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
