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Photosynthesis Flashcards

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1
Q

What organisms are capable of doing photosynthesis?

A

Plants, algae, & cyanobacteria. (These organisms can also do C.R.)

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2
Q

Why is Photosynthesis important?

A

It captures sunlight. Vital b/c evolved as a way to store the energy in solar radiation as high-energy electrons in the carbon-carbon bonds of carbohydrate molecules.

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3
Q

What is Photosynthesis?

A

Is the process of using sunlight to produce carbohydrate.
Requires sunlight, carbon dioxide, and water. Produces oxygen as a by-product.

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4
Q

What is the formula for Photosynthesis?

A

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

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5
Q

What is Photosynthesis a contrast of?

A

Cellular Respiration. Photosynthesis is anabolic and endergonic.Reduces CO2 to sugar.

C.R. is catabolic and exergonic. Oxidizes sugar to CO2.

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6
Q

Why do plants carry out Photosynthesis?

A

The glucose molecules provide organisms with two crucial resources:
1. Energy - Glucose can undergo C.R and produce ATP!
2. Fixed organic carbon- Carbon from CO2 (inorganic carbon) can be incorporated into organic molecules (AKA fixed carbon); CARBON FIXATION.

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7
Q

Where does photosynthesis take place?

A

Takes place in the leaves, which consist of several layers of cells. Particularly, the mesophyll (middle) layer. Each mesophyll cell contains chloroplasts - site of photosynthesis.

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8
Q

What is a stomata (stoma)?

A

Small pores found on the surface of leaves in most plants.
Let CO2 diffuse into leaves and mesophyll cells. Let O2 diffuse out. Also plays a role in the regulation of gas exchange and water balance. The stomata are typically located on the underside of the leaf, which helps to minimize water loss. Each stoma is flanked by guard cells that regulate the opening and closing of the stomata by swelling or shrinking in response to osmotic changes.

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9
Q

What is chloroplast?

A

Where photosynthesis takes place.

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10
Q

What is the structure of Chloroplast?

A

Chloroplasts have a double membrane envelope (composed of an outer membrane and an inner membrane). Within the chloroplast are stacked, disc-shaped structures called thylakoids. Embedded in the thylakoid membrane is chlorophyll, a pigment (molecule that absorbs light) responsible for the initial interaction between light and plant material, and numerous proteins that make up the ETC. The thylakoid membrane encloses an internal space called the thylakoid lumen. The stack of thylakoids is called a granum, and the liquid-filled space surrounding the granum is called stroma.

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11
Q

What is the proton and electron carrier in photosynthesis?

A

NADPH

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12
Q

What are the two parts of Photosynthesis?

A
  1. The light-dependent reactions, energy from sunlight is absorbed by chlorophyll and that energy is converted into stored chemical energy.
  2. Calvin Cycle, the chemical energy harvested during the light-dependent reactions drives the assembly of sugar molecules from carbon dioxide.
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12
Q

What is the light dependent reactions?

A

Occur in the Thylakoid membrane. Produce O2 from H2O. Produce NADPH from NADP+. Produce ATP. Needs light to produce energy.

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12
Q

What is the Calvin Cycle?

A

Occurs in the Stroma. Produce sugar (G3P) from CO2. Uses the ATP and NADPH from the Light-dependent reactions.

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13
Q

What is electromagnetic radiation?

A

A form of energy (solar energy)

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13
Q

What is the electromagnetic spectrum?

A

The range of wavelengths of electromagnetic radiation.

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14
Q

What is Light?

A

A type of electromagnetic radiation. Acts both particle-like and wave-like. As a particle, light exists in discrete packets called photons. As a wave, light can be characterized by its wavelength.

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15
Q

What is Visible light?

A

Electromagnetic radiation that humans can see.

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15
Q

Understanding Photons:

A

The energy of a photon of light is inversely proportional to its wavelength. Shorter wavelengths have higher energy photons than longer wavelengths. Photons may be absorbed, transmitted, or reflected when they strike an object.

15
Q

What are pigments?

A

Molecules that absorb only certain wavelengths of light.

16
Q

what are the 2 major pigments in plant leaves?

A
  1. The chlorophylls (chlorophyll a and chlorophyll b) . Absorb red and blue light. Reflect and transmit green light. This is why plants are green! Most effective at driving photosynthesis.
  2. The carotenoids. Absorb blue and green light. Reflect and transmit yellow, orange, and red light.
17
Q

What is the structure of chlorophyll?

A

A long hydrocarbon“tail”. Keeps the molecule embedded in the thylakoid membrane.
A “head” consisting of a large ring structure with a magnesium atom in the middle. Light is absorbed in the head.

18
Q

What is the role of car

A
19
Q

What is the role of Carotenoids and Other Accessory Pigments?

A

Are accessory pigments that absorb light. Pass the energy on to chlorophyll. Carotenoids absorb wavelengths of light not absorbed by chlorophyll. Important, because this extends the range of wavelengths that can plants can use to drive photosynthesis!

20
Q

What is the structure of Chloroplast?

A
  1. Surrounded by a double membrane - an inner and an outer membrane.
  2. Contains disc-like structures called thylakoids - form a 3rd membrane layer. Thylakoids are arranged in piles like stacks of pancakes that are known as grana (singular - granum).
    3.The membrane of each thylakoid contains green-colored pigments - chlorophylls that absorb light.
  3. Stroma - The fluid-filled space around the grana
  4. Thylakoid lumen - the space inside the thylakoid discs
21
Q

What is the proton & electron carrier in photosynthesis?

A

NADPH

22
Q

What are the 2 sets of reactions in photosynthesis?

A
  1. Light-dependent reactions
  2. Calvin cycle reactions
23
Q

What is the Light Dependent Reaction?

A

Occurs in the thylakoid membrane. Produces O2, NADPH, & ATP. Needs H2O, NADP+, & light energy.

24
Q

What is the Calvin Cycle?

A

Occurs in the Stroma. Produce sugar (G3P), ADP, Pi, & NADP+. Needs CO2, ATP, & NADPH from the Light-dependent reactions.
Does not need light.

25
Q

What is electromagnetic radiation?

A

A form of energy (solar energy).

26
Q

What is Light?

A

A type of electromagnetic radiation. Acts both particle-like and wave-like. As a particle, light exists in discrete packets called photons. As a wave, light can be characterized by its wavelength.

27
Q

What is the electromagnetic spectrum?

A

The range of wavelengths of electromagnetic radiation.

28
Q

What is visible light?

A

Electromagnetic radiation that humans can see. Each photon and wavelength has a specific amount of energy.

29
Q

The energy of a photon of light is inversely proportional to its wavelength:

A

Shorter wavelengths such as ultraviolet light have higher energy photons than longer wavelengths.

30
Q

What are pigments?

A

Molecules that absorb only certain wavelengths of light. Photons may be absorbed, transmitted, or reflected when they strike pigments.

31
Q

What are the 2 major pigments in leaves?

A
  1. The chlorophylls (chlorophyll a and chlorophyll b).Absorb red and blue light. Reflect and transmit green light. This is why plants are green!
  2. The carotenoids
    Absorb blue and green light.
    Reflect and transmit yellow, orange, and red light.Most effective at driving photosynthesis.
32
Q

Where are photosystems located?

A

Located in the thylakoid membrane and consist of two major elements:
1. An antenna complex (light harvesting complex)
2. A reaction center
Additionally, there are proteins that capture and process excited electrons

32
Q

What are photosystems?

A

Chlorophyll molecules work together in groups that form a complex called a photosystem

33
Q

What is the antenna complex?

A

Is composed of
Pigment molecules. When a red or blue photon strikes a pigment molecule in the antenna complex:The energy is absorbed and an electron excited
This begins the process of converting light energy into chemical energy.

This energy is passed to another chlorophyll molecule, exciting another electron; resonance.
Energy is transferred inside the antenna complex. Energy moves from one chlorophyll molecule to the next. Until it reaches the reaction center.

34
Q

What occurs when Electrons are excited when light energy strikes?

A

When a photon strikes chlorophyll. Its energy can be transferred to an electron in the chlorophyll head. The electron becomes excited—raised to a higher energy state.

35
Q

What is the reaction center?

A

Located at the center of the photosystem. Contains two chlorophyll molecules- called a special pair. When energy reaches the special pair: It is NOT transferred to other pigments. Instead, it will lose an electron when excited and pass it to the primary electron acceptor. This is how electromagnetic energy from sunlight is transformed to chemical energy

36
Q

What are the 2 photosystem in the light dependent reactions?

A

Photosystem II (PSII) Occurs before.
Photosystem I (PSI)

Each photosystem also replenishes its lost electrons from a different source

37
Q

What are the differences b/w Photosystem I & II.

A
  1. Different special pairs, named for the wavelength of light they absorb best:
    PSII- P680 PS1- P700
  2. Different primary electron acceptors:
    PSII - an organic molecule called pheophytin
    PSI - a chlorophyll called A0
38
Q

What are the steps of Light-Dependent Reaction?

A
  1. Photosystem II absorbs photons of light to energize electrons donated by a water molecule
  2. Electrons move from PSII to PSI through an electron transport chain (ETC)
  3. PSI electrons energized even more and continue through the ETC
  4. NADP+ serves as the final electron acceptor and is reduced to form NADPH
  5. An H+ ion gradient formed by the ETC is used to generate ATP via Chemiosmosis
39
Q
A

Biology (9 decks)

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