Chapter 8 Photosynthesis

Chapter 8.1 Energy and Life

Vocabulary:

•  ATP adenosine triphosphate
• ADP axdenosine diphosphate
• autotroph
• heterotroph
• photosynthesis

Objectives:

1. Why is ATP useful to cells?
2. What happens during the process of photosynthesis?

Jan Baptiste Van Helmont’s experiement

Jan Baptiste van Helmont (1577-1644) performed a classic experiment on photosynthesis. In paragraph below, van Helmont describes his experiment. Read the paragraph and then address the questions that follow.

I took an earthen pot and in it placed 200 pounds of earth which had been dried out in an oven. This I moistened with rain water, and in it planted a shoot of willow which weighed five pounds. When five years had passed the tree which grew from it weighed 169 pounds and about three ounces. The earthen pot was wetted whenever it was necessary with rain or distilled water only. It was very large, and was sunk in the ground, and had a tin plated iron lid with many holes punched in it, which covered the edge of the pot to keep air-borne dust from mixing with the earth. I did not keep track of the weight of the leaves which fell in each of the four autumns. Finally, I dried out the earth in the pot once more, and found the same 200 pounds, less about 2 ounces.

Write down Van Helmont’s data.

Data:

Initial mass of soil = _______              Initial mass of tree = _______

Final mass of soil = _______               Final mass of tree = _______

Change in mass of soil = _______     Change in mass of tree = _______

1.  What did van Helmont conclude from his work?
2. What reactant in photosynthesis did van Helmont not take into account?

Review Videos:

Crash Course Biology:  Photosynthesis

mhttps://www.youtube.com/watch?v=sQK3Yr4Sc_k

Private universe:  Photosynthesis (very long version) http://www.learner.org/resources/series26.html

Chapter 8.2 Photosynthesis:  An overview

Objectives:

1. What role do light and pigments play in photosynthesis?
2. Label the structures of a chloroplast
3. Describe the events of the light-dependent and light independent reactions

Vocabulary:

• pigment
• chlorophyll
• thylakoid
• grana
• stroma
• light dependent reaction
• light independent reaction

Photosynthetic organisms capture energy from sunlight with pigments

Pigments are light absorbing molecules

Examine the cross section of a chloroplast

Be able to identify the:

1.   thylakoid
2.   grana
3.  stroma

Describe the events of the light reaction and the light independent reaction.

The simple equation for photosynthesis is written below.

6 CO₂ + 6 H₂O –> C₆H₁₂O₆ + 6 O₂

carbon dioxide + water –>  glucose + oxygen

Photosynthesis actually involves two sets of reactions:

• the light dependent reaction
• the light independent reaction

 8.3  The Process of Photosynthesis

Factors that affect the rate of photosynthesis

temperature

light

water

Temperature- the reactions of photosynthesis relay on enzymes.  Photosynthesis occurs best between 0-35 degrees celcius.  Why is temperature a factor?

Examine the graphs where temperature is the x-axis and the rate of photosynthesis is the y-axis.

Which graph illustrates the rate of photosynthesis vs temperature?

Light- Intensity of light affects the rate of photosynthesis.

Examine the data.  What is the relationship between light intensity and the rate of photosynthesis?

Is there a maximum amount of light intensity?

Explain using data from the graph.

Water is a reactant or raw ingredient for photosynthesis.  Could photosynthesis occur without water?

Review activity:

http://www.phschool.com/science/biology_place/biocoach/photosynth/intro.html

Review video:

mhttps://www.youtube.com/watch?v=joZ1EsA5_NY