4C2 Plant Storage and Transportation

Question 1

What are the four important elements contributing to the health of photosynthetic plants?

Answer 1

• Nutrients
• Sunlight
• Temperature
• Water

Question 2

What determines the amount of water absorbed by a plant?

Answer 2

The diffusion pressure deficit.

(DPD)

It reflects the difference in water potential between the soil and the plant’s root cells.

This drives water uptake through osmosis, particularly when the plant cells have higher solute concentration than the surrounding soil.

Question 3

What is the diffusion pressure deficit (DPD) in plants?

Answer 3

The difference between the water potential outside and inside the cell, influencing water movement. It is calculated as osmotic pressure minus turgor pressure.

Turgor: The pressure put on the cell by the cytoplasm against the cell wall.

Question 4

What happens when the calculated diffusion pressure deficit (DPD) is greater than zero in plants?

Answer 4

Plants are in need of water and the roots will absorb water to reestablish turgor pressure within the plant cells.

Question 5

What is the role of root hairs in vascular plants?

Answer 5

Increase the surface area available for water absorption in plants.

Question 6

What is root pressure in plants?

Answer 6

Hydrostatic pressure created in the roots that allows water to move up into the xylem.

Question 7

How do roots adapt to water availability in a plant’s environment?

Answer 7

By increasing root density and root depth.

Question 8

What process involves the phloem carrying nutrients from the leaves to the roots in vascular plants?

Answer 8

Translocation

It is the process by which nutrients—primarily sugars produced during photosynthesis—are transported through the phloem from source tissues (like leaves) to sink tissues (like roots, fruits, or growing shoots).

Question 9

What are the three methods through which water travels into the cortex of a root?

Answer 9

• Apoplastic pathway
• Symplastic pathway
• Transmembrane pathway

Question 10

What is the apoplastic pathway of water movement in roots?

Answer 10

Water movement between the cells and through the cell walls of the cortex.

Question 11

What is the symplastic pathway of water movement in roots?

Answer 11

Transport from the cytoplasm of one cell to the cytoplasm of another cell within the cortex.

Question 12

What is the transmembrane pathway of water movement in roots?

Answer 12

Water travels across the plasma membranes of cells in the cortex.

Question 13

Where does water ultimately travel to within the cortex of a root?

Answer 13

Endodermal cells

They comprise the inner layer of the cortex.

Question 14

What specialized part of the root contains the xylem and phloem?

Answer 14

Stele

Question 15

What are plasmodesmata in plant cells?

Answer 15

Pores connecting adjacent cells to one another.

Question 16

What is imbibition in plant seeds?

Answer 16

The initial absorption of water by dry seeds, causing them to swell and triggering enzyme activity necessary for germination.

Question 17

How do non-vascular plants absorb water?

Answer 17

Directly through leaf-like structures.

Question 18

How does xylem move water against gravity?

Answer 18

Through capillary action, utilizing the unique properties of water including surface tension.

Question 19

What are the three unique properties of water that enable capillary action in xylem?

Answer 19

• Surface tension
• Water adhesion
• Cohesion

Question 20

How does water enter the roots of a plant?

Answer 20

Through osmosis.

Question 21

What does xylem transport?

Answer 21

Water and dissolved minerals.

Question 22

What does phloem transport?

Answer 22

Sugar and nutrients.

Question 23

What is the most well-supported theory explaining how nutrients in sap are transported throughout the phloem of the plant?

Answer 23

Pressure-flow hypothesis

Question 24

What does the sap transported by the phloem contain?

Answer 24

High concentrations of sugars created during photosynthesis and other nutrients.

Question 25

What **causes the movement of sugar** towards sinks in the pressure-flow hypothesis?

Answer 25

Sugars are actively transported into sieve tube elements at the source, **increasing pressure and causing flow** toward sink tissues where pressure is lower.

Question 26

What is the role of **sieve tube elements** in phloem transport?

Answer 26

Specialize in moving sap but lack nuclei and other organelles, with their metabolic functions carried out by surrounding companion cells.

Question 27

How does the plant **regulate the hydrostatic pressure** within the phloem?

Answer 27

By actively transporting sugars into sieve tube elements at sources (e.g., leaves), creating pressure that drives sap toward sinks (e.g., roots, fruits, growing tissues) where sugars are needed. ## Footnote Sinks are areas in the plant that require a higher level of glucose such as fruit, young or growing leaves, roots and growing stems.

Question 28

What happens to the **nutrients in the sap of roots** when phloem nutrients reach them?

Answer 28

Consumed rapidly by cellular respiration since roots are underground and cannot perform photosynthesis.

Question 29

What is the **process** by which water is lost through the stomata of leaves?

Answer 29

Transpiration ## Footnote It creates negative pressure that pulls water upward through the plant and helps regulate temperature and nutrient transport.

Question 30

What are **stomata** in plants?

Answer 30

**Openings in between guard cells** that allow plants to exchange gases, such as carbon dioxide and water vapor, with their outside environment.

Question 31

What is the process that moves water all the way up through tall plants?

Answer 31

Transpirational pull

Question 32

What is the significance of **transpiration** in plants?

Answer 32

* Suction pressure is created, aiding in water conduction from roots. * Helps maintain water balance in plants. * Assists in maintaining turgidity of plant cells. * Causes a cooling effect in plants. * Plays a crucial role in the cycling of water on Earth.

Question 33

What are **guard cells**?

Answer 33

A pair of curved plant cells, usually found on the underside of the leaf, that can expand and shrink, regulating gas flow.

Question 34

How do **guard cells** affect the opening and closing of stomata?

Answer 34

They surround stomata and control their opening and closing. ## Footnote When turgid, stomata opens; when flaccid, stomata closes.

Question 35

What is the **transpiration rate**?

Answer 35

The extent to which water is released from plant leaves into the environment.

Question 36

What factors **can affect the rate of transpiration**?

Answer 36

* Relative humidity: Decrease in relative humidity increases transpiration rate. * Light intensity: Higher light intensity increases transpiration rate. * Temperature: Increase in temperature leads to stomatal opening and transpiration. * Availability of water: If sufficient water is available, stomata opens.

Question 37

What is the **primary function** of photosynthesis?

Answer 37

Convert light energy from the sun into chemical energy.

Question 38

What are the **reactants** needed for photosynthesis?

Answer 38

* Water * Sunlight * Carbon dioxide

Question 39

Why is photosynthesis **important** to plants?

Answer 39

It **allows plants to make complex molecules like glucose** from simple molecules for energy, growth, cell development, and as a source of food for germinating seeds.

Question 40

**Where** does the process of photosynthesis take place in plants?

Answer 40

In the chloroplast. ## Footnote The light-dependent reaction occurs in the thylakoids and the light-independent reaction in the stroma.

Question 41

What are the **products** of the light-independent (Calvin cycle) reaction in photosynthesis?

Answer 41

* Glucose (or G3P) * ADP * NADP⁺