8. Which wavelengths do our eyes respond to, and why? About how long are short ultraviolet wavelengths to microwave lengths?
Our eyes only respond to the wavelengths in the range of visible light, which is from 0.4 μm to 0.7 μm. From the beginning of ultraviolet wavelengths to the longest microwave lengths is from 10 nm to about 1 cm.
correct, why do you think this is so?
Is this because of evolution? Unlike bees, we aren't looking for flowers to ensure our survival, so it would make sense then that not needing to see in other wavelengths causes us to lose the ability to do so (assuming we ever had it).
9. Where do extremophiles live? How do they get the energy they need for survival?
Extremophiles are organisms that gain their energy through chemosynthesis, or the extraction of inorganic chemical compounds.
Instead of?...
...photosynthesis, which is usually how other primary producers in an ecosystem start the supply of energy.
They thrive in extreme environments such as in the Earth's crust, on the ocean floor, and in hot springs. The energy that they collect help to fuel an ecosystem deep underwater near thermal vents, as they supply the initial energy that will eventually be cycled up the food chain.
10. Ecosystems require energy to function. From where does this energy come? Where does it go?
All the energy in an ecosystem stem from the sun at the most basic level. Primary producers (which are mostly all plants, organisms that can perform photosynthesis) are at the most basic trophic level, being able to extract energy directly from sunlight. As these plants are eaten by herbivores, the energy is cycled up a trophic level to primary consumers. Carnivores that prey on herbivores would then be secondary consumers in the ecosystem, getting energy again from the previous trophic level. However, the efficiency for this process is not very high, as much as 90% of the energy is lost for every change in level.
true. could you say that all energy on this planet (including geothermal and nuclear) is ultimately from the sun?
Think: nuclear is from isotopes borne in a supernova, and geothermal is from nuclear reactions deep in the earth's core...
I suppose then that the sun supplies most of the energy to primarily biological organisms on Earth? Nuclear and geothermal are forms of energy only harnessed recently, and even then only by humans.
11. How do green plants capture energy, and what do they do with it?
Green plants possess chloroplasts which contain chlorophyll that plants use to conduct photosynthesis. A light-dependent reaction happens that takes water and carbon dioxide (along with other lipids, sugars, proteins, and nucleotide molecules) and turns it into sugar and oxygen. This sugar stores energy in its chemical bonds, and when it is cycled up the trophic levels, organisms higher up in the chain conduct cellular respiration to release this stored energy.
Ok. Why do plants do this miraculous process? What is the advantage of doing this, and does it ever change?
They perform photosynthesis to create glucose for themselves to sustain life? I'm not sure I fully understand which direction you're pushing me for this..
12. Define the terms species, population, and biological community.
Species is all the organisms of the same kind that can interbreed to produce fertile offsprings. A population consists of all the members of a species in a select area at a given time. A biological community includes all the populations of all organisms in an area.
Ok, so what is a mule, mister Nebraska corn husker dude?
A hybrid? There is no scientific classification for such a species.
13. Why are big fierce animals rare?
Large animals are very high up in trophic levels and require lots of energy to survive. However, as only about 10% of energy is available for every trophic level from the previous one, a huge amount of land (and thus, area and space) is required to have enough plants to provide the sufficient energy at the very first trophic level to make its way up to the top predator.
Ok. does this then explain why dinosaurs went extinct, while alligators did not? (hint: alligators can eat decaying meat from the bottom of swamps)
Some dinosaurs were herbivores, some omnivores, and some carnivores. Did they occupy different niches in their ecosystem as well? A dinosaur that was a large herbivore would be feeding directly off the plants (though the amount that they must consume to sustain their size must be massive still). Alligators are much smaller than some species of dinosaurs too..
14. Most ecosystems can be visualized as a pyramid with many organisms in the lowest trophic levels and only a few individuals at the top. Give an example of an inverted numbers pyramid.
The amount of bacteria as a function of time can be envisioned as an inverted numbers pyramid. If a certain species of bacteria doubles every 36 hours, then one can envision each step to represent a 36 hour block, and each block up would be twice the width of the previous one.
Hmmmm....not sure
Better than Mariko's tree example at least?
15. What is the ratio of human-caused carbon releases into the atmosphere shown in figure 2.22 compared to the amount released by terrestrial respiration?
Humans release a total of about 7 gigatons of carbon into the atmosphere every year while terrestrial respiration releases a combined 100 gigatons of carbon into the atmosphere. While the amount of carbon released by humans may seem insignificant, the problem is that this extra amount of carbon is not being offset by photosynthesis, hence the steady increase of carbon dioxide in the atmosphere for the last 150 years.
exactly. couple this with the positive feedback loops we were discussing, and you have a serious runaway situation...
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