Experimental Plant Science Test 3

1.  Define transpiration.

Movement of water and mineral nutrients from soil to atmosphere in plants 

2. Define evapotranspiration. 

Landscape-level movement of water from soil to atmosphere 

3. What is controlling transpiration? Explain how it is being controlled.

Turgid guard cells 

4. Why are stomates generally open during the day?

It is open during the day for photosynthesis and closed at night to conserve water. 

5. What type of photosynthesis does xerophytes have? 

CAM photosynthesis 

6. How does H2O move in and out of guard cells?

When potassium enters the stomates, the water enters, opening the cell. When potassium is released, the cell is closed with less water. 

7. What are the leaf adaptations to growing in arid environments? Function? 

• Thick cuticle

• Long dermis

• Hairs

• Sunken stomates

8. What are cortical cells composed of? What is their function?

Cellulose

To absorb waters

9. Explain the transpiration-cohesion theory.

Water has cohesive and adhesive properties due to its polarity

10. What makes up water’s free energy?

Solute and pressure potential 

11. What is the sign of solute potential?

0 or (-)

12. What happens when solute concentration increases?

Decreases solute potential/makes it more negative

13. What is the sign of pressure potential? What is the name of the potential? 

Positive

Turgor pressure

14. What are the major essential nutrients? 

• Nitrogen

• Phosphorus

• Potassium

• Magnesium 

• Sulfur 

15. What does Nitrogen do? 

Forms proteins, nucleic acids, and chlorophyll

16. What does P do? 

Ormes nucleotides, nucleic acids, and phospholipids 

17. What does K do? 

Regulating guard cells

18. What does Mg do?

Chlorophyll

19. What does S do?

Certain amino acids

20. What does Ca do? 

Component of plant cell walls 

21. Why is the production of hydroponic tomatoes important?

It has better pest control and less heavy and expensive 

22. What is phytoremediation used for? 

The use of plants to clean up contamination from soils, sediments, and water. These plants are then burned after the plants absorb all the metals

23. Where does the translocation of sugars occur? 

It occurs in living phloem sieve tube members

24. Is ATP required for the translocation of sugars? 

Yes 

25. What does the translocation of sugars do? 

Primarily moves sucrose and other organic compounds from a source(where photosynthesis occurs) to a sink(where no photosynthesis occurs)

26. What is the pressure flow hypothesis? 

The mechanism that explains the translocation of sugars from source to sink

27. How does water and mineral nutrient transport differ from sugar transport in vascular plants?

Water and mineral transportation relies on solute and pressure potential. No ATP is required and is transported via xylem. Vascular plants need ATP in order to be transported and need phloem to transport. 

28. What two plants provide virtually all the commercial sucrose worldwide?

Sugar cane and sugar beat

29. What is the range that plants use light from?

400-700 nm 

30. Which pigments are the primary ones? 

Chlorophyll a P680/P700

31. List accessory pigments.

• Rest of chl a

• Chl b

• Carotenoids: 

  • Carotenes (orange) 

  • Xanthophylls (yellow)

32. Where are pigments and protein complexes formed?

In the thylakoid membrane

33. What portion of Chlorophyll a and b is hydrophobic and hydrophilic?

The tail is hydrophobic and the body is hydrophilic 

34. Are carotenoids hydrophobic or hydrophilic? 

Mainly hydrophobic

35. In fall, why do green pigment/ chlorophyll break down?

Due to the lower levels of nitrogen, the green pigment begins to break down while the carotenoid doesn't since they use CO2. 

36. What is the limiting growth nutrient in plants?

Nitrogen

37. Why don’t carotenoids break down during the fall?

Because CO2 is easy for the plant to get

38. What are the two phases of photosynthesis and where do they occur?

Light reactions (photochemical phase): thylakoid membrane 

Calvin Cycle (biochemical phase): Stroma 

39. What happens during carboxylase?

CO2 enters the plant 

40. What happens during oxygenase.

When O2 can fit into the active site 

41. What enzyme is responsible for carbon fixation in the C3 cycle?

Rubisco 

42. Explain the process of photorespiration, and is it good for the plant?

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

It is an inefficient process since an Oxygen is taking the slot of a Carbon

43. Where is Rubisco 4mM found?

Stroma 

44. Why is Rubisco 4mM unique? 

It is unusual since the enzyme is more abundant than the substrate since it is a slow enzyme than most. There also needs to be an abundance of Rubisco to make sure that carbon fixation is always occurring. 

45. What is the most abundant protein on earth? What percentage does it make up the leaf? 

Carbon is the most abundant and it makes up 25% of the leaf

46. How many times faster does rubisco fix CO2 than O2?

80 times

47. What is the ratio that CO2 outruns oxygenation?

3:1

48. In what environments do plants utilize the C4 Cycle?

In tropical grasses with warm season prairie grasses 

Mainly monocots

49. Why do some plants have the C4 cycle over the C3 cycle?

Due to warmer climates

50. Explain what happens during the C4 cycle.

Increases CO2 concentration in bundle sheath cells. Plants can rescue photorespiration and water loss in hot, dry environments 

But it costs ATP (less efficient if environment not hot and dry)

51. What environment do plants use the CAM cycle? 

Arid environments

52. When are stomates open in plants that use the CAM cycle?

At night

53. What is the initial carboxylating enzyme of the CAM cycle? 

PEP carboxylase