Q: If a cytochrome absorbs maximally at 420 nm, what is the energy of the absorbed photon? (Use $$h = 6.626 \times 10$$^{-34}$$ \, \text{J} \cdot \text{s}$$, $$c = 3.00 \times 10^8$ \, \text{m/s})$$

$$E = 4.74 \times 10$$^{-19}$$ \, \text{J}$$

Question 1

A mode of light is called a(n):

Accepted Answer

Einstein

Question 2

A characteristic absorbance in the 400 nm range displayed by molecules like cytochromes and photosystems is called:

Accepted Answer

Soret band

Question 3

Which equation correctly relates the energy of a photon to its frequency?

Accepted Answer

$$E = h \, 
u$$

Question 4

If a cytochrome absorbs maximally at 420 nm, what is the energy of the absorbed photon? (Use $$h = 6.626 	imes 10$$^{-34}$$ \, 	ext{J} \cdot 	ext{s}$$, $$c = 3.00 	imes 10^8$ \, 	ext{m/s})$$

Accepted Answer

$$E = 4.74 	imes 10$$^{-19}$$ \, 	ext{J}$$

Question 5

Which of the following best describes the Soret band?

Accepted Answer

A sharp absorption peak in the blue-violet region

Question 6

Which scientist's name is associated with the quantum of light energy?

Accepted Answer

Einstein

Question 7

If a pigment has an absorption maximum at 400 nm, what color of light does it most likely absorb?

Accepted Answer

Violet

Question 8

Which of the following is NOT a typical feature of the Soret band?

Accepted Answer

It is a broad absorption in the infrared region

Question 9

Which formula would you use to calculate the wavelength of light if you know its energy?

Accepted Answer

$$\lambda = \frac{hc}{E}$$

Question 10

A student claims that the Soret band is found at 700 nm. How would you respond?

Accepted Answer

Incorrect, the Soret band is typically found near 400 nm.

Question 11

Which of the following statements about photons is TRUE?

Accepted Answer

Photons are quanta of electromagnetic energy.

Question 12

Which property of light is most directly related to its energy?

Accepted Answer

Frequency

Question 13

A pigment absorbs light at 400 nm and emits at 700 nm. What process is this an example of?

Accepted Answer

Fluorescence

Question 14

Which of the following best explains why the Soret band is important in biochemistry?

Accepted Answer

It allows for the identification of porphyrin-containing proteins.

Question 15

If the energy of a photon is doubled, what happens to its wavelength?

Accepted Answer

It is halved.

Study Notes: Photophosphorylation and Light Absorption in Biochemistry

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