Question

Chapter 6 – Where it Starts - Photosynthesis
* Section 6.1 – Overview of Photosynthesis
o Apply the terms autotrophs and heterotrophs to the previously learned terms of producer and consumer. Going forward, autotrophs and heterotrophs are the terms you should use.
o How does the textbook define photosynthesis? From this textbook definition, what is the purpose (useful product) of photosynthesis?
o What are the names of each of the two sets of reactions in which photosynthesis occurs?
o Memorize the summary equation of photosynthesis. What goes in (reactants)? What comes out (products)?
o Be able to label the main parts of a chloroplast (figure 6.3 of your textbook)
o Where does the first set of photosynthetic reactions occur in a chloroplast? Where in the chloroplast does the last set of reactions occur?
* Section 6.2 – Sunlight as an Energy Source
o Explain the experiment by Theodor Engelmann. How did it work (Describe the set up)? What did he discover?
o What is a pigment? How is it involved in photosynthesis?
o Which pigment is most common in plants?
o What is an accessory pigment? How can this describe why many leaves change color in autumn?
* Section 6.3 – Light-Dependent Reactions
o What is a photosystem?
o In the non-cyclic pathway of light-dependent reactions, how many times is light required?   
o Look at figure 6.8 in your textbook (light-dependent non cyclic pathway). Understand that all of these motions and steps are working to build up Hydrogen ions inside the thylakoid compartment in large amounts, so that they naturally want to diffuse out of this space (like a inflated balloon wanting to burst). When the hydrogens flow out, they flow through the ATP synthase enzyme, and the flow of the ions powers the ATP synthase enzyme to do work. What work is it actually doing?
o Calvin-Benson Cycle (aka – light independent reactions). What goes in at the beginning? What comes out? Where do the carbon atoms in the sugar that is produced in photosynthesis come from (where do the plants get the carbon atoms)?
o What are stomata and why are they important for plants?
o Where do you find C4 plants? How about CAM plants? How do each of these types of plants perform photosynthesis differently so that they can survive in their environments?

Answer 1

Section 6.1

Answer 1. Autotrophs are the organisms that are capable of using the sunlight and with the help of it they can prepare their own food. Means they have the capability to convert the solar energy into the chemical energy, as plants do. Because they can prepare their own food thus, they are not dependent upon others for food.

Heterotrophs are the consumers because they are dependent upon others for their food. They are not having the capability to utilise the solar energy. Except plants and certain autotrophic bacteria most of the organisms on earth are the Heterotrophs. Human beings too are the example of it.

Answer 2. Photosynthesis is an Anabolic process, means it produces a complex molecule by the combination of many simple molecules.

It can be defined as the process through which plants prepare their food at the expense of carbon dioxide and water, oxygen is released as a by-product. The site of photosynthesis is chloroplast that contains all the enzymes and pigments to carry on this process.

Answer 3. Photosynthesis gets completed in 2 reactions:

• Dark reaction which occurs in dark in the stroma region of the chloroplast. This reaction prepares the glucose, that polymerises to form the starch.
• Light reaction occurs in the presence of light in the granta region of the chloroplast. This reaction manufacturers ATP and NADH, FAD for the dark reaction and release oxygen as a waste product.

Answer 4. The chemical reaction for photosynthesis is:

6CO2 + 6H2O + Light energy - - - > C6H12O6 + 6O2

It occurs in the chloroplast.

Answer 5. Kindly see the image:

Answer 6. The first set of reactions are the light reaction that takes place in the grana. These reactions provides raw material to the dark reactions in terms of ATP, NADH and FADH and oxygen is released as a by product.

The last set of reactions are the dark reactions that take place in the stroma. They manufactures the food for the plant. A glucose molecule is formed at the end of the dark reaction. Glucose show polymerisation to form the starch.