BIOLOGY UNIT 5: PHOTOSYNTHESIS

Light-independent reactions

Set of reactions in photosynthesis that do not require light; energy from ATP and NADPH is used to build high-energy compounds such as sugar; also called the Calvin Cycle.

Light-dependent reactions

Set of reactions in photosynthesis that use energy from light to produce ATP and NADPH.

Electron transport chain

Series of electron carrier proteins that shuttle high-energy electrons during ATP-generating reactions.

How many water and carbon dioxide molecules are needed to make 2 glucose molecules?

24 water molecules & 12 carbon dioxide molecules.

What are the products of photosynthesis?

6 oxygen molecules and 1 glucose molecule.

What is the equation for photosynthesis?

6CO2+6H2O+sunlight→6O2+C6H12O6

Equation for photosynthesis-

6H2O+6CO2+sunlight→oxygen and glucose water+carbon dioxide+sunlight→oxygen+glucose

What is chlorophyll and why is it important?

A green pigment that allows photosynthesis to occur.

Explain how energy is released from the ATP molecule.

A terminal (last) phosphate group is removed in a process called hydrolysis.

Explain the relationship between ATP and ADP.

ATP is like a charged battery, and ADP has lost a phosphate group and released energy. ATP is fully charged and has 3 phosphate groups.

What happens to NADPH after it is produced?

After NADPH is produced, it delivers the electrons & hydrogen ion and then turns back to NADP+.

What happens after the light-dependent reactions are done?

After the light-dependent reactions are done, the next thing is the light-independent stage. ATP & NADPH now go into the Calvin Cycle. The Calvin Cycle takes CO2 and fixes it into organic molecules that eventually will make glucose.

What happens to ATP & NADPH after they are used in the dark reactions? (Be specific and include details)

After they are used in dark, or light-independent reactions, ATP & NADPH go back to the light, or light-dependent, reactions to be re-energized after the reduction reaction.

Why do leaves appear red, orange, or yellow in the fall?

Because as temperatures drop, chlorophyll molecules break down first and the green pigment fades and what's left are red, orange, or yellow.

Why is the mitochondria known as the "power house" of the cell?

Because every cell needs ATP to function & it's mostly produced in the mitochondria.

Explain why photosystem 2 comes before photosystem 1 in the electron transport chain.

Because photosystem 1 was discovered first. They kept it in the order that they were discovered.

Why are light reactions called light reactions?

Because they require sunlight.

Pigment

Light-absorbing molecules used by plants to gather the sun's energy.

What are light-dependent reactions? Where do they take place? What are the products?

Light-dependent reactions are a set of reactions in photosynthesis that use energy from light to produce ATP and NADPH. They take place in the thylakoid. The products are NADPH & ATP.

NADP+

Carrier molecule that transfers high-energy electrons from chlorophyll to other molecules.

Photosystem

Cluster of chlorophyll and proteins found in thylakoids.

ATP synthase

Cluster of proteins that span the cell membrane and allow hydrogen ions (H+) to pass through it.

Adenosine triphosphate

Compound used by cells to store and release energy.

Why are pigments important?

Pigments are important because they are how photosynthetic organisms capture energy from sunlight and without them, photosynthesis wouldn't be possible.

What are other names for the Calvin Cycle? There are at least 3 more.

Dark reactions, light-independent reactions, and C3 cycle.

What are electron carrier molecules?

Electron carrier molecules are compounds that can accept a pair of high-energy electrons and transfer them ,along with most of their energy, to another molecule.

What is needed in the Calvin Cycle?

Energy and carbon dioxide

Explain what occurs during the light-dependent reactions. Include what is needed and what is produced.

Energy from the sun hits chlorophyll in the thylakoid membranes. Water is split, which releases oxygen as a waste gas, but it also provides hydrogen ions that are used to make ATP and NADPH. These can then pass through to the 2nd part of photosynthesis.

What is energy?

Energy is the ability to do work.

Summarize the Calvin Cycle.

Energy molecules travel to the stroma and react with existing carbon dioxide. Once these come together, glucose is made to travel to the rest of the plant.

What are pigments?

Pigments are light-absorbing molecules used by plants to gather the sun's energy.

Where does the ATP & NADPH needed in the light-independent stage come from?

From the light-dependent reaction.

What is produced in the Calvin Cycle?

Glucose

What are the products of photosynthesis?

Glucose (sugar) and oxygen.

Why do YOU need energy? Provide specific reasons why you need energy. Give examples of activities that might require energy.

I need energy to walk, talk, move, write, cook, think, breathe, and read.

What else is needed during the Calvin Cycle?

In addition to ATP & NADPH, CO2, RUBP, and rubisco are needed during the Calvin Cycle.

Where is energy stored in the ATP molecule?

In high-energy bonds between the phosphate groups.

Where do light-independent reactions occur?

In the stroma

Where do light-dependent reactions occur?

In the thylakoid

Where does the energy needed by organisms come from?

It comes from food that organisms eat, or with autotrophs, from the sun.

Explain what occurs during light-independent reactions. Include what is needed and what is produced.

It doesn't require any light. The ATP and NADPH are used in the Calvin Cycle. The Calvin Cycle takes CO2 from the atmosphere and uses the energy from ATP & NADPH to produce the glucose.

Describe the structure of ATP.

It had adenine, a 5-carbon sugar, called ribose, and 3 phosphate group.

What is the role of ATP?

It's an energy carrier. It transports energy to parts of the cell that need it.

What are the light-independent reactions? Where do they take place? What are the products?

Light-independent reactions are a set of reactions in photosynthesis that do not require light; energy from ATP & NADPH is used to build high-energy compounds such as sugar; also called the Calvin Cycle. They take place in the stroma. The products are glucose molecules.

Calvin Cycle

Light-independent reactions of photosynthesis in which energy from ATP and NADPH is used to build high-energy compounds such as sugar.

What is NADP+ and what is its purpose during photosynthesis?

NADP+ is an example of an electron carrier. It carries 2 high-energy electrons and a hydrogen ion. It turns into NADPH. When it's NADP+, it's empty, and when it's NADPH, it's full.

Thylakoid

Saclike photosynthetic membranes found in chloroplasts.

Autotroph

Organism that is able to capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer.

Heterotroph

Organism that obtains food by consuming other living things; also called a consumer.

What is the product of the light reactions?

Oxygen

Why do you think OXYGEN is considered a "waste" product of photosynthesis?

Oxygen is considered a "waste" product because it's sent back out into the atmosphere. Plants don't need oxygen, so it's released.

Why is photosynthesis important for living things?

Photosynthesis is important for living things because nearly all life on Earth depends on the autotrophs' ability to capture the sun's energy and store it in the molecules that make up food.

What is photosynthesis?

Photosynthesis is the process by which autotrophs use the energy from the sunlight to produce high-energy carbohydrates--sugars and starches--that can be used as food.

List the different structures found in the thylakoid membrane.

Photosystem 1, photosystem 2, chlorophyll, electron carriers, & ATP synthase.

Where is chlorophyll found?

Photosystem 2

Explain why plants are green?

Plants are green because leaves reflect green light. They have a lot of violet and blue pigment that causes green light to reflect.

Why do plants need sun and water to grow?

Plants need sun and water to grow because plants need to carry out photosynthesis.

What do plants need for photosynthesis?

Plants need water, light, and carbon dioxide.

Chlorophyll

Principal pigment of plants and other photosynthetic organisms.

Photosynthesis

Process used by plants and other autotrophs to capture light energy and use it to power chemical reactions that convert carbon dioxide and water into oxygen and energy-rich carbohydrates, such as sugars and starches.

What is needed for photosynthesis?

Raw materials⎯6 molecules of water, 6 of carbon, and sunlight.

What are other words fro CARBOHYDRATE?

Simple sugars & glucose

How many times does the Calvin Cycle need to happen for 1 glucose molecule to be made? Explain.

Since glucose has 6 carbon atoms, it takes 6 turns of the Calvin Cycle to make one glucose molecule.

What is needed for the light reactions?

Sunlight and water

Summarize what happens during light reactions.

Sunlight travels from the sun, through the atmosphere, and down towards the surface of the earth, go through the leaf, travel through the chloroplast, and then strike the thylakoid. While the sunlight's going in, water is also being transported into the chloroplast. The light then splits the water, so the oxygen is split apart from the hydrogen and then the oxygen floats freely in the chloroplast and create O2 molecules.

How does the carbon dioxide needed for the light independent reactions get into the chloroplast?

The carbon dioxide gets into the chloroplast by entering through the stomata and diffusing into the stroma of the chloroplast.

Explain how autotrophs and heterotrophs get the energy they use to produce ATP. Include details and examples.

The energy comes from simple chemical compounds, or food. Heterotrophs get food by consuming other living things, like grass, plant-eating animals, or for organisms like mushrooms, by decomposing organisms in the environment. Autotrophs, like plants, algae, and some bacteria, use energy from the sun to make their own food by using the process of photosynthesis.

What are the two parts of photosynthesis?

The light-dependent stage and the light-independent stage.

What are the functions of the outer and inner membranes?

The outer and inner membranes allow things to pass through.

Where in the chloroplast does photosynthesis occur?

The thylakoid and the stroma.

What is the difference between ATP and ADP?

There are only 2 phosphates in ADP, while there are 3 in ATP. ADP is low energy, like a dead battery, while ATP is like a full battery.

What is the function of the chloroplast?

They are the structures in which photosynthesis occurs. They make food for the plant.

What do the different structures in the thylakoid membrane form? And what is their function? (Be specific)

They form an electron transport chain. They can pick up electrons and they can be passed along down energy levels.

Describe the structure of the chloroplast.

They're a double membrane organelle, meaning they have an inner & outer membrane, which are together referred to as the envelope. The inner membrane is highly folded into thylakoids and is stacked up into grana. Surrounding all the thylakoids is a fluid called the stroma.

Describe the process of photosynthesis.

When it rains, water gets absorbed into the ground and plants suck it up through their roots, stomata bring in carbon dioxide, sunlight is absorbed through the plant's leaves.

ATP stands for...

adenosine triphosphate.

Where on the thylakoid do light dependent reactions occur?

the membrane (lumen).