BIOC*4520: Metabolic Process Lec 5

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Questions and Answers

What is the relationship between energy and wavelength for photons?

Energy increases with decreasing wavelength. (correct)

Energy is directly proportional to wavelength.

Energy is independent of wavelength.

Energy is inversely proportional to wavelength. (correct)

Using the formula $E = h.c / \lambda$, what happens to the energy of a photon as its wavelength increases?

The energy increases steadily.

The energy decreases. (correct)

The energy becomes negative.

The energy remains constant.

If a photon has a wavelength of 400 nm, what is its energy in kJ?

293 kJ (correct)

400 kJ

169 kJ

200 kJ

Which equation represents the relationship between energy, frequency, and Planck’s constant?

E = h.ν Signup and view all the answers

Autotrophs use as their carbon source, while heterotrophs use .

CO2, heterotrophs rely on organic carbon Signup and view all the answers

what is the answer to this Light energy is harnessed through , while chemical energy is harnessed through of organic/inorganic substances.

through photosynthesis, through oxidation Signup and view all the answers

briefly describe the Experiment Joseph Priestly carried out to show that plants release oxygen into the atmosphere

Joseph Priestley placed a candle and a mouse in a sealed jar, and both ran out of air. When he added a plant, the air was "restored," allowing the candle to relight and the mouse to survive. This showed that plants release oxygen. Signup and view all the answers

which three organisms obtain energy from sunlight

plants, green bacteria and cyanobacteria Signup and view all the answers

why do photosynthetic organisms avoid back reactions?

By avoiding back reactions, photosynthetic organisms maintain the high efficiency needed to sustain themselves in environments where energy might be limited. Signup and view all the answers

What does the annual CO₂ fixation rate of approximately 7 x 10¹⁴ kg suggest in terms of atmospheric turnover?

Atmospheric turnover happens in a few hundred years. Signup and view all the answers

How does the annual O₂ release rate of approximately 5.1 x 10¹⁴ kg relate to atmospheric oxygen turnover?

It implies turnover occurs in approximately 2000 years. Signup and view all the answers

Which of the following best explains the relationship between CO₂ fixation and climate change?

The slow turnover rate of CO₂ fixation contributes to the ongoing impact of climate change. Signup and view all the answers

define photosynthesis

series of processes in which electromagnetic energy is converted to chemical free energy Signup and view all the answers

what happens to an atom at ground state after absorbing energy

after absorbing energy at the specific wavelength to the atom, it gets excited and moves into its excited state Signup and view all the answers

what are the three pigments found in the thylakoid of the chloroplast

chlorophyll a Signup and view all the answers

all the 3 pigments absorb light in blue and red regions

False Signup and view all the answers

(accessory)Chlorophyll b shows the highest absorption in which region of the light spectrum?

blue Signup and view all the answers

Why do the pigments not absorb in the green light?

chlorophyll a and chlorophyll b absorb light in the blue and red regions but reflect light in the green region because plants are green themselves Signup and view all the answers

what is the primary pigment and what are the accessory pigments

<h1>chlorophyll a = primary chlorophyll b = accessory carotenoids = accessory</h1> Signup and view all the answers

what are the main backbones of the chlorophyll pigments

<ul> <li>the Mg+ cation that is coordinated with 4N</li> <li>polyene structure</li> </ul> Signup and view all the answers

what does the polyene structure in the chlorophyll pigments do

it has alternating single and double bonds which results in strong absorption of light Signup and view all the answers

although chlorophyll a and b have similar backbones they differ in functional groups. match the functional group with the backbone.

<h1>-ch3 = chlorophyll a -cho (ald) = chlorophyll b</h1> = Signup and view all the answers

what color does chlorophyll fluoresce when it absorbs high energy light (when illuminated with uv light)

it gives off the color red as it emits wavelengths of lower energy (wavelength is much longer than the uv absorbed) Signup and view all the answers

describe the role of the accessory pigments in relation to the reaction center

the reaction center is bundled up with the accessory pigment surrounding it. these accessory pigments absorb light energy and get excited which then transfers the energy to the reaction center containing chlorophyll a pigment Signup and view all the answers

whats the condition for fret to occur

there should be an overlap between the wavelength absorption spectrums for the donor and the acceptor. Molecules need to be physically close < 3 nm Signup and view all the answers

energy level of Chlb has to be higher than that of Chla so that transfer of energy can take place

True Signup and view all the answers

briefly define the role of the rxn centre

It is where light energy is converted into chemical energy Signup and view all the answers

whats the name of the complex formed by carotenoids and chlorophylls

antenna complexes Signup and view all the answers

Study Notes

Light and Photons

Light is composed of waves and particles called photons.
Photons are units of energy, also known as light quanta.
The energy of a photon is directly proportional to its frequency (ν) and inversely proportional to its wavelength (λ).
The relationship between energy (E), frequency (ν), wavelength (λ), and Planck's constant (h) is given by:
- E = hν
- λν = c (where c is the velocity of light in a vacuum)
- E = hc/λ
The energy of a photon is directly proportional to its frequency: E ∝ 1/λ.
This means that higher frequency photons have more energy.

Energy Content of Photons

The energy content of photons is measured in quanta.
A mole of quanta with a wavelength of 700 nm has an energy of 169 kJ.
A mole of quanta with a wavelength of 400 nm has an energy of 293 kJ.

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