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Life Sciences 2 Midterm 2 > Chapter 9: Photosynthesis > Flashcards

Chapter 9: Photosynthesis Flashcards

1
Q

What is photosynthesis?

Basic Definition

A

Photosynthesis is a chemical conversion that involves the synthesis of glucose.

  • Taking CO2 and converting it to Glucose
  • Main star: CHLOROPLAST
  • We use three items: water, fine capillary roots (plants), sunlight
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2
Q

Photosynthesis Equation

A

6CO2 + 12H2O+light energy ——> C6H12O6 +6O2 + 6H2O

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3
Q

Name the five photosynthetic organisms

A

Plants, Alga, Protist, Purple sulfur bacteria, Cyanobacteria

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4
Q

Difference between Autotrophs and Heterotrophs

A
  • Autotrophs (plants) make their own energy (glucose)
  • Heterotrophs: consumers and decomposers which need a source of organic molecules to survive
  • Humans are heterotrophs
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5
Q

What is light?

A
  • Light is a form of electromagnetic radiation
  • Plants absorb light and convert it to sugar/glucose
  • Light has different wavelength and quantities of energy
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6
Q

What are electromagnetic waves?

A

Disturbances of electric and magnetic fields

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7
Q

What is visible light?

A
  • Visible light are the colors, created by waves, that can be viewed by the human eye
  • Quantify light by wavelength and energy
  • Visible light goes from red to violet
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8
Q

What can you do with visible light? (3)

A

-Light can be reflected (bouncing back)
-Transmitted (goes through the organism)
-Absorbed (what can be captured)
»»Photosynthesis

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9
Q

What is the function of the chloroplast?

A

Absorb light.

They are why we see leaves as green/.

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10
Q

What are photons?

A

Each photon is a discrete unit that contains a fixed amount of energy. That energy is inversely proportional to its wavelength: the shorter the wavelength, the greater the energy of a photon

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11
Q

What is a pigment and what do they do?

A

-A pigment is something that can absorb light

  • When light is absorbed by the pigment, the stability of the atom is disturbed since it is given additional energy
  • Makes electrons shift from the orbit they’re supposed to be to different place
  • Will be at the excited state. Will try to go back to the stable state.
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12
Q

Ground state/Excited state

A

The electron goes into the excited state when the photon receives light/energy. The energy state is unstable, so the electron spends less time in that state. As it returns to the ground state, it emits energy. This energy is lost as heat or passed down to a neighboring molecule

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13
Q

How does water travel in the plant? Light?

A

Xylem allow the water (from the roots) to travel through the plant
->Through adhesion and cohesion forces

Get sunlight through leaf and high surface area

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14
Q

What is the function of the Stroma?

A

Remove carbon from CO2 and then mix it with oxygen and hydrogen to make a simple carbohydrate molecule (LIGHT INDEPENDENT REACTION)

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15
Q

Light reaction vs. Calvin-Benson cycle

A

Light reaction

  • Uses light energy, water, NADP+, ADP
  • Produces ATP and NADPH + (H+)

The Calvin-Benson Cycle

  • Reduction reaction since carbon is gaining hydrogen
  • Uses ATP, NADPH + (H+), and CO2
  • Produce sugars (phosphoglyceraldehyde)
  • **CO2 fixation
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16
Q

Where does photosynthesis occur?

A

Chloroplasts

  • Contains grana, which are made up of thylakoids (folded membrane)which contain chlorophyll
  • Inside the chloroplast is a fluid, stroma
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17
Q

Pigments

A
  • Capture light and use it to provide energy to carry out photosynthesis
  • located in the Thylakoid
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18
Q

What is a photosystem?

A

A bunch of molecules working together to make light

19
Q

PHOTOSYSTEM II (STEPS)

A

○ Light is shining at the photosystem
○ A molecule of the photosystem is receiving and absorbing the light
○ Molecule goes to the excited state
§ It is going to take the energy and dump it to the next molecule in its vicinity
§ Second molecule received energy and transfers it to the next and so on.
□ Eventually it gets to the reaction center
□ The reaction center (P680)will keep the energy and lose/transfer an electron
□ **every molecule is transferring energy except for the reaction center

  • The electron lost from the reaction center goes to the electron transport chain and generates ATP by chemiosmosis
  • In order to re-stabilize the reaction center, an H20 is broken down. The O2 is released into the environment and the hydrogens (pumped from thylakoid lumen to stroma) are used to power ATP synthase (phosphorylation) in the ETC
20
Q

PHOTOSYSTEM I (STEPS)

A

○ Transfer of molecules to the reaction center
§ Gets electrons from the ETC
§ Electrons are passed to Fd
§ NADP reductase catalyzes the transfer of electrons to NADP+ (becomes NADPH)
§ Acyclic: one electron is being transferred form a photosystem to another

21
Q

PQ

A

PLASTOQUINONE

Electron Transport Chain

22
Q

Cyt

A

CYTOCHROME

Electron Transport Chain

23
Q

PC

A

PLASTOCYANIN

Electron Transport Chain

24
Q

Fd

A

FERRODOXIN

Electron Transport Chain

25
Q

NADP reductase

A

Reduces NADP+ TO NADPH

Electron Transport Chain

26
Q

Result of Activeproton transport

A

Proton Motive Force: a difference in pH and electric charge across the membrane

27
Q

Does the Calvin-Benson cycle use light directly or indirectly?

A

Indirectly. Uses products of light reactions: ATP and NADPH

28
Q

Other carbon source for Calvin-Benson Cycle

A

The other carbon source is RuBP
○ RATE LIMITING STEP
§ Without it, we can’t have the process
§ The slower it happens, the slower the Calvin-Benson cycle is

29
Q

What is Rubisco?

A
  • Rate limiting enzyme

- Product: 3PG (on its way to become glucose)

30
Q

What does Rubisco stand for?

A

Ribulose biphosphate carboxylase/oxygenase

31
Q

Major steps of the Calvin-Benson Cycle

A

CARBON FIXATION STEP
○ Captures the CO2 and becomes attached to RuBP (catalyzed by rubisco) and makes a 6-carbon molecule that breaks down into 3-phosphoglycerate (3PGA)

REDUCTION AND SUGAR PRODUCTION
○ Carbon gains hydrogens
○ Where we're creating the glucose/sugar
	§ Some of the sugar is stored to be used
REGENERATION OF RuBP
○ Needed to keep reaction going
32
Q

G3P Function

A

5/6 is recycled back to RuBP

1/6: (1/3) Starch and (2/3) Sucrose

33
Q

(Basic) Purpose of Calvin Benson Cycle

A

To generate sugar to be used as energy and endergonic chemical reactions

34
Q

What else happens to the carbon from Glucose?

A

They convert glucose into Amino acids, lipids, and nucleic acids.

Remember that g3P?

35
Q

Metabolic Pathways

other products of G3P

A

G3P CAN BE MADE INTO STARCH, SUCROSE, GLUCOSE, ATP OR USED IN CELL RESPIRATION, ACETYL CO, FATTY ACIDS, GLYCEROL, TRIGLYCERIDE

These chemical reactions are made up of redox reactions

36
Q

Chloroplast structure

A
  • Pigments
  • Grana: consists of Thylakoid
  • Stroma
37
Q

Where do are photosystems I and II occur?

A

Thylakoid membrane

38
Q

What are the absorption ranges for each photosystem?

A

Photosystem I: P700

Photosystem II: P680

39
Q

What is the difference between cyclic and non-cyclic photophosphorylation?

A

cyclic photophosphorylation creates ATP

non-cyclic photophosphorylation creates ATP and NADPH

40
Q

How does the light independent reaction work?

A

(carbon fixation reactions) do not use light directly, but instead use ATP, NADPH (made by light reactions) and carbon dioxide to produce carbohydrates (sometimes called dark reactions)

41
Q

What is Carbon Fixation?

A
  • It is the conversion of carbon dioxide into organic compounds during photosynthesis.
  • Mostly refers to the processes found in autotrophs
  • Usually driven by photosynthesis, whereby carbon dioxide is changed into sugars.
42
Q

What is the main product of the Calvin Cycle?

A

G3P

43
Q

Where do light dependent reactions occur?

A

Thylakoid membrane

44
Q

Where does the light independent (Calvin Cycle) occur?

A

Stroma

Life Sciences 2 Midterm 2 (6 decks)

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