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Bio 5A Lecture > Chapter 10: Photosynthesis > Flashcards

Chapter 10: Photosynthesis Flashcards

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Biology 101 flashcards
1
Q

Define Chloroplasts

A

An organelle found in plants and photosynthetic protists that absorb sunlight and uses it to drive the synthesis of organic compounds from CO2 and H2O.

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2
Q

Define Photosynthesis

A

The conversion of light energy to chemical energy that is stored in sugars or other organic compounds.

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3
Q

An organism acquires the organic compounds it uses for energy and carbon skeletons by one of the two major modes:

A

Autotrophic Nutrition and Heterotrophic Nutrition. AH

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4
Q

Define Autotrophs

A

An organism that obtains organic food molecules without eating other organisms or substances derived from other organisms. They use the energy from the sun or from the oxidation of inorganic substances to make organic molecules from inorganic ones. Autotroph basically means “self-feeder”

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5
Q

Almost all _____ are autotrophs.

A

Plants

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6
Q

Define Heterotrophs

A

An organism that obtains organic food molecules by eating other organisms or substances derived from them.

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7
Q

Heterotrophs are the biosphere’s _____.

A

Consumers

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8
Q

_____ are the sites of photosynthesis in plants.

A

Chloroplasts

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9
Q

Chloroplasts are found mainly in the cells of the _____.

A

Mesophyll

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10
Q

Define Mesophyll

A

Leaf cells that are specialized for photosynthesis.

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11
Q

Mesophyll’s are usually located in the _____ tissue of the leaf.

A

Interior

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12
Q

Carbon dioxide enters the lad, and oxygen exits, by way of microscopic pores called _____.

A

Stomata

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13
Q

Define Stomata

A

A microscopic pore 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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14
Q

A chloroplast has _____ membranes surrounding a dense fluid called the _____.

A

2-Stroma

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15
Q

Define Stroma

A

The dense fluid within the chloroplast surrounding the thylakoid membrane and containing ribosomes and DNA; involved in the synthesis of organic molecules from CO2 and H2O.

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16
Q

Define Thylakoids

A

A flattened, membranous sac inside a chloroplast. Thylakoids often exist in stacks called grana that are interconnected; their membranes contain molecular “machinery” used to convert light energy to chemical energy.

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17
Q

Define Chlorophyll

A

A green pigment located in membranes within the chloroplasts of plants and algae and in the membranes of certain prokaryotes.

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18
Q

What is the general, simplified equation of photosynthesis?

A

6 CO2+ 6H2O + Light Energy —-> C6H12O6 + 6O2

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19
Q

The _____ splits water into hydrogen and oxygen.

A

Chloroplast.

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20
Q

A significant result of the shuffling of atoms during photosynthesis is the extraction of _____ from water and its incorporation into _____.

A

Hydrogen-Sugar

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21
Q

What are the two parts of photosynthesis?

A

Light Reactions-Calvin Cycle

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22
Q

Define Light Reactions

A

The first of two major stages in photosynthesis (preceding the Calvin Cycle). These reactions, which occur on the thylakoid membranes of the chloroplast or on membranes of certain prokaryotes, convert solar energy to the chemical energy of ATP and NADPH, releasing oxygen in the process.

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23
Q

Define Calvin Cycle

A

The second of two major stages in photosynthesis (following the light reactions), involving fixation of atmospheric CO2 and reduction of the fixed carbon into carbohydrate.

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24
Q

Define NADP+

A

The oxidized form of nicotinamide adenine dinucleotide phosphate, an electron carrier that can accept electrons, becoming NADPH. NADPH temporarily stores energized electrons produced during the light reactions.

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25
Q

Define NADPH

A

The reduced form of nicotinamide adenine dinucleotide phosphate; temporarily stores energized electrons produced during the light reactions. NADPH acts as “reducing power” that can be passed along to an electrons acceptor, reducing it.

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26
Q

Define Photophosporylation

A

The process of generating ATP from ADP and phosphate by means of chemiosmosis, using a proton-motive force generated across the thylakoid membrane of the chloroplast or the membrane of certain prokaryotes during the light reactions of photosynthesis.

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27
Q

The Calvin cycle begins by incorporating _____ from the air into organic molecules already present in the chloroplast.

A

CO2

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28
Q

Define Carbon Fixation

A

The initial incorporation of carbon from CO2 into an organic compound by an autotrophic organism (a plant, another photosynthetic organism, or a chemoautotrophic prokaryote).

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29
Q

The _____ of the chloroplast are the sites of the light reactions, while the Calvin Cycle occurs in the _____.

A

Thylakoids-Stroma

30
Q

The _____ reactions convert solar energy to the chemical energy of ATP and NADPH.

A

Light

31
Q

What type of energy is light?

A

Electromagnetic Radiation

32
Q

Define Wavelength

A

The distance between rests of waves, such as those of the electromagnetic spectrum.

33
Q

Define Electromagnetic Spectrum

A

The entire spectrum of electromagnetic radiation, ranging in wavelength from less than a nanometer to more than a kilometer.

34
Q

Define Visible Light

A

The portion of the electromagnetic spectrum that can be detected as various colors by the human eye, ranging in wavelength from about 380nm to about 750nm.

35
Q

Define Photons

A

A quantum, or discrete quantity, of light energy that behaves as if it were a particle.

36
Q

What is the relationship between wavelength and energy?

A

Inverse

37
Q

What is a general definition of pigments?

A

Substances that absorb visible light.

38
Q

The color we see objects are the color of the wavelength they are _____.

A

Reflecting

39
Q

The ability of a pigment to absorb various wavelengths of light can be measured with an instrument called a _____.

A

Spectrophotometer

40
Q

Define Chlorophyll a

A

A photosynthetic pigment that participates directly in light reactions, which convert solar energy to chemical energy.

41
Q

Define Chlorophyll B

A

An accessory photosynthetic pigment that transfers energy to chlorophyll A.

42
Q

Define Carotenoids

A

An accessory pigment, either yellow or Orange, in the chloroplast of plants. By absorbing wavelength gets of light that chlorophyll cannot, carotenoids broaden the spectrum of colors that can drive photosynthesis.

43
Q

What is an important function of carotenoids?

A

Photoprotection: these compounds absorb and dissipate excessive light energy that would otherwise damage chlorophyll or interact w/ oxygen, forming relative oxidative molecules that are dangerous to the cells.

44
Q

Define Photosystem

A

A light capturing unit located in the thylakoid membrane of the chloroplast or in the membrane of some prokaryotes, consisting of a reaction-center complex surrounded by numerous light harvesting complexes. There are two types of photosystems, I AND II: they absorb light at different wavelengths.

45
Q

Define Reaction-Center Complex

A

A complex of proteins associated with a special pair of chlorophyll A molecules and a primary electron acceptor. Located centrally in a photosystem, this complex 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.

46
Q

Define Light-Harvesting Complex

A

A complex of proteins associated with pigment molecules that captures light energy and transfers it to the reaction-center pigments in a photosystem.

47
Q

Define Primary Electron Acceptor

A

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

48
Q

Define Photosystem II

A

One of the two light capturing units in a chloroplast’s thylakoid membrane or in the membrane of some prokaryotes; it has two molecules of P680 chlorophyll A at its reaction center.

49
Q

Define Photosystem I

A

A light capturing-unit in a chloroplast’s thylakoid membrane or in the membrane of some prokaryotes; it has two molecules of P700 chlorophyll A at its reaction center.

50
Q

Define Linear Electron Flow

A

A route of electron flow during the light reactions of photosynthesis that involves both photosystems (I AND II) and produces ATP, NADPH, and O2. The net electron flow is from H2O to NADP+

51
Q

What is the electron transport chain between PS II AND PS I made of?

A

Plastoquinone and Plastocyanin

52
Q

The potential energy stored in the proton gradient is used to make ATP in a process called _____.

A

Chemiosmosis

53
Q

Define Cyclic Electron Flow

A

A route of electron flow during the light reactions of photosynthesis that involves only one photosystem and that produces ATP but NOT NADPH OR O2. ONLY PS1 is used

54
Q

The Calvin Cycle uses the chemical energy of ATP and NADP to reduce _____ to _____.

A

CO2 to Sugar

55
Q

Define Glyceraldehyde-3-Phosphate

A

A three-carbon carbohydrate that is the direct product of the Calvin cycle; it is also an intermediate in glycolysis.

56
Q

For the net synthesis of one molecule of G3P, the cycle must take place _____ times.

A

3

57
Q

What are the three phases present in the Calvin cycle?

A

Carbon Fixation-Reduction-Regeneration of the CO2 Acceptor. CRR

58
Q

Define Rubisco

A

Ribulose Biphosphate carboxylase-oxygenate, the enzyme that normally catalyzes the first step of the Calvin Cycle (the addition of CO2 to RuBP). When excess O2 is present or CO2 levels are low, rubisco can bind oxygen, resulting in photorespiration.

59
Q

For the net production of one G3P molecule, what does the Calvin Cycle consume?

A

9 ATP and 6NADPH

60
Q

Define C3 Plants

A

A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a 3-carbon compound as the first stable intermediate.

61
Q

Define Photorespiration

A

A metabolic pathway that consumes oxygen and ATP; releases CO2 and decreases photosynthetic output. Photorespiraiton generally occurs on hot, dry, bright days, when stomata close and the O2/CO2 ratio in the leaf increases, favoring the binding of O2 rather than CO2 by rubisco.

62
Q

However, unlike normal cellular respiration, photorespiration uses _____ rather than generating it.

A

ATP

63
Q

Define C4 Plants

A

A plant in which the Calvin Cycle is preceded by reactions that incorporate CO2 into a 4-carbon compound, the end product of which supplies CO2 for the Calvin Cycle.

64
Q

What are the two types of cells present in C4 Plants?

A

Bundle Sheath Cells and Mesophyll.

65
Q

Define Bundle Sheath Cells

A

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

66
Q

Define PEP Carboxylase

A

An enzyme that adds CO2 to phospho-enol-pyruvate (PEP) to form oxaloacetate in Mesophyll cells of C4 plants. It acts prior to photosynthesis.

67
Q

What type of affinity does PEP Carboxylase have for CO2 and O2?

A

High affinity for CO2 (even higher than Rubisco) and NO affinity for O2.

68
Q

What type of affinity does PEP Carboxylase have for CO2 and O2?

A

High affinity for CO2 (even higher than Rubisco) and NO affinity for O2.

69
Q

Is C4 photosynthesis more efficient or C3 photosynthesis? Why?

A

C4; because it uses less water and resources.

70
Q

Define Crassulacean Acid Metabolism (CAM)

A

An adaptation for photosynthesis in arid conditions. In this process, a plant takes up CO2 and incorporates it into a variety of organic acids at night; during the day, CO2 is released from organic acids for use in the Calvin Cycle.

Bio 5A Lecture (16 decks)

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