Photosynthesis I & II

Question 1

Define photosynthesis

Answer 1

The process by which plants and other photoautotrophs use light energy to synthesize organic compounds from CO2

Question 2

What is the overall reaction for photosynthesis?

Answer 2

6 H2O + 6 CO2 –> C6H12O6 + 6O2

Question 3

Which reactant in photosynthesis is reduced?

Answer 3

Atmospheric CO2 is reduced to a carbohydrate molecule (glucose)

Question 4

Which product of photosynthesis is oxidized?

Answer 4

Water

Question 5

What is produced as a byproduct of water being oxidized?

Answer 5

molecular oxygen (O2)

Question 6

In this lab, what is used as an assay of photosynthetic rate?

Answer 6

Oxygen production

Question 7

If the photosynthetic rate is greater, will the leaf disks rise to the surface more quickly or slowly?

Answer 7

quickly

Question 8

What was the additional source of CO2 used in this experiment?

Answer 8

Sodium bicarbonate aka baking soda

Question 9

What is the summary of the equation for baking soda in water?

Answer 9

NaHCO3 + H+ –> Na+ + H2O + CO2

Question 10

What type of energy is needed to synthesize organic compounds via photosynthesis?

Answer 10

Light energy

Question 11

What was the plant species used for the leaf disk assay? Give the common and latin name

Answer 11

Spinach

Spinacia oleracea

Question 12

After all the air has been removed from the leaf disks, what is produced that causes the leaf disks to float again?

Answer 12

oxygen

Question 13

What is the purpose of the syringe?

Answer 13

To create a vacuum

Question 14

What is the purpose of creating a vacuum within the syringe?

Answer 14

to remove all the gases from the intercellular spaces within the leaf disks and make the leaf disks sink

Question 15

What happens to the leaf disks when the vacuum has been successfully made?

Answer 15

They sank

Question 16

T or F: all the leaf disks cut will contain the same number of chloroplasts and will therefore photosynthesize at the same rate

Answer 16

False

Question 17

What do photoautotrophs obtain the nutrients they require from?

Answer 17

water, soil minerals and atmospheric carbon dioxide

Question 18

The conversion of atmospheric CO2 into organic materials provides the foundation for what four major things?

Answer 18

4 major macromolecules:

proteins
nucleic acids
carbohydrates
lipids

Question 19

Photosynthesis occurs in the presence of what 2 things?

Answer 19

enzymes

light energy

Question 20

Which organelles of plants conduct photosynthesis? Where are they located?

Answer 20

The chloroplasts located in the mesophyll tissues of leaves

Question 21

What are the 2 major stages of photosynthesis?

Answer 21

1. light dependent reactions

2. light independent reactions aka the Calvin Cycle

Question 22

Where do the light dependent reactions occur?

Answer 22

in the thylakoid membranes of chloroplasts

Question 23

Overall, what occurs during the light dependent reactions?

Answer 23

the stages of photosynthesis that convert light energy into chemical energy in the form of ATP and NADPH

Question 24

What is NADPH?

Answer 24

the reduced form of NADP+

Question 25

Briefly outline the steps of the light dependent reaction

Answer 25

1. a water molecule is broken apart to provide a supply of electrons and protons - oxygen gas is produced as a byproduct 2. electrons and protons release from the water are transferred to the acceptor NADP+ --> reducing it to NADPH 3. Chemiosmosis joins a phosphate group to ADP to synthesize ATP during photophosphorylation

Question 26

What are the products of the light reactions?

Answer 26

NADPH and ATP Oxygen gas as a byproduct

Question 27

Where does the Calvin Cycle occur?

Answer 27

the stroma of the chloroplasts

Question 28

Overall, what occurs during the Calvin Cycle?

Answer 28

the stages of photosynthesis that convert inorganic CO2 into sugars

Question 29

What happens when inorganic CO2 enters the stroma?

Answer 29

inorganic CO2 is converted into an organic form through CARBON FIXATION with the help of the rubisco enzyme

Question 30

Which enzyme aids in carbon fixation in the Calvin Cycle?

Answer 30

rubisco

Question 31

What is the final product of carbon fixation per one molecule of CO2 in the Calvin Cycle?

Answer 31

two 3-phosphoglycerate molecules

Question 32

What happens to the 3-phosphoglycerates produced by carbon fixation in the Calvin Cycle?

Answer 32

Both of them are separately bonded to a phosphate group released from ATP to form 1,3-bisphosphoglycerate

Question 33

What happens to 1,3-bisphosphoglycerate in the Calvin Cycle?

Answer 33

It is reduced by NADPH to produce glyceraldehyde 3-phosphate (G3P)

Question 34

What is the product of the Calvin Cycle?

Answer 34

glyceraldehyde 3-phosphate (G3P), a carbohydrate

Question 35

What is the function of the final stage of the Calvin Cycle?

Answer 35

regenerates the rubulose bisphosphate (RuBP) sugar to maintain the continuous fixation of inorganic CO2

Question 36

What was the purpose of this experiment?

Answer 36

to determine whether the rate of photosynthesis by spinach is affected by varying concentrations of sodium bicarbonate

Question 37

How was the rate of photosynthesis determined?

Answer 37

By measuring the time for 50% of the leaf disks to float

Question 38

Why can it be predicted that photosynthetic rates will become greater/faster with a higher concentration of sodium bicarbonate?

Answer 38

because sodium bicarbonate is the source of CO2 in this experiment and CO2 is essential for the producing carbohydrates during photosynthesis

Question 39

Which hypothesis was rejected based on the results?

Answer 39

The null hypothesis

Question 40

What was the supported hypothesis?

Answer 40

the alternative: the concentration of sodium bicarbonate (%) in tap water will have an effect on the rate of photosynthesis (seconds) by spinach, Spinacia oleracea.

Question 41

Briefly describe the steps of the procedure for this experiment

Answer 41

1. pour water into clear cup 2. add amount of sodium bicarbonate to the water and gently mix 3. obtain a few leaves from the spinach and use a straw to cut out X amount of disks per replicate 4. gently put the leaf disks into the syringe and push the plug to the bottom carefully 5. draw 2-3 mL of the sodium bicarbonate solution into the syringe and expel all the air out 6. create the vacuum by covering the top of the syringe with thumb and pushing and pulling on the plunger until all the leaves sink 7. label a plastic cup to indicate treatment and mark 3cm 8. transfer leaf disks and solution into cup 9. fill cup to 3cm mark with sodium bicarbonate solution 10. use pipette to spread out leaf disks so they're not overlapping 11. place light source 10 cm above cup 12. record time until 50% of leaf disks float or no change occurs after 20 minutes 13. repeat steps for all replicates and treatments

Question 42

Is it possible for the leaf disks to float in the control group?

Answer 42

yes, there is still a small amount of sodium bicarbonate present in tap water

Question 43

What was the control group?

Answer 43

the solution without any additional CO2 added/no baking soda added

Question 44

Why did the leaf disks float at different times?

Answer 44

chloroplast density will differ throughout different sections of the leaf chloroplasts are where photosynthesis occurs so if there are less chloroplasts in one leaf disk, the rate of photosynthesis will be reduced compared to a leaf disk with a higher density