GLT 313 – BIO. AND CHEM. INSTRUMENTATION OSUNTECHCOLLEGE 2023/2024 First Semester Examination

ANWSER

Question 1:

(a) Define microscope and microscopy

• A microscope is an optical instrument used to magnify small objects, allowing them to be seen in detail.
• Microscopy is the science of using microscopes to view objects that are too small to be seen by the naked eye.

(b) Draw a well-labelled diagram of a compound microscope
(Diagram should be drawn showing key parts: eyepiece, objective lens, stage, coarse and fine adjustment knobs, diaphragm, and light source.)

(c) State the uses of the following in a microscope:

• Eyepiece: Magnifies the image formed by the objective lens.
• Fine adjustable knobs: Used for precise focusing to get a sharp image.
• Diaphragm: Regulates the amount of light entering the microscope.
• Coarse adjustable knobs: Moves the stage up and down for initial focusing.
• Stage clip: Holds the slide in place on the stage.

Question 2:

(a) Highlight any three types of a named machine used in separating biological fluids.

1. Centrifuge – Separates fluids based on density using centrifugal force.
2. Dialysis Machine – Used for filtering waste from blood in patients with kidney failure.
3. Chromatography Machine – Separates components of biological mixtures based on solubility.

(b) Determine the differences between physical and chemical methods of sterilization.

(c) Separating biological fluid is subjected to a force, name the force and its dynamic operational procedure.

• Force: Centrifugal Force
• Operational Procedure: A centrifuge spins biological samples at high speed, creating a force that separates components based on density (e.g., blood separation into plasma and cells).

Question 3:

(a) Define the term “colorimetry”.

• Colorimetry is the science of measuring the absorption of light at a specific wavelength by a colored solution to determine the concentration of a substance.

(b) Mention four (4) uses of a colorimeter.

1. Determining concentration of colored solutions.
2. Measuring enzyme activity in biochemical analysis.
3. Water and food quality testing.
4. Clinical diagnostics, e.g., hemoglobin measurement.

(c)(i) State three (3) advantages and three (3) disadvantages of a colorimeter.
Advantages:

1. Simple and easy to use.
2. Provides quick and accurate results.
3. Cost-effective compared to spectrophotometers.

Disadvantages:

1. Limited to colored solutions.
2. Less sensitive than advanced spectrophotometers.
3. Cannot measure absorbance in ultraviolet or infrared ranges.

(c)(ii) Mention two types of colorimeter.

1. Visual Colorimeter
2. Photoelectric Colorimeter

Question 4:

(a) Describe the six (6) basic principles of UV spectroscopy.

1. Absorption of UV Light: Molecules absorb UV radiation, causing electronic transitions.
2. Beer-Lambert’s Law: Absorbance is proportional to the concentration of the sample.
3. Energy Transitions: Electrons move between energy levels when exposed to UV light.
4. Wavelength Dependency: Different compounds absorb light at specific wavelengths.
5. Calibration and Standardization: Instruments must be calibrated using known standards.
6. Quantitative and Qualitative Analysis: Used to determine concentration and structure of compounds.

(b) Mention at least five (5) factors affecting the intensity of flame emission spectroscopy.

1. Temperature of the flame.
2. Type of solvent used.
3. Concentration of the sample.
4. Presence of interfering substances.
5. Nature of the excitation source.

(c) List two (2) advantages of spectrophotometry.

1. Highly accurate for quantitative analysis.
2. Can analyze a wide range of samples, including UV-visible spectra.

Question 5:

Outline the five (5) processes of calibrating a pH meter.

1. Turn on the pH meter and allow it to warm up.
2. Rinse the electrode with distilled water and dry it.
3. Immerse the electrode in a standard buffer solution (e.g., pH 7.0).
4. Adjust the meter to read the correct pH of the buffer.
5. Repeat with additional buffers (e.g., pH 4.0 and 10.0) to ensure accuracy.

(a) Briefly define “Camera Lucida”.

• A Camera Lucida is an optical device that allows the user to superimpose an image of an object onto a drawing surface for accurate sketching.

(b) Enumerate the functions of Camera Lucida.

1. Helps in detailed scientific drawing.
2. Assists in scaling and proportion accuracy.
3. Used in biological and medical illustrations.
4. Facilitates accurate replication of microscopic observations.

(c)(i) List six (6) areas of application of Camera Lucida.

1. Scientific research.
2. Medical illustrations.
3. Forensic sketching.
4. Paleontology.
5. Microscopy observations.
6. Fine arts and architecture.

(c)(ii) Explain “Optics of Wollaston’s Camera Lucida”.

• Wollaston’s Camera Lucida uses a prism to reflect an image onto a surface, enabling the user to trace it while viewing both the object and the drawing simultaneously.

Question 6:

(a) Write a short note on autoclave.

• An autoclave is a device that uses high-pressure steam at high temperatures to sterilize equipment, media, and waste materials in laboratories and medical facilities.

(c) Explain the principle of operation of an autoclave.

• An autoclave works on the principle of steam sterilization. Steam under high pressure (121°C at 15 psi for 15-20 minutes) penetrates materials, killing bacteria, viruses, and spores by coagulating their proteins.

(d) List five (5) precautions for effective use of an autoclave.

1. Do not overload the chamber.
2. Ensure proper sealing of the door before operation.
3. Use appropriate sterilization cycles for different materials.
4. Allow proper cooling before opening to avoid burns.
5. Regularly maintain and validate performance.

Question 7:

(a) How does a manual colony counter work?

• A manual colony counter uses a magnifying lens and light source to help a microbiologist visually count bacterial colonies on agar plates.

(b) What are the pros of an automated colony counter?

1. Faster and more accurate counting.
2. Reduces human error and fatigue.
3. Provides digital records for documentation.

(c) Elucidate the mechanism of operation of autoradiography.

• Autoradiography detects radioactive isotopes in biological samples. A photographic film is placed over the sample, where radioactive emissions expose the film, creating an image of molecular distributions.

(d) What are the shortfalls of autoradiography?

1. Requires handling of radioactive substances.
2. Time-consuming exposure and development process.
3. Limited sensitivity compared to modern imaging techniques.