11. Energy flows and disspitates Flashcards
What is the definition for ecosystem
Biological community and its interactions with the abiotic world
Fill in the blank: 2nd law of thermodynamics
a) ___ is always increasing (disorder at a molecular level)
b) ___ is always increasing
c) Usable energy is always is always ___ in every chemical reaction
d) T/F: Some things can be 100% efficient
e) T/F: No such thing as perpetual motion machines
f) Water turbines are amongst the ___ (most/least) efficient: ___% of gravitational energy transferred to electricity
a) Entropy
b) Disorder
c) Decreasing
d) False
e) True
f) Most, 90%
Give examples of how the 2nd law of thermodynamics relates to ecological “reactions”
Wolf eats dear, human eats meal: energy flows and dissipates (you cannot capture energy, it always flows away)
Fill in the blank: ecosystem dynamics
a) Energy ___ and ____
b) Fate of all energy is ___
c) Where does all the heat go?
d) Earth is a(n) ___ (closed/open) system re: energy
e) Pyramid of energy or net production: law of physics (See graph).
i. There will always be more energy at the ___ of the food chain than at the ___ (sun’s energy is at the ___).
ii. One of the reasons why there are so ___ (few/much) carnivores (little energy gets up to the ___ trophic levels)
a) flows and dissipates
b) heat
c) it dissipates on earth (warmer to colder)
d) open
e) i. Bottom, top, bottom
ii. few, top
Explain the 10% rule of thumb of energy flow.
When energy is passed in an ecosystem from one trophic level to the next, only 10% of the energy will be passed on. Hence, the bottom of the pyramid starts at 100%, then the second level is 10%, followed by 1%, and so on.
Give 2 examples of transfer efficiencies
Adult humans eating food: 0% Plants capturing light: 1-2% Wolves eating moose: 1.3% Hydra eating prey in lab: 7% Daphnia eating prey in lab: 13% Endothermic carnivores: 1-5% Ectothermic carnivores: 5-15% Herbivores: approximately 10% So, energy flows and dissipates!
What is better for the environment? Electronic or gasoline car? (If my electricity comes from fossil fuels)
Go with fewer conversions. But, it depends on the transfer efficiencies! Answer has changed recently: Energy efficiency of an electric car: 76% in total. Energy efficiency of a gas car: 16% (ew). Energy efficiency of burning oil for electricity: 35%.
0.76*0.35 = 26.6% > 16%
Hence, electric cars are now better than gas cars in most of the world unless your energy comes from dirty coal.
Explain how the 2nd law of thermodynamics affects conservation biology
Larger mammals have larger home ranges and need bigger parks. Example: Grizzly bears in YellowStone: MVP = 50. 50 bears require 49,000km2. YellowStone: 8991km2. Kootenay-Banff-Jasper-Yoho: 20,000km2
Consequences of 2nd law: Carnivores are rare (partly because they are big). Greater risk of extinction. Need bigger parks for protection.
What is ecological vegetarianism?
Reduce your ecological footprint by eating lower on the food chain, minimize losses to entropy, leave more space for nature, less space to produce your food.
