Lecture 16 - Energy, Organisms, and the Biosphere Flashcards
thermodynamics
transformations of energy
Explain thermodynamics in reference to sunlight and plant cells and how it is transfered to consumers
“producers”/plants absorb light energy (sunlight) and transform it into chemical energy
- > chemical energy transferred from producers to consumers
- > plant cells use chemical energy to do work such as growing new leaves
explain thermodynamics in reference to animal muscle cells
- > animal muscle cells convert chemical energy to kinetic energy
- > energy is used to do work, some is converted to thermal energy, which is lost as heat
How does energy flow through ecosystems
energy flows through ecosystems, usually entering as light, exiting as heat
Why/ how is life governed by thermodnamic laws
organisms require continuous inputs of energy to stay alive
first law of thermodynamics
energy can be transformed, but never created/destroyed
second law of thermodynamics
every transfer or transformation of energy increases the entropy (disorder) of the universe
Energy and Entropy
H = energy (enthalpy)
- > measured in Joules
S = entropy (disorder)
*Picture*
an ecosystem has more order (lower S) and has more energy (higher H) than a mixutre of atoms
describe equilibrium in terms of energy and entropy
when free energy reaches a minimum and entropy reaches maxiumum, the organisms is dead/ decomposing
- > everything is trying to break down to its simplest state
Gibb’s free energy (G)
formation of complex molecules requires __________
input of energy
- > breakdown is spontaneous
Explain bottom-ups control vs top-down control
Bottoms Up
- > concentrates attention on how resources (space and nutrients) influence higher trophic forms
Top Down
- > focuses on interactions at top level consumers (predators) and their prey influence on lower trophic forms
how does energy enter a biosphere
through producers (i.e. photosynthetic prokaryotes, protists and plants)
to maintain life organisms must _________
expend energy
Why must organisms expend energy to maintain life
- > constant energy supply/burn required for growth, repair, reproduction and activity
- > consumers obtain energy through food and use it to produce ATP (loss of heat at every step)
bioenergetics
flow and transformation of energy through an organism
Basal Metabolic Rate (BMR)
minimum metabolism of an unstressed, non-growing endotherm at rest on an empty stomach
Standard Metabolic Rate (SMR)
The minimum metabolic rate needed to sustain life at a specified temperature. The SMR is measured in organisms that are resting in a post-absorptive state and in darkened conditions.
ECTODERMS
Endotherms vs Ectotherms
Endotherms
- > organisms which use their metabolic processes to maintain their temperatures
Ectoderms
- > organisms whose body temperature is determined by external conditions
how is BMR influenced by size
there is a positive relationship between BMR and body mass
- > the amount of energy required per gram of body mass is inversely related to body size
* requires more energy consumption to maintain cells and tissues
other factors that influence metabolic demands
- > activities
- > reproduction
- > growth
Adaptations for adverse conditions
Adverse conditions
- > may become challenging for organisms to meet their energy demands
1. Hibernation - > long term topor
- > metabolism slows and body temp decreases
- > oftem inturupted by periods of arousal
2. Estivation - > slowing of metabolism and inactivity associated with summer months
