Did you know…

Chameleons often have tongues longer than their bodies.

A worm is both male and female at the same time (a hermaphrodite.)

“Why do leaves change color in the fall?” Article1. What are annuals?2. What are perennials?3. What is the difference btwn deciduous trees &

evergreen trees? Give 1 example of each.4. How do plants function during the summer?5. What is the abscission layer of a leaf?6. How does the abscission layer change in Fall?7. List 4 types of pigments & tell which color we

see them as.8. What causes leaves to change color in the fall?

1. Annuals complete their life cycle in 1 growing season. They “die” during winter, but seeds last through the cold & sprout in the spring.

2. Perennials have life cycles of more than 2 yrs. During winter, herbaceous parts (leaves/stems) above ground die, but stored food (wood/roots/bulbs) remains alive.

3. Deciduous trees (elms, oaks, & maples) shed their leaves in fall. Evergreen/coniferous trees (holly, pines, & firs) keep their waxy needles/leaves through winter.

4. During summer, leaves over-produce glucose & store to prepare for winter.

5. Abscission layer of leaf: separation layer at base of each leaf. Contains small tubes carrying water to leaf & food from leaf to other plant parts.

6. In fall, abscission layer swells & turns into cork substance that blocks small carrier tubes.

7. Carotene pigment appears orange.Xanthophyll pigment appears yellow.Anthocyanin pigment appears red & purple.Chlorophyll pigment appears green.

8. When abscission layer swells, glucose/waste become trapped in leaf. No new water can reach leaf, causing chlorophyll to disappear. As chlorophyll disappears, other pigments already present in leaf become visible.

To make glucose from light◦ “photo-”: light + “synthesis”: to make

Chem equation:6CO2 + 6H2O –light C6H12O6 + 6O2

carbon dioxide+water —light glucose+oxygen (reactants) --reaction (products)

Belgian physician (1643)

Test: do plants grow by absorbing soil?

Results: ◦Soil mass didn’t change◦Less water mass

Conclusion: plants gain mass from water

http://www.youtube.com/watch?v=pdgkuT12e14 English minister (1771) Test: how plants’ byproducts

affect other objects (candle) Results:

◦Candle by itself = burned out◦Candle + mint leaf = didn’t burn out

Conclusion: plants release invisible product called oxygen (O2)

Dutch scientist (1779) Tested: how plants’ byproduct

changes when in light & dark

Results: candle stayed lit only when plant in sunlight

Conclusion: light is necessary for oxygen to be produced

Energy from sun “White” light: mixture of ALL light

wavelengths/colors

Absorb certain light wavelengths/energy Reflect other wavelengths/energy

Pigments in chloroplasts

Chlorophyll a & b absorb blue-violet & red wavelengths

Green light is not absorbed

Green light is reflected = plants look green

http://www.youtube.com/watch?v=C1_uez5WX1o

1. Photosystems: pigments absorb light energy

2. Thylakoids: flattened sacs filled w/ photosystems

◦Light-DEPENDENT rxns

1

2

3. Granum: stack of thylakoids

4. Stroma: clear gel filling chloroplast◦Light-INDEPENDENT rxns

5. Bilayer: double-layered membrane

3

45: Inner

5: Outer

1. Light-Dependent Rxn:◦Requires light◦Requires energy carriers (ATP & NADPH) Sun’s energy excites/heats e-

Electron carriers/“oven mitts” transport excited/“hot” e-

◦Occurs in photosystems/thylakoids

◦Overall reactants: light/energy, H2O, ADP◦Overall products: O2, ATP

2. Light-Independent Rxn:◦ aka Calvin Cycle or “Dark” Rxn◦ Does NOT require light (light-independent)◦ Uses ATP (short-term energy) from light-

dependent rxns to produce sugars (long-term energy)

◦ Occurs in stroma

◦ Overall reactants: CO2, ATP◦ Overall products: energy molecules (glucose

sugar), ADP

1. Water◦ More water = more PS

2. Temp◦ Enzymes work best btwn 0-35°C

3. Intensity & wavelength of light:

◦ More intensity = more PS◦ Red & blue = more PS

PS incr until max rate is reached