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biology (paper one) > plant tissues, organs and systems (topic 2) > Flashcards

plant tissues, organs and systems (topic 2) Flashcards

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1
Q

explain why it was important to use the same plant cutting each time to make these experiments fair (2)

A

different plants have different:
- sizes
- numbers of leaves
- sizes of leaves

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2
Q

(factors affecting rate of transpiration / water uptake)

  • air movement
  • humidity
  • light intensity
  • temperature

more of these would increase rate

A

c b a

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3
Q

most water enters a plant through

A

root hairs

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4
Q

the water is transported up the stem to the leaves in the

A

xylem

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5
Q

carbon dioxide enters leaves through

A

stomata

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6
Q

sugars in a leaf are transported to

A

storage organs

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7
Q

sugars in a leaf are transported through

A

phloem

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8
Q
A
  • increase then decrease
  • maximum rate at 36 - 38 (°C ) / 540 - 560 (grams per day)
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9
Q

explain why the use of the same size of plant shoot made the investigation a fair test (2)

A
  • same surface area (or number of leaves)
  • from which water evaporates
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10
Q

(would originally be 1.9 w out plastic bag)

A
  • 0.3 g
  • plastic bag reduces air flow across leaves or air is humid around the leaves
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11
Q

describe how water moves from roots to the leaves (2)

A
  • by transpiration stream
  • in xylem
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12
Q

(3)

A
  • mount epidermis on a slide
  • count stomata in one area
  • repeat in four more areas
  • repeat method on other surface of leaf
  • calculate mean
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13
Q

the plant has very few stomata on the upper surface of the leaf, explain why this is an advantage to the plant (2)

A
  • less water loss
  • so it does not wilt
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14
Q
A
  • species / plant
  • length of time
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15
Q
A
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16
Q
A
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17
Q

explain what happens to the heart in coronary heart disease (3)

A
  • fatty material in coronary arteries
  • narrows arteries, reducing flow
  • decreases oxygen supply (to heart muscle)
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18
Q

list three types of plant tissue and state their functions

A
  • epidermal tissues form the outer layer of the plant (or provide protection)
  • palisade mesophyll is where most photosynthesis occurs
  • spongy mesophyll (contains air spaces to) facilitate gas exchange
  • xylem is involved in the transport of water and mineral ions
  • phloem is involved in the transport of sugars
  • meristem tissue is responsible for plant growth
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19
Q

cell membrane function

A

controls the movement of substances in and out of the cell

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20
Q

cell wall function

A

provides support and structure to the cell

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21
Q

cytoplasm function

A

where most of the cells metabolic reactions occur

22
Q

describe the pathway of water through a plant and explain the factors that affect the rate of transpiration (6)

A

transpiration stream (max 3 marks):
- water is absorbed by the root hair cells, by osmosis
- it then moves into the xylem
- from the xylem, water is transported up the plant to the leaves
- once in the leaves, water evaporates from the spongy mesophyll cells into the air spaces and exits the leaf through the stomata
factors affecting the rate of transpiration (max 3 marks):
- more light increases the rate of photosynthesis
- opens the stomata (increases transpiration)
- higher temperatures increase the rate of evaporation/ transpiration
- wind can remove the layer of humid air around the stomata
- wind increases the water potential gradient
- lower humidity increases the rate of transpiration

23
Q

explain the role of stomata and guard cells in plants (3)

A
  • stomata allow gas exchange between the plant and the atmosphere
  • guard cells control the opening and closing of stomata
  • guard cells regulate gas exchange and water loss
24
Q

explain why stomata are typically found on the lower epidermis of leaves (2)

A
  • the lower epidermis is less exposed to sunlight
  • lower epidermis is less prone to evaporation
25
Q

suggest why stomata can close at night (4)

A
  • stomata can close at night to reduce water loss
  • photosynthesis requires open stomata / uptake of carbon dioxide
  • but photosynthesis does not occur in the absence of sunlight
  • by closing the stomata plants can conserve water at night, when carbon dioxide uptake is not necessary
26
Q

explain how the structure of guard cells allows them to control the opening and closing of stomata (4)

A
  • when the guard cells are filled with water
  • bend outwards
  • causing the stoma to open
  • when the guard cells lose water
  • return to the original shape (the cell wall moves inwards)
  • causing the stoma to close
27
Q

describe the process of transpiration (5)

A
  • transpiration is the process by which water is transported from the roots to the leaves of a plant
  • water is then evaporated into the atmosphere
  • transpiration is driven by the evaporation of water from the leaves
  • evaporation creates a water potential gradient
  • which pulls water up from the roots
28
Q

explain the effect of changing temperature, humidity, air movement, and light intensity on the rate of transpiration (6)

A
  • increasing temperature increases the rate of transpiration
  • it increases the evaporation of water from the leaves
  • increasing humidity decreases the rate of transpiration
  • it decreases the water potential gradient
  • increasing air movement increases the rate of transpiration
  • it removes water vapour from around the leaf
  • (air movement) maintains a high water potential gradient
  • increasing light intensity increases the rate of transpiration
  • it causes the stomata to open wider
  • open stomata allow more carbon dioxide in for photosynthesis
29
Q

describe how a potometer can be used to measure the rate of transpiration (4)

A
  • measures the rate of water uptake by a plant
  • the plant stem is sealed into the potometer
  • water is drawn up the stem
  • it pulls a bubble of air through the capillary tube of the potometer
  • by measuring the movement of this air bubble over time
  • the rate of transpiration can be estimated
30
Q

how is xylem tissue adapted for the transport of water in the transpiration stream (3)

A
  • xylem consists of dead cells
  • xylem cells are hollow tubes
  • xylem tissues are strengthened by lignin
31
Q
A
  • A = waxy cuticle
  • prevents water loss from the leaf
  • B = upper epidermis
  • covers the leaf (or limits water loss or protects from infection)
  • C = palisade mesophyll
  • where majority of photosynthesis occurs
  • D = spongy mesophyll
  • contains air spaces to facilitate gas exchange
  • E = guard cells
  • control the opening and closing of the stomata
32
Q
A

translocation is the movement of sugars through the phloem

33
Q

describe the process of translocation (6)

A
  • translocation transports dissolved sugars
  • translocation from the leaves
  • to the rest of the plant (for immediate use or storage)
  • translocation happens via the phloem
  • driven by a pressure difference
  • between the source (where sugars are loaded into the phloem)
  • and the sink (where sugars are unloaded)
34
Q

explain why translocation is important to plants (2)

A
  • sugars are made in the leaves
  • they need to be moved to other parts of the plant for respiration / growth / storage
35
Q

an aphid feeds by inserting its sharp mouthpiece into the stem of a plant, give the reason why the mouthpiece of an aphid contains a high concentration of dissolved sugars after feeding

A

(the aphid) has been feeding from the phloem

36
Q

explain how xylem and phloem tissues are adapted to their functions (4)

A

xylem
- dead cells (with no end walls)
- (form) hollow tubes / no cell contents
- strengthened by lignin (or lignin stops the xylem from collapsing)
phloem
- tubes of elongated living cells / sieve tubes / contain no nuclei
- the end walls of the cells have pores / sieve plates
- each cells cytoplasm is connected to the next
- sucrose and amino acids are translocated within the cytoplasm of the sieve tubes
- companion cells provide energy (to the attached sieve tube)

37
Q

(as light intensity increases, the rate of transpiration also increases) why does light intensity have this effect on the rate of transpiration (2)

A
  • increasing light intensity opens the stomata
  • increases transpiration
38
Q

describe what happens during transpiration (2)

A
  • water evaporates (on surface of spongy mesophyll)
  • water (vapour) diffuses through the stomata
39
Q

the student kept environmental conditions like air movement, humidity, and temperature, constant, why was it important to keep the temperature the same

A
  • an increase in temperature would increase evaporation
40
Q

explain the effect of decreasing air temperature on the rate of transpiration (2)

A
  • transpiration would decrease
  • as there is less evaporation from the surface of the leaf
41
Q

the volume of water lost from the plant can be calculated by measuring the distance a bubble moves along the capillary tubing, calculate the rate of water loss from the plant in mm3/s if the volume of water lost was 15 mm3 in 10 minutes

A
  • to convert minutes into seconds, multiply by 60
  • 10 mins = 600 s
  • rate of loss = volume lost ÷ time taken
  • rate of loss = 15 ÷ 600
  • 0.025 (mm3/s)
42
Q

rate of water loss equation

A

rate of loss = volume lost / time taken

43
Q

the scientist wants to extend the investigation by considering factors that affect the rate of transpiration, state two variables, other than temperature, that she could investigate

A
  • humidity
  • air speed / wind / air movement
  • light intensity
44
Q

why is a coverslip placed on top of the leaf impression (1)

A

to keep leaf peel flat

45
Q

explain why the student prepared a leaf impression with nail varnish rather than attempting to observe the whole leaf with a microscope (2)

A
  • the leaf peel is thin / leaf is too thick
  • as the leaf peel allows light to pass through it / the leaf would not allow light to shine through it
  • to enable the stomata / cells / guard cells to be identified
46
Q

describe how stomata open (4)

A
  • the guard cells take in water
  • by osmosis
  • become turgid
  • bend outwards / open the stoma
47
Q

(2)

A
  • an increase in ion concentration leads to an increase in plant height
  • the higher the ion concentration, the greater the plant growth
48
Q

calculate the average weekly growth of the plant in the 2% ion concentration (2)

A
  • calculation of total growth:
  • 16.3 cm - 3.1 cm = 13.2 cm
  • calculation of average weekly growth:
  • 13.2 cm / 4 weeks = 3.3 cm/week
49
Q

explain how active transport is related to the observed growth of the plants in this experiment (3)

A
  • (active transport) allows plants to absorb mineral ions (from the soil) against a concentration gradient
  • higher concentration of ions provides more nutrients for absorption
  • (more nutrients absorbed) lead to better growth
50
Q

suggest a way the biologist could modify the experiment to test the effect of different types of ions on plant growth (2)

A
  • the biologist could use different ions/given examples of ions (potassium, nitrate, etc) in different pots
  • keeping total ion concentration constant

biology (paper one) (15 decks)

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