BIOL 1500 Chapter Notes - Chapter 7: Photosynthesis, Light-Independent Reactions, Rubisco

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Unit 7 BIOL1500 February 28th, 2016.
TEXTBOOK: 87-102
Photosynthesis and Climate Change
5.1 The Greenhouse Gas Effect
-global warming is the progressive increase of Earth’s average temperature that has been
occurring in the past century. The average temperature is warming and is due to humans.
-global climate change is the local changes in average temp., precipitation and sea level
relative to historical conditions, humans have drastically impacted the rate of change.
-the greenhouse gas effect is the presence of Co2 in the atmosphere (and other
greenhouse gases like methane) warmth from the sun heats Earth’s surface, and radiates
heat outward. Most heat is radiated into space but some warms up the greenhouse gases
in the atmosphere and radiates into Earth’s surface. To an extent, this process is normal
and needed for earth, however, the danger is the amount of Co2 in excess.
(a) Water, Heat and Temperature: bodies of water absorb energy to maintain
temperatures. Heat is the total amount of energy associated with the movement of atoms
and molecules in a substance. Temperature is a measure of the intensity of heat. The
formation of Hydrogen bonds make water more cohesive and resistant to temperature
change. (heat energy disrupts hydrogen bonds) As temperature rises, individual H2O
molecules can move fast enough to break free of hydrogen bonds and rise as water
vapour. When the water cools, hydrogen bonds reform and releases heat.
5.2 The Flow of Carbon
-Co2 taken up by plants, algae, and bacteria is converted into carbohydrates by sunlight,
organisms depend on these as cellular energy and release Co2 by consuming them,
combustion by humans is creating the most issues
-the stored carbohydrates are called fossil fuels (petroleum, coal, natural gas) formed
from the buried remains of ancient plants and microorganisms
-these carbohydrates were transformed by heat and pressure in earth’s crust into highly
concentrated energy sources, in humans using these as energy, we have released millions
of years of stored carbon into the atmosphere as Co2
-the current levels are the highest they’ve ever been, past comparisons are measured
using ice sheets
5.3 Can Photosynthesis Slow Down Global Climate Change?
-Photosynthesis is the process that traps light energy from the sun and uses it to convert
carbon dioxide into water and sugar (transforms solar energy to chemical energy)
(b) The Process of Photosynthesis: Co2+H2o+Light Energy Glucose+ Oxygen
-use carbohydrates to grow/supply energy to their cells, any excess is stored in the body
of the plant and can become raw material for fossil fuel production
-the 1st step harvests energy from the sun during light reactions which occur when there
is sunlight. Reactions occur within thylakoids of chloroplast and generate ATP and
energized electrons which are transported around the cell via NADPH.
-Second (synthesis) step called the Calvin Cycle uses the ATP and NADPH generated by
light reaction to synthesize sugars from Carbon dioxide. Can occur with or without
sunlight.
5.4 How High Temperatures Might Reduce Photosynthesis
-leads to higher temperatures which leads to more evaporation
-Co2 enters the leaves of land plants through tiny openings called stomata which are
openings surrounding by kidney shaped cells called guard cells. When the guard cells
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