Biology Quiz - Section 4.2

Photosynthesis provides more than ______ of the energy used by living things on Earth

99%

______ are the organelles where photosynthesis takes place.

Chloroplasts

During the light reactions, ______ and NADPH are produced.

ATP

Light Reactions - Step 5

Enzymes in the thylakoid membrane transfer the newly re-energized electrons to a compound called NADP+. Along with a hydrogen ion, this produces the energy-carrying molecule NADPH that is used in the Calvin Cycle

ATP and NADPH are the reactants of the light reactions.

False

All cells have chloroplasts.

False

Both stages of photosynthesis need sunlight to proceed.

False

During the light reactions, water molecules are made.

False

In photosynthesis, the Calvin Cycle comes before the light reactions.

False

Like photosynthesis, chemosynthesis relis on sunlight.

False

Most autotrophs make food through the process of ______

Photosynthesis

Light Reactions - Step 3

The 2 electrons from step 1 are passed from molecule to molecule down the electron transport chain and along the way their energy is used to pump more hydrogen (H+) into the thylakoid membrane

Essentially the oxygen we breath is ______

a waste product of photosynthesis

The correct sequence of events in the light reactions is ______

absorbtion of light, splitting of water, electrons flow down electron transport chain, ATP is made

Light Reactions - Step 6

all the hydrogen pumped out during the 2 electron transport chains flows from the thylakoid membrane to the stroma, making ATP in the process. ATP is saved to be used in stage 2 of the Calvin Cycle

Most _____ make food using photosynthesis.

autotrophs

chemiosmotic gradient

causes hydrogen ions to flow back across the thylakoid membrane to the stroma, where their concentration is lower

Making food with chemical energy instead of sunlight is called ______

chemosynthesis

The green pigment, ______ , absorbs light to start photosynthesis.

chlorophyll

During the Calvin Cycle, ______ is produced.

glucose

One turn of the Calvin Cycle produces one molecule of ______

glucose

Chloroplasts contain ______ which are made of sac-like membranes called thylakoid membranes.

grana

chlorophyll

green pigment in a chloroplast that absorbs sunlight in the light reactions of photosynthesis

photosystem

group of molecules, including chlorophyll, in the thylakoid membrane of a chloroplast that captures light energy

By the end of the light reactions, energy from sunlight ______

has been stored in NADPH and ATP

The Calvin Cylce occurs ______

in the stroma surrounding the thylakoid membrane of the chloroplast

Light Reactions - Step 1

light (photon) strikes chlorophyll and is absorbed by 2 electrons (2e-). The 2 electrons now have enough energy to leave the chlorophyll molecule

Light Reactions - Step 2

light energy splits water to make 2e- to replace those lost in step 1 and oxygen is released as a waste product. The 2 hydrogen ions (2H+) are used later

Stage 1 of photosynthesis is called the ______

light reactions

glucose

main product of photosynthesis

thylakoid membrane

membrane in a chloroplast where the light reactions of photosynthesis occur

During the first stage of photosynthesis, a molecule of ______ is released.

oxygen

chemosynthesis

process of using the energy in chemical compounds to make food

grana

within the chloroplast, consists of sac-like membranes, known as thylakoid membranes

Light Reactions - Step 4

When the 2 electrons reach the end of the electron transport chain their energy is used up and here they are re-energized by more light and sent down a 2nd electron transport chain

light reactions

first stage of photosynthesis in which light energy from the sun is captured and changed into chemical energy that is stored in ATP and NADPH

The light reactions occur in the ______

thylakoid membranes

Stage 2 of photosynthesis is called the ______

Calvin Cycle

Calvin Cycle - Step 1

Carbon fixation - Carbon dioxide combines with a simple, five-carbon compound called RuBP with the help of an enzyme named RuBisCo and it produces 3PG

Calvin Cycle - Step 2

Reduction - Molecules of 3PG gain energy from ATP losing a Phosphate and NADPH losing a hydrogen. They re-arrange themselves to form a more powerful version of 3PG, called G3P. One of the G3P molecules goes on to form glucose, while the rest of the G3P molecules go on to Step 3.

Calvin Cycle - Step 3

Regeneration - The remaining G3P molecules use energy from ATP (in the form of a phosphate) to form RuBP, the five-carbon molecule that started the Calvin cycle. This allows the cycle to repeat.

Which steps in the light reactions happen at the same time?

Step 1 and Step 2

During the Calvin Cycle, ATP and NADPH are used to make glucose.

True

Earth's oxygen comes from photosynthesis

True

Electron transport occurs in the thylakoid membranes

True

Light is absorbed by photosystems in the thylakoid membranes of chloroplasts.

True

Photons of sunlight can excite and energize electrons.

True

Photosynthesis provides almost all of the energy used by living things on Earth.

True

The Calvin Cycle takes place in the stroma surrounding the thylakoid membranes of the chloroplast.

True

During the first stage of photosynthesis, two ______ are passed from molecule to molecule down the electron transport chain.

electrons

Calvin cycle

second stage of photosynthesis in which carbon atoms from carbon dioxide are combined, using the energy in ATP and NADPH, to make glucose

electron transport chain

series of electron-transport molecules that pass high-energy electrons from molecule to molecule and capture their energy

stroma

space outside the thylakoid membranes of a chloroplast where the Calvin cycle of photosynthesis takes place

The Calvin Cycle occurs in the ______

stroma