Quaestio: How does photosynthesis support life on Earth? Nunc Agenda: List at least 3 ways you benefit from the capture and usage of the sun’s energy

Photosynthesis Overview A process that captures energy from sunlight to make sugars that store chemical energy The energy for almost all organisms begins as sunlight Photo = light Synthesis = make Plants “make” usable forms of energy from “light” energy.

Photosynthesis Equation sunlight CO2 + H2O O2 + C6H12O6 Carbon Dioxide + Water + Light Energy  Oxygen + Glucose

Questions: What are the “raw” materials needed for photosynthesis? What are the products? Where does the energy for this process come from?

The Electromagnetic Spectrum The Electromagnetic Spectrum: The entire range of frequencies or wavelengths of electromagnetic waves. Can you think of different forms of electromagnetic radiation?

Visible Light Visible light is all of the electromagnetic radiation that humans can detect with their own eyes. All of the frequencies of visible light produce white light when combined (the light we see). Visible light is only a small sliver of the electromagnetic spectrum.

Light Energy All of the light energy on Earth comes from our closest star… the Sun

Another View

Light from the Sun Sustains Life on Earth

Light Energy, Cont’d Light travels in waves but also acts as a particle when it strikes matter. Photon: a particle of light with a fixed amount of energy.

How Light and Matter Interact How do plants “capture” the energy from the sun? Plants absorb the energy contained in photons. The plant uses this absorbed energy to create chemical bond energy.

Pigments A substance the absorbs light the pigment in plant cells is chlorophyll When you “see” an object’s color, you are seeing the wavelengths of visible light that are reflected from it.

The pigment chlorophyll absorbs more light energy at certain wavelengths.

A leaf acts as a “sun net” Plants convert the energy of the sun into chemical energy they can use. A leaf acts as a “sun net” Cover of “Nature”

Leaves and their cells are green because of chlorophyll.

Where does photosynthesis occur? In the chloroplast of Plant cells.

The Plant Cell

Leaf cross section Vein Mesophyll Stomata CO2 O2 Chloroplast Mesophyll cell 5 µm

Chloroplast Structure Chloro- = green -plast = body Thylakoid Photosynthetic membrane Contains chlorophyll Grana Stacks of thylakoids Stroma Fluid inside the thylakoid

More Chloroplasts Q:Where do you think the chlorophyll concentration is most dense? A: Thylakoids

Elodea w/ Chloroplasts

*Key Idea* The energy for life comes primarily from the Sun. Photosynthesis provides a vital connection between the Sun and the energy needs of living systems. Heterotrophs rely on autotrophs.

Questions Where in the cell does photosynthesis take place? Where does the energy needed for photosynthesis come from? What substance is released as a waste product? How do you think changing the amount of available CO2 will affect the rate of photosynthesis?

Regents Part C question Photosynthesis is a vital process on Earth. Explain its importance to an organism by answering each bullet point. Identify the organelle where this process occurs. Identify 2 raw materials needed for this process. Identify 1 energy-rich molecule that is produced. State how organisms use the energy-rich molecule. State how a gas produced by the process is recycled in nature.