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Biol 2390 > Topic 7 > Flashcards

Topic 7 Flashcards

1
Q

Photosynthesis

A

process where energy from the sun is used to transform CO2 into carbohydrates and O2

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2
Q

Where does photosynthesis take place in plants

A

specialized cells (mesophyll cells) in the leaf

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3
Q

Process of photosynthesis

A

Chlorophyll (light absorbing pigment) traps light energy → synthesizes ATP → this energy drives CO2 → O2 + sugars

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4
Q

Photosynthesis is depend on..

A

enzyme called rubisco

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5
Q

Photosynthesis can be broken down into 2 reactions

A
  • light reactions

- dark reactions

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6
Q

Light reactions

A

generate energy transferred by carrier molecules and produces O2

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7
Q

Light reaction process

A

light energy is funnelled into energy carriers (ATP or NADPH) via elections and H2O is the source of elections yielding waste O2 as byproduct

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8
Q

Dark reactions

A

fix carbon (CO2) into sugars. energy carriers are used to power the calvin cycle. depleted energy carriers are returned to light reactions

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9
Q

Dark reaction process (C3 pathways)

A

CO2 fixed by rubisco in a 3 carbon compound in Calcin cycle. simple sugars (glucose) eventually formed

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10
Q

C3 pathway drawback

A

rubisco can bind oxygen instead of CO2 causing photorespiration, decreased efficiency of photosynthesis because energy is lost powering calvin cycle, has no CO2 fixation and leads to reduced sugar output

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11
Q

Respiration

A

in the mitochondria of cells, carbs are broken down to generate energy (ATP) releasing CO2

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12
Q

Plants both use and produce ..

A

CO2

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13
Q

Difference in the rates of using and producing CO2 =

A

net photosynthesis = photosynthesis - respiration (aka = carbon uptake-carbon loss)

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14
Q

CO2 diffuses in to the leaf through..

A

openings in the surface of the leaf (stomata)

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15
Q

Transpiration

A

CO2 diffuses into the leaf, water diffuses out of the leaf

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16
Q

CO2 evers

A

atmosphere&raquo_space;> leaf

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17
Q

Water leaves

A

atmosphere &laquo_space;leaf

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18
Q

Plants must require what essential resources

A

light, CO2, water, nutrients

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19
Q

Leaf tissue

A

photosynthesis (uptake of CO2)

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20
Q

Stem tissue

A

structural support (gain access to light)

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21
Q

Root tissue

A

water and nutrient uptake from soil

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22
Q

Plants adapt to different environmental conditions to keep ..

A
  • photosynthesis > respiration (+ carbon balance to grow)

- photosynthesis > transpiration (+ water balance to survive)

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23
Q

Individuals must tolerate environmental conditions that..

A

influence the acquisition of all essential resources

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24
Q

Adaptations that allow a plant to successfully grow, source and reproduce under on set of environmental conditions may limit its ability to..

A

do equally well under different environmental

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25
Q

Tree top (direct sunlight)

A

smaller, thick leaves to reduce water loss in direct sunlight

26
Q

Tree bottoms (shade)

A

larger, thinner to increase photosynthetic rate in shade

27
Q

Leaves in arid environments minimize evaporation by

A

angling leaves away from the sun

28
Q

In shade photosynthesis is

A

limited by availability of light

29
Q

Shade tolerant (low light)

A

lower production of rubisco in leaf tissue (don’t expend energy producing high amounts of rubisco) equals lower maximum photosynthetic rate

30
Q

Shade tolerant plants compensate by

A
  • higher production of chlorophyll (light absorbing pigment)
  • higher leaf surface area
  • higher growth of leaves than roots
31
Q

Increase the photosynthetic surface area to..

A

offset the decrease in photosynthetic rate (due to low rubisco)

32
Q

Shade tolerant grow..

A

similarly under sunlight and shade

33
Q

Shade intolerant grow..

A

highly under sunlight and low under shade

34
Q

Mountain Avens

A

flowers track movement of the sun. parabolic formation of steals concentrate light to maintain constant temp of 25C

35
Q

Photosynthesis and respiration respond directly to

A

variations in temp

36
Q

As temp rise above 0 rate of both respiration and photosynthesis

A

increase

37
Q

Protein denature and respiration and photosynthesis ..

A

stop

38
Q

Heat loss of leaf by convection

A

transfer of heat to a moving fluid body (ie. Wind)

39
Q

Heat loss of leaf by conduction (radiation)

A

Heat moving from a warmer to a cooler body

40
Q

Heat loss of leaf by evaporation (transpiration)

A

Evaporation causes a loss of heat energy and temperatures drop due to evaporative cooling

41
Q

Transfer of heat from a plant to environment is influenced by..

A

the boundary layer (layer of still air adjacent to surface of leaf)

42
Q

Conditions of true boundary layer are

A

slightly different from the environment because its modified by water and CO2 moving to/from plant surface

43
Q

Boundary layer of leaf is related to

A

size and surface roughness (small smooth leaves lose heat faster (desert plants))

44
Q

Pubescence

A

small light coloured hairs that line leafs surface and reflect. less heat obtained from solar radiation and creates insulted boundary layer

45
Q

Skunk cabbage

A

Metabolically generates heat in the spring to thaw snow and attract pollinator. endothermic plant

46
Q

Accumulation of compounds (sugar, amino acids, etc)

A

lowers the freezing point of water to prevent ice4 formation

47
Q

Supercooling

A

Special anti freeze proteins preventing ice crystal growth allowing plants to survive up to -35C. present in floral and shoot buds

48
Q

Frost hardening

A

Changes composition of membranes allowing cells to export water and ice to form between cells instead of within. allows survival up to -50C

49
Q

Deciduous trees

A

adaptive loss of leaves as temp drops in fall. programmed death to survive winter when leaves would freeze

50
Q

When the atmospheric humidity and soil moisture levels are low plants will

A

close their stomata

51
Q

Mid day stomata close to..

A

conserve water (short term scale)

52
Q

Leaf curling or wilting

A

reduces surface area of leaf exposed to solar radiation and water loss

53
Q

Moderate time scales (acclimatory/developmental) water plant adaptions

A

individuals can balance leaf vs root tissue in wet and dry conditions

54
Q

Wet conditions (ideal)

A

increase leaf tissue and lower root and shoot. increase the photosynthetic surface (maximizes CO2 uptake and photosynthetic rates → growth)

55
Q

Dry conditions

A

increase root tissue and decrease leaf and shoot. increases the volume of tissue in soil to extract water and reduces surface area of leaf tissue to reduce water loss

56
Q

Leaf morphology adaptations to dry conditions

A
  • smaller thicker leaves (water storage)
  • smaller stomata
  • cover leaves in wax, resin, little hairs
57
Q

C4 photosynthesis

A

3% of plants most common in grasses

58
Q

CAM photosynthesis

A

7% of plants, common in epiphytes and cacti.

59
Q

Alternative photosynthetic pathways

A
  • C4 photosynthesis

- CAM photosynthesis

60
Q

CAM photosynthesis adds an extra step in the conversion of

A

CO2 into an organic acid before entering Calvin cycle (dark reactions)

61
Q

Advantages of photosynthetic adaptations to water

A
  • Reduces O2 binding by rubisco (reduced energy loss)
  • Concentrates CO2 to rubisco (faster fixation speeds)
  • Much higher maximum rate of photosynthesis is possible
62
Q

Due to higher photosynthetic rate a plant loses ..

A

less water per unit go photosynthetic product. means C4 and CAM plants have a greater water use efficiency relative to C3 plants (successful in hot dry climates)

Biol 2390 (34 decks)

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