Presentation on theme: "Trapping Energy Interest Grabber Section 8-2"— Presentation transcript:
1 Trapping EnergyInterest GrabberSection 8-2Have you ever used a solar-powered calculator? No matter where you go, as long as you have a light source, the calculator works. You never have to put batteries in it.
2 Interest Grabber continued 1. A solar-powered calculator uses solar cells that are found in rows along the top of the calculator. Into what kind of energy is the light energy converted so that the calculator works?2. Recall that plants use light energy from the sun to make food. Into what kind of energy is the light energy converted by plants?3. Most plants, no matter what size or shape they are, have some parts that are green. Which parts of a plant are usually green?4. What does the green color have to do with the plant’s ability to convert light energy into the energy found in the food it makes?
3 Photosynthesis: An Overview Chapter 8.2Photosynthesis: An Overview
4 PhotosynthesisPlants use energy of sunlight to convert water and carbon dioxide into high-energy carbohydrates – sugars and starches – and oxygenOxygen is considered a waste product of photosynthesis
6 Jan van HelmontExperiment find out if plants grew by taking material out of the soilDetermined mass of dry soil and seedlingWatered seed regularlyAfter 5 years – mass of tree changed, while mass of soil remained unchangedConcluded that increase in mass was due to the waterAccounts for “hydrate” in carbohydrateCarbon from carbon dioxide accounts for “carbo” in carbohydrate
8 Joseph Priestly Experimented with fire in a jar with a sprig of mint Fire needed oxygen to keep burningPutting a jar over the flame put the fire outIf mint was placed in jar, fire would keep burningConcluded that plants gave off oxygen
9 Summary:burning candle + bell jar → candle goes out + add a mint plant → candle can be relitmouse + bell jar → dead mouse + add a mint plant → mouse livesQuestions:1. Why did the candle burn out when placed under bell jar?2. Why could the candle be relit after allowing it growth with a mint plant?3. Why does a mouse die when it is placed under a bell jar?4. Why was the mouse able to survive when placed in the jar with a mint plant?
10 Jan IngenhouszShowed that the experiment done by Priestly only occurred if the plant was in lightLight is needed to produce oxygenPut all three scientists together:In the presence of light, plants transform carbon dioxide and water into carbohydrates, and they also release oxygen
12 Light Light is a form of energy that travels in waves White light is a mixture of light of different wavelengthsWhen broken down, white light produces the visible spectrum (400nm – 750 nm)ROY G. BIVRed, orange, yellow, green, blue, indigo, violetRed has a longer wavelength than violet
13 Pigments of Plants Pigments – light absorbing pigments Because light is energy – energy is absorbed by the pigmentsTheir electrons get excited to a higher energy levelChlorophyll – main light absorbing pigment of plantsTwo types: chlorophyll a and chlorophyll bAbsorbs light in the blue-violet and red regions; reflects green light
15 Chlorophyll a and Chlorophyll b Absorption of Light byChlorophyll a and Chlorophyll b1. How does the color spectrum at the bottom relate to the graph?2. In what region of the spectrum does chlorophyll a absorb light best?3. In what region of the spectrum does chlorophyll b absorb light best?4. In what region of the spectrum do neither types of chlorophyll absorb light well at?Chlorophyll bChlorophyll aVBGYOR
16 Pigments of PlantsCarotenoids – red, orange, and yellow pigments in plantsAbsorb light in the other regions of the spectrumLeaves change color because the chlorophyll molecules fade away and the carotenoids are left over