Exam 3 Material

Question 1

What is the word that describes the movement of water and mineral nutrients from soil to atmosphere in plants?

Answer 1

Transpiration

Question 2

When do we say water evaporates from leaf cells?

Answer 2

When the relative humidity is less than 100 percent.

Question 3

What is the term that describes the landscape-level movement of water from the soil to the atmosphere?

Answer 3

Evapotranspiration

Question 4

Stoma are usually open during the day but are closed at night. Why?

Answer 4

Because photosynthesis needs to occur during the day, so the stomata are closed at night to prevent water loss.

Question 5

When guard cells are open, it means they are…

When guard cells are closed, it means they are…

Answer 5

Turgid

Flaccid

Question 6

What is the name for the plant that has adapted to dry environments and typically uses CAM photosynthesis meaning they open their stomata at night?

Answer 6

Xerophytes

Question 7

What are some of the adaptations and functions of those adaptations that plants in drier environments use?

Answer 7

1. Smaller leaves - less surface area less chance of water escaping
2. Sunken Stomata - often surrounded by hairs that trap moisture in
3. Thick, waxy cuticle - prevent water loss
4. Less stomata - same
5. CAM photosynthesis - CO2 is stored as an acid stomata open at night

Question 8

What does the transpiration cohesion theory state?

Answer 8

That water has cohesive properties and adhesive properties (cell wall) due to hydrogen bonds

Question 9

How does water get from soil to a root epidermal cell?

What changed?

Answer 9

soil :
(solute potential) -0.1 + (pressure potential) 0.0 = (Total water potential) -0.1

epidermal cell:
(solute potential) -0.3 + (pressure potential) 0.1 = (Total water potential) -0.2

The solute potential and pressure potential = water potential is lower in the epidermal cell.

Question 10

How does water get from a root epidermal cell to a parenchyma cell?

What changed?

Answer 10

epidermal cell:
(solute potential) -0.3 + (pressure potential) 0.1 = (Total water potential) -0.2

parenchyma cell:
(solute potential) -0.4 + (pressure potential) 0.1 = (Total water potential) -0.3

The solute potential is lower in the parenchyma cell = lower water potential.

Question 11

How does water get from a root parenchyma cell to a
functional xylem cell?

Answer 11

parenchyma cell:
(solute potential) -0.4 + (pressure potential) 0.1 = (Total water potential) -0.3

xylem cell:
(solute potential) -0.01 + (pressure potential) -0.4 = (Total water potential) -0.41

xylem cell has more negative water potential because of the negative pressure in xylem cells.

Question 12

How does water get from a functional xylem cell to a leaf mesophyll (parenchyma) cell?

Answer 12

xylem cell:
(solute potential) -0.01 + (pressure potential) -0.4 = (Total water potential) -0.41

mesophyll cell:
(solute potential) -0.6 + (pressure potential) 0.1 = (Total water potential) -0.5

mesophyll cell has more negative water potential because of the lower solute potential.

Question 13

What is the main function of potassium in plant cells?

Answer 13

To regulate stomata closure

Question 14

What does the increase in K+ ion movement into the vacuoles of guard cells during the day do?

Answer 14

Water moves in via osmosis and turgor pressure increases.

Question 15

What are the two ways that water can move into a plant cell?

Answer 15

1. Root hairs
2. Mycorrhizal fungi (extensions)

Question 16

How did pioneers kill trees?

Answer 16

They peeled the bark back from trees which is called girdling which exposes the xylem preventing the sugar transport that needs to happen to the roots.

Question 17

What are the 6 mineral nutrients that plants need and why?

Answer 17

1. N - amino acids, ATP, DNA
2. K - stomata closure regulation
3. P - phospholipids, ATP
4. Mg - chlorophyll function
5. S - amino acids that contain it
6. Ca - needed for cells wall

Question 18

Are C, O, H considered mineral nutrients?

Why do plants need them?

Answer 18

Because they are needed for sugars.

and No

Question 19

What is the process of using plants to remove contamination of soil water and sediments?

Answer 19

Phytoremediation

Question 20

Where does the translocation of sugars in plants occur?

Answer 20

In the living phloem sieve tube members

Question 21

Sugars move from a source like….

To a sink like…

Answer 21

Source - leaves or photosynthetic stems

Sink - roots or phloem

Question 22

What are the two plants that produce all of the sugar in the world?

Answer 22

1. Sugar cane
2. Sugar beets

Question 23

How much of the radiant energy from the sun is utilized in photosynthesis?

Answer 23

40%

Question 24

What wavelengths of light can plants use?

Answer 24

Visible spectrum - 400 to 700 nm

Question 25

What are the primary photosynthetic pigments in green plants? What do they do?

Answer 25

They donate electrons. Cholorphyll a P680 or P700

Question 26

What are the accessory pigments a part of?

Answer 26

The light harvesting system - rest of chlorophyll a - chlorophyll b - carotenoids - carotene (orange) and xanthophylls (yellow)

Question 27

What is the difference between chlorophyll a and b?

Answer 27

The R group in A is CH3 and the R group in B is CHO

Question 28

Describe the spectrum of absorption for the pigments.

Answer 28

A - works best near 420 and 680 B works best near 480 and 640 Carotenoids - works best near 480 and 500

Question 29

Why are chlorophyll A and B broken down in the fall but not the carotenoids?

Answer 29

Because the A and B contain Nitrogen and Mg that needs to be reabsorbed by the plant, while the carotenoids just have stuff that is in sugars.

Question 30

Describe the funneling of light energy to chlorophyll A in the reaction center.

Answer 30

It hits the carotenoids, then the B and then A

Question 31

Explain the light dependent reactions.

Answer 31

In the light reactions of photosynthesis, water is split by Photosystem II (PSII), releasing oxygen, protons (H⁺), and electrons. The electrons are picked up by *plastoquinone* and move through a chain of proteins, including the *cytochrome b6f complex*. As they move, more protons are pumped into the thylakoid lumen, creating a buildup of H⁺ (a pH gradient). This gradient is later used to make ATP. The electrons continue to Photosystem I (PSI), where they get re-energized by light, then pass to *ferredoxin* and finally to an enzyme called *FNR*, which uses them to turn NADP⁺ and H⁺ into NADPH. In the end, water provides electrons, and light energy powers the production of both ATP and NADPH, which are needed for the Calvin Cycle to make sugars.

Question 32

What does rubisco stand for?

Answer 32

Ribulose bisphosphate carboxylase/oxygenase

Question 33

What is photorespiration?

Answer 33

Rubisco catalyzes the fixation of O2 to RuBP (oxygenase activity)

Question 34

What is it called when Rubisco fixates CO2 on RuBP?

Answer 34

Carboxylation

Question 35

In what type of plants is the C4 cycle found?

Answer 35

warm-season prairie grasses, maize, corn, sugarcane

Question 36

What are two advantages and 1 disadvantage of the C4 cycle?

Answer 36

Advantages 1. Increases the CO2 concentration in the bundle sheath cells 2. Reduces photorespiration Disadvantages 1 Uses ATP and is even less efficient when the environment is not hot and dry

Question 37

What are the common monosaccarides?

Answer 37

1. glucose 2. Fructose 3. Galactose

Question 38

What are the common disaccharides?

Answer 38

1. Sucrose 2. Maltose 3. Lactose

Question 39

Why is cellulose considered a fiber?

Answer 39

Can't break it down - no enzymes

Question 40

What are the soluble forms of fiber?

Answer 40

1. Pectin 2. mucilage

Question 41

What are the insoluble forms of fiber?

Answer 41

1. Lignin 2. Cellulose