# Protein Engineering Questions and Answers – Structural Study – X-ray Crystallography – 1

This set of Protein Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Structural Study – X-ray Crystallography – 1”.

1. What does the interaction of electromagnetic radiation with matter cause the electrons to do?
a) Turn into proton
c) Move forward
d) Oscillate

Explanation: When electromagnetic radiation interacts with matter, it causes the electrons to oscillate. They neither degrade, move forward, or turn into a proton.

2. What does the superposition of waves give rise to?
a) Destructive interference
b) Constructive interference
c) Diffraction
d) Interference

Explanation: The accelerated electrons which have interacted with electromagnetic radiation emit radiations of the same frequency as the incident radiation. These radiations are called secondary waves. The superposition of these waves gives rise to interference.

3. Which of the following is a form of high energy electromagnetic radiation?
a) UV rays
b) Visible rays
c) Infrared rays
d) X – rays

Explanation: X – rays are a form of high energy electromagnetic radiation. UV rays, visible rays, and infrared rays are also electromagnetic radiations but of comparatively lower energy. Different parts of the X-ray spectrum are used in different applications.

4. Find the odd one out.
a) Cathode rays
b) Beta – rays
c) Alpha – rays
d) X – rays

Explanation: X – rays are electromagnetic radiations. Cathode rays, beta – rays, and alpha – rays do not belong to the electromagnetic radiation category. Hence, X – rays is the odd one out.

5. What is the wavelength range of X – rays?
a) 1 pm to 10 nm
b) 100 pm to 1 nm
c) 1 pm to 1 nm
d) 10 pm to 10 nm

Explanation: The wavelength range of X – rays is 10 pm to 10 nm. They have energies in the range of 100 eV to 200 keV. The wavelength of X – rays are shorter than those of UV rays and typically longer than those of gamma rays.

6. Which of the following radiation is also referred to as Rontgen radiation?
a) Alpha – radiation
b) Beta – radiation
d) X – radiation

Explanation: X – radiation is also referred to as Rontgen radiation. It was named after the German scientist Wilhelm Rontgen. X – radiation has a wavelength range of 10 pm to 10 nm.

7. Who discovered X – rays?
a) Paul Villard
b) J. J. Thompson
c) Ernest Rutherford
d) Wilhelm Rontgen

Explanation: Wilhelm Rontgen discovered X – rays. Hence, it is also known as Rontgen radiation. Paul Villard discovered gamma radiation. Ernest Rutherford discovered beta – radiation. J. J. Thompson first demonstrated cathode rays.

8. Which of the following radiations carry enough energy to ionize atoms and disrupt molecular bonds?
d) X – rays

Explanation: X – rays carry enough energy to ionize atoms and disrupt molecular bonds. Thus, it belongs to the category of ionizing radiation. These radiations are harmful to living tissue.

9. Which of the following rays can be utilized in cancer treatment to kill malignant cells?
a) Visible rays
b) Infrared rays
c) Gamma rays
d) X – rays

Explanation: X – ray scan be utilized in cancer treatment to kill malignant cells. This is known as radiation therapy. Visible rays, infrared rays, and gamma rays cannot be utilized in cancer treatment to kill malignant cells.

10. X – rays have a much shorter wavelength than visible light, which makes it possible to probe structures much smaller than that can be seen using a normal microscope.
a) False
b) True

Explanation: The above statement is true. X – rays have a much shorter wavelength than visible light, which makes it possible to probe structures much smaller than that can be seen using a normal microscope. This property is used in X-ray crystallography to determine the positions of atoms in crystals.

11. Find the odd one out.
a) Fluoroscopy
b) Computed Tomography
d) Immunotherapy

Explanation: Fluoroscopy, computed tomography, and radiotherapy are techniques that utilize X – rays. Immunotherapy has no relation to X – rays, hence, Immunotherapy is the odd one out.

12. Which of the following technique is used to investigate the molecular structure through the growth of solid crystals?
b) Fluoroscopy
c) Computed Tomography
d) X – ray crystallography

Explanation: X – ray crystallography is used to investigate the molecular structure through the growth of solid crystals. Radiotherapy, fluoroscopy, and computed tomography have no role in the investigation of molecular structure.

13. Which of the following technique can be used to determine the three-dimensional structure of proteins?
b) Liquid chromatography
c) Mass spectrometry
d) X – ray crystallography

Explanation: X-ray crystallography can be used to determine the three-dimensional structure of proteins. Radioimmunoassay, liquid chromatography, and mass spectrometry cannot be used to determine the three-dimensional structure of proteins.

14. Which of the following is known as maximum reinforcement in the superposition of waves?
a) Maximum interference
b) Interference
c) Destructive interference
d) Constructive interference

Explanation: Constructive interference is known as maximum reinforcement in the superposition of waves. Depending upon the displacement (phase difference) between two waves, the amplitudes either reinforce or cancel out each other.

15. Which of the following is true for destructive interference?
a) The phase difference of 0°
b) The phase difference of 360°
c) The phase difference of 90°
d) The phase difference of 180°

Explanation: When the phase difference between the two interfering waves is 180° it results in destructive interference. Phase differences between 0°, 360°, and 90° do not result in destructive interference.

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