Exam 2

Question 1

(T/F) The presence of air spaces around the mesophyll cells in leaves helps in the absorption of light by the leaf due to refraction of light within the leaf.

Answer 1

TRUE

Question 2

(T/F) Under low O2 conditions the CO2 compensation point for both C3 and C4 plants would both be expected to be about the same.

Answer 2

TRUE

Question 3

(T/F) Photosynthesis and respiration each have optimal temperatures and the optimal temperature for respiration is higher than for photosynthesis.

Answer 3

TRUE

Question 4

(T/F) The effect of temperature on net photosynthesis is the effect of temperature on total photosynthesis minus the effect of temperature on respiration and photorespiration.

Answer 4

TRUE

Question 5

(T/F) In C3 plants, the quantum yield decreases with increasing temperature due to increased photorespiration at higher temperatures.

Answer 5

TRUE

Question 6

(T/F) C4 plants generally have a higher internal concentration of CO2 than C3 plants and this results in lower rates of photorespiration and therefore a lower CO2 compensation point.

Answer 6

TRUE

Question 7

(T/F) Even when light, CO2, and temperature are optimal, plant growth can be limited if the supply of water is not adequate.

Answer 7

TRUE

Question 8

(T/F) When a plant cell expands, it is due to the fact that the water potential of the cell is more negative than that of the exterior of the cell which leads to the accumulation of water in the cell which causes the build up of turgor pressure in the cell.

Answer 8

TRUE

Question 9

(T/F) Osmosis is the movement of water through a differentially permeable membrane to achieve an equal water concentration on both sides of the membrane.

Answer 9

TRUE

Question 10

(T/F) Water potential and changes in water potential play a role in the movement of compounds through the phloem.

Answer 10

TRUE

Question 11

When the water potential of the soil is less negative than the water potential of the plant, the plant will wilt.

Answer 11

FALSE, plant expands

Question 12

When sugars move into the phloem in the leaves, the water potential becomes more negative and this causes water to move into the phloem.

Answer 12

TRUE

Question 13

Roots elongate by taking up water and pushing through the soil, and the meristem serves to protect the tip of the root as it moves through the soil.

Answer 13

FALSE

Question 14

When phloem cells unload sucrose, the water potential of the phloem becomes more negative and this leads to a movement of water into the phloem cells.

Answer 14

FALSE

Question 15

Which of the following is the best explanation for why C4 plants don’t show light saturation?

a. C4 plants have both bundle sheath and mesophyll cells.
b. C4 plants are more efficient in their use of water than C3 plants.
c. C4 plants are able to continue to utilize light energy to photosynthesize even under very low CO2 levels.
d. C4 plants have the same light compensation point as C3 plants.
e. C4 plants are specially adapted to hot and dry environments.

Answer 15

c. C4 plants are able to continue to utilize light energy to photosynthesize even under very low CO2 levels.

Question 16

16. Which of the following statement(s) is/are true about the effect of the environment on plants?
17. Shade plants generally have less chlorophyll per photosystem, more Rubisco per cell and higher light compensation points than sun plants.
18. The presence of air spaces around the mesophyll cells in leaves helps in the absorption of light by the leaf due to refraction of light within the leaf.
19. The total net photosynthesis of a plant depends only on the light and CO2 levels.
20. For a plant to have a positive rate of net photosynthesis, the CO2 level must exceed the CO2 compensation point and the light intensity must exceed the light compensation point.
21. In both C3 and C4 plants the net rate of photosynthesis eventually saturates with increasing CO2 concentration, but C4 plants have a lower CO2 compensation point than C3 plants.

a. none of the above
b. 1, 2, 3, 5
c. 2, 3, 4
d. 2, 4, 5
e. all of the above

Answer 16

d. 2, 4, 5

Question 17

17. Which of the following statement(s) is/are true about the interaction of light with plants?
18. The sieve effect refers to the fact that some light can pass through a leaf without being absorbed.
19. Solar tracking is the ability of a leaf to track the movement of the sun to optimize light absorption.
20. Leaves have a few layers of cells to decrease the probability that light will be absorbed.
21. Leaves are usually thin to minimize the total respiratory load of the leaf.
22. Chloroplasts can change their orientation in leaf cells to optimize their light absorption.

a. one of the above
b. two of the above
c. three of the above
d. four of the above
e. all of the above

Answer 17

d. four of the above

1, 2, 4, 5

Question 18

18. Which of the following is/are true statement(s) about the effect of light on plants?
19. Shade plants have more chlorophyll per photosystem.
20. Sun plants have more chlorophyll b and accessory pigments than plants that are adapted to low light environments.
21. Leaves can move by the process of solar tracking in order to optimize their light absorption.
22. The chloroplasts within cells can move to maximize or minimize light absorption.
23. Photoinhibition occurs at very high light intensities and is characterized by a decrease in the net rate of photosynthesis with increasing light.

a. one of the above
b. two of the above
c. three of the above
d. four of the above
e. all of the above

Answer 18

d. four of the above

3, 4, 5

Question 19

19. Which of the following statement(s) is/are true about the effect of temperature on plants?
20. Photosynthesis and respiration each have optimal temperatures and the optimal temperature for respiration is higher than for photosynthesis.
21. The effect of temperature on photosynthesis is more pronounced at higher CO2 levels than at lower CO2 levels.
22. In C4 plants the quantum yield is constant as a function of temperature, and this is because they have low rates of photorespiration.
23. The effect of temperature on net photosynthesis is the effect of temperature on total photosynthesis minus the effect of temperature on respiration and photorespiration.
24. In C3 plants, the quantum yield decreases with increasing temperature due to increased photorespiration at higher temperatures.

a. none of the above
b. two of the above
c. three of the above
d. four of the above
e. all of the above

Answer 19

e. all of the above

Question 20

20. Which of the following statement(s) is/are true?
21. Leaves usually have several layers of cells to increase the chance that light can be absorbed if it is not absorbed by the top layer of cells.
22. If leaves have too many layers of cells then the respiratory load on the leaf would be higher without providing much additional photosynthetic capacity.
23. Solar tracking refers to the fact that leaves can change their orientation to the sun to optimize light absorption.
24. Chloroplasts can change their orientation inside the cell to optimize light absorption.
25. The sieve effect refers to the fact that some light can pass through a cell or a leaf without being absorbed.

a. none of the above
b. 1, 3, 5
c. 2, 4, 5
d. 1, 5
e. all of the above

Answer 20

e. all of the above

Question 21

21. Which of the following statement(s) is/are true about water and osmosis?
22. Water has a high specific heat and a high heat of vaporization.
23. Osmosis is the movement of water from an area of low water concentration to an area of high water concentration. (HIGH –> LOW)
24. Water is absorbed by the roots and moves through the plant to the leaves.
25. The transport of water in the plant occurs mostly via the phloem. (XYLEM)
26. Water moves by bulk flow in the plant, not by diffusion.

a. none of the above
b. two of the above
c. three of the above
d. four of the above
e. all of the above

Answer 21

c. three of the above

1, 3, 5

Question 22

22. Which of the following statement(s) is/are true about transpiration?
23. Transpiration is the evaporation of water from the leaves of the plant. (from leaves through the stomata)
24. Transpiration is the driving force for water movement through the plant.
25. When the humidity is 100% the water potential of the air is zero, and transpiration would not be expected to occur. (humidity decreases transpiration)
26. Transpiration leads to an increase in the temperature of the leaf. ( transpiration provides evaporative cooling)
27. Nearly all of the water that enters a plant is lost through transpiration. (99% lost)

a. none of the above
b. two of the above
c. three of the above
d. four of the above
e. all of the above

Answer 22

d. four of the above

1, 2, 3, 5

Question 23

23. Which of the following choices contains four true statements about transpiration?

a. transpiration increases in the light relative to darkness
transpiration increases as the temperature increases
transpiration increases as the wind increases
transpiration decreases as the humidity increases

b. transpiration increases in the light relative to darkness
transpiration decreases as the temperature increases
transpiration increases as the wind increases
transpiration decreases as the humidity increases

c. transpiration decreases in the light relative to darkness
transpiration increases as the temperature increases
transpiration decreases as the wind increases
transpiration decreases as the humidity increases

d. transpiration decreases in the light relative to darkness
transpiration decreases as the temperature increases
transpiration increases as the wind increases
transpiration decreases as the humidity increases

e. transpiration increases in the light relative to darkness
transpiration increases as the temperature increases
transpiration increases as the wind increases
transpiration increases as the humidity increases

Answer 23

a. transpiration increases in the light relative
to darkness
transpiration increases as the temperature
increases
transpiration increases as the wind
increases
transpiration decreases as the humidity
increases

(LTWH):
L increases Transpiration
T increases Transpiration
W increases Transpiration
H decreases Transpiration

Question 24

24. Which of the following statement(s) is/are true about water and water potential?
25. The concept of water potential provides an explanation for how water moves throughout a plant.
26. Water will move from an area of more negative water potential to an area of less negative water potential, assuming that there aren’t any barriers that prevent the movement. (moves from an area of less negative to a more negative)
27. Because of transpiration water is pulled up a plant and is not pushed up a plant.
28. Increased light, increased temperature, increased wind and increased humidity all contribute to an increase in the rate of transpiration. (humidity decreases transcription)
29. The cells in xylem tissue have large secondary cell walls.

a. none of the above
b. 1, 2, 4
c. 2, 5
d. 1, 3, 5
e. all of the above

Answer 24

d. 1, 3, 5

Question 25

25. Which of the following statement(s) is/are true about water potential? 1. The water potential in a plant can be quickly regulated by the movement of solutes in plant cells and tissues. 2. The water potential of the air is generally less negative (closer to zero) than the water potential of the plant. (more negative) 3. Differences in water potential are primarily responsible for the movements of nutrients throughout the plant. 4. When a plant cell expands it is due to the fact that the water potential of the cell is more negative than that of the exterior of the cell which leads to the accumulation of water in the cell which causes the build up of turgor pressure in the cell. 5. When the water potential of the plant is more negative than the water potential of the soil, a plant will wilt. (plant will burst) a. none of the above b. 1, 3, 4 c. 2, 4, 5 d. 1, 2, 3 e. all of the above

Answer 25

b. 1, 3, 4

Question 26

26. Which of the following is/are propertie(s) of water? 1. It readily forms hydrogen bonds. 2. It has a high specific heat that helps to minimize temperature fluctuations. 3. It acts as a solvent and also participates in chemical reactions. 4. It can bond to itself and to other molecules by hydrogen bonding. 5. It often is the one factor that can limit the productivity of plants. a. one of the above b. two of the above c. three of the above d. four of the above e. all of the above

Answer 26

e. all of the above

Question 27

27. Which of the following is/are similaritie(s) between the xylem and phloem? 1. Both the xylem and phloem cells have primary cell walls. 2. Both the xylem and phloem cells have secondary cell walls. (phloem does, xylem doesn't) 3. Water potential and differences in water potential play a role in the movement of substances in the xylem and phloem. 4. The cells in both the xylem and phloem are dead cells. 5. Transpiration is directly responsible for the movement of substances in both the xylem and phloem. (water transport in xylem is through bulk flow) a. none of the above b. 1, 2, 3, 5 c. 1, 3 d. 1, 4, 5 e. all of the above

Answer 27

c. 1, 3

Question 28

28. Which of the following statements are true about the regulation of water potential? 1. Movement of ions within the plant is a rapid way to change the water potential. 2. When the ion concentration increases in a part of the plant, it displaces water and results in a decrease in the water concentration in that area. 3. Potassium is commonly used ion to regulate water potential. 4. Potassium is a common component of fertilizers. 5. The metabolism of polymers to monomers or the metabolism of monomers to polymers is a slow way to regulate the water potential. a. 1, 3, 4, 5 b. 2, 3, 4 c. 1, 2, 3, 4 d. 2, 4, 5, e. 1, 2, 3, 4, 5

Answer 28

a. 1, 3, 4, 5

Question 29

29. Which of the following processes occur when a plant cell enlarges? 1. Turgor pressure stimulates the release of auxin. 2. Auxin stimulates an acidification of the apoplast. 3. Enzymes are activated that loosen the cell wall and allow the turgor pressure to enlarge the cell. 4. Enzymes are thought to be involved in the process because conditions that affect enzyme activity also affect cell enlargement. 5. After the cell enlarges, these enzymes are reversible. a. 1, 2, 3 b. 1, 3, 4, 5 c. 1, 2, 3, 4, 5 d. 1, 2, 3, 4 e. 1, 2, 3, 5

Answer 29

c. 1, 2, 3, 4, 5

Question 30

30. You are given two plant cells: Cell A Cell B ψw = - 40 ψw = - 25 ψs = - 50 ψs = - 35 ψp = +10 ψp = +10 Which direction will water move between these two cells? At equilibrium, what is the relationship between the water potentials of the two cells, and how are the water potential, osmotic potential and pressure potential related? ``` a. from A to B ψw of A will be greater than ψw of B ψw = ψs + ψp b. from B to A ψw of A will be greater than ψw of B ψs = ψw + ψp c. from A to B ψw of A will be equal to ψw of B ψp = ψw + ψs d. from B to A ψw of A will be greater than ψw of B ψw = ψs + ψp e. from B to A ψw of A will be equal to ψw of B ψw = ψs + ψp ```

Answer 30

e. from B to A ψw of A will be equal to ψw of B ψw = ψs + ψp

Question 31

31. Which of the following statement(s) is/are true about the role of nutrients in plants? 1. Understanding the role of nutrient in agriculture has led to large increases in plant productivity. 2. If the pH of soil is too low, the soil can become depleted in anions, and adding acid to the soil can correct this situation. (depleted in cations) 3. Minerals are dissolved in water and enter the plant through the root where they are distributed throughout the plant by the phloem. (xylem) 4. Both the plasmodesmata and the apoplast can play a role in the transport of sucrose throughout the plant. 5. The two major types of root systems are fibrous and taproot. a. none of the above b. 1, 4, 5 c. 3, 5 d. 1, 2, 4, 5 e. all of the above

Answer 31

b. 1, 4, 5

Question 32

32. Which of the following statement(s) is/are true about the pressure flow hypothesis of nutrient transport in the phloem? 1. Movement of nutrients through the phloem is primarily due to differences in water potential. 2. When sugars move into the phloem in the leaves, the water potential becomes more negative and this causes water to move into the phloem. 3. When sugars leave the phloem, the water potential of the phloem becomes less negative and the water can enter the xylem. 4. When water enters the xylem, it moves up the plant due to differences in water potential. 5. Plasmodesmata are important in both the loading and the unloading of the phloem. a. one of the above b. two of the above c. three of the above d. four of the above e. all of the above

Answer 32

e. all of the above

Question 33

33. Which of the following statement(s) is/are true about the role of nutrients in plants? 1. Soil particles are negatively charged and therefore are good at retaining cations. 2. If the pH of soil is too low the soil can become depleted in cations. 3. Minerals are dissolved in water and enter the plant through the root where they are distributed throughout the plant by the phloem. (by the xylem) 4. Sucrose is frequently found in the phloem, and sucrose is a major means for moving carbon throughout the plant. 5. The two major types of root systems are fibrous and taproot. a. none of the above b. 1, 4, 5 c. 3, 5 d. 1, 2, 4, 5 e. all of the above

Answer 33

d. 1, 2, 4, 5

Question 34

34. Which of the following statement(s) is/are true about roots? 1. The root system of a plant is always a small part of the entire plant. (extensive) 2. Minerals are absorbed through the roots and are carried into the plant as water is absorbed. 3. The root hairs serve to protect the root apical meristem. (root cap protects the root apical meristem) 4. Roots grow by root cells elongating and pushing through the soil. The elongation of the cells is due to water uptake by the root cells as a result of differences in water potential. 5. When the water potential of the soil is more negative than the water potential of the roots you would expect the roots to not grow. a. none of the above b. 2, 4, 5 c. 1, 2, 5 d. 1, 4, 5 e. all of the above

Answer 34

b. 2, 4, 5

Question 35

35. Which of the following statement(s) is/are true about roots and the role of nutrients in plants? 1. If the pH of soil is too low the soil can become depleted in anions. (depleted in cations) 2. The region of the root where cell division takes place is called the root cap. (apical meristem - cell division) 3. The root system is always a small percentage of the total biomass of the plant. (large percentage) 4. Sucrose is frequently found in the xylem, and sucrose is a major means for moving carbon throughout the plant. (sucrose is found in PHLOEM) 5. Roots elongate by taking up water and pushing through the soil, and the meristem serves to protect the tip of the root as it moves through the soil. (root cap protects tip of the root) a. none of the above b. 1, 4, 5 c. 3, 5 d. 1, 2, 4, 5 e. all of the above

Answer 35

a. none of the above

Question 36

36. Which of the following statement(s) is/are true about roots and the mineral nutrition of plants? 1. Soil particles are generally negatively charged and therefore tend to retain anions more than cations. (soil particles are negatively charged, they retain/bound cations (+). anions(-) are not absorbed) 2. The technique of hydroponics is a good way to determine which elements are essential to a plant. 3. For most plants, the optimal pH of the soil is slightly acidic. (root growth favored by low pH (5.5-6.5) (slightly acidic soil) 4. Root hairs do not contribute much to the surface area of roots. (they do, most of root surface is root hairs) 5. Roots grow continuously to reach areas of soil with fresh nutrients and the rate at which the roots grow depends on the availability of water. a. none of the above b. 2, 3, 5 c. 1, 2, 4, 5 d. 1, 2, 4 e. all of the above

Answer 36

b. 2, 3, 5

Question 37

37. Which of the following are characteristics of plants that are adapted to the shade? (shade plants) 1. They have low respiratory rates. 2. They have thinner leaves than sun plants. 3. They have more Rubisco than sun plants. (no, sun plants have more rubisco) 4. They have lower light compensation points than sun plants. 5. They have a higher ratio of chlorophyll b to chlorophyll a than sun plants. (shade plants have more chl b /chl a) a. none of the above b. 1, 2, 3 c. 1, 2, 4, 5 d. 3, 4, 5 e. all of the above

Answer 37

c. 1, 2, 4, 5

Question 38

38. In the following figure identify the areas of the curve that are represented by (A), (B), and (C). a. CO2 compensation point, light saturation, respiration rate b. CO2 compensation point, light saturation, light compensation point c. photon flux rate, light compensation point, light saturation d. light compensation point, light saturation, respiration rate e. O2 production rate, CO2 uptake rate, respiration rate

Answer 38

d. light compensation point, light saturation, respiration rate light compensation point: point on x-axis light saturation: dotted line respiration rate: negative point