Ch 10 - Photosynthesis

How do photosynthetic cells use light to change carbon dioxide and water into organic molecules and oxygen?

How do photosynthetic cells use light to change carbon dioxide and water into organic molecules and oxygen?

Carbon dioxide and water are used in photosynthesis. Photosynthesis will also use light energy in order to generate organic molecules and dioxide from the CO2 and H2O that we started with.

These organic molecules are then used in cellular respiration which generate ATP and our starting molecules. Now the cycle can take place again.

Photosynthesis

The process that converts light energy into chemical energy stored in sugars and other organic molecules

Photosynthesis takes place in which organisms?

Plants, algae, and some photosynthetic prokaryotes

Directly or indirectly, _____ will nourish the entire living world.

Photosynthesis

What are the two types of organisms with regard to how they gain their energy?

Autotrophs and Heterotrophs

Autroph

An organism that sustains itself without eating anything derived from other organisms. It makes its own food inside its body.

Almost all plants are *_*

Autotrophs and producers (they provide nutrients and oxygen for other organisms)

Photoautotroph

Organisms that use light as a source of energy to synthesize organic substances (ex: plants)

Heterotroph

An organism that obtains organic food molecules by eating other organisms or substances derived from them

Consumers

Living organisms that have to hunt, gather and eat their food. They are heterotrophs.

Decomposers

Organisms that break down dead and decaying organic matter. They are also considered heterotrophs/consumers because they consume organisms for their energy instead of producing their own food.

Chloroplasts

An organelle found in plants and photosynthetic protists that absorb sunlight and use it to synthesize organic compounds from CO2 and H2O

They are the site of photosynthesis.

_____ are the major sites of photosynthesis in most plants.

(Chloroplasts are the site of photosynthesis but this question is asking about which part of the plant does the photosynthesis)

Leaves

Mesophyll

The tissue of the interior of the leaf. The cells of this tissue are specialized for photosynthesis.

Chloroplasts are found mainly in the cells of the ____

Mesophyll

In C3 and CAM plants, mesophyll cells are located where?

Between the upper and lower epidermis

In C4 plants, mesophyll cells are located where?

Between the bundle-sheath and the epidermis

Stoma (plural, stomata)

A microscopic pore surrounded by guard cells in the epidermis of leaves and stems that allow gas exchange between the environment and the interior of the plant

CO2 enters the leaf and O2 exits, by way of microscopic pores called ____

Stomata

A typical mesophyll cell has about how many chloroplasts?

About 30 to 40

A chloroplast has how many membranes?

Two

Stroma

The dense fluid within the chloroplast that is involved in the synthesis of organic molecules from CO2 and H2O

Stroma surrounds the _____

thylakoid membrane

Stroma contain ____

Ribosomes and DNA

Thylakoid

A flattened, membranous sac inside a chloroplast. Thylakoid membranes convert light energy to chemical energy of ATP and NADPH

Thylakoids often exist in interconnected stacks called _____

Grana

Chlorophyll

A green pigment that gives leaves their color. Located in thylakoid membranes of the chloroplasts.

Light absorbed by _____ drives the synthesis of organic molecules in the chloroplasts

Chlorophyll

6CO2 + 12 H2O + Light Energy → C6H12O6 + 6O2 + 6H2O

This is the equation of _____

Photosynthesis

Carbon dioxide + water + light energy become Glucose, Dioxide, and Water

Photosynthesis and _____ undo each other

Cellular respiration

Chloroplasts split water into _____, incorporating the electrons of hydrogen into sugar molecules

Hydrogen and Oxygen

What type of process is photosynthesis?

Redox Process

How is photosynthesis a redox process?

It oxidizes water and reduces carbon dioxide

Photosynthesis consists of two processes. These two stages are ______.

Light reactions (the photo part of photosynthesis) and the Calvin Cycle (the synthesis part of photosynthesis)

Light reactions

The first stage in photosynthesis. These reactions convert solar energy to ATP and NADPH, split water and release oxygen

Light reactions take place where?

On the thylakoid membranes of the chloroplasts or on the membranes of certain prokaryotes

Calvin Cycle

The second stage of photosynthesis. This stage involves fixation of atmospheric CO2 and reduction of the fixed carbon into carbohydrate. Produces sugar.

NADP+

An acceptor. This is the oxidized form of Nicotinamide Adenine Dinucleotide Phosphate, an electron carrier that can accept electrons, becoming NADPH.

Light reactions use solar energy to reduce NADP+ to _____ by adding a pair of electrons along with an H+

NADPH

NADPH

The reduced form of NADP+ (nicotinamide adenine dinucleotide phosphate).

It temporarily stores energized electrons produced during the light reactions. It also reduces electron acceptors.

Function of NADPH

Temporarily stores energized electrons produced during the light reactions and reduces electron acceptors

Photophosphorylation

The process of generating ATP from ADP and phosphate by means of chemiosmosis. This process is done during light reactions.

What is the energy currency of cells?

ATP

Calvin cycle is named after ____

Melvin Calvin

The first step of the Calvin cycle is carbon fixation, which is?

The initial incorporation of carbon from CO2 into an organic compound by an autotrophic organism

Light

A form of energy known as electromagnetic energy, also called electromagnetic radiation

Like other electromagnetic energy, light travels in _____

Rhythmic waves

Wavelength

Distance between crests of waves

Wavelength determines ____

The type of electromagnetic energy

Electromagnetic Spectrum

The entire spectrum of electromagnetic radiation, ranging in wavelength from less than a nanometer to more than a kilometer

Visible Light

The segment of the electromagnetic spectrum that can be detected as various colors by the human eye, ranging in wavelength from about 380nm to about 740nm

Photons

A quantum, or discrete quantity, of light energy that behaves as if it were a particle

Light behaves as though it consists of discrete particles called _____

Photons

The amount of energy is inversely related to the wavelength of the light. The shorter the wavelength, the ____ the energy of each photon of that light and vice versa.

Greater

Plants like which light colors?

Blue (450-500nm) and Red (650-750nm)

Gamma Rays can result in what illness?

Cancer

X-Rays can result in what illness?

Sterility

UV Rays if long term can give you what illness?

Skin Cancer

UV Rays can be seen by which animals?

Birds and insects

Infrared light can be seen by which animals?

Reptiles, bats, and insects

Pigments

Substances that absorb visible light. Different pigments absorb different wavelengths.

Wavelengths that are not absorbed are _____

Reflected or transmitted. For example, chlorophyll looks green because it does not absorb green wavelengths.

Absorption Spectrum

A graph plotting a pigment’s light absorption versus wavelength

Spectrophotometer

An instrument that measures the proportions of light of different wavelengths absorbed and transmitted by a pigment solution

Chlorophyll a

The main photosynthetic pigment. It participates directly in light reactions.

Chlorophyll b

An accessory photosynthetic pigment that transfers energy to chlorophyll a.

Action Spectrum

A graph that profiles the relative effectiveness of different wavelengths of radiation in driving a particular process

The absorption spectrum of chlorophyll a suggests that these two colors work best for photosynthesis: ______

Violet-blue and Red

Other accessory pigments include Carotenoids, which are?

An accessory pigment, either yellow or orange, in the chloroplasts of plants and in some prokaryotes. By absorbing wavelengths of light that chlorophyll cannot, carotenoids broaden the spectrum of colors that can drive photosynthesis.

Accessory pigments, such as chlorophyll b, function to _____. These pigments are also called carotenoids.

Broaden the spectrum used for photosynthesis

When a pigment absorbs light, its state changes from _____ to ____

Ground state to excited state which is unstable

When excited electrons fall back to the ground state, photons are given off, an afterglow called _____

Fluorescence

Photosystem

A light-capturing unit is located in the chloroplast's thylakoid membrane or in some prokaryotes' membranes.

Below is extra info I will put on a separate question:

There are two types of photosystems: Photosystems 1 and 2

A photosystem consists of a reaction-center complex surrounded by numerous light-harvesting complexes

There are two types of photosystems; What are they?

Photosystem I and Photosystem II (they are numbered by the order of their discovery)

A photosystem is composed of _____

A reaction-center complex surrounded by several light-harvesting complexes. These light-harvesting complexes funnel the energy of photons to the reaction center.

Reaction-Center Complex

An organized association of proteins holding a special pair of chlorophyll a molecules and a primary electron acceptor.

Where is the reaction-center complex located?

Center of a photosystem

What triggers the light reactions of photosynthesis?

Reaction-Center Complexes

Light-Harvesting Complex

A complex of proteins associated with pigment molecules that captures light energy and transfers it to reaction center pigments in a photosystem

Includes chlorophyll a, chlorophyll b, and carotenoids

The two photosystems work together to use light energy to generate ______

ATP and NADPH

Photosystem II functions first and is best at absorbing a wavelength of _____

680nm (red)

Photosystem I is best at absorbing a wavelength of _____

700 nm

Photosystem I is used to create _____

NADPH

Photosystem II is used to make _____

ATP

Primary Electron Acceptor

In the thylakoid membrane of a chloroplast or in the membrane of some prokaryotes, a specialized molecule that shares the reaction-center complex with a pair of chlorophyll a molecules and that accepts an electron from them

The first step of the light reactions is?

Solar-powered transfer of an electron from a chlorophyll a molecule to the primary electron acceptor

Photosystem II

One of two light-capturing units. It has two molecules of P680 chlorophyll a at its reaction center

Located in a chloroplast’s thylakoid membrane or in the membrane of some prokaryotes.

Photosystem I (PS I)

One of two light capturing units. It has two molecules of P700 chlorophyll a at its reaction center

Located in a chloroplast’s thylakoid membrane or in the membrane of some prokaryotes

Linear/Noncyclic Electron Flow

The primary route of electron flow during the light reactions that involves both photosystems and produces ATP, NADPH, and O2. The net electron flow is from H2O to NADP+

Cyclic Electron Flow

A route of electron flow during the light reactions of photosynthesis that uses only photosystem I and produces surplus ATP, satisfying the higher demand in the Calvin Cycle

Similarities and Differences Between Chemiosmosis in Chloroplasts and Mitochondria

1. Chloroplasts and mitochondria generate ATP by _____but have a different source of energy

2. Mitochondria transfer chemical energy from food to ATP; Chloroplasts transform light energy into the chemical energy of ATP

3. The spatial organization of chemiosmosis different in chloroplasts and mitochondria

Chemiosmosis

Similarities and Differences Between Chemiosmosis in Chloroplasts and Mitochondria

1. Chloroplasts and mitochondria generate ____ by chemiosmosis but have a different source of energy

2. Mitochondria transfer chemical energy from food to ATP; Chloroplasts transform light energy into the chemical energy of ATP

3. The spatial organization of chemiosmosis different in chloroplasts and mitochondria

ATP

Similarities and Differences Between Chemiosmosis in Chloroplasts and Mitochondria

Both give energy to ATP, but how is it different for mitochondria and chloroplast?

Mitochondria transfer chemical energy from food to ATP and chloroplasts transform light energy into the chemical energy of ATP

The Calvin Cycle used ATP and the reducing power of NADPH to convert CO2 to ____

Sugar

Like the citric acid cycle, the calvin cycle will _____

regenerate its starting material after molecules enter and leave the cycle

___ enters the Calvin Cycle as CO2 and leaves as a sugar named glyceraldehyde-3-phosphate (G3P)

Carbon

Carbon enters the Calvin Cycle as CO2 and leaves as a sugar named _____

glyceraldehyde-3-phosphate (G3P)

glyceraldehyde-3-phosphate (G3P)

A three-carbon carbohydrate that is the direct product of the Calvin Cycle; it is also an intermediate in glycolysis

For the net synthesis of one G3P, the calvin cycle must take place how many times?

Three times, therefore also needed 3 molecules of CO2

The Calvin Cycle has 3 phases. What are they in order?

Carbon Fixation, Reduction, and Regeneration