photosynthesis(unit 5)

Question 1

Write out the equation for photosynthesis.

Answer 1

6CO2 + 6H2O + light energy → C6H12O6 + 6O2

Question 2

Where in the plant (or algal) cell does photosynthesis take place?

Answer 2

Chloroplasts

Question 3

What is the pigment that makes leaves look (reflect) green?

Answer 3

Chlorophyll

Question 4

How many different types of chlorophyll exist in nature?

Answer 4

5 but the main ones are chlorophyll a and chlorophyll b involved in photosynthesis

Question 5

What is the metal in the middle of the chlorophyll molecule?

Answer 5

Magnesium

Question 6

What 2 colors of visible light are absorbed by the pigment?

Answer 6

Blue and red

Question 7

Besides chlorophyll, what are the accessory pigments? Why do plants need accessory pigments?

Answer 7

Accessory pigments: Xanthophyll and Carotene. They need these to broaden the range of light wavelengths they can use for photosynthesis.

Question 8

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

Answer 8

Due to the breakdown of chlorophyll. Chlorophyll production slows down, and other pigments like Carotene and Xanthophyll become more visible.

Question 9

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

Answer 9

Anthocyanin. Used for protection from UV radiation.

Question 10

Describe, in molecular terms, why you need to get carotenoids in your diet.

Answer 10

For vision, carotenoids cut in half into Vitamin A, which oxidizes to retinal (purple pigment in eye).

Question 11

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

Answer 11

Cone cells. Blue, green, red.

Question 12

Light dependent reaction: Where does it take place in the chloroplast?

Answer 12

Thylakoid membrane of the chloroplast.

Question 13

What does light excite in the chlorophyll molecule?

Answer 13

Electrons

Question 14

What is the color of the fluorescence if the excited electron falls back into the hole?

Answer 14

Red/Orange

Question 15

What do we call the next photosystem the excited electron goes to?

Answer 15

Photosystem II to Photosystem I

Question 16

What is the name of the electron carrier?

Answer 16

NADPH

Question 17

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

Answer 17

Photosystem II

Question 18

What is the waste product of the splitting of water?

Answer 18

Oxygen

Question 19

The electron is used to pump the hydrogens across what membrane?

Answer 19

Thylakoid membrane

Question 20

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

Answer 20

ATP synthase. Thylakoid membrane.

Question 21

Which product of the light dependent reaction is a toxic waste product to the plant?

Answer 21

Oxygen

Question 22

What are the two ‘energy’ molecules produced?

Answer 22

ATP and NADPH

Question 23

Where in the chloroplast does the Calvin cycle take place?

Answer 23

Stroma

Question 24

What are some other names for the Calvin cycle?

Answer 24

C3 Pathway, Dark Reaction/Light-Independent Reaction, Carbon-Fixing reaction.

Question 25

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

Answer 25

It starts and ends with a five-carbon sugar called RuBP.

Question 26

What is the famous enzyme that combines the gas and the 5 carbon sugar?

Answer 26

RuBisCO

Question 27

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

Answer 27

ATP

Question 28

What molecule is used to reduce the 3 carbon (acid)?

Answer 28

NADPH

Question 29

What molecule comes out of the cycle and forms the basis of all organic molecules? How many carbons is it?

Answer 29

Glyceraldehyde-3-phosphate (G3P). 3 carbons.

Question 30

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

Answer 30

ATP

Question 31

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

Answer 31

Two molecules of G3P

Question 32

Why do plants make sucrose (disaccharide, aka table sugar)?

Answer 32

For Energy Transport - main.

Question 33

What is the polysaccharide used for structural purposes in plants? Where is it found?

Answer 33

Cellulose, found in the plant cell.

Question 34

What is the stored energy molecule called?

Answer 34

Starch

Question 35

How is a solar panel like a leaf?

Answer 35

They both harness energy and have large surface for efficiency.

Question 36

What time of day is the most sunlight hitting us?

Answer 36

Solar noon around 12 pm.

Question 37

What direction are you facing if you are looking directly at the sun at solar noon?

Answer 37

South in Northern hemisphere, North in Southern hemisphere.

Question 38

What are some adaptations of plants to maximize sunlight absorption for their leaves?

Answer 38

Maximize surface area for most amount of energy, stomata regulation, leaves follow sun.

Question 39

What is the current CO2 concentration in the atmosphere?

Answer 39

425.26 ppm (0.0425%)

Question 40

When was the Great Oxidation Event? What does that tell us?

Answer 40

Over 2 billion years ago. Photosynthesis started.

Question 41

What endosymbiosis came first: engulfing a mitochondria or cyanobacteria? Explain.

Answer 41

Engulfing of mitochondria around 2 billion years ago, followed by cyanobacteria around 600 million years ago.

Question 42

If an alien was looking for carbon based life, what planet would they visit first: Mars or Earth? Explain why.

Answer 42

Earth because it contains significant amounts of oxygen and carbon dioxide, gases needed for living organisms.

Question 43

Stomata: The hole in the leaf allows what gas used for photosynthesis to enter?

Answer 43

Carbon Dioxide

Question 44

What cells control the opening and closing of the stomata? How do they open in the light?

Answer 44

Guard cells. Light activation triggers proton pumps, leading to water influx and turgor pressure.

Question 45

Stomata: The hole in the leaf allows what toxic gas (to the plant) to exit? What precious vapor is also lost when the stomata is open?

Answer 45

Oxygen and Water vapor.

Question 46

Would you expect to find more or fewer stomata on the bottom side of the leaf? Explain why.

Answer 46

More stomata on the bottom side to reduce water vapor loss.

Question 47

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

Answer 47

Carbon dioxide to malic acid, reduce number of stomata, close stomata during hottest parts of day.

Question 48

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

Answer 48

Minimize photorespiration, efficient carbon fixation, water use efficiency, higher photosynthetic rates.