U2 Chapter 10: Photosynthesis

Question 1

Photosynthesis

Answer 1

Converts the energy of sunlight into chemical energy stored in sugars

Question 2

Autotrophs (“producers”)

Answer 2

Produce their organic molecules from CO2 and other inorganic raw materials; plants are photoautotrophs that use light energy to do this

Question 3

Heterotrophs (consumers, including decomposers)

Answer 3

Unable to make their own food and live on compounds produced by others

Question 4

Chloroplasts

Answer 4

Organelles that contain thylakoids (stacks of thylakoids form grana)
6CO2 + 12H2O + Light => C6H12O6 + 6O2 + 6H2O

Question 5

Light Reactions

Answer 5

Within the thylakoid membranes split water, releasing O2, producing ATP and forming NADPH

Question 6

Calvin Cycle

Answer 6

Within the stroma and forms sugar from CO2, using ATP for energy and NADPH for reducing power

Question 7

Visible Light

Answer 7

Light is a form of electromagnetic energy, thus the colors we see as visible light are also included in wavelengths that drive photosynthesis

Question 8

Chlorophyll “a”

Answer 8

The main photosynthetic pigments in plants

Other accessory pigments absorb different wavelengths of light and pass the energy on to chlorophyll “a”

Question 9

Photon

Answer 9

A tiny particle of light or electromagnetic radiation that boosts one of the pigment’s electrons to a higher-energy orbital

Question 10

Photosystem

Answer 10

Composed of a reaction-center complex surrounded by light-harvesting complexes that funnel the energy of photons to the reaction-center complex

Question 11

Primary Electron Acceptor

Answer 11

A special pair of reaction-center chlorophyll “a” molecules absorbs energy, one of its electrons is boosted to a higher energy level and transferred to this system

Question 12

Linear Electron Flow

Answer 12

H20 → NADPH → Calvin Cycle
During the light reactions used both photosystems and produces NADPH, ATP, and oxygen

Question 13

Cyclic Electron Flow

Answer 13

Electrons are recycled around photosystem I. As a result, a trans thylakoid proton gradient (ΔpH) is generated, leading to the production of ATP without concomitant production of NADPH, thus increasing the ATP/NADPH ratio within the chloroplast
- employs only one photosystem, producing ATP but no NADPH or O2

Question 14

G3P

Answer 14

Glycerol-3-phosphate (G3P) is an obligatory component of energy-producing reactions including glycolysis and glycerolipid biosynthesis. G3P levels in the plant are regulated by enzymes directly/indirectly involved in G3P biosynthesis, as well as those involved in G3P catabolism

Question 15

C3 Plants

Answer 15

Wheat, oats, rye, orchard grass are some of the examples of C3 plants. These plants carry out the C3 cycle to fix carbon from carbon dioxide into 3 carbon sugars
- on dry days, they close their stomata, conserving water but keeping CO2 out and O2 in
- photorespiration can occur where rubisco binds O2 instead of CO2, consuming ATP and releasing CO2 without producing ATP or carbohydrate

Question 16

C4 Plants

Answer 16

Minimizes the cost of photorespiration by incorporating CO2 into four-carbon compounds in mesophyll cells

Question 17

Bundle-Sheath Cells

Answer 17

Where they release carbon dioxide for use in the Calvin cycle

Question 18

CAM Plants

Answer 18

Open their stomata at night, incorporating CO2 into organic acids, which are stored in the mesophyll cells
- during the day, the stomata close and the CO2 is released from the organic acids for use in the Calvin cycle