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bio > bio chap 9 - nutrition and transport in flowering plants > Flashcards

bio chap 9 - nutrition and transport in flowering plants Flashcards

1
Q

what are the 3 external features of a leaf?

A

leaf blade
network of veins
leaf stalk

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2
Q

what is the function of the leaf blade

A

it has large flat surface compared to its volume, enabling it to obtain the maximum amount of light for photosynthesis

it is large and thin so that co2 can he produced rapidly reach the inner cells of the leaf

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3
Q

what is the function of the network of veins in leaves?

A

veins carry water and mineral salts to the cell in the leaf blade
carry manufactured food from these cells to other parts of the plant

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4
Q

what is the function of the leaf stalk?

A

holds leaf blade away from the stem so that it can obtain sufficient light and air

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5
Q

name the 6 parts of the internak structure of the leaf

A

upper epidermis
palisade mesophyll & spongy mesophyll
lower epidermis
cuticle
stomatal pore
guard cell

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6
Q

what are the characteristics of the upper epidermis?

A

it is made up of a single layer of closely packed cells
covered on the outside by a waxy and transparent cuticle

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7
Q

what is the mesophyll?

A

contains 2 types of tissue - palisade mesophyll and spongy mesophyll

main site of photosynthesis

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8
Q

what are the characteristics of the palisade mesophyll

A

consists of half layers of closely packed long and cylindrical cells
contains numerous chloroplasts

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9
Q

what is the function if the palisade mesophyll

A

main site for photosynthesis

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10
Q

what are the characteristics of spongy mesophyll?

A

contains irregularly shaped cells

numerous large intercellular air spaces among the loosely packed cells

cells covered with a thin film of moisture

contains transport tissues (xylem amd phloem) grouped together forming vascular bundle

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11
Q

what is the function of the spongy mesophyll

A

carries out photosynthesis
but has fewer chloroplasts than the palisade mesophyll

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12
Q

what are the characteristics of the lower epidermis

A

consists of a single layer of closely packed cells

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13
Q

what are the characteristics and function of the cuticle?

A

cells are covered by an outer layer of cuticle
reduces water loss through epidermal cells

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14
Q

what are the characteristics of the stoma/stomatal pore?

A

many minute openings called stomata

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15
Q

what are the characteristics and function of a guard cell?

A

contains chlorophyll, not present in any other epidermal cells

a pair surrounds each stoma and helps to regulate the rate of transpiration by opening and closing the stoma

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16
Q

what are the 6 adaptations of the leaf to carry out photosynthesis

A

waxy cuticle on upper/lower epidermis
stomata ptrsent in epidermal layers
chloroplasts containing chlorophyll in all mesophyll cells
more chloroplasts in upper palisade tissue
interconnecting system of air spaces in spongy mesophyll
veins containing xylem and phloem situation close to mesophyll cells

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17
Q

what is the function of this adaptation of the leaf
waxy cuticle on upper/lower epidermis

A

reduces water loss through evaporation from the leaf
transparent so that light can enter the leaf

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18
Q

what is the function of this adaptation of the leaf
stomata present in epidermal layers

A

stomata open in presence of light causing co2 to diffuse in and o2 out of the leaf

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19
Q

what is the function of this adaptation of the leaf
chloroplasts containing chlorophyll in all mesophyll cells

A

chlorophyll absorbs energy from light
transfers it to chemical stores of energy in glucose molecules

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20
Q

what is the function of this adaptation of the leaf
more chloroplasts in upper palisade tissue

A

more light absorbed near upper leaf structure

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21
Q

what is the function of this adaptation of the leaf
interconnecting system of air spacew in spongy mesophyll

A

allow rapid diffusion of co2 and o2 into and out of mesophyll

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22
Q

what is the function of this adaptation of the leaf
veins containing xylem and phloem situated close to mesophyll cells

A

xylem transports wayer and mineral salts to mesophyll
phloem transports sucrose away from the leaf

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23
Q

how do guard cells control the size of stomata

A

stomata opens in light and closes in dark
guard cells help to regulate the passage of gases between the leaf anf environment

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24
Q

explain how guard cells control the opening of stoma

A

guard cells manufacture glucose by photosynthesis as
increase in glucose concentration decreases water potential of cell sap on the cell

water enters guard cells via osmosis
guard cells become turgid and more curved as
cell wall around stoma is thicker than other parts of the cell causing it to curve around the stoma, and the stoma opens

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25
Q

explain how the guard cells control the closing of the stoma

A

when the leaf loses too much water, the stomata close as
excess evaporation causes guard cells to become flaccid
this prevents excessive water loss by the leaf

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26
Q

how does carbon dioxide enter the leaf through the stomata?

A

in the daylight, photosynthesis occurs
carbon dioxide in leaf is rapidly used up
co2 conc in leaf is lower than in the atmospheric air causing a diffusion gradient to exist
this causes co2 to diffuse from the surrounding air through stomata into intercellular air spaces in the leaf

surfaces of mesophyll cells are always covered by a thin film of water so that co2 can dissolve in it

dissolved co2 diffuses into cells

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27
Q

how does the xylem transport water and mineral salts to the leaf?

A

the xylem transportd water and dissolved mineral salts to the leaf from the roots

once out the veins, water and mineral salts move from cell to cell through mesophyll and lewf

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28
Q

what happens after the xylem transports water and mineral salts to the leaf?

A

once the green cells receive the essential raw materials such as co2 and h2o, it manufactures food by photosynthesis

phloem transports sugars made in the leaf to other parts of the plant

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29
Q

what are the characteristics and function of the xylem?

A

conducts water and dissolved mineral salts from the roots to the stems and leaves

provides mechanical support for the plant

xylem tissue consists mainly of xylem vessels made up of many dead cells

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30
Q

explain the adaptations of the xylem
empty lumen

A

the xylem has an empty lumen without cytoplasm or cross walls
-> xylem vessels form a long hollow continuous tube which stretches from root to leaf
-> lack of cross walls in the xylem vessels reduce resistance to water flowing through the xylem

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31
Q

explain the adaptations of the xylem
lignin

A

inner walls of xylem vessels are strengthened by deposits of lignin
it is a hard and rigid substance that prevents collapsing of the vessel

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32
Q

explain the adaptations of the xylem
mechanical support

A

all xylem vessels provide mechanical support to the whole plant
lignin is deposited in the form of rings or the whole vessel may be lignified except in the regions called pits

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33
Q

what are the characteristics and functions of the phloem

A

conducts manufactured food substances (glucose and amino acids) from the green parts of the plant to other parts of the plant

consists mainly of long tubes made up of a row of living cells

34
Q

explain the adaptation of the phloem

A

each tube stretches form the leaf to other parts of the plant
the cross walls separating the cells have a lot of minute pores
this allows rapid flow of manufactured food substances through the tube

35
Q

how are the vascular tissues organised in stems

A

within a vascular bundle, the xulem is located closer inside
the phloem lies outside the xylem with a tissue called the cambium between them

the stem is covered by a layer of celle called the epidermis
epidermal cells are protected by a waxy and waterproof cuticle and reduces the evaporation of water from the stem

36
Q

where are the xylem and phloem located in the leaf

A

xylem is closer to upper surface of the leaf
phloem is closer to the lower surface of the leaf

37
Q

what is photosynthesis

A

the process where chlorophyll absorbs the energy from light to make glucose from co2 and water and releases o2

38
Q

what is the word equation for photosynthesis

A

co2 +h2o -> (light up, chlorophyll down) glucose + oxygen

39
Q

how does light intensity affect photosynthesis?

A

when light intensity increases the rate of photosynthesis decreases
because more light is supplied to the plant causing an increase in the amount of energy that can be used for photosynthesis

after a certain point, rate of photosynthesis remains constant even when light intensity increases

40
Q

how does carbon dioxide concentration affect the rate of photosynthesis

A

when the conc of co2 increases, the rate of photosynthesis increases
because more co2 is available for the plant to carry out photosynthesis and produce more glucose

after a certain point the rate of photosynthesis remains constant evej when co2 conc increases

41
Q

how does temperature affect the rate of photosynthesis?

A

when temperature increases to optimum temperature, the rate of photosynthesis increases

beyond the optimum temperature, the rate of photosynthesis decreases rapidly as enzymes involved are being denatured

42
Q

how is glucose utilised in plants - leaves

A

used immediately in the leaves
for cellular respiration provide energy for cellular activities
forming cellulose cell walls

43
Q

how is glucose utilised in the leaves - conversion between glucose and starch

A

conversion between glucose and starch
in daylight, excess glucose made is converted to starch for storage
in darkness, starch is converted back to glucose

44
Q

how is glucose utilised in plants - conversion to sucrose

A

sucrose is transported to other parts kf the plant/storage organs such as seeds and root tubers
sucrose is converted into other forms of storage compounds at storage organs
sucrose may be converted back to glucose by enzymes for respiration
sucrose is a component of nectar in flowers to attract insects for pollination

45
Q

how is glucose utilised in plants - converted to amino acids in leaves

A

amino acids form proteins needed to build protoplasm in leaves
transported to other parts of the plant for

synthesis of new protoplwsm
for storage as proteins

46
Q

how is glucose utilised in plants - formation of fats

A

glucose is utilised to form fats
for storage
synthesis of new protoplasm
used in cellular respiration

47
Q

explain the importance of photosynthesis - chemical energy

A

photosynthesis makes chemical energy available for organisms that cannot make their own food

during photosynthesis, chlorophyll absorbs energy from light and transfers it to chemical stores of energy in carbs

these carbs are converted to fats, proteins and other organic compounds that become food for other organisms

plants are producers in food chains and all organisms obtain chemical energy directly or indirectly from them

48
Q

explain the importance of photosynthesis - removal and release of gases

A

photosynthesis removes co2 and release o2
o2 allows living things to carry out respiration and release energy for all cell activities

this mantains a constant level of oxygen and co2 in the atmosphere

49
Q

explain the importance of photosynthesis - storing energy in fossil fuels

A

coals are formed from trees
when coal is burnt, energy in chemical store of coal is used to drive machinery
and transferred to other energy stores

50
Q

explain the procedure of the experiment to investigate light intensity on the rate of photosynthesis

A

vary the distance, xcm, of light source from the plant for each investigation
a shorter distance would give a stronger light intensity

co2 conc and temp are kept constant

results are obtained by counting number or bubbles releasee per time

51
Q

explain the procedure of the experiment to investigate co2 conc on the rate of photosynthesis

A

use different concs of xm3 of solution
sodium hydrogen carbonate is a source for co2 gas

constant factors are light intensity and co2 conc

results obtained by counting number of bubbles released per time

52
Q

explain the procedure of the experiment to investigate temperature on the rate of photosynthesis

A

use dif temperatures, x°c of solution

constant factors are light intensity and temp

results obtained by counting number of bubbles released per time

53
Q

how to study photosynthesis by testing for starch on leaf

A

when photosynthesis is carried out actively, glucose is formed more quickly than it is used up
causing excess glucose converted into starch for storage in the leaf

54
Q

why is it that starch formation may not indicate that photosynthesis has taken place

A

starch can be formed in the roots/underground storage organs of plants

55
Q

why must we destarch before experimenting on photosynthesis by placing plants in the dark

A

in darkness, no photosynthesis occurs, enzymes cannot convert starch into sucrose causing no starch to be left in the leaves

this ensures that starch is not present in leaves before experiement so that we can assume that all starch present in the leaves after experiment must have been formed during the experiment

56
Q

what is translocation?

A

transport of food, mainly sucrose in the phloem tissue

57
Q

what is the evidence to show that the transport manufactured food subsyances occurs through the phloem

A

a ring of bark with phloem is removed from the stem of a woody plant
after some time, the stem above the cut region swells immediately

this is because when the phloem was removed, food substances from the leaves cannot reach the stem below the cut region

food substances accumulate in the region above the cut region and swells up

58
Q

explain the 5 step procedure of the entry of water into a plant

A
  1. each root hair is a narrow extemsion of epidermal cell
    it grows between the soil particles, coming into close contact with surrounding soil solution
  2. film of liquid, a dilute solution of mineral salts, surrounds each soil particle
  3. cell sap in the RHC is a concentrated solution of sugars and salts
    hence it has a lower water potential than soil solution
    cell sap and soil solution is separated by ppm of RHC
    water enters root hair by osmosis
  4. entry of water dilutes cell sap
    cell sap of RHC has a higher water potential than that of the next cell
    water passes by osmosis from RHC to the inner cell
  5. water passes from the inner cell to the next cell of the cortex
    process continues until the water enters xylem vessels and moves up the plant
59
Q

how do root hairs absorb ions/ mineral salts

A

when the conc of certain ions in soil solution is higher than in the RHC, and enter the cell by diffusion

when conc of ions in soil solution is lower than in the RHC sap, energy used to absorb ions against a conc gradient

60
Q

how is the root hair cell adapted to its function of absorption

A

RHC has a long and narrow extension
which increases the surface area to volume ratio and increases the rate of absorption of water and mineral salts

cell membrane of RHC prevents cell sap from leaking out

cell sap contains sugars, amino acids, and salts
when the cell sap’s water potential is lower than the soil solution, water enters roots by osmosis

61
Q

what is transpiration

A

loss of water vapour from the aerial parts of a plant, mainly through the stomata of the leaves

62
Q

explain the 5 steps of transpiration pull

A
  1. when water moves out the mesophyll cells, it forms a thin layer of moisture over their surfaces, then it evaporates into the intercellular air spaces
  2. this causes the concentration of water vapour in the intercellular air spaces to increase
    and allows it to diffuse out through the stomata
    this causes a loss of water vapour from the leaves / transpiration
  3. thin film of moisture is replenised by more water moving out of mesophyll cells as it evaporates
  4. this causes water potential of their cell sap lesser than that of mesophyll cells deep inside the leaf
    this allows water to move from the inner mesophyll cells to the thin film of moisture via osmosis
  5. mesophyll cells deeper inside the leaf extract water from the xylem vessels via osmosis
    this produces suction force that pulls water upward in the vesells, the transpiration pull
63
Q

what is the importance of transpiration - transportation of water

A

water can be transported to leaves for photosynthesis which keep cells turgid and replace water lost by cells
turgid cells enable the leaves to spread out widely to trap light for photosynthesi

transpiration pull moves water & mineral salts up the roots to the stems and leaves

64
Q

what is the importance of photosynthesis - absorb heat

A

a leaf exposed to direct sunlight will absorb heat
its temp might increase to a level that would kill the leaf

its water evaporating from the leaf helps cool the leaf down

65
Q

how to experiment to investigate factors affecting the rate of transpiration - balance

A

factor: light intensity
changed factor: light intensity - place one set up in a sunny area and another in a dark room

constant variables: air humidity, wind conditions, temperature

  1. record initial weight of apparatus
  2. record final weight of the apparatus
  3. rate of transpiration = loss in weight/time taken
66
Q

what is a potometer

A

an instrument used to measure the uptake of water by a plant

67
Q

what is the assumption when using a potometer to investigate the rate of transpiration?

A

water uptake = water loss by transpiration
as some water may be used by plants for photosynthesis

68
Q

how does using a potometer to investigate the rate of transpiration work

A

when the plant transpires, it absorbs water from the potometer to replace water loss by evaporation through the stomata

this causes water in the collumn in the capillary tube to move from x to y

69
Q

how to calculate rate of transpiration using formula

A

a cm + t second
-> a is the length/ volume moved from x to y
-> t is time taken for air bubbles to move from x to y

70
Q

what precautions should be taken when using a potometer to investigate the rate of transpiration

A

plant must be cut underwater to prevent air being trapped in the xylem
cut end is kept immersed in water for a few hours before use
this is to allow shoot to adjust to the conditions in the potometer

71
Q

how does air temperature affect the rate of transpiration

A

transpiration will take place more rapidly when the surrounding temperature is higher

this is because water from leaves will evaporate more readily at higher temperatures

72
Q

how does presence of wind affect the rate of transpiration

A

in still air, air surrounding a leaf becomes saturated with water vapour that diffuses out of it
causing less steep concentration gradient of water vapour between leaf and air
hence rate of transpiration decreases

73
Q

how does light affect the rate of transpiration

A

light affects the size of stomata
in daylight, stomata are open
water vapour in the leaves can easily diffuse out into the atmosphere, increasing the rate of transpiration

at night, stomata close and transpiration is greatly reduced

74
Q

how does humidity affect the rate of transpiration

A

intercellular air spaces in a leaf are usually saturated with water creating a water vapour concentration gradient between the leaf and surrounding air

the decreasing air humidity causes a lower amount of water vapour in the air

this causes a steeper concentration gradient between the leaf and the air increasing the rate of transpiration

hence water vapour can diffuse from the leaf into drier or less humid air causing a steeper concentration gradient of water vapour between the leaf and air

75
Q

what are the adaptations that plants living in hot and dry environments have developed to reduce water loss

A

sunken stomata that lie in grooves in the upper surface of the leaves have numerous tiny hairs that trap water vapour diffusing out of the stomata

this gives rise to increasing humidity around the stomata that helps reduces rate of transpiration

76
Q

what is turgor pressure

A

pressure exerted by the fluid, inside the cells of a plant against the cell wall

77
Q

why is it important for there to be turgor pressure in the mesophyll cells

A

to support the leaf and keep it firm as it can spread out widely to absorb light for photosynthesis

78
Q

how does a plant wilt

A

when rate of transpiration is more than the rate of absorption by the roots in strong light,

cells lose their turgor and become flaccid, causing the plant to wilt

79
Q

what are the advantages of plants wilting

A

their leaves fold up to decrease surface area exposed to sunlight, decreasing exposure of stomata to the atmosphere, causing a decrease in the rate of water loss through stomata

guard cells become flaccid and close stomata lowering the rate of transpiration

80
Q

what are the disadvantages of plants wilting

A

there is a decrease in the amount of carbon dioxide entering the leaves causing carbon dioxide to be a limiting factor that decreases the rate of photosynthesis in the plant

wilting decreases the surface area exposed to light, decreasing the rate of photosynthesis

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