lecture 12

Question 1

what are the two major functions of leaves?

Answer 1

photosynthesis and transpiration/gas exchange

Question 2

what are some other functions of leaves?

Answer 2

• regulate water content
• storage
• chemical secretion to attract or deter animals
• protection
• generation and signaling of hormones
• reproduction
• nutrition

Question 3

where are leaf primordia generated?

Answer 3

near the shoot apical meristem

Question 4

what are leaf veins made up of?

Answer 4

xylem and phloem

Question 5

what are leaf veins responsible for?

Answer 5

carrying water and other materials to the leaf and away from the leaf

Question 6

why are leaves flat?

Answer 6

• more surface area to photosynthesize
• gas exchange
• transport
  -vein organization

Question 7

what are the functions of the dermal tissue in leaves?

Answer 7

• protection
• limit water loss
• facilitate gas exchange with the environment (stomata)

Question 8

what does the dermal tissue in leaves consist of?

Answer 8

epidermis and guard cells

Question 9

what does the vascular tissue in leaves consist of?

Answer 9

xylem and phloem

Question 10

what are the functions of the vascular tissue in leaves?

Answer 10

• supply water and nutrients
• export of photosynthate

Question 11

what are the functions of the ground tissue in leaves?

Answer 11

• photosynthesis
• site of gas exchange
• storage of carbohydrates, water, and nutrients
• overwintering

Question 12

what does the ground tissue in leaves consist of?

Answer 12

parenchyma cells that make up the mesophyll (palisade and spongy mesophyll)

Question 13

what are the parenchyma cells that make up leaf mesophyll responsible for?

Answer 13

capturing light energy and using it to synthesize carbohydrates

Question 14

palisade mesophyll vs spongy mesophyll

Answer 14

palisade mesophyll:
- right angles to adaxial surface of the leaf
- long, thin, tightly packed
spongy mesophyll:
- irregularly spaced and sized
- many air spaces for gas exchange via diffusion

Question 15

how do guard cells regulate the rate of water loss?

Answer 15

by changing the size of the central pore

Question 16

what did Theodore Engelmann show? 1

Answer 16

not all wavelengths of light are as efficient at driving photosynthesis

Question 17

what are the two separate sets of reactions that occur during photosynthesis?

Answer 17

light-dependent (electron transfer)
light-independent (enzymatic reactions)

Question 18

what do intact chloroplasts do?

Answer 18

absorb light energy and synthesize carbohydrates

Question 19

what do isolated thylakoids do?

Answer 19

generate O2 and ATP, but no sugars

Question 20

which pigments are present in photosystem I?

Answer 20

chlorophyll a and chlorophyll b

Question 21

what is the reaction center of photosystem I?

Answer 21

P700

Question 22

which pigments are present in photosystem II?

Answer 22

chlorophyll a, chlorophyll b, and carotene

Question 23

what is the reaction center of photosystem II?

Answer 23

P680

Question 24

photosystem I vs photosystem II

Answer 24

photosystem I:
- greater proportion of chlorophyll a than b in light harvesting complex
- sensitive to longer wavelength light
photosystem II:
- equal amounts of chlorophyll a and b
- light-harvesting complex sensitive to shorter wavelength light

Question 25

why don’t isolated thylakoids synthesize sugar?

Answer 25

can’t run the calvin cycle because the necessary enzymes have been washed away

Question 26

what are the 3 major steps in the conversion of CO2 to carbohydrate though the calvin cycle?

Answer 26

1. carboxylation: addition of CO2 to RuBP
2. reduction: reduction of 3-PGA to PGAL (addition of electrons)
3. regeneration: reconstituting RuBP from PGAL