Photosynthesis study guide

Question 1

What is the equation for photosynthesis?

Answer 1

The equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2.

Question 2

Where in the plant cell does photosynthesis take place?

Answer 2

Photosynthesis takes place in the chloroplasts of plants.

Question 3

What pigment makes leaves look green?

Answer 3

The pigment that makes leaves look green is chlorophyll.

Question 4

How many different types of chlorophyll exist in nature?

Answer 4

There are 5 different types of chlorophyll that exist in nature: chlorophyll a, b, c, d, and e.

Question 5

What metal is in the middle of the chlorophyll molecule?

Answer 5

The metal in the middle of a chlorophyll molecule is magnesium.

Question 6

What colors of visible light are absorbed by chlorophyll?

Answer 6

Chlorophyll primarily absorbs red and blue light wavelengths.

Question 7

What are the accessory pigments and why do plants need them?

Answer 7

The accessory pigments are xanthophyll and carotenoids. Plants need accessory pigments to absorb light at different wavelengths that chlorophyll can’t, maximizing the light for photosynthesis.

Question 8

Why do leaves on certain trees turn yellow in the fall?

Answer 8

The chlorophyll breaks down, showing the yellow color which is carotenoids. This was masked by the chlorophyll before.

Question 9

What pigment is red/purple in a leaf and what is its function?

Answer 9

The pigment that is red/purple in a leaf is anthocyanin. This protects the leaf from UV radiation by filtering out yellow and green light.

Question 10

Why do you need carotenoids in your diet?

Answer 10

You need carotenoids in your diet to produce retinol, which is then oxidized to retinal. Retinal combines with a protein called opsin to form rhodopsin, which you need to see light especially in the dark.

Question 11

What cells in your eye give you color vision and what colors do they absorb?

Answer 11

The cells in your eyes that give you color vision are cone cells, and they absorb red, green, and blue light wavelengths.

Question 12

Where does the light-dependent reaction take place in the chloroplast?

Answer 12

It takes place in the thylakoid membrane.

Question 13

What does light excite in the chlorophyll molecule?

Answer 13

Light excites the electrons in the chlorophyll molecule.

Question 14

What happens if an excited electron falls back into the hole it created?

Answer 14

If it falls back into the hole that was created, it will give off light. The color of that fluorescence is red or orange compared to the initial light.

Question 15

What is the next photosystem an excited electron goes to?

Answer 15

The next photosystem it goes to is photosystem 1.

Question 16

What is the name of the electron carrier that transports the electron?

Answer 16

The name of the electron carrier is NADP+, which gets reduced to NADPH once it accepts the electron.

Question 17

Which photosystem splits water to fill the hole left by the excited electron?

Answer 17

Photosystem 2 splits the water to fill the hole left by the excited electron.

Question 18

What is the waste product of the splitting of water?

Answer 18

The waste product of the splitting of the water is O2.

Question 19

What membrane do the electrons pump hydrogens across?

Answer 19

The electrons are used to pump the hydrogens across the thylakoid membrane.

Question 20

What enzyme uses the hydrogen gradient to make ATP and where is it located?

Answer 20

The enzyme that uses the hydrogen gradient to make ATP is ATP synthase, and it is located in the thylakoid membrane.

Question 21

What is the toxic waste product of the light reaction?

Answer 21

The product of the light reaction that is a toxic waste product to the plant is oxygen.

Question 22

What are the two energy molecules produced in the light reaction?

Answer 22

The two energy molecules are ATP and NADPH.

Question 23

Where in the chloroplast does the Calvin cycle take place?

Answer 23

The Calvin cycle takes place in the stroma of the chloroplast.

Question 24

What are some other names for the Calvin cycle?

Answer 24

The Calvin cycle is also called the ‘dark reactions’, ‘Calvin-Benson cycle’, and ‘light independent reaction’, all indicating that it doesn’t need light to function.

Question 25

Why is the Calvin cycle called a cycle and what is the 5 carbon sugar it starts and ends with?

Answer 25

It is called a cycle because it starts, ends, and starts again with the same 5 carbon sugars. The 5 carbon sugar is called ribulose bisphosphate (RuBP).

Question 26

What enzyme combines the gas and the 5 carbon sugars?

Answer 26

The famous enzyme that combines the gas and the 5 carbon sugars is RuBisCO.

Question 27

What energy molecule is used to split the 6 carbon molecule into two 3 carbon molecules?

Answer 27

The energy molecule that is used to split the 6 carbon molecule into two 3 carbon molecules is ATP.

Question 28

What molecule is used to reduce the 3 carbon acid?

Answer 28

The molecule that is used to reduce the 3 carbon is NADPH.

Question 29

What molecule comes out of the Calvin cycle and forms the basis of all organic molecules?

Answer 29

The molecule that comes out of the cycle and forms the basis of all organic molecules is G3P, which contains 3 carbon atoms.

Question 30

What energy molecule is used to regenerate the 5 carbon sugars?

Answer 30

The energy molecule that is used to regenerate the 5 carbon sugars is ATP.

Question 31

How many molecules that come out of the Calvin cycle are used to make one glucose molecule?

Answer 31

Two molecules are used that come out of the Calvin cycle to make one glucose molecule.

Question 32

Why do plants make sucrose?

Answer 32

Plants make sucrose as a way to store and transport energy from photosynthesis, making it an available source of carbon for plants that cannot photosynthesize themselves.

Question 33

What polysaccharide do plants use for structural purposes and where is it found?

Answer 33

The polysaccharide that plants use is cellulose, which is found in the cell walls of plant cells.

Question 34

How is a solar panel like a leaf?

Answer 34

Both capture sunlight and use it as energy.

Question 35

What time of day is the most sunlight hitting us and what direction are you facing if looking directly at the sun?

Answer 35

The sunlight hits the most around noon and you would be facing south if you were looking directly at it.

Question 36

What are some adaptations of plants to maximize sunlight absorption?

Answer 36

Some adaptations are the ability to move with the sun by redirecting their stems, large surface areas to absorb more light, and accessory pigments to capture the most light wavelengths.

Question 37

What is the current CO2 concentration in the atmosphere?

Answer 37

The current carbon dioxide concentration in the atmosphere is 421 ppm.

Question 38

When was the Great Oxidation Event and what does it tell us?

Answer 38

The Great Oxidation Event happened around 2.5 billion years ago. It tells us that photosynthetic organisms like cyanobacteria began to produce a lot of oxygen as a byproduct, changing the atmosphere and filling it with oxygen.

Question 39

What endosymbiosis came first: engulfing a mitochondria or cyanobacteria?

Answer 39

The engulfing of a mitochondria came first, because mitochondria are essential components to all eukaryotic cells.

Question 40

If an alien was looking for carbon-based life, which planet would they visit first?

Answer 40

The alien would visit Earth first because it is the only planet to definitely harbor life which is carbon-based.

Question 41

What gas does the stomata in the leaf allow to enter for photosynthesis?

Answer 41

The hole in the leaf allows for carbon dioxide to enter for photosynthesis.

Question 42

What cells control the opening and closing of the stomata?

Answer 42

The cells that control and open the stomata are guard cells. They open by getting potassium ions, making them swell.

Question 43

What toxic gas exits through the stomata and what precious vapor is lost?

Answer 43

The hole in the leaf allows for oxygen to exit. Water vapor is also lost due to transpiration.

Question 44

Where would you expect to find more stomata on a leaf and why?

Answer 44

You would expect to find more on the bottom side of the leaf because they have more shade, minimizing water loss due to transpiration.

Question 45

How do desert-adapted plants avoid losing too much water through the stomata?

Answer 45

They only open their stomata at night to collect carbon dioxide and store it as acid in their vacuoles, then use it during the day for photosynthesis when the stomata is closed.

Question 46

Why are C4 plants more efficient at making sugars than C3 plants?

Answer 46

Because C4 plants can concentrate carbon dioxide around Rubisco, reducing photorespiration.