Exam 2 Flashcards
Physical Limitations to Life
Temperature (Heat, Cold) Water Gas exchange Light Body size Metabolism (Energy acquisition, Energy use) Nutrient acquisition Waste elimination
Physical Ecology of the Organism
The physical environment can affect abundance and distribution of species
Organisms adapt to their environment
Temperature
Enzymes work best in a narrow temperature range
Freezing destroys cells
Heating de-natures proteins
Temperature affects water balance
Water balance affects temperature
Light levels affect temperature
Temperature affects metabolism
Organisms regulate their body temperatures
Several different strategies are used (slides 10-17, 20-21 lec 9)
Temperature
Cold-blooded/warm-blooded:
- animals are cool/warm to the touch
Temperature
Poikilotherm:
- body temperature varies
slide 24 lec 9
Temperature
Homeotherm:
- body temperature stays constant
Temperature
Endotherms:
- generate heat internally via metabolism
Temperature
Ectotherms:
- require an external heat source
Organisms gain and lose heat many ways
Conduction
Radiation
Convection
Evaporation
(Slide 28 lec 9)
Conduction:
- Two objects in direct contact
E.g. a lizard basking on a hot rock
Radiation
- Energy gained as light —> heat
- Energy lost as heat
Convection
- Heat transfer between 2 bodies through a liquid or gas layer
Evaporation
- Water requires much energy to become gas
- Water can remove excess heat from the body
- But water loss can lead to dehydration —> over-heating
Counter-Current Heat Exchange: Staying Warm
Animals in cold climates could radiate significant heat through limbs (a)
Run warm arterial blood next to colder venous blood to warm it up (b)
(Slide 29 lec 9)
Counter-Current Heat Exchange: Staying Cool
Evaporation through nose/mouth rete cools venous blood before it returns to heart
Run warm arterial blood past cooled venous blood
Rete cools blood before it reaches the rest of the body
(Slide 30 lec 9)
There is a relationship between metabolic rate and rate of acceleration of chemical reactions
This is the temperature coefficient, a.k.a. Q10
The Q10 shows…
The Q10 shows the effect of temperature on the organism’s function
For ectotherms, metabolism (O2 use) increases with temperature
As the organism warms up, it becomes more active (uses more oxygen)
Q10 =
= the rate of biological processes generally increases 2-4 times per each 10°C increase (in normal physiological range)
Organisms have the ability to acclimate to new environmental conditions
Acclimation takes time; sudden change can lead to death
Acclimation can allow the organism to tolerate higher/lower temperatures than it normally would
Organisms can adapt to cold
Fish have developed antifreeze proteins
Plants have multiple adaptations including antifreeze proteins, supercooling, ice crystal nucleating agents OUTSIDE of cells.
Reptiles and invertebrates can supercool (no ice crystals form) due to glycoproteins
Size and Shape of Organisms
Size of organisms affects aspect of their lives
Larger animals have relatively less surface area (to volume) than smaller animals
The smaller “organism” has relatively more surface area
The larger “organism” has relatively less surface area
(Slide 38-42)
Surface area is important for:
Gas exchange
Heat absorption
Heat loss
Water loss
Surface Area
Leaf size and shape affect:
Heat exchange
Transpiration
Photosynthesis
Photosynthesis
6 CO2 + 12 H20 –> C6H12O6 + 6 O2 + 6 H2O
2-part process:
Light reaction: sun needed directly to produce ATP and NADPH
Dark reaction: CO2 made into simple sugars (G3P, glucose, starch); can occur without sunlight