Ch.10 Photosynthesis BIO 1210 EXAM 3

The goal of photosynthesis

plants using sunlight to make food (glucose), and store that energy for the plant

Equation for photosynthesis

reactants of photosynthesis (IN)

carbon dioxide and water

products of photosynthesis (OUT)

glucose and oxygen

the energy source of photosynthesis

sunlight

Light reactions occur in….

thylakoid membranes

Calvin cycle occurs in…..

stroma

What are the main outputs of the light reactions, and how are they used in the Calvin Cycle ?

Outputs: ATP, NADPH

How they are used: ATP gives energy, NADPH gives electrons

What is the role of water in photosynthesis

water is split to provide electrons and hydrogen, then it releases oxygen

What is the function of chlorophyll and accessory pigments ?

Chlorophyll - absorbs light

Accessory Pigments: absorb extra colors and pass energy to chlorophyll

What is a photosystem and why is it important ?

Photosystem: a group of pigments and proteins that capture light

Important: it starts the process of making energy (ATP and NADPH)

How does the electron transport chain make ATP

• The electrons move through proteins, which release energy

• That energy pumps hydrogen ions, which create a gradient

• The gradient powers ATP production

Define photophosphorylation

the act of making ATP using light energy during photosynthesis

What is NADPH and what is its role in photosynthesis

NADPH: a high-electron carrier

Role: carries electrons and hydrogen to the Calvin Cycle - creates sugar

Step by Step how light energy gets turned into ATP and NADPH

1. Light excites electrons in Photosystem II

2. Water is split

3. Electrons pass through the Electron Transport Chain

4. ATP is generated

5. Electrons are re-excited in Photosystem I

6. NADPH is produced

Each step of how energy gets turned into ATP and NADPH (WHAT IS HAPPENING WHY IT MATTERS)

1. Light energy boosts electrons to a higher energy level, matters because it starts the whole process of making energy

2. Water is bring broken into electrons, hydrogen ions, and oxygen, matters bc replaces lost electrons and releases oxygen to air

3. Electrons move through a series of proteins, matters because their energy will then be used to pump hydrogen ions and build a gradient

4. Hydrogen ions flow through a protein to make energy molecules, matters because this provides energy for the Calvin Cycle

5. Light energy boosts the electrons again, matters because it gives them enough energy to be used to make electron carriers

6. Electrons and hydrogen are now added to form a high-energy carrier, matters because those carriers carry electrons to the Calvin Cycle to help build sugar

What happens during water splitting and why does it matter ?

During water splitting, water molecules are broken apart into electrons, hydrogen ions, and oxygen

• Water gives electrons and oxygen

What happens during proton gradient formation and why does it matter?

During PGF, hydrogen ions build up on one side of the thylakoid membrane as electrons move through the ETC

• creates stores energy to make ATP

What happens during NADPH production and why does it matter?

electrons and hydrogen are added from a high-energy electron carrier

• carries electrons to Calvin Cycle to make sugar

Calvin Cycle: What enzyme is responsible for carbon fixation

RuBisCO

Calvin Cycle: What molecule does carbon dioxide combine with at the start ?

ribulose biphosphate (RuBP)

What are the three phases of the calvin cycle ?

1. Carbon fixation 2. Reduction 3. Regeneration of RuBP

carbon is fixed, sugar is built, starting molecule is reset

What phase of the Calvin Cycle produces sugar ?

reduction phase

Why are ATP and NADPH required for the calvin cycle ?

ATP provides energy

NADPH provides electrons

energy + electrons = sugar

What is G3P, and what can it be used to make ?

a small sugar molecule made in the calvin cycle

can be used to make bigger sugars

What is photorespiration

When Rubisco uses oxygen instead of carbon dioxide due to it being low and oxygen being high

• this wastes energy and does NOT make sugar

How are the light reactions and the Calvin Cycle interdependent

the light reactions make energy (ATP) and electron carriers (NADPH) that the calvin cycle uses to make sugar

light makes energy, calvin cycle uses to make sugar, cycle repeats

Trace the path of energy from sunlight to glucose

Sunlight - excited electrons - energy used to make ATP and NADPH - used in calvin cycle - glucose made

sunlight - electrons - energy - glucose/sugar

Why is photosynthesis the foundation of most ecosystems ?

It produces glucose and oxygen, which support almost all life

In cyclic electron flow, what is produced?

ATP only

What is the IMMEDIATE product of the calvin cycle

G3P (smaller sugar) - which then goes on to make glucose (bigger sugar)