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Bio Term 2 > Lecture 6 > Flashcards

Lecture 6 Flashcards

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Biology 101 flashcards
1
Q

In any region, water energy is the SUM of the:

A

Solute (osmotic) potential energy (0 or negative)

Pressure potential energy (any value, negative, positive or 0)

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2
Q

process of: Water evaporates from moist cells (like how clothing dries on clothes line outside, will dry down to level of atmosphere) in leaf stomatal

A

transpiration

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3
Q

Water potential is lowered (because water is being pulled out like a rope) at air-water interface; causing negative pressure in xylem

A

tension

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4
Q

Hydrogen bonds hold water molecules together

A

cohension

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5
Q

Xylem under tension gradient: pressure potential _____at top, _____ as you go down the plant

A

negative, getting more positive as you go down the plant

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6
Q

Water and minerals enter roots by osmosis because….

A

there is higher solute concentration inside plant than in soil

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7
Q

special cells that open and close to allow for the exchange of gases

A

guard cells

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8
Q

Gas exchange couldn’t happen through the cell wall of land plants because of _________

A

the waxy cuticle

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9
Q

type of cell?
Have microfibrils oriented transversally
When cell swells (turchid; filled with water) it causes opening
Create an opening, the inside (the stomata)

A

guard cell

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10
Q

How does the plant open and close the guard cells?

A

Pumping potassium ions

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11
Q

How To open guard cells

A 
The plant pumps K ions into cell
Solute potential, osmotic potential, goes down 
Water enters spontaneously
Guard cells swell
Stoma is open
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12
Q

what is conducted by abscisic acid

A

the closing of guard cells

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13
Q

the process of closing guard cells

A

Conducted by abscisic acid
Abscisic acid tells K ions to leave guard cells
Water leaves guard cells once solute is out of guard cells
Guard cells close
No access to stoma

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14
Q

cues for plant to open stomata at dawn?

A

Light
CO2 depletion
Circadian rhythms

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15
Q

what does the plant do in dry conditions to avoid water loss? How do they do this?

A

Abscisic acid (hormone)
Causes K positive to leave guard cells
Stimulates stomata closure

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16
Q

phloem transport, passive or active?

A

active

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17
Q

method of phloem transport?

A

bulk flow

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18
Q

: extra cells, parts of the phloem; type of parenchyma cells; actively pump sugar water

A

companion cells

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19
Q

companion cell that is where water starts

A

source cell

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20
Q

companion cell where water ends up

A

sink cell

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21
Q

what does Sucrose being pumped by source cell goes into sieve tube do to the osmotic potential?

A

osmotic potential goes down; more negative

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22
Q

What happens to the top of the tube if the osmotic potential is down due to sucrose having been just pumped into it?

A

water rushes in to balance out the sucrose molecules; water flows into the sieve tube

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23
Q

where does the water that rushes into the sieve tube when osmotic potential is down come from?

A

xylem tube next to it

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24
Q

what happens to the pressure of the sieve tube in the top area where water and sucrose was just pumped into?

A

the pressure goes up

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25
Q

The pressure going up in the top of the sieve tube causes what?

A

water and sucrose to flow down to the lower pressured end

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26
Q

What is the sink cell’s role in bulk flow?

A

The sink cell at the lower pressure end actively takes sugar out

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27
Q

when the sink cell takes out sucrose molecules, what happens to the osmotic pressure and the water?

A

the osmotic pressure goes up so the water flows back into the xylem tube beside the sieve tube

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28
Q

what type of cells are the sink and source cell?

A

companion cells

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29
Q

why does the water not follow the sugar into the companion cells?

A

the pressure in companion cell is higher than pressure in phloem; water wants to flow into lowest pressured spot

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30
Q

location of source and sink cells in fall? why?

A 
source in leaves
sink in roots
- Leaves make glucose 
Turn it into sucrose 
The plant moves sucrose through phloem tissue down to the roots
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31
Q

location of sink and source in winter? why?

A

nothing happens in winter

  • the sucrose is stored in the roots as starch
  • plant loses its leaves
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32
Q

location of sink and source in spring? why?

A

source is root
sink is leaves
- Plant needs to make leaves so it can photosynthesize again
- Plant takes starch from roots, turns back into sucrose
- Moves sucrose through stem from roots to the buds
- Makes new leaves and starts photosynthesising

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33
Q

what are the sources of oxygen in the atmosphere? percentages?

A

50% terrestrial plants

50% phytoplankton and macroalgae

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34
Q

what is the carbohydrate ratio

A

1C: 2H: 1O

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35
Q

most basic sugar most other sugars are made from

C6H12O6

A

glucose

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36
Q

What are the two stages of photosynthesis?

A 
light reactions
dark reactions (Calvin cycle)
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37
Q

Organelle that makes plants green

A

chloroplast

38
Q

organelle that used to be cyanobacterium
Has two membranes
has own genome

A

chloroplast

39
Q

light reactions happen in _____

A

thylakoids

40
Q

Calvin cycle occurs in

A

stroma

41
Q

step 1 of light reaction

A

Light hits chlorophyll molecule (chlorophyll is a pigment, it absorbs wavelengths when light hits it)

42
Q

step 2 of light reaction; what happens when light hits chlorophyll

A

When chlorophyll absorbs light, electrons increase in energy, some increase then go back down but some increase so much in energy that they bounce off the chlorophyll molecule

43
Q

step 3 of light reaction: what does chlorophyll do after it loses some electrons

A

Chlorophyll steals electrons from H2O to compensate for its lost electrons

44
Q

what happens to water after chlorophyll steals its electrons in the light reactions?

A

photolysis: falls apart

45
Q

what does photolysis create?

A

oxygen

46
Q

what creates the oxygen we breath all the time?

A

photolysis: the falling apart of WATER

47
Q

how is NADPH created

A

NADP+ + 2e- + H+ = NADPH

takes electrons that other molecules have lost and and takes a proton/H from the photolysis of water

48
Q

Photophosphorylation reaction?

A

ADP + Pi = ATP

49
Q

is an accessory pigment that extends the wavelengths that can be used by chlorophyll a, takes its energy and passes it to chlorophyll a

A

chlorophyll b

50
Q 
Makes sugar (precursor)
Supply light reactions with NADP+  and ADP
A

dark reactions: calvin reaction

51
Q

Occurs in stroma of chloroplast
Does not require light
Rubisco takes inorganic carbon from CO2 and adds it to organic carbon RuBP (5 carbon sugar)

A

dark reactions; calvin reaction

52
Q 
Very special protein 
Most abundant protein
Most important protein
Dual nature
Grabs CO2
Grabs oxygen
A

rubisco

53
Q

step one of calvin cycle

A

Rubisco adds CO2 to RuBP creating unstable 6-carbon compound

54
Q

step 2 of calvin

A

6-carbon compound breaks into two 3-carbon compounds (3-phosphoglycerate)

55
Q

step 3 of calvin

A

ATP and NADPH is used- don’t worry about the details

56
Q

Two-faced jekyll and hyde enzyme (CO2 and O2); dual nature exposed when oxygen is too plentiful

A

rubsico

57
Q

step 4 of calvin

A

Finally G3P (Glyceraldehyde-3-phosphate; sugar) is produced

58
Q

step 5 of calvin? what leaves the cycle?

A

1 G3P LEAVES calvin cycle, 5 G3P stay (six total)

59
Q

step 6 of calvin: what happens to product of calvin?

A

The G3P that leaves becomes the 6-carbon glucose

60
Q

step 7 of calvin: what happens to remaining items in calvin cycle?

A

The 5 G3P that stayed turn into 3 RuBP

61
Q

why is the calvin cycle a “true cycle”?

A

Start with RuBP and end RuBP

62
Q

: first stable organic molecule in calvin cycle

A

3-phosphoglycerate

63
Q

: photosynthesis using 3-phosphoglycerate because it has three carbons. Occurs in 85% plant species

A

C3 photosynthesis

64
Q

enzyme that is used in 15% of plant species; particularly of plant species in dry regions (like desert plants)

A

PEP carboxylase (PEPC)

65
Q 
Used by two kinds of photosynthetic mechanisms 
C4 photosynthesis (common in tropical grasses)
CAM photosynthesis
A

PEP C

66
Q

Photosynthetic mechanism that uses the enzyme PEPC
Commonly used by tropical grasses like corn or sugar cane
Air comes into the mesophyll cell (they are open to atmosphere) on the outside of the leaf
The bundle sheath cell of C4 plants surrounds the vascular tissue
Allows plant to keep rubisco from atmosphere

A

C4 photosynthesis

67
Q

step 1 in C4 pathway

A

1) CO2 comes in, from atmosphere mesophyll cell is exposed to, and is attached by the PEPC to PEP which creates acids (like oxaloacetate and malate)

68
Q

step 2 in C4 pathway

A

2) The acids are pushed into the bundle sheath cell, which is shielded from outside world, The malate is broken down to CO2 which then enters the calvin cycle as CO2 usually does

69
Q

step 3 in C4 pathway

A

3)Rubisco is used in calvin cycle in bundle sheath cell, which is not exposed to atmosphere air

70
Q

step 4 in C4 pathway

A

4) The calvin cycle gives off a G3P, which is eventually turned into glucose, and goes to the vascular tissue

71
Q

Why is it called C4 photosynthesis?

A

Called C4 photosynthesis because first stable carbon molecule has 4 carbons
PEPC doesn’t grab to Oxygen/ It doesn’t have the problem Rubisco has

72
Q

Crassulacean Acid Metabolism
Occurs in 10% of species
Occurs in plants of crassulaceae family
Photosynthesis of all succulent plants (jade plant, pineapple, agave)

A

CAM photosynthesis

73
Q

CAM photosynthesis during night

A

photosynthesizing using PEPC

74
Q

CAM photosynthesis during the day

A

close stomata, break down products made with PEPC (malate acid), turn it into CO2 and then the CO2 enters carbon cycle in the day

75
Q

fun fact: taste difference in CAM plant night vs morning?

A

if you taste CAM plant in early morning it is much sourer than later on in the day because during the day the calvin cycle is making sugar from the PEPC products made at night

76
Q

Why does the CAm photosynthesis cycle work from keep Rubisco from Oxygen?

A

This works from keeping Rubisco from attaching to O2 because the stomata are open during the night

77
Q

plant physical defences?

A

Thorns

Trichomes

78
Q

plant chemical defences?

A

Distasteful compounds
Toxic compounds
Ex: caffeine, cocaine, codeine

79
Q

: organic substance made in one place and transported to another place, where it affects growth and other processes

A

hormone

80
Q

hormone action step 1

A

Hormone binds to specific protein receptor, either in membrane or cytoplasm

81
Q

hormone action step 2

A

Receptor protein goes through conformational change

82
Q

hormone action step 3

A

Stimulates production of “relay molecules” in cytoplasm

83
Q

hormone action step 4

A

Relay molecules trigger various responses to the original signal

84
Q

what is responsible for plants bending towards light?

A

auxins

85
Q

where are auxins primarily found?

A

Primarily in…
Young leaves
Shoot apical meristems

86
Q

phototropism

A

: stem elongation towards light (low concentrations only)

87
Q

what is auxins effect on roots? how does it get to the roots?

A

Auxins are made in the shoots and travel down the vascular tissue to the roots and in the roots they promotes root branching

88
Q

what is auxins affect on the stem/ internode region?

A

Enhances apical dominance/ suppresses lateral branch formation (opposite of roots)
In shoots they inhibit side branches
So they promote central stem being dominant stem

89
Q

when is phototropism easy to see? what side is what?

A

when one side of the plant is darker than the other

elongate greater on dark side

90
Q

how does the plant stem bend?

A

The cells elongate more greatly on the dark side, the shaded side

91
Q

how does auxin promote elongation?

A

Promotes cell elongation by:

Loosening cell walls → loosening the “glue” (like pectin)

92
Q

what is the acid growth hypothesis?

A

Auxin increases in proton activity/ pumping
Increased H concentration increases acidity
So.. increase in proton pumping causes cell wall to become more acidic
Once more acidic, a number of reactions occur…

1) Auxin increases activity of proton pumps (H pumps)
2) Acidity increases in wall. Ion uptake increases
3) Expansins (enzymes), activated by a low pH, separate microfibrils from cross linking polysaccharides (remember from cell wall lecture)
4) The polysaccharides are now more accessible to further enzymes that loosen cell wall

Bio Term 2 (7 decks)

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