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Quiz Friday!. covering: the physical environment biomes physiological ecology (today and Wednesday). Physiological Ecology. Two themes : Homeostasis – maintenance of constant internal conditions in varying environments Adaptation of organisms to specific environments. Three big problems.

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Quiz friday
Quiz Friday!

covering:

  • the physical environment

  • biomes

  • physiological ecology (today and Wednesday)


Physiological ecology
Physiological Ecology

Two themes:

  • Homeostasis – maintenance of constant internal conditions in varying environments

  • Adaptation of organisms to specific environments


Three big problems
Three big problems

  • Obtaining energy and nutrients

  • Maintaining temperature

  • Obtaining and holding onto water




Autotrophs – acquire energy from sunlight or chemicals in the environment

  • Chemosynthetic autotrophs:

    • obtain energy from inorganic chemicals like methane or hydrogen sulfide

    • sea-vent bacteria

  • Photosynthetic autotrophs:

    • combine energy from sunlight and CO2 to make sugars

    • many bacteria, some protists (algae), and nearly all plants


Chemical equation for photosynthesis:

energy + 6CO2 + 6H2O → C6H12O6 + 6O2

(sunlight) (from air) (from soil) (sugar) (to air)


Question 1. Interpret this graph

Overstory plant

Rate of photosynthesis

Understory plant

Light level


  • All organisms store and use energy in the form of carbon compounds

  • Respiration – the process of breaking up carbon compounds to release CO2 and energy

C6H12O6 + 6O2→ energy + 6CO2 + 6H2O


  • Other important nutrients (and their uses)

    • Nitrogen - proteins

    • Phosphorus – many chemicals

    • Sulfur – proteins

    • Potassium – ion in cells

    • Calcium – bone, wood, cell signalling

    • Magnesium – chlorophyll, enzymes

    • Iron – hemoglobin, enzymes

  • Lack of nutrients can limit plant growth





  • Water moves freely across cell membranes as

  • Relative to the outside environment, a cell can be:

    • hypo-osmotic: having a lower solute concentration than the environment

    • hyperosmotic: having a higher solute concentration than the environment

    • iso-osmotic: having the same solute concentration as the environment


If left unchecked, osmosis will lead to equilibration of solute concentrations in and outside of cells

Hypo-osmotic Iso-osmotic Hyperosmotic


Question 2. What happens to the slugs? solute concentrations in and outside of cells



Transpiration concentrations of solutes in cells (homeostasis).– when plants lose water to the atmosphere as they obtain CO2

Transpiration


Plants must take up water at their roots to make up for transpiration

Plants use osmotic potential to draw water into their roots (root cells are hyperosmotic)

Water is pulled up through the xylem into the leaves.

Water leaves the plant through the stomata (transpiration).




Today
Today: transpiration

  • Finish up water relations

  • Temperature

  • The bigger picture


Question 1. Interpret this graph transpiration

Overstory plant

Rate of photosynthesis

Understory plant

Light level



CO transpiration2 + RuBP → 2 PGA → sugar

(1 carbon) (5 carbons) (3 carbons)

  • Normal photosynthetic pathway:

  • Requires a lot of CO2, so stomata must be open, allowing water loss

  • Water loss is a big problem in dry places


C transpiration4 Photosynthesis – spatial separation

  • Mesophyll cell, near leaf surface:

  • Bundle sheath cell, in leaf interior:

  • Occurs in many plants found in hot, dry places (corn)

CO2 + PEP → OAA (reaction requires little CO2)

(1 carbon) (3 carbons) (4 carbons)

OAA → PEP + CO2 → photosynthetic pathway

(4 carbons) (3 carbons) (1 carbon)


  • CAM Photosynthesis transpiration – temporal separation (Crassulacean Acid Metabolism)

  • Nighttime reaction (stomata open):

  • Daytime reaction (stomata closed):

  • Occurs in succulent plants, cacti

CO2 + PEP → OAA

(1 carbon) (3 carbons) (4 carbons)

OAA → PEP + CO2

(4 carbons) (3 carbons) (1 carbon)


Water Acquisition in Animals transpiration

  • Wet environments

    • drinking

    • absorbing from the environment (amphibians)

  • Dry environments

    • metabolic water (C6H12O6 + 6O2→ 6CO2 + 6H2O)

    • water in food sources (insectivores)

    • water reabsorbed in digestive/excretory systems


Water Balance in Marine Animals transpiration

  • Marine invertebrates maintain iso-osmotic internal solute concentrations equal to seawater

  • Marine fish are hypo-osmotic compared to seawater.

    • they gain solutes and lose water

    • solutions:

      • constant drinking

      • secreting salt into the water



  • Water Balance in Freshwater Fish blood, making them iso-osmotic compared to seawater.

  • Freshwater fish are hypo-osmotic compared to water and absorb water continuously.

  • They excrete large quantities of diffuse urine while actively retaining salts.


Organisms in variable environments adjust their solute levels based on the salinity of the water.


Temperature

Temperature levels based on the salinity of the water.


Why does temperature matter? levels based on the salinity of the water.


  • At hot temperatures levels based on the salinity of the water.

    • biological processes speed up

    • proteins and other organic compounds may break down

  • At cold temperatures

    • ice crystals may damage or destroy cells

    • life processes slow or stop


  • Homeothermic levels based on the salinity of the water. organisms maintain constant body temperature (birds and mammals)

  • Poikilothermic organisms have varying body temperature, in response to external temperatures (all other animals)

  • BUT poikilothermic animals may regulate their body temperature…


  • Endothermy levels based on the salinity of the water. – body heat generated internally

  • Ectothermy – body heat generated externally

  • Most ectotherms regulate their body temperature by

    • basking

    • moving between shade/sun

    • being active at certain times of day



  • Countercurrent Circulation levels based on the salinity of the water.

  • Reduce rate of heat loss to the environment by creating a temperature gradient.

  • Heat is transported from arterial blood leaving the body to venous blood returning to the body.


Optimum levels based on the salinity of the water. – narrow range of environmental conditions to which an organism is best suited


Each organism has an optimum environment… levels based on the salinity of the water.

Local optimum:


  • Sugar maple:

  • summer temps: below 24ºC

  • winter temps: above -18ºC

  • annual precip.: > 50 cm




Quiz friday1
Quiz Friday! precipitation and temperature

covering:

  • the physical environment

  • biomes

  • physiological ecology (slides on the website later today)


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