Photosynthesis

Chlorophyll (definition)

A light-absorbing pigment in chloroplasts that plays a central role in converting solar energy to chemical energy.

Photosystem (definition)

A light-harvesting unit of a chloroplast's thylakoid membrane; consists of several hundred molecules, a reaction-center chlorophyll, and a primary electron acceptor.

NADPH (Nicotinamide Adenine Dinucleotide Phosphate) (definition)

An electron carrier (a molecule that carries electrons) involved in photosynthesis. Light drives electrons from chlorophyll to NADP+ forming NADPH, which provides the high-energy electrons for the reduction of carbon dioxide to sugar in the Calvin Cycle.

Chloroplast (definition)

An organelle found in plants and photosynthetic protists. Enclosed by two membranes, a chloroplast absorbs sunlight and uses it to power the synthesis of organic food molecules.

Photoautotrophs (definition)

Are the producers for most ecosystems. Not only feed but cloth us. Example: clothes=cotton fiber. house=wood. etc

_____ releases energy that is used to pump hydrogen ions from the stroma into the thylakoid compartment. (homework)

B: The energy released as electrons are passed along the electron transport chain is used to pump protons into the thylakoid compartment.

What is the main purpose of photosynthesis?

Best Answer Photosynthesis is the ultimate source of energy for nearly every ecosystem on Earth. Its purpose is to transform light energy into chemical energy with Co2 and H2o as starting material and O2 as a byproduct. additional... To convert radiant energy from the sun into chemical energy that can be used for food.

Calvin Cycle (definition)

The second of two stages of photosynthesis; a cyclic series of chemical reactions that occur in the stroma of a chloroplast, using the carbon in CO2 and the ATP and NADPH produced by the light reactions to make the energy-rich sugar molecule G3P, which is later used to produce glucose.

The product of photosynthesis is (homework)

sugar

Chlorophyll B (definition)

is very similar to chlorophyll a, absorbs mainly blue and orange light, and conveys absorbed energy to chlorophyll a.

Chlorophyll A (definition)

participates directly in the light reactions and absorbs mainly blue-violet and red light.

Why are most plant leaves green?

-The selective absorption of light by leaves explains why they appear green to us; light of that color is poorly absorbed by chloroplasts and is thus reflected or transmitted toward the observer. -Chlorophyll and other pigments in chloroplasts reflect or transmit green light while absorbing other colors.

Stage 1, Light Reactions pt 4

1) Photons excite electrons in the chlorophyll of the first photosystem. These photons are then trapped by the primary electron acceptor. This photosystem then replaces the lost electrons by extracting new ones from water. This is the step that releases O2 during photosynthesis. 2) Energized electrons from the first photosystem pass down an electron transport chain to the second photosystem. The chloroplast uses the energy released by this electron "fall" to make ATP. 3) The second photosystem transfers its light-excited electrons to NADP+, converting it to NADPH.

Approximately what wavelength of light is best absorbed by chlorophyll a, the pigment that participates directly in the light reactions? (homework)

435 nm

Which wavelength of light is best absorbed by chlorophyll b? (homework)

455 nm

Which equation best summarizes photosynthesis? (homework)

6 CO2 + 6 H2O → C6H12O6 + 6 O2

Chlorophyll can be found in _____. (homework)

A and C: The photosystems contain chlorophyll.

Carbohydrate (definition)

A biological molecule consisting of a simple sugar (a monosaccharide), two monosaccharides joined into a double sugar (a disaccharide), or a chain of monosaccharides (a polysaccharide).

Photon (definition)

A fixed quantity of light energy. The shorter the wavelength of light, the greater the energy of a photon.

ATP (adenosine triphosphate) (definition)

A molecule composed of adenosine and three phosphate groups; the main energy source for cells. A molecule of ATP can be broken down to a molecule of ADP (adenosine diphosphate) and a free phosphate; this reaction releases energy that can be used for cellular work.

ADP (adenosine diphosphate) (definition)

A molecule composed of adenosine and two phosphate groups. The molecule ATP is made by combining a molecule of ADP with a third phosphate in an energy-consuming reaction.

Reducing Agent (definition)

A molecule that can donate electrons. A reducing agent reduces the molecule that it donates electrons to.

Turgor or Plant Turgor

A plant cell is turgid (very firm) and healthiest in a hypotonic environment, with a net inflow of water. Although the elastic cell wall expands a bit, the back pressure it exerts prevents the cell from taking in too much water and bursting. Turgor is necessary for plants to retain their upright posture and the extended state of their leaves.

Stoma, or stomate (plural stomata) (definition)

A pore surrounded by guard cells in the epidermis of a leaf. When stomata are open, CO2 enters the leaf, and water and O2 exit. A plant conserves water when its stomata are closed.

ATP Synthase (definition)

A protein cluster, found in a cellular membrane (including the inner membrane of mitochondria, the thylakoid membrane of chloroplasts, and the plasma membrane of prokaryotes), that uses the energy of a hydrogen ion concentration gradient to make ATP from ADP. An ATP synthase provides a port through which hydrogen ions (H+) diffuse.

Electron Transport (definition)

A reaction in which one or more electrons are transferred to carrier molecules. A series of such reactions, called an electron transport chain, can release the energy stored in high-energy molecules such as glucose.

Electron Transport Chain (ETC) (definition)

A series of electron carrier molecules that shuttle electrons during a series of chemical reactions. These reactions release energy that is used to make ATP; located in the inner membrane of mitochondria, the thylakoid membrane of chloroplasts, and the plasma membrane of prokaryotes.

Electron (definition)

A subatomic particle with a single unit of negative electrical charge. One or more electrons move around the nucleus of an atom.

Stroma (definition)

A thick fluid enclosed by the inner membrane of a chloroplast. Sugars are made in the stroma by the enzymes of the Calvin Cycle.

_____ splits water into 1/2 O2, H+, and e- . (homework)

A: Photosystem II splits water into 1/2 O2, H+, and e- .

Chemical Cycling between Photosynthesis and Cellular Respiration (book)

Book Note: The reactants of photosynthesis-carbon dioxide (Co2) and water (H2o) are the same as the waste products of cellular respiration. Also the photosynthesis produces what respiration uses- glucose (C6H12O6) and oxygen (O2). Photosynthesis recycles the "Exhaust" of cellular respiration and rearranges its atoms to produce food and oxygen.

Energized electrons from ____ enter an electron transport chain and are then used to reduce NADP+. (homework)

C: Energized electrons from photosystem I are used to reduce NADP+.

Deforestation

Deforestation which removes a lot of photosynthetic plant life, thereby reduces the ability of biosphere to absorb carbon.

Which of these phosphorylates ADP to make ATP? (homework)

E: ATP synthase phosphorylates ADP.

Isotonic (definition)

Having the same solute concentration as another solution. (Note: a plant cell immersed in an isotonic solution is flaccid (floppy), and the plant wilts.)

Photosynthesis Harnesses Sunlight to Make Carbohydrates (professor slide)

Photosynthesis converts electromagnetic energy to chemical energy - Requires sunlight, carbon dioxide, and water - Produces oxygen as a by-product • The overall reaction is CO2 + H2O + light energy →→→C6H12O6 + O2 • It is the opposite of cellular respira0on

Hydrogen Ion (H+) / Proton (definition)

Hydrogen ion, otherwise known as a proton. The atomic number of hydrogen is 1, meaning that it has only one proton in its nucleus. A positively charged hydrogen atom (H+) has lost its only electron and is an ion, meaning that its one proton in its nucleus gives it a positive charge of +1. Hydrogen does not have neutrons unless it is an isotope, so an H+ ion consists of only one proton. For this reason, the terms proton and H+ are used interchangeably most of the time in biology.

Hypertonic (definition)

In comparing two solutions, referring to the one with the greater concentration of solutes.

Hypotonic (definition)

In comparing two solutions, referring to the one with the lower concentration of solutes. (Note: plant cells thrive in a hypotonic environment.)

Light Reactions (definition)

In the light reactions, chlorophyll in the thylakoid membranes absorbs solar energy (the "photo" the part of photosynthesis), which is then converted to the chemical energy of ATP (the molecule that drives most cellular work) and NADPH (an electron carrier). During the light reactions, water is split, providing a source of electrons and giving off O2 gas as a by-product.

Stage 1, Light Reactions pt 3

In the thylakoid membrane, chlorophyll molecules are organized with other molecules into photosystems. Each photosystem has a cluster of a few hundred pigment molecules. This cluster of pigment molecules functions as a light-gathering antenna. When a photon strikes one of the pigment molecules, the energy jumps from molecule to molecule until it arrives at the reaction center of the photosystem. The reaction center consists of chlorophyll a molecules that sit next to another molecule called primary electron acceptor. This primary electron acceptor traps the light-excited electron from the chlorophyll a in the reaction center.

Describe the process of photosynthesis including what goes into (reactants), and what comes out of (products), both major stages. Where does each stage occur?

Light Reactions Inputs: H2o, Light, NADP+, ADP, Outputs: O2, ATP, NADPH Calvin Cycle: Inputs: Co2, ATP, NADPH, Outputs: 3 Carbon Sugar, ADP, NADP+ 2 Major Stages 1) The light reactions capture sunlight and store it in high-energy molecules (ATP and NADPH). - Occurs: thylakoid membrane 2) The Calvin Cycle uses those high-energy molecules to produce sugar. - Occurs: stroma

Producers (definition)

Most ecosystems depend entirely on photosynthesis for food. For this reason, biologist refer to plants and other autotrophs as producers. (Formal Definition: An organism that makes organic food molecules from carbon dioxide, water, and other inorganic raw materials: a plant, alga, or autotrophic bacterium; the trophic level that supports all others in a food chain or web).

Which of the following is produced by the light reactions of photosynthesis and is consumed by the Calvin cycle? (homework)

NADPH

____ and ____ store energy from the light reactions for use in the Calvin cycle. (homework)

NADPH and ATP

Do plants turn carbon dioxide into oxygen?

No In what stage is O2 produced? Light reactions. Plants "split apart" H2o molecules in order to obtain "electron rich" H+ ions. The excess oxygen is released as a by-product. Is this why plants need water? Yes. Without water, the plant would not be able to gather enough energy and would therefore not survive. OXYGEN IS A WASTE PRODUCT IN PHOTOSYNTHESIS.

Thylakoid (definition)

One of a number of disk-shaped membranous sacs inside a chloroplast. Thylakoid membranes contain chlorophyll and the enzymes of the light reactions of photosynthesis. A stack of thylakoids is called a granum.

_____ is a waste product of photosynthesis. (homework)

Oxygen

Why are some other leaves not green (like a plum tree leaf)?

Plants are green because they contain the pigment chlorophyll. This pigment primarily absorbs light in the red part of the visible spectrum (long wavelengths), but light is also absorbed in the blue region (short wavelengths). Green light isn't as readily absorbed, it's mostly reflected, so the plant appears green. The surface of the leaves are greener than the other non green leaves because they contain more chlorophyll - more sunlight is trapped by the upper surface than the bottom surface. Plants that have other colors contain pigments that trump the chlorophyll. In the case of the purple colors of the plum tree leaves the lower surface of its leaves contains a higher concentration of anthocyanin than chlorophyll, which is less adept at absorbing red light.

Plants Perform both... (note from book)

Plants perform both photosynthesis to produce fuel molecules and cellular respiration to burn them, while animals only perform cellular respiration.

Autotroph (definition)

Plants, algae, and photosynthetic bacteria are autotrophs (self-feeders) are organisms that make all their own organic matter - including carbohydrates, lipids, proteins, and nucleic acids- from nutrients that are entirely inorganic: carbon dioxide from the air and water minerals from the soil. In other words, autotrophs make their own food; they don't need to eat to gain energy to power their cellular processes.

How is the electron transport chain in the mitochondria similar to the one in the chloroplast? How are they different?

Similarities -Both use ATP synthase -Located on inner membrane Differences -Mitochondria use chemical energy, chloroplasts use light energy. -Mitochondria: inner mitochondrial membrane, Chloroplasts: thylakoid membrane. -Mitochondria have O2 as final electron acceptor, chloroplasts have NADPH.

RuBisCo

The CO2-fixing enzyme is rubisco (ribulose 1,5- bisphosphate carboxylase/oxygenase) Rubisco is - Found in all photosynthetic organisms that use the Calvin cycle to fix carbon - Thought to be the most abundant enzyme on Earth

The light dependent reactions of photosynthesis make ATP, why doesn't the plant just use that ATP, why does it go on to the Calvin Cycle to make glucose?

The Calvin Cycle indirectly depends on the light reactions to produce sugar because it requires the supply of ATP that the light reactions produces. The plant REQUIRED the glucose produced by the Calvin Cycle for growth and energy. The plant also needs to produce glucose in order to be able to undergo cellular respiration. -The Calvin Cycle relies on ATP produced in light reactions. -Calvin Cycle is NECESSARY because plants undergo both photosynthesis AND cellular respiration. The plant needs the glucose produced in Calvin Cycle in order to undergo cellular respiration.

Stage 1, Light Reactions

The LIGHT REACTIONS: capturing energy • Energy from sunlight is absorbed by chlorophyll. • H2O is split, producing O2. • High-energy molecules of ATP and NADPH are produced. • This process takes place in the thylakoid of chloroplast.

Osmoregulation (definition)

The control of the gain or loss of water and dissolved solutes in an organism.

Wavelength (definition)

The distance between the crests of two adjacent waves is called wavelength.

Light Reactions (definition)

The first two stages in photosynthesis; the steps in which solar energy is absorbed and converted to chemical energy in the form of ATP and NADPH. The light reactions power the sugar-producing Calvin Cycle but produce no sugar themselves.

Electromagnetic Spectrum (definition)

The full range of radiation, from the very short wavelengths of gamma rays to the very long wavelengths of radio signals, is called the electromagnetic spectrum. Visible light is a small fraction of the spectrum that our eyes see as different colors. When sunlight shines on a pigmented material, certain wavelengths (colors) of the visible light are absorbed. The colors that are not absorbed are reflected by the material.

Stage 1, Light Reactions pt 5

The image shows the location of the light reactions in the thylakoid membrane. The two photosystems and the electron transport chain that connects them transfer electrons from H2O to NADP+, producing NADPH.

Carbon Fixation (definition)

The initial incorporation of carbon from Co2 into organic compounds is called carbon fixation. This process has important implications for global climate, because the removal of carbon from the air and its incorporation into plant material can reduce the concentration of carbon dioxide in the atmosphere.

Stage 2, Calvin Cycle

The inputs are Co2, from the air as well as two products of light reactions: ATP (which provides energy) and NADPH (which provides electrons). Using carbon from Co2 energy from ATP, and high-energy electrons from NADPH, the Calvin Cycle constructs an energy-rich sugar molecule called glyceraldehyde 3-phosphate (G3P). The plant cell can then use G3P as the raw material to make the glucose and other organic compounds (such as cellulose and starch) that it needs. STEPS 1) An enzyme adds each Co2 to a five-carbon sugar called RuBP. The resulting molecule breaks into two three-carbon molecules. 2) Using energy from ATP and NADPH produced by the light reactions, enzymes convert each three-carbon molecule to the three-carbon sugar G3P. 3) For every three molecules of Co2 that enter the cycle, the net output is one G3P sugar. The other G3P sugars continue in the cycle. 4) Using energy from ATP, enzymes rearrange the remaining G3P sugars to regenerate RuBP.

Proton Gradient (definition)

The movement of protons from the lumen to the stroma, or from high to low concentration, in chloroplasts. The proton gradient is exploited to generate ATP and NADPH.

Photosynthesis (definition)

The process by which plants, algae, and some bacteria transform light energy to chemical energy stored in the bonds of sugars. This process requires an input of carbon dioxide (CO2) and water (H2O) and produces oxygen gas (O2) as a waste/by product.

What is the summary equation of photosynthesis?

The process of photosynthesis is commonly written as: 6CO2 + 6H2O → C6H12O6 + 6O2. This means that the reactants, six carbon dioxide molecules and six water molecules, are converted by light energy captured by chlorophyll (implied by the arrow) into a sugar molecule and six oxygen molecules, the products.

Photorespiration (definition)

The process where ribulose-1,5-bisphosphate carboxylase oxygenase (RuBisCo), an enzyme, catalyzes the attachment of oxygen (O2) to the 5-carbon ribulose-1,5-bisphosphate (RuBP) in the stomata of plant leaves. The end products are phosphoglycerate (PGA) and carbon dioxide (CO2). Photorespiration is thought to reduce the efficiency of photosynthesis in some plants but is still actively being studied.

So can plants grow without soil?

The short answer is Yes. Plants can grow without soil if they get adequate nutrients from other sources. Plants get their nutrients from the soil that they are planted in. If the essential nutrients are given to the plants with another medium then the plant does not need soil. Soil-less farming techniques are now the latest technology in farming.

Endosymbiosis (definition)

The theory that explains how mitochondria and chloroplasts became organelles of other cells. Endosymbiosis is the condition of living within the body or cells of another organism. There is evidence that, millions of years ago, the ancestors of mitochondria and chloroplasts, two organelles ("mini organs") were actually prokaryotic organisms that entered into endosymbiotic relationships with eukaryotic cells.

An action spectrum plots the rate of photosynthesis at various wavelengths of visible light, and it shows that blue light with a wavelength of about 490 nm is effective in driving photosynthesis. Based on this information and the absorption spectra shown at left, what role may chlorophyll b and carotenoids play in photosynthesis? (homework)

These pigments are able to absorb more wavelengths of light (and thus more energy) than chlorophyll a alone can absorb. As part of light-harvesting complexes in photosystems, they broaden the range of light that can be used in the light reactions.

You obtain the pigments called carotenoids in your diet when you eat carrots. Why do carotenoids appear yellow and orange? (homework)

They absorb blue/green light and reflect yellow and red wavelengths of light.

Transpiration (definition)

Transpiration is the evaporation of water from plants. It occurs chiefly at the leaves while their stomata are open for the passage of CO2 and O2 during photosynthesis. The water, warmed by the sun, turns into vapor (evaporates), and passes out through thousands of tiny pores (stomata) mostly on the underside of the leaf surface. This is transpiration. It has two main functions: cooling the plant and pumping water and minerals to the leaves for photosynthesis.

Why do plants need water? Carbon dioxide? How do they make oxygen?

Water = Yes - Without water, the plant would not be able to gather enough energy and would therefore not survive. -All living things need water to stay alive, and plants are living things! -Plants need water for photosynthesis -Absorbed by the roots, water travels through a plant's stems to the chloroplasts in the leaves -Water also helps move nutrients from the soil into the plant -All living things need water because life requires a LOT of chemical reactions. Carbon Dioxide Plants take in carbon dioxide, nutrients from the soil, water, and sunlight and create oxygen and a kind of simple sugar that they use for energy. Plants extract the carbon dioxide from the air and use it in photosynthesis process to feed themselves. The carbon dioxide enters the leaves of the plant through small pores called stomata. Once the carbon dioxide enters the plant, the process begins with the help of sunlight and water. Oxygen Light reactions. Plants "split apart" H2o molecules in order to obtain "electron rich" H+ ions. The excess oxygen is released as a by-product. OXYGEN IS A WASTE PRODUCT IN PHOTOSYNTHESIS.

_______ is used in the light reactions, and ________ is used in the Calvin cycle. (homework)

Water and carbon dioxide

Carotenoids

absorb mainly blue-green light and absorb and dissipate excessive light energy that might damage chlorophyll. Example: Falling autumn temperatures cause a decrease in the levels of green chlorophyll within the foliage of leaf-bearing trees. This decrease allows the colors of the carotenoids to be seen.

The end products of photosynthesis are __________ and __________. (homework)

glucose ... molecular oxygen

The waste products of cellular respiration include (homework)

water and carbon dioxide