2.10 - Light & Photosynthesis

Question 1

Different types of electromagnetic radiation differs because of…

Answer 1

Their wavelengths (λ)

Question 2

Light with shorter wavelengths have more or less energy?
What visable light colours are they?

Answer 2

• They have more energy
• colours with shorter wavelengths are purple and blue

Question 3

True or False:
Each chlorophyll pigment has the same wavelength amount it can absorb?

Answer 3

False
- Each pigment has a specific wavelength of light that it’s best at absorbing energy from
- plants must have a variety of pigments

This is associated with the colour of the plant

Question 4

What is chlorophyll-a?

Answer 4

• It’s a type of chlorophyll that is used in the creation of sugar
• energy absorbed from other pigments must pass through this frst to form sugar

Question 5

What are accessory pigments?

Answer 5

When energy is transfered from pigment to pigment

Question 6

Why do we see the colour green on plants?

Answer 6

• we see the colour that the pigments can NOT absorb
• Ex) chlorophyll-a & -b mostly absorb red and violet light while reflecting green

Question 7

What colour would a pigment be if it could absorb ALL visable light?

Answer 7

Absorbs λ -> looks black
(reflects NO light)

Question 8

What colour would a pigment be if it could reflected all visable light?

Answer 8

Reflects λ -> looks white
(reflects ALL light)
Ex. prism

think Pink Floyd Darkside of the Moon album cover

Question 9

Fill in the blanks:
The shorter the wavelength, the [—–] the frequency, the [—–] energy carried

Answer 9

…the higher the frequency
…the more energy carried

Question 10

Fill in the blanks:
The higher the wavelength, the [—–] the frequency, the [—–] energy carried

Answer 10

…the lower the frequency
…the less energy carried

Question 11

What is photoexcitation?
How does it work?

also known as photo oxidation

Answer 11

• when pigments capture energy from light, going from a ground state to an exited state
• an electron can absorb the energy of the light & jump out of the atom as a high energy electron
• electrons can only absorb the energy if it has a specific quantity of energy
• YOU MUST hit the right pigment with the right w/the right wavelength to achive photoexcitation

Question 12

How many types of photoexcitation are there?
Name them.

Answer 12

There are 4 types.
- Thermal Dissipation
- Fluorescence
- Excitation Transfer
- Electron Transfer

Question 13

What is thermal dissipation?

photoexcitation

Answer 13

electron returns to ground state by releasing energy as heat

Question 14

What is fluorescence?

photoexcitation

Answer 14

electron returns to ground state by releasing energy as light

Question 15

What is excitation transfer?

photoexcitation

Answer 15

energy is transfered between neighbouring molecules

Question 16

What is electron transfer?

photoexcitation

Answer 16

• electron is transfered to an electron acceptor.
• og molecule loses the electron (oxidized)
• electron must be replaced by splitting H2O (O2 is a by-product)

Question 17

What are photosystems?

Answer 17

• teams/clusters of pigments working together as a whole so they can absorb the broadest possible spectrum of light
• chlorophyll-a is the most important b/c it’s assisted by accessory pigments (ie. chlorophyll-b & carotenoids)

Question 18

What is the absorbtion spectrum?

Answer 18

• how light absorbtion capacity is measured
• a typical plant absorbtion specturm is at it’s lowest in the middle due to the green wavelengths