e., organic molecules) from inorganic molecules. Originates from the Greek words "auto" meaning self and "trophe" meaning nourishing. Plants convert inorganic molecules (CO2, NO3, NH4^+, SO4^{2-}) to organic molecules, while animals generally do not.

• Animal: Heterotrophic, eukaryotic, multicellular, takes in oxygen (O_2) (with few exceptions), has specialized sensory organs.

• Theory: An explanation of a natural phenomenon supported by many observations. Same results occur repeatedly using the scientific method. Example: the Theory of Gravity.

Water

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

• Most (~71%) of Earth’s surface is water.

• Water makes all life possible.

Fresh vs. Salt Water

• ~97% of Earth’s water is saline (marine).

• ~3% remaining is freshwater (most in ice/snow or groundwater).

Earth's Water Budget

• Earth's Water:

  • Saline (Oceans): 97%

  • Fresh Water: 3%

• Fresh Water:

  • Icecaps and Glaciers: 68.7%

  • Groundwater: 30.1%

  • Other: 0.9%

• Fresh Surface Water:

  • Lakes: 87%

  • Wetlands: 11%

  • Rivers: 2%

Formative Assessment: QR Codes

• Not graded or required.

• Not used for attendance or extra credit.

• Helpful for students and instructor.

• Don’t work ahead.

Properties of Water

1. Polarity

   • In water molecules (H_2O), hydrogen and oxygen have an unequal sharing of electrons.

   • Hydrogen is partially positive (H^+), oxygen is partially negative (O^-), creating a "bent" molecular shape at "poles."

   • Partial charges attract other polar molecules, often dissolving them.

   • Water dissolves MORE substances than any other liquid.

2. Universal Solvent

   • Water dissolves more substances than any other liquid.

3. Cohesion

   • "Cohesion": sticks to itself (water molecules are "sticky").

   • Creates surface tension.

4. Adhesion

   • "Adhesion": sticks to other things, adhering.

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

Water Transport in Plants

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

• Water absorbed by roots and root hairs.

• Water molecules exposed to air and evaporate through pores (i.e., stomata) in leaf (process is transpiration).

Water Transport in Plants (Continued)

• Water and nutrients passively absorbed through roots via osmosis.

• Water moves up the stem in xylem tissue system (capillary action) and adhesion + cohesion "stickiness."

• Water evaporates through stomata (transpiration).

Transport in REALLY TALL Plants

• Since nutrients are absorbed through roots, and water moves up stem against gravity, how is it possible that redwood trees are so tall (300+ ft)?

Nutrients

• Essential Compounds and Their Functions:

  • Nitrogen (N)*: Proteins, nucleic acids.

  • Phosphorous (P)*: Nucleic acids, phospholipids, bone.

  • Sulfur (S): Proteins.

  • Potassium (K)*: Solute in animal cells.

  • Calcium (Ca): Bone, plant cells, cell permeability regulator.

  • Magnesium (Mg): Chlorophyll, enzymes.

  • Iron (Fe): Hemoglobin, enzymes.

  • Sodium (NA): Solute in animals.

Nutrients: Availability Varies by Biome

• Bedrock: Underlying geology (e.g., limestone has different minerals than granite).

• Water: Movement of nutrients and weathering of rock.

• Soil Type: Different types/sizes of soil retain nutrients better.

Nutrients: Availability Varies by Soil Type

• Three classes of soil types: clay, silt, sand.

• Properties of sand:

  • Largest particle size.

  • Greatest "room" in between particles (pore size).

  • Warm up faster since more air can circulate.

  • Composed of silica ("glass"), does not adhere to other molecules well.

Different Biomes = Different Challenges

• Desert

  • Desert soils are mostly sandy.

  • Little precipitation.

  • Little/no weathering processes.

  • Release of nutrients from bedrock is very slow.

  • Low amounts of organic material.

  • Very nutrient poor.

• Tropical Rain Forest

  • Tropical soils are variable (mixture of clay, loam, and sand types).

  • Abundant precipitation.

  • Fast weathering processes.

  • High organic material, quickly reused.

  • Acidic soils do not trap nutrients.

  • Very nutrient poor.

Adaptations to Nutrient Availability: Plants

• Succulent, waxy leaves.

• Spines & hairs.

• Carnivory.

• Root allocation is also essential for plants.

Adaptations to Nutrient Availability: Animals

• Structural adaptations: e.g., seabirds secrete excess nutrients through the nasal cavity.

• Resource adaptations: e.g., adapting to foods where there is less competition.

• Metabolic adaptations: e.g., freshwater fish produce lots of dilute urine, marine produce little urine that is concentrated.

Resource Locations

• Water & Nutrients: Underground (Root, Water, Minerals).

• Light & Energy: Aboveground (Sunlight, Oxygen, Glucose, Light Energy, Carbon Dioxide).

Energy Needs

• All living things need energy.

  • Solar energy.

  • Photosynthesis: 6CO2 + 6H2O \rightarrow C6H{12}O6 + 6O2 (carbon dioxide + water yields glucose + oxygen).

Photosynthesis: Overview

• CO2 + H2O + sunlight \rightarrow C6H{12}O6 + O2

• Carbon dioxide + water + light energy -> glucose + oxygen

• Simplified Photosynthesis Definition: Conversion of inorganic carbon dioxide into organic compounds using water and light energy.

Light is Energy

• Electromagnetic Spectrum of Light.

• Plants have specialized molecules that absorb some light wavelengths.

• Action Spectrum: Chlorophyll a (Chla), Chlorophyll b (Chlb), Carotenoids. Most effective wavelengths (λ): blue and red.

• What happens to wavelengths outside of the “action spectrum” (between ~500-650 nm)?

Summary

• Water has unique properties that allow life to sustain on Earth (e.g., solvent, adhesion, cohesion).

• Nutrients are made available via several properties that shape biome characteristics and influence plant and animal adaptations.

• Light & Energy: As all life requires energy, photosynthesis is the main process used by plants to convert light energy into chemical energy.