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BIO 110 > Chapter Ten > Flashcards

Chapter Ten Flashcards

1
Q

What is light energy?

A

it can be kinetic or potential, and is electromagnetic radiation stored as photons.

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2
Q

What is electromagnetic radiation?

A

radiation propagated as waves and particles

the amount of energy in the wave is inversely proportional to wavelength (small wavelength -> greater energy)

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3
Q

What is a photon?

A

they are packets that store energy, (particles of light)

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4
Q

What does absorbed energy do?

A
  1. absorbed energy adds energy to the molecule (makes it excited)
    it boosts an electron in the molecule into a shell farther from the nucleus which makes it more unstable and reactive
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5
Q

What do pigments do with the sun’s light?

A

they absorb specific wavelengths in the visible range

the other light / wavelengths are scattered or transmitted which imparts the colors we see

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6
Q

Explain what are absorbed wavelengths.

A

Light can be absorbed only in certain wavelengths and it all depends on the PIGMENT

chlorophyll a and b absorb red and blue wavelengths
carotenoids absorb blue and violet

Only absorbed light is useful for photsynthesis

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7
Q

Explain the reflected wavelengths.

A

Hardly no wavelength is absorbed from 500-625

No pigment absorbs pure green light, so it is reflected, which is why we perceive leaves to be green

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8
Q

What is the importance of photosynthesis?

A

The primary function / importance of photosynthesis is to convert solar energy into chemical energy and then store that chemical energy for future use, but it also makes oxygen as a byproduct.

Without photosynthesis, cellular respiration wouldn’t have a hope in functioning i.e it sustains all the food chains in an ecosystem

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9
Q

What is the general reaction of photosynthesis?

A

6 H2O + 6 CO2 through use of light energy -> C6H12O6 + 6 O2

Water + Carbon Dioxide in the presence of light YIELD Glucose and Oxygen gas

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10
Q

What are the two pathways of photosynthesis?

A
  1. Light reactions (dependent)
  2. Carbon fixation (light independent) Calvin Cycle
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11
Q

What is the input and output of light reactions?

A

Input: Sunlight, 6H2O, ADP, Pi, NADP+

Output: 6 O2, ATP, NADPH

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12
Q

What is the input and output of the carbon fixation (light independent reactions?)

A

Input: 6 CO2, 12 NADPH, 18ATP

Output: 2 G3P (can form one glucose), 12 NADP+, 18 ADP, and 18 Pi

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13
Q

How are the light dependent reactions connected to the carbon fixation reactions?

A

The ATP and NADPH made in the light dependent reactions are used in the carbon fixation reactions

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14
Q

What are photosystems?

A

multi-protein light harvesting complexes embedded in the thylakoid membrane

they contain pigment molecules, like chlorophyl that absorb the photon and make the molecule excited.

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15
Q

In which pathway are photosystems used?

A

They are used in the light dependent reactions

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16
Q

Explain light harvesting complexes and reaction centers.

A

When a pigment molecule absorbs a photon, the molecule becomes unstable and the energy is released quickly, so the energy is absorbed by other pigment molecules and is passed to the reaction centers, where it is converted to chemical energy (when the excited molecule gives up an electron to the electron acceptor

Chlorophyll in the reaction center is oxidized

The electron acceptor molecule is reduced

17
Q

Explain the orientation of the light harvesting complexes and reaction centers.

A

A protein complex that includes chlorophyll molecules and carotenoid molecules make up the antenna system (light harvesting complex)

Inside the antenna system there are different proteins that contain other chlorophylls

This entire thing is embedded in the thylakoid membrane

18
Q

What is light energy converted to and what is the final electron acceptor in the photosystems?

A

The light energy is converted into chemical energy in the form of potential energy.

The electron acceptor in the photosystem is only the first of many

*The final electron acceptor is NADP+

19
Q

What photosystems are used in noncyclic electron transport?

A

Photosystem II - when an chlorophyll gives up its excited electron it is unstable and grabs another electron from water, and the water becomes oxidized (the H+ are dropped in the thylakoid place)

The electron is passed through an ETC which pumps H+ into the thylakoid space by using the energy of the electron and ATP synthase eventually synthesizes

Photosystem I - chlorophyll takes an electron from the last carrier in PS2 and the excited electron is passed through several other carriers and reduces NADP+ to NADPH

20
Q

What photosystems are used in cyclic electron transport?

A

Photosystem I - when the chlorophyll gives up its excited electron, the energetic electron then passes through the ETC which pumps H+ into the thylakoid space by using the energy of the electron and then ATP synthase does its thing phosphorylate ADP

The electron is then accepted by the chlorophyll again and the process re-starts

21
Q

How is ATP produced during light dependent reactions?

A

It is formed by photophosphorylation,

when H+ flows back across the membrane from the lumen to the stroma through ATP synthase in the thylakoid membrane, it uses that energy to synthesize ATP

22
Q

What two things contribute to the H+ gradient?
Hint: (ones in the lumen and ones in the stroma)

A

Water oxidation in the lumen and NADP+ reduction in the stroma

23
Q

Why is ATP synthase important?

A

If ATP synthase isn’t woking correctly, the H+ concentration will just keep building up potential energy but there will no way to release it.

The ATP produced in the light dependent reactions is needed for the light independent reactions

24
Q

What is CO2 reduced to in the light independent (carbon fixation) reactions and where does the energy come from to do this?

A

it is reduced to carbohydrates, and it uses the energy stored as potential energy in ATP and NADPH

25
Q

Where do the carbon fixations occur?

A

they occur in the stroma

26
Q

What enzyme is involved in the Calvin Cycle?

A

Rubisco

27
Q

For every turn of the Calvin Cycle, what happens?

A

One CO2 is fixed and One RuBP is regenerated

28
Q

What is photorespiration?

A

It is when RuBP reacts with O2 in the Calvin Cycle instead of CO2

it consumes O2 and releases O2, and it happens only in night

it wastes ATP and NADPH and reduces the net carbon fixed by the Calvin cycle

29
Q

How do C4 and CAM plants avoid photorespiration?

A

C4 plants they have physically separated the Calvin Cycle (mesophyll and bundle sheath cells) from O2 rich spaces in the leaf, so the rubisco always encounters high CO2

CAM plants only open their stomata at night

30
Q

What are some examples of energy loses in photosynthesis?

A
  1. Wavelengths that couldn’t be absorbed - 50%
  2. Light energy not absorbed due to plant structure - 30%
  3. Inefficiency of light reactions 10%
  4. Inefficiency of CO2 fixation pathways 5%

BIO 110 (19 decks)

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