Bill Nye: Plants Open-notes Quizzie

1. Plants make _________ & _________ for animals (and other organisms). 2. Plants convert the sun’s light energy into __________ (type of energy). 3. Carbon dioxide is made of what 2 elements? 4. What does the word “photosynthesis” mean?

5. ________ is the green chemical found in leaves that traps light for photosynthesis 6. EXPLAIN one way plants have to disperse seeds. 7. EXPLAIN one adaptation desert plants have for living in this environment. 8. What biological process puts some of the carbon dioxide necessary for photosynthesis into the atmosphere?

9. In addition to carbon dioxide, what other 2 things are needed for plants to do photosynthesis? 10. Explain one SPECIFIC medicinal use of plants.

Where does the mass come from?

Photosynthesis Ch. 8

Photosynthesis 6CO2 + 6H2O --(light) C6H12O6 + 6O2 Carbon + water  glucose + oxygen Dioxide

Anabolic vs catabolic reactions Catabolic processes break down molecule release energy Anabolic processes construct molecules require input of energy Is photosynthesis catabolic or anabolic? What about respiration?

Leaves CO2 enters and O2 exits through stomata water travels through veins Leaves contain the most chloroplasts Concentrated in the mesophyll

Chloroplasts – where PS takes place Thylakoids are suspended in the stroma of the chloroplast

Chlorophyll – plant pigment Absorbs light Chlorophyll a is the most important Also have accessory pigments Pigments are bundled in photosystems in the thylakoid membrane

Photosynthesis Two sets of reactions: Light reactions: Light dependent reactions Calvin cycle: Light independent reactions The light reactions make the materials needed for the light independent reactions!

Two steps of photosynthesis

Light energy  chemical energy A molecule of water is split, releasing an electron Electron is passed to chlorophyll a in photosystem II Light energy “excites” the electron

Light energy  chemical energy PS II passes its electron to the electron transport chain

Light reactions Energy from the chain is used to make ATP Electron is passed to photosystem I

Light reactions Photosystem I re-excites electron Electron bonds to a NADP+ creating a NADPH ATP and NADPH are used to power the Calvin cycle

The _____________ reactions occur in the ______________ membrane The _____________ reactions occur in the ______________ membrane. It begins with splitting a _____________ molecule to release an electron. The electron is grabbed by a ______________ in photosystem _______. The electron is excited by the energy from ____________. The electron is passed to an _________ _________ chain, where its energy is used to make _________. The electron is grabbed by a pigment in photosystem _________ where it is ___________ again by light. A molecule of _________ picks up the excited electron becoming _________. The two high energy molecules, __________ & ___________, leave the thylakoid membrane to go to the next step, the _______________ _______________.

Light dependent reactions Take place in the thylakoid membrane The photosystems absorb light energy; electrons will travel from: Photosystem II Electron transport chain Photosystem I

Calvin Cycle – Light independent reactions

The Calvin Cycle Takes in 3 molecules of carbon dioxide Where does CO2 comes from? The energy in ATP and electrons in NADPH turns the 3CO2 into a G3P molecule 2 G3P = 1 glucose!

Calvin Cycle Start with 3 RuBPs, 5 carbon sugar 3 CO2 are added to RuBP, forming 3 unstable 6 carbon molecules 3 molecules split into 6 PGAs ATP and NADPH (from light rxns) add energy and electrons to convert 6 PGAs into 6 G3Ps (direct product of photosynthesis) ADP and NADP+ return to the thylakoid membrane

Calvin Cycle 1 G3P drops out of the cycle will be used to make glucose, cellulose, etc. ATP is used to rearrange the remaining carbon atoms into 3 RuBPs, and it starts again!