Transport in Plants Flashcards

1
Q

Over small distances, substances move by

A

Diffusion and cytoplasmic streaming supplemented by active transport

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2
Q

Transport over longer distances proceeds through

A

Vascular system - translocation

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3
Q

Transport in xylem is

A

Unidirectional - root—->stem

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4
Q

Transport of PGRs is

A

Sometimes in a strictly polarized or unidirectional manner

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5
Q

Only means of gaseous movement within plant body

A

Diffusion

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6
Q

Diffusion of any substance across cell membrane depends on

A

Its solubility in lipids

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7
Q

Hydrophilic substances can easily pass through cell membrane - true/false

A

False

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8
Q

Facilitated diffusion is sensitive to

A

Inhibitors which react with protein side chains

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9
Q

Porins are

A

Proteins that form large pores in outer membrane of plastids, mitochondria, some bacteria

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10
Q

Water channels are made up of

A

8 different types of aquaporins

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11
Q

Pumps are

A

Proteins that use energy to transport substances across cell membrane

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12
Q

Facilitated diffusion and active transport are under

A

Hormonal regulation

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13
Q

Watermelon has over ____ % water

A

92

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14
Q

Most herbaceous plants have ___ to ___ % of fresh weight as dry weight

A

10 to 15%

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15
Q

Mature corn plant absorbs ___ litres of water per day

A

3

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16
Q

Mustard plant absorbs water

A

Equal to its own weight in 5 hours

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17
Q

Water potential of pure water at standard temperature and pressure is

A

Zero

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18
Q

Solute potential is

A

Always negative

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19
Q

The more the solute molecules the ______ is the solute potential

A

Lower (more negative)

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20
Q

For a solution at atmospheric pressure

A

Solute potential = Water potential

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21
Q

Pressure potential is usually

A

Positive

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22
Q

Water potential =

A

Pressure potential + Solute potential

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23
Q

Osmosis occurs through

A

Selectively permeable membrane

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24
Q

Osmotic pressure =

A
  • Osmotic potential
25
Plasmolysis occurs when
Water moves out of the cell and the cell membrane shrinks AWAY from the cell wall
26
Water is lost first from ______ and then from _____
Cytoplasm, vacuole
27
Pressure responsible for enlargement and extension growth of cells
Turgor pressure
28
Imbibition is a special type of diffusion when water is absorbed by
Solids - colloids
29
Water potential gradient is not essential for imbibition - true/false
False - imbibition is similar to diffusion
30
Size of typical plant cell
50 micrometer
31
The time taken by a molecule to move across a plant cell (50 micrometer) by diffusion is
2.5 seconds
32
Translocation
Bulk movement of substances through vascular tissues
33
Xylem is associated with translocation of
Water, mineral salts, organic nitrogen and hormones (PGRs)
34
Phloem is associated with translocation of
Organic and inorganic solutes
35
Water, along with mineral solutes in plants is absorbed by
Root hairs, PURELY by DIFFUSION
36
Apoplast is continuous throughout the plant except
Casparian strips of endodermis in the root
37
Mass flow occurs in apoplast due to
Adhesive and cohesive properties of water
38
Symplastic movement may be aided by
Cytoplasmic streaming
39
Most water flow in roots occurs via
Apoplast
40
In young roots, water enters directly into
Xylem vessels/tracheids (apoplast)
41
Greatest contribution of root pressure is to
Reestablish the continuous chains of water molecules in xylem
42
Rate of upward flow of water through xylem
15 metres/hour
43
Less than __ % of water reaching the leaves is used in photosynthesis and plant growth
1%
44
Inner wall of each guard cell is
Thick and elastic
45
Opening of stomata is also aided due to
Orientation of microfibrils in cell WALL of guard cells - cellulose microfibrils are oriented radially rather than longitudinally
46
Adhesion is
Attraction of water molecules to polar surfaces (surface of tracheary elements)
47
Tracheids and vessel elements have
Small diameter
48
Forces generated by transpiration can lift a xylem sized column of water upto
130 metres
49
What supplies water for photosynthesis
Transpiration
50
Transpiration can cool leaf surfaces by upto
10 to 15 degrees
51
C4 plant loses only ___ % water as compared to a C3 plant
50%
52
Most minerals enter the root by
Active absorption
53
Root endodermis can actively transport ions in
ONLY ONE DIRECTION
54
Unloading of mineral ions occurs at fine vein endings through
Diffusion and active uptake
55
Elements most readily mobilized are
Phosphorous, sulphur, nitrogen, potassium
56
Most of the nitrogen is carried as
Organic nitrogen - amino acids, etc.
57
Substances translocated through phloem
Water, sucrose, other sugars, hormones, amino acids
58
Sucrose is moved into companion cells and sieve tube cells by
Active transport