Chapter 10: Photosynthesis Flashcards

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1
Q

Photosynthesis

A
  • Conversion of light energy to chemical energy that is stored in sugars or other organic compounds
  • Occurs in plants, algae, and certain prokaryotes
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2
Q

Autotroph

A
  • Organism that obtains organic food molecules without eating other organisms or substances derived from other organisms
  • Use energy from the sun or from the oxidation of inorganic substances to make organic molecules from inorganic ones
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3
Q

Heterotroph

A

Organism that obtains organic food molecules by eating other organisms or substances derived from them

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4
Q

Mesophyll

A
  • Leaf cells specialized for photosynthesis
  • In C3 and CAM plants, located between the upper and lower epidermis
  • In C4 plants, they are located between the bundle-sheath cells and the epidermis
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5
Q

Stomata

A
  • Microscopic pores surrounded by guard cells

- In the epidermis of leaves and stems that allow gas exchange between the environment and the interior of the plant

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6
Q

Stroma

A
  • Dense fluid within the chloroplast surrounding the thylakoid membrane
  • Contains ribosomes and DNA
  • Involved in the synthesis of organic molecules from carbon dioxide and water
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7
Q

Thylakoid

A
  • Flattened membrane sac inside the chloroplast

- Used to convert light energy into chemical energy

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8
Q

Chlorophyll

A

Green pigment located in membranes within the chloroplasts of plants and algae and in the membranes of certain prokaryotes

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9
Q

Light Reactions

A
  • First of two major stages in photosynthesis
  • Comes before the Calvin Cycle
  • Occur on the thylakoid membranes of the chloroplast or on membranes of certain prokaryotes
  • Convert solar energy into the chemical energy of ATP and NADPH
  • Releases oxygen
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10
Q

Calvin Cycle

A
  • Second of two major stages in photosynthesis

- Involves the fixation of atmospheric carbon dioxide and the reduction of fixed carbon into carbohydrate

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11
Q

NADP+

A
  • Nicotinamide adenine dinucleotide phosphate
  • Electron acceptor
  • As NADPH, temporarily stores energized electrons produced during the light reactions
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12
Q

Photophosphorylation

A

Process of generating ATP from ADP and phosphate by means of a proton-motive force generated by the thylakoid membrane of the chloroplast during the light reactions of photosynthesis

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13
Q

Carbon Fixation

A

Initial incorporation of carbon from carbon dioxide into an organic compound by an autotrophic organism (i.e. plant, other photosynthetic organism, chemoautotrophic prokaryote)

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14
Q

Wavelength

A

DIstance between crests of waves, such as those of the electromagnetic spectrum

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15
Q

Electromagnetic Spectrum

A
  • Entire spectrum of electromagnetic radiation

- Ranges in wavelength from less than a nanometer to more than a kilometer

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16
Q

Visible Light

A
  • Portion of the electromagnetic spectrum that can be detected as various colors by the human eye
  • Ranges in wavelength from about 380 nm to about 750 nm
17
Q

Photon

A

Quantum/ discrete quantity of light energy that behaves as if it were a particle

18
Q

Spectrophotometer

A

Instrument that measures the proportions of light of different wavelengths absorbed and transmitted by a pigment solution

19
Q

Absorption Spectrum

A
  • Range of a pigment’s ability to absorb various wavelengths of light
  • Also a graph of such a range
20
Q

Chlorophyll a

A

Photosynthetic pigment that participates directly in the light reactions

21
Q

Chlorophyll b

A

Accessory photosynthetic pigment that transfers energy to chlorophyll a

22
Q

Carotenoid

A
  • Accessory pigment in the chloroplasts of plants
  • Either yellow or orange
  • Absorbs wavelengths of light that chlorophyll cannot
  • Broaden the spectrum of colors that can drive photosynthesis
23
Q

Photosystem

A
  • A light-capturing unit located in the thylakoid membrane of the chloroplast or in the membrane of some prokaryotes
  • Consists of a reaction-center complex surrounded by numerous light-harvesting complexes
  • Two types: I and II
  • Absorb light best at different wavelengths
24
Q

Reaction-Center Complex

A
  • Complex of proteins associated with a special pair of chlorophyll a molecules and a primary electron acceptor
  • Located centrally in a photosystem
  • Triggers the light reactions of photosynthesis
  • Excited by light energy, the pair of chlorophylls donates an electron to the primary electron acceptor, which passes an electron to an electron transport chain
25
Q

Light-Harvesting Complex

A
  • Complex of proteins associated with pigment molecules (including chlorophyll a, chlorophyll b, and carotenoids)
  • Captures light energy and transfers it to reaction-center pigments in a photosystem
26
Q

Primary Electron Acceptor

A

In the thylakoid membrane of a chloroplast or in the membrane of some prokaryotes, a specialized molecules that shares the reaction-center complex with a pair of chlorophyll a molecules and accepts an electron from them

27
Q

Photosystem II (PS II)

A
  • One of two light-capturing units in a chloroplast’s thylakoid membrane or in the membrane of some prokaryotes
  • Occurs first
  • Has two molecules of P680 chlorophyll a at its reaction center
28
Q

Photosystem I (PS I)

A
  • Light capturing unit in a chloroplast’s thylakoid membrane or in the membrane of some prokaryotes
  • Happens second
  • Has two molecules of P700 chlorophyll a at its reaction center
29
Q

Linear Electron Flow

A
  • Route of electron flow during the light reactions of photosynthesis –Involves both photosystems (I and II)
  • Produces ATP, NADPH, and O2
  • Net electron flow from H2O to NADP+
30
Q

Cyclic Electron Flow

A
  • Route of electron flow during the light reactions of photosynthesis
  • Involves only photosystem I
  • Produces ATP but not NADPH or oxygen
31
Q

Glyceraldehyde 3-phosphate (G3P)

A
  • Three-carbon carbohydrate
  • Direct product of the Calvin Cycle
  • An intermediate in glycolysis
32
Q

Rubisco

A
  • Ribulose carboxylase
  • Enzyme that catalyzes the 1st step of the Calvin cycle (addition of CO2 to RuBP, or ribulose bisphosphate)
  • Can bind to oxygen when excess oxygen is present or carbon dioxide levels are low
33
Q

C3 Plant

A
  • Plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material
  • Form a three-carbon compound as the first stable intermediate
34
Q

Photorespiration

A
  • Metabolic pathway
  • Consumes oxygen
  • Releases carbon dioxide
  • Doesn’t generate ATP
  • Decreases photosynthetic output
  • Generally on hot, dry, and bright days, when stomata close and the oxygen concentration in the leaf exceeds that of carbon dioxide
35
Q

C4 Plant

A

Plant in which the Calvin cycle comes after reactions that incorporate CO2 into a four-carbon compound, the end product supplying CO2 for Calvin cycle

36
Q

Bundle-Sheath Cell

A

In C4 plants, a type of photosynthetic cell arranged into tightly packed sheaths around the veins of a leaf

37
Q

PEP Carboxylase

A
  • Enzyme that adds CO2 to phosphoenolpyruvate (PEP) to form oxaloacetate in C4 plants
  • Acts prior to photosynthesis
38
Q

Crassulacean Acid Metabolism (CAM)

A
  • Adaptation for photosynthesis in arid conditions
  • First discovered in the family Crassulaceae
  • Plant takes up CO2 and incorporates it into a variety of organic acids at night when stomata are open
  • During the day, CO2 is released from organic acids for use in the Calvin cycle while stomata are closed
39
Q

CAM Plant

A

-Plant that uses crassulacean acid metabolism (adaptation for photosynthesis in arid conditions)