Photosynthesis Flashcards

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1
Q

photosynthesis

A

process by which plants, algae, and some bacteria use the sun’s energy to produce its own food (energy)

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2
Q

autotrophs

A

self-feeder - use inorganic molecules to produce organic compounds

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3
Q

heterotrophs

A

consume organic compounds

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4
Q

What is the photosynthesis equation

A

6 H2O + 6 CO2 —–> C6H12O6 + 6O2

6 molecules of water plus 6 molecules of carbon dioxide equals glucose plus 6 molecules of oxygen

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5
Q

Where does photosynthesis occur

A

in the chloroplasts

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6
Q

pigments

A

capture light energy at various wavelengths

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7
Q

what are the type of pigments?

A

Chlorophyll A and Accessory pigments (chlorophyll b and carotenoids)

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8
Q

Chlorophyll a

A

most abundant with a green pigment - it reflects green light and absorbs red and blue light

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9
Q

Accessory pigments

A

allows plant to absorb more energy than with chlorophyll a alone

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10
Q

Chlorophyll B

A

reflects green light and absorbs red and blue

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11
Q

carotenoids

A

appear red, orange, and yellow (absorb longer wavelengths)

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12
Q

stomata (stoma)

A

small openings in the epidermis of the stem or leaf that allow for an exchange of CO2 and O2

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13
Q

mesophyll

A

internal cells of the leaf where the chloroplasts are located

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14
Q

Stroma

A

(NOT STOMA) gelatinous fluid that contains DNA, ribosomes, enzymes, and Grana and are composed of stacks of thylakoids which are studded with photosynthetic pigments (enclosed: makes the thylakoid space)

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15
Q

Photosystem

A

Very organized system that consists of chlorophyll a and accessory pigments

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16
Q

How many chlorophyll a and accessory pigments?

A

300 Chlorophyll A and 50 accessory pigments - all absorb energy but only 1 (chlorophyll a) molecule uses the energy

17
Q

Reaction center

A

chlorophyll a molecule in photosynthetic reaction

18
Q

antenna pigments

A

all other pigments in system (chlorophyll a and accessory) that relay/pass along their absorbed energy to the reaction center

19
Q

What are the two stages of photosynthesis?

A

light reactions (photo) and carbon reactions (synthesis)

20
Q

light reactions

A

convert the sun’s energy to chemical energy - light dependent reaction that occurs in the thylakoid membrane and produces ATP and NADPH

21
Q

Carbon reactions

A

light independent reaction that occurs in the stroma and converts ATP and NADPH to glucose

22
Q

NADPH

A

electron carrier that reduces CO2 in the carbon reactions

23
Q

Carbon reactions: Calvin cycle

A

uses NADPH and ATP to assemble CO2 into sugars (Cyclic and all plants use this cycle

24
Q

C3 (Calvin Cycle

A

3 carbon molecule (PGA) is the first stable compound; C3 plants use ONLY this pathway to fix carbon

25
Q

weakness of C3

A

inefficient on cloudy days

26
Q

photorespiration

A

when rubisco uses O2 instead of CO2 and loses CO2 that is already fixed, wasting ATP and NADPH

27
Q

where does photorespiration usually occur?

A

in hot, dry climates

28
Q

dilemma of photorespiration

A

stomata open or closed; open: risk losing water, dry up, wilt; closed: run out of O2 and build up of CO2

29
Q

C4

A

light reactions occur in mesophyll cells and CO2 combines with a 4-C compound

30
Q

what happens when CO2 combines with a 4-C compound?

A

molecule then moves to bundle-sheath cells for Calvin cycle; no exposure to atmospheric O2 (rubisco more likely to bump into CO2); this is COSTLY as molecules must transport CO2 to bundle-sheath (2 ATP)

31
Q

CAM (crassulacean acid metabolism)

A

open stomata to fix carbon at night only (closed during the day); combines with a 4-C compound and is stored in large vacuoles

32
Q

What happens when the carbon combines with a 4-C compound and is stored in large vacuoles?

A

stored molecule moves from vacuoles to chloroplast and releases CO2 and the Calvin cycle begins, then less CO2 is available