Plant Transport Flashcards

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1
Q

Draw a diagram of a root cross section and label it

A

Should include epidermis, cortex, endodermis and vascular bundle with xylem and phloem

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2
Q

Draw a diagram of a stem cross section and label xylem and phloem

A

Vascular bundle should be in circles around outside. Xylem on inside phloem on outside

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3
Q

How are mineral ions like nitrate absorbed into root hair cells?

A

Active transport

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4
Q

Give two adaptations that root hair cells have.

A

Large surface area, many mitochondria and transport proteins

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5
Q

What is the apoplast pathway?

A

Movement of water through the cellulose cell wall

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6
Q

What is the symplast pathway?

A

Movement of water through the cytoplasm and plasmodesmata

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7
Q

Which is the fastest pathway for water through the root and why?

A

Apoplast is fastest because it has least resistance to flow, vacuolar is slowest because it has the greatest resistance due to the number of membranes that need to be crossed

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8
Q

Where is the Casparian strip located and what is it made of?

A

Endodermis cells, suberin (waterproof wax)

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9
Q

Why does water move into the xylem?

A

Cohesion and the transpiration stream, capillary action and root pressure

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10
Q

What is root pressure?

A

Mineral ions are actively transported from the endodermis into the pericycle. This lowers the water potential in the pericycle and water follows by osmosis

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11
Q

What is the function of the casparian strip?

A

To block the apoplast pathway and force water into the symplast pathway, meaning it must pass through a cell membrane

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12
Q

What four factors can affect the rate of transpiration?

A

Humidity, temperature, wind speed, light intensity

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13
Q

Why is water uptake in a plant not the same value as water lost by transpiration?

A

Water is used in photosynthesis and hydrolysis, made in respiration and used to increase turgor of cells

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14
Q

What does a potometer measure?

A

The distance moved by an air bubble in one minute, which can be used to calculate rate of water uptake

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15
Q

Describe the structure of the xylem

A

Dead tissue, divided into tracheids (narrower) and vessels (wider). Surrounded by waterproof lignin. Presence of pits

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16
Q

Describe the structure of the phloem

A

Living tissue. Companion cells packed with organelles, connected to sieve tubes by plasmodesmata. Sieve tubes have very reduced cell contents

17
Q

How do sugars and amino acids move through the phloem?

A

Translocation, potentially by mass flow

18
Q

List the problems with the mass flow theory

A

Presence of sieve plates, companion cells, mitochondria. Use of oxygen, stopped by cyanide, 10000x faster than diffusion

19
Q

Give three alternative hypotheses to mass flow

A

Cytoplasmic streaming, protein filaments, active loading of phloem

20
Q

Give the features of a xerophyte that help to reduce waterloss

A

Rolled leaves, sunken stomata, hairs. All of these trap water vapour and reduce the diffusion gradient.