Photosynthesis Part 4

The stomata open and close as needed. If the level of carbon dioxide dropped inside the leaf, would you expect the stomata to open or close? Explain your answer.

If the level of carbon dioxide drops in the leaf, the stomata would open to allow more carbon dioxide to enter the leaf.

The Calvin cycle requires energy. Where does this energy come from? 1. the energy of the sun is absorbed by chlorophyll 2. the energy is provided by the ATP and NADPH 3. the energy is provided by the splitting of water molecules 4. the removal of oxygen from carbon dioxide releases energy

2. the energy is provided by ATP and NADPH

Describe 2 ways that the energy of ATP is used in the Calvin cycle.

a) ATP is used to convert PGA into PGAL b) ATP is used to convert some PGAL into more RuBP

PGAL is produced during the Calvin cycle. What are two possible uses of these PGAL molecules?

a) PGAL + PGAL = one molecule of glucose b) Some PGAL is converted into RuBP.

__________ is a 5-carbon sugar used in the Calvin cycle.

RuBP

As the light intensity increases, the rate of photosynthesis would: 1. increase 2. decrease 3. remain the same 4. would initially increase but would soon decrease

1. increase

The light independent reactions are also known as ____1____ and ____2____.

1. the Calvin cycle 2. the dark reaction

The unstable 6-carbon compound (found in carbon fixation) breaks apart to form 2 molecules of _____11_____, both of which are 3-carbon compounds. PGA must now be converted to another 3-carbon compound known as ____12_____. A series of reactions involving ____13____ and ____14____from the light dependent reactions are used to convert PGA to _____15_____.

11. PGA 12. PGAL 13. ATP 14. NADPH 15. PGAL

There are two possibilities for these molecules for PGAL. _____16____ molecules of PGAL are combined together to form one molecule of ____17_____. Some of the PGAL will be used to regenerate molecules of ____18_____ so that the Calvin cycle can occur again.

16. Two 17. glucose 18. RuBP

Which of the following are combined to form molecules of glucose? 1. PGA 2. PGAL 3. RuBP 4. carbon dioxide

2 PGAL

List all of the following that are produced at some point during the photosynthetic process? 1. Carbon dioxide 2. oxygen 3. NADP+ 4. NADPH 5. glucose 6. ATP 7. ADP 8. sunlight

2, 3, 4, 5, 6, 7

The carbon from carbon dioxide is combined with RuBP to form which of the following? 1. PGA 2. PGAL 3. a 6- carbon compound 4. oxygen 5. carbon dioxide

3. a 6-carbon compound

Light independent reactions (calvin cycle and dark reactions) occur in the _____3____ of the chloroplast. The purpose of this stage of photosynthesis is to take the ___4____ from the atmosphere and the high-energy products of the light dependent reaction, ____5_____ and _____6____ and use them to form molecules of _____7______.

3. stroma 4. carbon dioxide 5. ATP 6. NADPH 7. glucose

Which one of the following is produced during the light dependent reactions and used during the light independent reactions? 1. oxygen 2. carbon dioxide 3. ADP 4. NADPH 5. NADP+

4. NADPH

Which of the following are needed for the Calvin cycle? 1. water 2. oxygen 3. glucose 4. carbon dioxide 5. NADP+

4. carbon dioxide

An increase in which one of the following would cause a decrease in the rate of photosynthesis? 1. light intensity 2. carbon dioxide levels in the atmosphere 3. water availability 4. temperature

4. temperature

___8____ is combined with a 5-carbon compound known as ___9____ to form a very unstable 6-carbon compound. This process is known as ____10____.

8. carbon dioxide 9. RuBP 10. carbon fixation

Why are the light dependent reactions important to the Calvin cycle?

ATP and NADPH are required for the Calvin cycle. These are produced in the light dependent reactions. The Calvin cycle will not take place unless the light dependent reactions occur first.

______________ and ________ are 3-carbon compounds formed in the Calvin cycle.

PGA and PGAL

T/F: ATP molecules are produced during the light independent reactions.

False

T/F: An increase in temperature above 40 degrees Celsius allows the photosynthetic enzymes to work better and faster.

False

T/F: Carbon dioxide is required for both the light independent and the light dependent reactions.

False

T/F: Glucose is formed when RuBP combines with carbon dioxide.

False

T/F: The Calvin cycle takes place in the stroma of the mitochondria.

False

T/F: The light independent reactions will take place even if the light dependent reactions do not occur.

False

T/F: The water molecules required for the light dependent reactions are obtained through the stomata along with the carbon dioxide needed for the light independent reactions.

False

Which of the following are used to regenerate RuBP? 1. PGA 2. PGAL 3. RuBP 4. carbon dioxide

2. PGAL

In the Calvin cycle, ___________________ combines with _________ to form a very unstable 6-carbon compound.

carbon dioxide RuBP

The light independent reactions could not take place without the high-energy products produced in the light dependent reactions. These high-energy products are ___________ and _________________.

ATP and NADPH

What is carbon fixation?

Carbon fixation occurs when carbon dioxide is combined with RuBP to form the unstable 6- carbon compound.

Name three factors that affect the rate of photosynthesis

The availability of water, light intensity, temperature.

Explain the "water loss dilemma" that plants face each day.

The stomata must open to let carbon dioxide into the leaf. When the stomata are open, water vapor will escape the leaf. If too much water escapes from the leaf, the plant will wilt. If the stomata close to conserve water, the carbon dioxide needed for the Calvin cycle cannot enter the leaf.

T/F: A decrease in light intensity will cause a decrease in the rate of photosynthesis

True

T/F: A decrease in water availability will cause a decrease in the rate of photosynthesis.

True

T/F: The light dependent reactions will take place even if the light independent reactions do not occur.

True

T/F: The stomata must open to allow carbon dioxide to enter the leaf.

True

T/F: To sum up this entire unit on photosynthesis: The energy from the sun has been stored as a chemical energy in molecules of glucose.

True