plants and people exam #1 week 3
Photosynthesis
-Use light energy to synthesize organic compounds (C-H) -Organic compounds store energy for the plant and other organisms to use -More bonds = More energy stored
Light-dependent reactions are very exciting!!
-Water gets split, O2 is released; electrons are freed -Electrons from H2O get shuttled around, transferring energy -What happens to the Hydrogen? -Where is the energy in the end?
Define photorespiration and describe two adaptations of plants that avoid this process and facilitate photosynthesis in different environments.
-a process by which a plant consumes O2 and releases CO2 in photosynthesis. This is especially problematic in hot dry environments when the leaves stop taking in carbon dioxide because they lose water at the same time. -adaptions with c4 plants and cam plants
Write a formula describing photosynthesis, connecting the chemical inputs and outputs in the process.
6CO2 + 12H2O + Light Energy + pigments ---> C6H12O6 + 6O2 + 6H2O
C: What products of light reactions of photosynthesis are used in the Calvin cycle?
ATP and NADPH Carbon dioxide and water ADP and photons *Glucose and oxygen ?
Which of the following can be problematic for the plant when it takes in CO2?
ATP destruction Leaf swelling Excess sugar formation *Water loss ?
The oxygen released by plants is produced by breaking down which of these compounds?
Air CO2 Soil *H2O ?
C: The oxygen that plants release in photosynthesis comes from which of the following compounds?
Air H2O CO2 Soil *All of the above ?
Englemann's experiment, 1883
Algae photosynthesizes Bacteria cluster around O2
inputs of light independent reactions
CO2, ATP, NADPH
Light-independent Reaction is Sweet!
Calvin Cycle Carbohydrates from Carbon dioxide Chloroplast is where it occurs Recycles the ATP and NADPH for use in the light-dependent reactions
Name the compound that is the primary source of chemicals for the wood in this tree. What makes up most of the dry mass?
Carbon dioxide from air
C: Which of the following compounds combine to make sugars through photosynthesis?
H2O + CO2 H2O + C6H12O6 CO2 + C6H12O6 CO2 + O2 All of the above ?
light independent in photosynthesis
High energy compounds produced in first part are used to make sugars from Hydrogen (in H2O) and CO2 Sugars store energy and can be converted to other compounds
IF-AT #8: How does this system compare to natural photosynthesis?
In both systems, O2 is being produced by splitting the water.
IF-AT #7: Which of these statements is correct?
In chloroplasts, pigments absorb light of certain wavelengths and shuttle the light energy to the chlorophyll a molecules in the center where electrons get excited.
In which of the following parts of photosynthesis is water split and oxygen released?
Light Independent Reactions Light Dependent Reactions Calvin Cycle Dark Reactions ?
light dependent in photosynthesis
Light energy comes in the form of photons Water provides electrons Photosynthesis uses light energy to form high energy chemical compounds -ATP, NADPH
C: In which reaction are sugars (C6H12O6) made?
Light-dependent *Light-independent Both Neither ?
C: Plant adaptations to reduce photorespiration in hot climates include
Making sugar from CO2 in different cells (C4 plants) Taking in CO2 and making sugar at night (CAM) *Both Neither
Photosynthesis by plants converts which of these greenhouse gases to carbohydrates?
O2 HCl *CO2 All of these
Photosynthesis occurs in which of the following?
Some bacteria Algae Plants All of the above
IF-AT #9: Which of the following correctly describes the relationship between biofuels and photosynthesis?
The production of plant material that is used in biofuels occurs during the light-dependent reactions.
Which of the following describes a process in the light-independent reactions?
Water is converted into hydrogen and oxygen CO2 is converted into sugars Cellular respiration Nothing occurs; the plant rests in the dark
A plant exchanges gases for photosynthesis through stomata in leaves If it is dry, stomata close to prevent water loss
When stomata close, no new CO2.
C: Biofuels are the only true "green" energy source
false
Distinguish between non-renewable and renewable resources.
fossil fuel is not considered renewable because it takes millions of years to form. Biofuel, on the other hand, comes from biomass, which can be produced year after year if sustainable farming practices are followed. Biomass is simply organic matter, such as kernels of corn, mats of algae, and stalks of sugar cane. This means biomass and biofuel are renewable (we can replace used biofuel over a very short period of time).
C: The photosynthetic pigment chlorophyll reflects
green light
C: The production of the plant material that is used in biofuels is made during which part of photosynthesis?
light-dependent reaction *Calvin cycle (light-independent reaction) Cellular respiration All of the above
C: Which of the following is NOT needed for plant photosynthesis?
mitochondria
C: Fossil fuels take thousands, if not millions of years to form and are therefore considered
non-renwable
autotroph
organisms that are able to harvest the carbon they need directly from inorganic compounds such as CO2. Autotrophs are the foundation of all life on earth, in that other organisms (the heterotrophs) are able to utilize only organic forms of carbon: carbon that has been fixed by autotrophs.
photoautotroph
photosynthetic, which means that they use light energy from the sun to break up CO2 molecules and make glucose, which they are then able to use to build up the organic matter that constitutes their own cellular matter and — ultimately — food for all other living organisms.
C: Throughout history, scientists have studied photosynthesis using which of these?
plants bacteria radioactive O *all of these ?
Name three types of photosynthetic organisms.
plants, algae, and certain types of bacteria
photosynthesis
process by which photosynthetic organisms use light energy to drive the synthesis of organic (Carbon) compounds from carbon dioxide. The photosynthetic process depends on a set of complex protein molecules that are located in and around a highly organized membrane.
CAM plants
(such as pineapple) also use a different enzyme to fix CO2 initially but this occurs at night when it is cooler and there is less water loss. This is a temporal (time) separation of the processes of taking in CO2 with conversion to sugars. CAM plants tend to be prickly.
Cellulosic Ethanol Feedstock
-Leftover stalk after harvest used for biofuel (20% of sorghum currently used) -The USDA reports that sweet sorghum ethanol will produce 12-16 Btus of energy compared to 1.3-1.8 from corn
C: Which of the following is a correct formula for photosynthesis?
6CO2 + 12H2O + Light C6H12O6 + 6O2 + 6H2O ?
Describe both the advantages and negative impacts of biofuel production and use. Evaluate their feasibility in reducing greenhouse gas emissions.
advantages: -sugars extracted from feedstock are easy to extract and ferment making large scale ethanol production affordable -biodiesel has reduced greenhouse emissions compared to fossil fuels -biofuels are renewable negative impacts: the use of ethanol in biofuels will result in higher and more volatile food prices and a further intensification of corn production in the u.s. -agriculture land prices have raised by $800 billion -unintended ecological consequences are a result and environmental pollution -pollution associated with corn based ethanol are often greater than by building fossil fuels
C: One advantage of biofuels compared to fossil fuels is that biofuels
are renewable and therefore more sustainable.
Explain why biofuels are not necessarily considered "green."
because they produce greenhouse gasses and green energy means it is also good for the planet because it does not harm ecosystems, contribute to acid rain, or worsen global warming.
Compare and contrast the light dependent and light-independent reactions in photosynthesis, identifying the inputs and outputs for each.
below
C: Photosynthesis fixes carbon from CO2, converting it to organic compounds that can be used to provide mechanical energy as...
biofuels
C: Which of the following helps prevent cancer?
chlorophyll pigments
C: The primary distinction between first and second-generation biofuels is related to
food sources
Biofuels are made from
plant waste from agriculture
C: Which of these is a sustainability effort at the Pacific Biodiesel plant in Hawaii that helps reduce greenhouse gas emissions?
use of local food waste.
C4 plants
(such as corn and sugarcane) use a different enzyme to fix the carbon dioxide initially and then shuttle it to special cells in the plant leaves. This increases the concentration of CO2 in those cells where the RuBisCo can bind to it. This spatially separates the processes of taking in CO2 with conversion to sugars. Many of the C4 plants are used in agriculture.
Define a biofuel and describe its relationship to photosynthesis.
-A biofuel is defined as any fuel whose energy was obtained through biological carbon fixation, such as occurs through photosynthesis. -a biofuel is made from photosynthesis
Plants can also be burned through combustion, which releases stored carbon dioxide more quickly
-Both metabolism and combustion return carbon dioxide (CO2) to the atmosphere -Is combustion of biofuels considered "green?"
Net Primary Productivity
-Cellular respiration uses stored energy in carbohydrates to do work (e.g. growing)
Describe the purpose of chlorophyll in photosynthesis and how it may support human health (part of this can be found in a study by Kim et al. 2011, at the end of photosynthesis readings).
-Chlorophyll are the green pigment of plants and also a crucial requirement for the energy processes of life. In photosynthesis chlorophyll moves out of its pigment but is replaced by an electron from water (water is then split into hydrogen and oxygen by the photosystem, creating a ready supply of electrons. -chlorophyll supports human health by assisting in exporting toxic materials -chlorophyll also processes an anti-cancer effect by reducing carcinogenic activity.
Name the compounds and structures that are used in photosynthesis and describe their respective roles.
-Co2 is required for photosynthesis growth -H20 is required -light energy -glucose
Symbiotic associations between non-photosynthesizing organisms and photoautotrophs
-Ground lichen used by Navajo weavers for dyes. -Many corals obtain food from single-celled algae called zooxanthellae, which live in their tissues -Lichen = Fungal filaments & Algae
Explain how the scientific process has been used by people throughout history to elucidate our understanding of photosynthesis.
-In the 1770s Joseph Priestley, an English chemist and clergyman, performed experiments showing that plants release a type of air that allows combustion. He demonstrated this by burning a candle in a closed vessel until the flame went out. He placed a sprig of mint in the chamber and after several days showed that the candle could burn again. Although Priestley did not know about molecular oxygen, his work showed that plants release oxygen into the atmosphere.
switch grass (second generation)
-Inside the cell long cellulose fibers provide structure and are surrounded by hemicellulose and lignin -Cellulose is very stable - difficult to break down -Cellulose is constructed of glucose (C6H12O6) molecules -Raw Feedstock e.g. Switchgrass
outputs of light dependent reactions
-O2 -ATP & NADPH
Inputs of light dependent reactions
-Photons of Light -Water
Photosynthesis & Cellular Respiration
-Plants store energy through photosynthesis. -When "burned" or metabolized, this energy is released.
photorespiration
-RuBisCo is an enzyme that helps create sugars. It can bind oxygen instead of carbon dioxide -When stomata close, no new CO2 but O2 is available. -Costly for the plant (uses ATP and NADPH) and no sugar produced
Evaluate the biofuels plant in Hawaii in terms of its sustainability, listing any questions or concerns you have about the process.
-The biofuel plant in Hawaii received the first certification for sustainability -the certification is intended to help clean fuel producers distinguish themselves to customers seeking green products
State the primary difference between first and second generation biofuels and describe the impacts.
-the primary difference between first and second generation biofuels is that first generation biofuels are made from sugars, starches, oil, and animal fat while second generation are made from non-food crop or agricultural waste like switch grass or wood chips. -First generation biofuels contain harmful chemicals like ethanol and use food crops, while second generation (often referred to as advanced biofuels) are watched on how they threaten food supply and emit greenhouse gasses.
other notes photosynthesis
-the primary source of energy for 6h20 nearly all life is the sun - key element in photosynthetic energy conversion is electron transfer within and between protein complexes and simple organic molecules. -The electron transfer reactions are rapid (as fast as a few picoseconds) and highly specific. -The thylakoid are membranes within the chloroplast. These membranes fold into disk-like structures called grana (a singular disk is called a granum). - photosynthesis depends on electron donation and acceptor reactions and that the O2 released during photosynthesis comes from the oxidation of water.
extra notes
-the production of the plant material that is used in fossil fuels occurs during light independent reactions
C: Photosynthesis is the process that uses light energy to extract hydrogen atoms from which of the following sources?
Glucose Chlorophyll CO2 Water
outputs of light independent reactions
C6H12O6, ADP, NADP+
First or second generation?
Cellulosic Ethanol crops, compared to corn crops: - more ethanol (+82%) - more grain for food (+4%) - lower N leaching (-15 to -22%) - reduced GHG emissions (-29 to -473) Davis et al. 2012 (OU Researcher/Prof)
Plant adaptations that reduce photorespiration
Convert CO2 into a transition compound Make sugars in different cells (C4) away from light-dependent reactions OR at night (CAM) when stomata can open
What is the source of chemicals needed to build photosynthates?
Experiments over the next centuries demonstrated the involvement of light & air Reaction for photosynthesis in plants: CO2 + H2O + light energy CH2O + O2 van Neil identified this reaction in purple sulfur bacteria (1928): CO2 + 2H2S + light energy CH2O + 2S + H2O These bacteria do not produce oxygen van Neil proposed this general equation for photosynthesis after studying photosynthetic bacteria: CO2 + 2H2A + light energy CH2O + 2A + H2O in plants, H2A = H2O 6CO2 + 12H2O + Light Energy C6H12O6 + 6O2 + 6H2O More evidence that the source of O2 is H2O Hill reaction (chloroplasts produce O2 without CO2) heavy isotopes of O move from H2O to O2
Sorghum
Food (Metabolism) & Fuel (Combustion)
C: The conversion of light to chemical energy is called
Photosynthesis ?
Which of the following is the most accurate description of photosynthesis?
Photosynthesis is the process by which plants and other organisms use energy from the sun to convert carbon dioxide into carbohydrates.
C: Which of the following is true of pigments used in photosynthesis?
Photosynthesizing bacteria do not have pigments A pigment absorbs all wavelengths of light Pigments absorb water for photosynthesis *In plants, they are found in chloroplasts ?
Which of the following is a source of energy for photosynthesis?
Pigments *Photons of light Oxygen Carbohydrates ?
Structures and compounds in photosynthesis
Pigments --> substances that absorb light Chloroplasts --> contain pigments, membrane Water (H20) --> electrons; hydrogen for sugars Carbon dioxide (CO2) --> converted to sugars
Van Neil proposed the equation, CO2 + 2H2S + light energy CH2O + 2S + H2O for photosynthesis in the organism he studied, which was...
Plants Algae Bacteria All of the above ?
C: The best description of a photoautotroph is
a consumer of organic matter available in other organisms. an organism that uses the sun's energy to make food from CO2 *an organism that gains energy directly from CO2 all of the above ?
Carbon fixation
a process that takes inorganic carbon (compounds such as CO2) and converts it into organic compounds (e.g. sugars)
Explain the impact of photosynthesis on climate.
the process has a profound impact on the earth's atmosphere and climate. Each year more than 10% of the total atmospheric carbon dioxide is reduced to carbohydrate by photosynthetic organisms. Most, if not all, of the reduced carbon is returned to the atmosphere as carbon dioxide by microbial, plant and animal metabolism, and by biomass combustion. In turn, the performance of photosynthetic organisms depends on the earth's atmosphere and climate.