14 Ass 7 pt 2 Plant transport Flashcards

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1
Q

As the young leaf matures, the quantity of sugar taken up by the leaf decreases to zero, but the need for water increases.

Suggest and explain why the quantity of sugar taken up by the developing leaf decreases to zero over time, but the need for water increases. 4

A

The sugar uptake decreases because as the leaf matures from sink to source,

it produces sugar which is transported out of the leaf to the rest of the plant through photosynthesis

the need for water increases due to increased transpiration

and the need to maintain turgidity

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2
Q

What types of sugars are transported as part of phloem sap?

A

Monosaccharides and disaccharides

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3
Q

Define the term disaccharide

A

A sugar made of 2 monosaccharides joined together

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4
Q

Define the term polysaccharide and give 3 examples 4

A

A polymer made of more than 2 sugar monomers and is not a sugar.

starch
glycogen
cellulose

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5
Q

Q22 b read context & draw diagram

A

See memo

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6
Q

What causes the mass flow of phloem sap from source to sink?

A

A pressure gradient in sieve tubes

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7
Q

What happens to cause the pressure gradient in plants that causes mass flow?

A

A decrease in water potential & increase in hydrostatic pressure in phloem sap

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8
Q

What causes a decrease in water potential of phloem sap during mass flow?

A

High sucrose concentration from loading of assimilates into sieve tube elements

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9
Q

What causes an increase in hydrostatic pressure of phloem sap during mass flow?

A

large volume of water moving in and out of phloem tubes by osmosis

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10
Q

Define the term transpiration. 3

A

When water is absorbed through roots

before traveling up the plant

and being released as water vapor through the stomata in the leaves

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11
Q

Q 23 b) use table 5.1 to calculate the mean rate of movement of the bubble

A

(12.5+12+11.5)/3 = 36/3 =12

It’s in 10 minutes and we’re calculating how fast it moves per minute, so 12/10=1.2

1.2 mm min^-1

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12
Q

Explain why air movement increases the rate of transpiration

A

The water potential gradient is steeper from there being less water in the air around the plant

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13
Q

Explain how water moves up through a xylem vessel in the stem of the plant 5

A

Water moving out of the leaf creates tension in the xylem vessel

this allows water to move up, down the water potential gradient

Water molecules are attracted to each other, through hydrogen bonding, forming cohesion

Adhesion is created from water being attracted to polar molecules in cellulose and lignin

This creates a continuous column of water

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14
Q

Define adhesion

A

Water molecules sticking to cellulose molecules in lining of the xylem vessel

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15
Q

Q24 b read context and see fig. The general pattern of results in Fig. 4.1 is the same for the three Barlinka
grapevines. Explain why the general pattern of results is the same. 3

A

During the day, the stomata are open

so the rate of transpiration is higher

The daytime is also warmer

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16
Q

Q24 b read context and see fig.With reference to Fig. 4.1, explain the differences in the results between the
three grapevines, 1, 2 and 3. 2

A

A greater total surface area of the leaf leads to a higher rate of transpiration due to more stomata,

as seen by how grapevine 1 has the greatest surface area and the highest rate of transpiration

17
Q

Q24 b read context and see fig.Suggest an explanation for the decrease in flow rate of xylem sap shown at time P

A

It could have been cloudy or rainy

18
Q

Outline how you would determine the surface area of one side of a leaf 3

A

Trace around the leaf over some graph paper

count the number of whole squares

double that number

19
Q

Q19 The diagram shows a model to demonstrate mass flow. In a plant, what is W?

A

Phloem

20
Q

Q19 The diagram shows a model to demonstrate mass flow. In a plant, what is X?

A

Xylem

21
Q

Q19 The diagram shows a model to demonstrate mass flow. In a plant, what is Z?

A

roots

22
Q

Q19 The diagram shows a model to demonstrate mass flow. In a plant, what is Y?

A

leaves

23
Q

Q19 The diagram shows a model to demonstrate mass flow. In a plant, what is the direction of flow along W?

A

Y to Z

24
Q

Q20 the diagram shows a xerophytic leaf in different conditions, P and Q. What is the difference btw the cells in layer Y of P and Q? 2

A

More negative water potential in P than Q

More cells plasmolysed in P

25
Q

Q5 see diagram. What is 1 and how can you identify it?

A

Xylem, because of pits

26
Q

Q5 see diagram. What is 2 how can you identify it?

A

Phloem, because it’s small

27
Q

Q5 see diagram. What is 3 how can you identify it?

A

Amyoplast (stores starch) because it’s big