What is the R

In order to continue to demonstrate the process of photosynthesis, we will utilize a “virtual” lab.

Please read instructions carefully during the activity and remember, if something does not “gel” you can do it many, many time!

The first part of the virtual lab is to re-enforce what we did in lab. Introduction, part 4A- In this laboratory you will separate plant pigments using chromatography. You will also measure the rate of photosynthesis in isolated chloroplasts. The measurement technique involves the reduction of the dye DPIP. The transfer of electrons during the light-dependent reactions of photosynthesis reduces DPIP, changing it from blue to colorless.

Exercise 4A: Plant Pigment Chromatography-Go through this as needed to complete the lab quiz below:

What is the R

value for xanthophyll calculated from the chromatogram below?

(Show your work in the space provided to the right!)

Exercise 4B: Plant components and photosynthesis- click on “continue” after the on-line quiz to you reach 4-II “Key concepts II” and the animation with the expanded view of the top of a thylakoid and purple electron acceptors.

OVERVIEW: The process of photosynthesis involves the use of light energy to convert carbon dioxide and water into sugar, oxygen, and other organic compounds. This process is often summarized by the following reaction:

6 H2O + 6 CO2 + light energy → C6H12O6 + 6 O2

This process is an extremely complex one, occurring in two stages. The first stage, called the light reactions of photosynthesis, requires light energy. The products of the light reactions are then used to produce glucose from carbon dioxide and water. Because the reactions in the second stage do not require the direct use of light energy, they were once called the dark reactions of photosynthesis. Today they are referred to as the Calvin Cycle.

In the light reactions, electrons derived from water are “excited” (raised to higher energy levels) in several steps, called photosystems I and II. In both steps, chlorophyll absorbs light energy that is used to excite the electrons. Normally, these electrons are passed to a

cytochrome-containing electron transport chain. In the first photosystem, these electrons are used to generate ATP. In the second photosystem, excited electrons are used to produce the reduced coenzyme nicotinamide adenine dinucleotide phosphate (NADPH). Both ATP and NADPH are then used in the Calvin cycle to produce glucose.

In this experiment, a blue dye (2,6-dichlorophenol-indophenol, or DPIP) will be used to replace NADP in the light reactions. When the dye is oxidized, it is blue. When reduced, however, it turns colorless. Since DPIP replaces NADPH in the light reactions, it will turn from blue to colorless

when reduced during photosynthesis. THIS IS THE CRUX OF THE EXPERIMENT! ASK IF YOU DO NOT GET IT!!!!

OBJECTIVES: In this experiment, you will

• Use a Colorimeter or Spectrometer to measure color changes due to photosynthesis.

• Study the effect of light on photosynthesis.

• Study the effect that the boiling of plant cells has on photosynthesis. And compare the rates of photosynthesis for plants in different light conditions.

 Please go to this website:

http://www.phschool.com/science/biology_place/labbench/lab4/intro.html

 Click on Lab 4 “Photosynthesis and Pigments” if you are not taken there directly!

 As you read through each page, pay close attention to each underlined term and when ready click on “next” to advance. If there is an option to “take closer look” please do that!

1. Play the starting page animatione, but before moving on identify all of these items and their jobs:

A. Large green oval

B. Small light green ovals on the big oval

C. Purple ovals

D. Yellow squiggly arrow E. NADP

F. ADP

2. Once you have watched the video, briefly explain A) what the red outlined, spastic star is. (What is its full chemical name?) B) What is it used to actually do? C) How does it reduce activation energy?

3. Before you move on, answer these questions, A) where does the H come from to form NADPH?

And B) What would happen to the chloroplast if we have no NADP? C) Where, specifically in the cell do you want a high concentration of NADP?

4. The idea here is to confirm that both light and pigments and the structures in the chloroplast’s membrane are needed for photosynthesis to occur. To do this we need a measurable way to see that light oxidizes pigments that can supply energy to make something or do some sort of work. Watch the movie again and explain what DPiP is and what its role will be in this experiment.

5. What is a spectrophotometer?

6. How will it be used to measure whether or not light reactions have run in photosynthesis? (HINT:

higher light % transmission = less pigments in solution to trap the light = more blue color= ? )

7. Go through the experiment and make sure you understand what is happening!

8. Please complete the graphs (3) as instructed in “analysis of results” below.

9. Perform the quiz until you get a 100% and you know what and why all the correct answers are correct!

10. Name 3 specific things that can directly affect the rate of photosynthesis.

11. Last regular photosynthetic concept is to introduce climate issues that plants must adapt to. In order to do this, we must discuss a by-product of photosynthesis and some basic plant anatomy and physiology.

Please watch this video regarding transpiration video:

https://www.youtube.com/watch?v=U4rzLhz4HHk

It’s imperative you understand this concept prior to lab we do on this in class. Define these terms:

Transpiration Guttation

Review water potential, osmosis, diffusion, cohesion and adhesion of water as needed

Root pressure

PLANT ANATOMICAL STRUCTURES: What are the structures below and what are their functions?

Xylem

Phloem Epidermis

On the diagram of the tree below, indicate the following with labels and arrows to illustrate the terms and the water direction when applicable:

Transpiration

Root Pressure Guttation

Capillary action Stoma

12. Look at the diagram below and complete this statement:

A) When guard cells are constricted and full of water, they cause the stoma to be _______________

(open or closed)

B) When guard cells are lose and dehydrated, they are cause the stoma to be ___________. (open or closed)

C) Open stoma means a(n )________________ (increase or decrease) of water loss.

D) An open stoma means that ___________ gas is let out while ____________ gases are let in. (In C3 plants)

E. The 3 items that can enter and leave an open stoma are: