Unit 4: Photosynthesis

Question 1

How do ADP and ATP molecules store and release energy?

Answer 1

Store: Phospate groups store energy, there is more storage when reattaching a free phosphate molecule to ADP, turning back to ATP

Release: When the last covalent bond between phosphate is broken (via Hydrolosis Reaction/ adding H20)

Question 2

Pigments + Role

Answer 2

-substances that absorb visible light
-found in thylakoid membranes
-wavelengths that are not absorbed are reflected or transmitted (why leaves are green)

Role in Photosynthesis - capture sunlight and convert it into chemical energy

Question 3

How do pigments absorb energy in the form of sunlight?

Answer 3

During LDR, when light energy reaches the pigment molecule, it energizes and excites the electrons within them and these electrons move to transport chains within the thylakoid membrane

Question 4

Why do not all types of light are not equally as “good” for a plant while performing photosynthesis? (link type of light (energy) to pigments)

Answer 4

Not all types of light are “good” for photosynthesis as some colors (or wavelengths) like green, have a lower absorbance, meaning that not much light (energy) will be used, essential to power photosynthesis.

Question 5

Thylakoids

Answer 5

-Sac-like membranes arranged in stacks.
-Where LDR takes place

Question 6

Grana (plural version of granum)

Answer 6

Stack of thylakoids.

Question 7

Stroma

Answer 7

Fluid portion of chloroplast.
-where Calvin Cycle takes place

Question 8

Photosynthesis

Answer 8

Process of glucose creation in plant cells (plant food source) with sunlight’s help.
Occurs in chloroplasts.

Basic equation:
6CO2 + 6H2O + energy (light) → C6H12O6 (glucose) + 6O2 (oxygen).

Question 9

The Role of Reactant of Photosynthesis in Creating the Products

Answer 9

6CO2 - Provides carbon atoms that are used to form glucose.

6H2O - Supplies hydrogen atoms and electrons necessary for the creation of glucose and contributes to the release of oxygen as a byproduct.

Sunlight - Supplies the energy needed to drive the photosynthesis process.

Question 10

Light - Dependent Reaction

Answer 10

1) PHOTOSYSTEM II
-sunlight is absorbed by pigments
-H20 splits into H+, e-, and O2
-electrons travel on Electron Transport Chain (ETC)

2) H+ ions are actively pumped into Thylakoid from Stroma

3) PHOTOSYSTEM I
-sunlight excites electrons (traveled on ETC)
- electrons, H+, and NADP+ all combine to form NADPH (which carries electrons)

4) ATP Synthase - H+ passively diffuse through ATP Synthase combining ADP and P to make ATP

Question 11

Calvin Cycle

Answer 11

1) Atmospheric C02 enters the Stroma (via chloroplast mem.)

2) C02 molecules then combine with other carbon molecules in Stroma.

3) ATP provides energy for these rections and NADPH drops off their electrons that also power these reactions .

4) After C02 goes through these reactions with other carbon molecules, glucose (C6H1206) is eventually produced.

Question 12

How LDR + Calvin Cycle are Similar and Different

Answer 12

Similar:
- Both occur in the chloroplast of a plant
- both use forms of ATP and NADPH

DIfferent:
- no light is needed in the Calvin Cycle (LIR)
- Calvin Cycle occurs in Stroma while LDR occurs in Thylakoid
- Have different reactants and products

Question 13

Reactants and Products of LDR and where they occur

Answer 13

Basic Equation: Sunlight + H2O + ADP + NADP+ → O2 + ATP + NADPH + electrons

Pigment Activation:
Reactants: Sunlight
Products: High-energy electrons

Water Splitting:
Reactants: Water (H₂O)
Products: Oxygen (O₂), H⁺ ions, electrons

Electron Transport Chain:
Reactants: Electrons from Photosystem II
Products: H⁺ ions pumped into the thylakoid space, energy for ATP Synthase

NADPH Formation:
Reactants: NADP⁺, electrons, H⁺ ions
Products: NADPH

ATP Synthesis:
Reactants: ADP + P, H⁺ ions
Products: ATP

Location: Thylakoid

Question 14

How do electrons “flow” during photosynthesis (from pigments to eventually making high-energy glucose)?

Answer 14

1) electrons flow from pigments to the electron transport chain, powered by sunlight.

2) H20 is then split water and eventually generates energy (ATP and NADPH-carries electrons).

3) These electrons caried into the Calvin Cycle by NADPH provide power the reactions of carbon dioxide as it becomes high-energy glucose.

Question 15

Role of high energy molecules: NADPH and ATP in photosynthesis and how they are made

Answer 15

NADPH: Provides power for the Calvin cycle by bringing in electrons; made in the LDR when elctrons, NADP+, and hydrogen ions combine.

ATP: Supplies energy for the Calvin cycle; produced in LDR during ATP synthase, or when hydrogen ions, ADP, and P combine.

Question 16

Role of Water in Photosynthesis

Answer 16

It is split up within PII of the LDR to create hydrogen and electrons needed within the photosynthesis process and also produced oxygen as a byproduct.

Question 17

Identify the reactants and products of each step within the Calvin Cycle and where they occur

Answer 17

Basic Equation: ATP + electrons + NADPH + CO2 → glucose + ADP + NADP+

Reactants: ATP, NADPH, CO₂
Products: Glucose, ADP, NADP⁺
Location: Stroma

Question 18

How photosynthesis affects the levels of carbon dioxide and oxygen in the air

Answer 18

Potosynthesis uses CO2 and admits O2, so after photosynthesis occurs there becomes less CO2 in the air and more O2

Question 19

What are the variables and how do they affect the rate of photosynthesis (light intensity, water, temperature)

Answer 19

Light Intensity
- more light absorbed = faster photosynthesis
- Light absorbed speeds up reactions but has a limit.

Temperature (Best between 0℃ - 35℃)
- Enzymes need the right temp to work; too hot or cold slows or stops reactions.

3. Water
   
   • Water is essential for Photosynthesis
   • Not enough water? Photosynthesis slows or stops.

Question 20

Where does the mass of a tree comes from?

Answer 20

Carbon dioxide within the air.