Download Photosynthesis and Respiration: Providing Matter and Energy

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TOC#_____ Photosynthesis and Respiration: Providing Matter and Energy Read and highlight/annotate the reading on the left. Take notes about what you are reading on the right. Why do plants do photosynthesis? Ultimately, all energy used by organisms to produce the building blocks of life and to drive life processes originated as solar energy. This energy was captured by plants during photosynthesis. Only a small fraction, less than 2 percent, of the total solar light energy received by a plant is absorbed and transformed by photosynthesis into energy­containing organic molecules (glucose). The rest of the sun’s energy passes out of the plant as heat. Because plants do not rely on other organisms to provide their energy needs, they are referred to as primary producers, or autotrophs (meaning “self­feeding”). In addition to light energy, plants must absorb water, carbon dioxide gas, and simple nutrients, such as nitrate and phosphate, to produce various organic molecules during photosynthesis. Oxygen gas is also produced as a waste product. What do plants do with the glucose (high energy matter)? Have you ever stood next to a Giant Sequoia tree in California and wondered how this tree got to be so big? Some Giant Sequoias are more than 2000 years old and can weigh over 2 million pounds (987,185 Kg) and grow to be over 300 ft tall. Think about it! That's a lot of biomass added as the tree grows from a tiny Sequoia seed to a mature tree! Where does all that biomass come from? Watch this video: ​
http://richannel.org/where­do­trees­come­from Sugars are the first energy­containing organic molecules produced in photosynthesis, and they can be changed to other, more complex, molecules, such as starches, proteins, and fats that the plant needs. The energy in the sugar molecules can be used immediately by the plants to maintain their own respiration needs, stored as starches and fats, or can be converted to new plant tissue. It is the stored organic matter plus new tissue that contributes to the growth of plants and to biomass. What is Biomass Biomass is the amount of organic matter, such as animal and plant tissue, found at a particular time and place. Plant and animal biomass consists mostly of carbon­rich molecules, such as sugars, starches, proteins, and lipids, and other substances, such as minerals, bone, and shell. The carbon­rich organic molecules (like sugar) are not only the building blocks of life but also the energy­rich molecules used by organisms to fuel their activities. Notes: So how does photosynthesis lead to more biomass/plant structure? ​
So, here is what a tree must do to build itself: 1. Absorb carbon dioxide (CO2) from the air via photosynthesis. 2. Use the CO2 absorbed from the air and H2O drawn up from the roots to make glucose sugar molecules ­ a carbon­compound. 3. Do cellular respiration with some of the glucose sugar molecules for the energy needed by the tree to carry out all of its life functions. Release some CO2 to the air as a by­product of cellular respiration. 4. Break the remaining glucose sugar molecules apart and combine the carbon atoms with hydrogen, oxygen, nitrogen, phosphorus, and sulfur atoms to build complex organic carbon compounds such as carbohydrates, proteins and nucleic acids (DNA and RNA) which help the plant function and produce more biomass. How does photosynthesis connect to ecosystems? Animals are heterotrophs; they cannot carry out photosynthesis. This means that they have to eat other things to get the carbohydrates, fats, proteins, vitamins and minerals which they need.​
One way to think about how energy is used and stored within an ecosystem is: Carbon In, Carbon Out and Carbon Stored. Carbon atoms are continually on​
the move into and out of air, trees and soil. Carbon atoms do not move as single atoms but instead move as part of carbon­compounds such as carbon dioxide (CO​
) or 2​
glucose (C​
H​
O​
). Photosynthesis and cell respiration are critical to 6​ 12​ 6​
moving carbon atoms into and out of trees and other plants whereas biosynthesis is critical to building the biomass of trees and storing carbon. Photosynthesis​
is the key carbon cycle process that moves carbon atoms from the air into trees and all other plants. Carbon atoms move into the biosphere via this process. Respiration​
is the key carbon cycle process that moves carbon atoms out of plants into the atmosphere, soil or water. All organisms, not just plants, carry out cell respiration. In plants, the difference between carbon uptake via photosynthesis and carbon release via respiration is called ​
net carbon uptake​
and is the amount of carbon that gets stored. Biosynthesis​
the carbon cycle process ALL organisms use to build new carbon compounds from the carbon atoms it takes in via photosynthesis and eating food. In order for a tree to gain biomass, grow and store carbon, trees need to take in more carbon atoms during photosynthesis than they release during cell respiration. These extra carbon atoms are used for biosynthesis of organic carbon­compounds necessary to life. For example, the cellulose molecule on the right is produced via the process of biosynthesis.