Lecture 5 Flashcards
What does the sun make possible?
Capture of light energy which us turned into chemical energy
Photosynthesis (pretty much all plant energy derived from this)
What would happen without photosynthesis?
Life would crash because of entropy
How many billions of metric tons of sugar are created by plants per year?
280
How does energy flow in the biosphere work?
Radiant energy from nuclear fusion of sun gets captured by chloroplasts, which uses H2O and CO2 to make carbohydrates and oxygen (a by-product).
Mitochondria dies cellular respiration and breakdowns the carbohydrate to release chemical energy (ATP) and make CO2 and H2O
What is entropy?
The measure of a system’s thermal energy per unit of temperature that is available to do something not useful
What happens in term of entropy when sugar is made?
Less (more order and less chaos)
Higher free energy
When sugar is consumed, what happens in term of entropy?
Lower free energy so increase entropy
Why do we say that energy flow is unidirectional?
With each transformation, some energy is lost to the environment
What would happen if the sun stopped shining tomorrow and why?
The world would crash and life wouldn’t exist.
Energy production is essential for life and constant input is required
What is the first intermediate of photosynthesis and what does it need to happen?
Triose sugar (3 carbon)
Needs energy from 6 H2O to convert 3 molecules of CO2
What is the end product of photosynthesis?
Glucose (6 carbon)
What do plant produce during photosynthesis and how many cycles do C3 plants do?
CH2O
3 cycles
What is anoxygenic photosynthesis?
Instead of stripping electrons off water, they use H sulphide as a substrate and produce globules of sulphur.
How was the Earth and atmosphere like before photosynthesis?
All energy on the planet was essentially conserved
Atmosphere mostly nitrogen (no O2)
What is an example of a type of living being that uses anoxygenic photosynthesis?
Purple sulfur bacteria
What were some consequences of photosynthesis?
Solar energy was its new endless supply
Oxygen produced as a by-product
Allowed for creation of biomass
When was the Great oxidation?
2.4 billion years ago
What are chemoautotrophs?
Obtain energy from oxidation of electron donors
Uses Fe2+ as an electron donor and radiant energy to assimilate CO2 into biomass
From Fe2+ to Fe3+
What is an example of chemotroph?
Iron-oxidizing bacteria
What is horizontal gene transfer?
They have homologous genes and two conjugate bacteria give their genes.
It spread its capability to distant bacterial lineage
Explain the visible light spectrum.
Spectrum of colours from violet (shortest wavelength) to red (biggest wavelength)
Small part of the electromagnetic spectrum
All radiation travels in waves
The shorter the rays, the more energy there is.
Violet rays have twice the energy of red rays
What are wavelengths?
Distance from one crest to the next
Explain the photoelectric effect.
Light energy dislodges electrons from metal atoms
The wnergy of a photon is inversely proportional to the wavelength
It is part of particle theory of light
Why do we see color in plants?
Its is the wavelength that is reflected so not absorbed by the pigment
