Photosynthesis

What is energy?

the ability to do work

Know different forms of energy

Light energy, Chemical energy, and electrical energy

What does ADP stand for

adenosine diphosphate

What does ATP stand for

adenosine triphosphate

Where is available energy in cells stored?

In molecules of ATP.

How much ATP do most cells have?

only a small amount, enough to last for only a few seconds of activity

What is the energy storage capacity difference between sugar and ATP.

Sugar stores a lot more energy than ATP, but ATP is quicker for cells to use.

What are autotrophs?

Make their own food (plants, algae).

What are heterotrophs?

Get food by eating other living things (animals, humans).

Where does energy in food originally come from?

sun

What is photosynthesis?

The process by which a cell captures energy in sunlight and uses it to make food

What is pigment?

A pigment is a chemical that gives color and absorbs light.

What is chlorophyll?

The green pigment in plants that captures sunlight for photosynthesis.

What is the structure of chloroplasts

The part of the cell where photosynthesis happens.

What is the structure of thylakoids

Small, flat sacs inside the chloroplast that hold chlorophyll.

What is the structure of stroma

The space around the thylakoids.

What does NADP+ stand for

Nicotinamide adenine dinucleotide phosphate

What is the function of NADP+

It is an electron carrier

Know chemical equation of photosynthesis.

6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂ (Carbon dioxide + water + light → glucose + oxygen)

What is the differences for light-dependent reaction

Needs sunlight, happens in the thylakoids, makes ATP and NADPH.

What is the differences for light-independent reaction

Doesn't need light, happens in the stroma, uses ATP and NADPH to make sugar.

Where do light dependent reactions take place

thylakoid membrane

Where do light independent reactions take place

stroma

What do electron carriers do?

transport high energy electrons

Why does transporting high-energy electrons require special carriers?

Because the electrons have too much energy to travel safely on their own.

Relationship between the two reactions (ADP, ATP, NADP+, NADPH):

Light-dependent makes ATP and NADPH.

Light-independent uses ATP and NADPH to make sugar and turns them back into ADP and NADP+.

What is a photosystem composed of and what does it do?

A photosystem has proteins and chlorophyll. It captures sunlight and makes high-energy electrons.

Where do light-dependent reactions take place, and where do they begin?

They happen in the thylakoid membrane and start in Photosystem II.

What happens first in light-dependent reactions?

Light hits chlorophyll, giving energy to electrons.

What is the electron transport chain and what does it do?

It's a series of proteins that move high-energy electrons to make ATP.

In light-dependent reactions, why is water needed?

Water provides electrons and hydrogen. It also makes oxygen as a waste product.

How does photosynthesis help animals (including us)?

It gives us oxygen to breathe and food to eat.

What breaks water molecules apart, and what are they broken into?

Light energy breaks them into oxygen, hydrogen ions (H⁺), and electrons.

In which photosystem do high-energy electrons leave from, and where are they re-energized?

They leave from Photosystem II and are re-energized in Photosystem I.

How are high-energy electrons related to the pumping of H⁺ from stroma into thylakoid space?

The energy from electrons is used to pump H⁺ into the thylakoid space.

What enables NADP+ to convert into NADPH

Electrons and hydrogen ion from the light-dependent reactions combine with NADP+ to form NADPH

How do H+ in the thylakoid space get transported back to the stroma

They move through the enzyme ATP synthase

What is ATP synthase, and what does it do?

It's an enzyme that makes ATP by letting H⁺ ions pass through it.

Where does ATP synthase get its energy from?

From the movement of H⁺ ions across the membrane.

What do light-independent reactions do?

They use carbon dioxide, ATP, and NADPH to make sugar.

Why is the light-independent reaction called the Calvin Cycle?

Because it was discovered by Melvin Calvin and happens in a cycle.

Where do carbon dioxide molecules in the Calvin Cycle come from?

the air

What happens to carbon dioxide when it first enters the Calvin Cycle?

It combines with other molecules to start making sugar.

Midway through the Calvin Cycle, twelve 3-carbon molecules are made — what happens to them?

Some are used to make sugar; others are recycled to keep the cycle going.

How many carbon dioxide molecules are needed to make one 6-carbon sugar?

Six CO₂ molecules.

How do temperature, light, and water affect photosynthesis?

Too little light, water, or low temperature slows it down.

Too much heat can stop it.

What is a characteristic of C4 photosynthesis?

C4 plants can capture CO₂ even when it's hot.

Give an example of a C4 plant.

Corn or sugarcane.

What is a characteristic of CAM photosynthesis?

CAM plants open their pores at night to save water.

Give an example of a CAM plant.

Cactus or pineapple.

What happens to ATP after it releases energy?

It becomes ADP

What happens to water molecules during the light-dependent reactions?

They are split into oxygen, hydrogen, and electrons.

What is the main purpose of the Calvin Cycle?

To use ATP, NADPH, and CO₂ to make sugar (glucose).