Biochemistry Lab Techniques Quiz
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Questions and Answers

What is the formula for actual measurement when using a micrometer?

  • Actual measurement = Stage Micrometer ÷ Ocular Scale
  • Actual measurement = No. of divisions ÷ Calibration Constant
  • Actual measurement = Calibration Constant + No. of divisions
  • Actual measurement = Calibration Constant X No. of divisions (correct)

An ocular micrometer can only be used at 10X magnification.

False (B)

What is the purpose of placing the calibration slide on the stage?

To observe and align the ocular scale with the stage micrometer scale for calibration.

The reading in micrometers (µm) is obtained by multiplying the calibration constant with the number of ______ measured.

<p>divisions</p> Signup and view all the answers

Match the following components with their functions:

<p>Ocular Micrometer = Used for measuring the size of specimens Stage Micrometer = Provides a standard scale for calibration Calibration Constant = Factor used to convert ocular divisions to actual size Microscope = Instrument for viewing small objects</p> Signup and view all the answers

What is the purpose of heating the mixture at 80º C for 5-15 minutes?

<p>To develop a reddish brown color (A)</p> Signup and view all the answers

The absorbance of the solution is read at 675 nm.

<p>False (B)</p> Signup and view all the answers

What is the concentration of glucose in test tube S1?

<p>0.1 mg/ml</p> Signup and view all the answers

In test tube S2, the volume of D/W used is ______ ml.

<p>0.8</p> Signup and view all the answers

Which test tube contains the highest concentration of glucose?

<p>S3 (C)</p> Signup and view all the answers

Potassium sodium tartrate is included in the preparations at the same volume for all test tubes.

<p>True (A)</p> Signup and view all the answers

What is the initial step mentioned for preparing the test solutions?

<p>Fill the test tubes with reagents.</p> Signup and view all the answers

Match the test tubes with their respective concentrations of glucose:

<p>S1 = 0.1 mg/ml S2 = 0.2 mg/ml S3 = 0.3 mg/ml</p> Signup and view all the answers

What is the purpose of a photometer in a spectrophotometer?

<p>To measure the amount of light passing through the sample (B)</p> Signup and view all the answers

What is the primary function of chlorophyll in plants?

<p>To trap sunlight energy for photosynthesis (B)</p> Signup and view all the answers

A cuvette must be opaque on all sides to ensure accurate measurements.

<p>False (B)</p> Signup and view all the answers

Chlorophyll is predominantly found in the nucleus of the plant cell.

<p>False (B)</p> Signup and view all the answers

What law explains the relationship between absorbance and concentration in solutions?

<p>Beer-Lambert's law</p> Signup and view all the answers

In the equation A = εlc, 'l' represents the _____ of the sample.

<p>path length</p> Signup and view all the answers

What are the two main types of chlorophyll?

<p>Chlorophyll a and Chlorophyll b</p> Signup and view all the answers

Chlorophyll supplies the much-needed micronutrient __________.

<p>magnesium</p> Signup and view all the answers

Which component of a spectrophotometer determines the wavelength of light used?

<p>Monochromator (D)</p> Signup and view all the answers

How does chlorophyll enhance the absorption spectrum?

<p>Through different side groups in chlorophyll a and b (B)</p> Signup and view all the answers

What should a cuvette be cleaned with to ensure accurate spectroscopic readings?

<p>Distilled water and soft tissue paper</p> Signup and view all the answers

Match the components of a spectrophotometer with their functions:

<p>Light source = Generates light for the analysis Cuvette = Holds the sample Photometer = Measures light intensity Galvanometer = Displays the signal voltage</p> Signup and view all the answers

Match the chlorophyll type with its side chain composition:

<p>Chlorophyll a = -CH3 Chlorophyll b = CHO</p> Signup and view all the answers

Chlorophyll absorbs sunlight to synthesize carbohydrates from CO2 and _____.

<p>water</p> Signup and view all the answers

What is the E number for chlorophyll when registered as a food additive?

<p>E140</p> Signup and view all the answers

Which piece of equipment is used to measure the absorption of chlorophyll?

<p>Spectrophotometer (A)</p> Signup and view all the answers

How much standard glucose solution is added to test tube S4?

<p>0.4ml (C)</p> Signup and view all the answers

Distilled water is added to each test tube to make up the volume to 2ml.

<p>False (B)</p> Signup and view all the answers

What is added to test tube B?

<p>1ml of distilled water</p> Signup and view all the answers

In test tube S5, _______ ml of glucose solution is added.

<p>0.5</p> Signup and view all the answers

Match the test tubes with the amount of glucose solution added:

<p>S1 = 0.1ml S2 = 0.2ml S3 = 0.3ml S5 = 0.5ml</p> Signup and view all the answers

Which of the following test tubes contains a known solution?

<p>S5 (A), T1 (C)</p> Signup and view all the answers

Each test tube S1 to S5 has a different amount of glucose solution added.

<p>True (A)</p> Signup and view all the answers

What is the total volume in each test tube S1 to S5 after adding distilled water?

<p>1ml</p> Signup and view all the answers

What is the purpose of ninhydrin in the chromatography process described?

<p>To develop color for visualizing amino acids (D)</p> Signup and view all the answers

The mobile phase consists of N-Butanol, acetic acid, and distilled water in a ratio of 4:1:1.

<p>True (A)</p> Signup and view all the answers

What is the Rf value in chromatography?

<p>The ratio of the distance traveled by the substance to the distance traveled by the solvent front.</p> Signup and view all the answers

A 1% amino acid solution is prepared by dissolving ______ of amino acid in 1ml of 0.1 N Hydrochloric acid.

<p>10 mg</p> Signup and view all the answers

Match the following materials with their functions in the chromatography process:

<p>Chromatography chamber = Provides a sealed environment for solvent vapor Capillary tube = Allows for precise spotting of samples Ninhydrin = Develops colors for amino acids Whatmann paper = Serves as the stationary phase</p> Signup and view all the answers

What is the correct procedure for marking the spots of amino acids on the chromatography paper?

<p>Label them A1, A2, and U. (D)</p> Signup and view all the answers

The chromatography paper should be placed in the chamber with the origin line below the solvent level.

<p>False (B)</p> Signup and view all the answers

After spraying ninhydrin on the paper, the spots may be developed in an oven set at ______ degrees Celsius.

<p>50</p> Signup and view all the answers

Flashcards

Calibration constant

The number of divisions on the stage micrometer scale that correspond to one division on the ocular micrometer scale. It is a constant value for each objective lens.

Stage micrometer

A specialized slide with a precise scale etched on it, used to calibrate the ocular micrometer.

Ocular micrometer

A small, clear glass disc inserted into the eyepiece of a microscope, containing a graduated scale for measuring objects.

Points of coincidence

The points where the divisions of the stage micrometer and ocular micrometer align perfectly.

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Calibration of the ocular micrometer

The process of determining the calibration constant by aligning the stage micrometer scale with the ocular micrometer scale.

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Spectrophotometer

A device that measures the amount of light that passes through a sample. The light is first passed through a wavelength selection device (monochromator or filter) to choose the specific wavelength of light to be used.

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Absorbance

The amount of light that is absorbed by a sample, expressed as the ratio of the intensity of the incident light to the intensity of the transmitted light.

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Cuvette

A small tube made of quartz used to hold samples for spectroscopic experiments. It allows a single beam of light to pass through the sample.

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Beer-Lambert Law

A law that states that the absorbance of a solution is directly proportional to the concentration of the absorbing species and the path length of the light beam through the solution.

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Molar Absorptivity (ε)

The ability of a substance to absorb light at a particular wavelength. It is a measure of how strongly a substance absorbs light.

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Path Length (l)

The distance that the light beam travels through the sample.

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Chlorophyll

The pigment responsible for absorbing light energy during photosynthesis.

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Photosynthesis

The process by which plants use light energy to synthesize carbohydrates from carbon dioxide and water.

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Reagent

A specific solution used in a laboratory test or experiment.

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Distilled water (D/W)

A colorless liquid used to dilute solutions or adjust their concentrations.

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DNSA

A solution of a chemical that absorbs light at a specific wavelength.

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Potassium sodium tartrate

A chemical used to create a reddish-brown color in a reaction.

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Heat the mixture at 80º C for 5-15 minutes

The process of heating a solution to initiate a chemical reaction and develop color.

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Cool the solutions to room temperature

The process of allowing a solution to cool to room temperature, after heating.

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What is chlorophyll?

Chlorophyll is a pigment found in chloroplasts that absorbs light energy, primarily in the visible spectrum, for photosynthesis. It contains a porphyrin ring with a central magnesium atom.

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What are the two main types of chlorophyll?

Chlorophyll a and chlorophyll b are the two main types of chlorophyll. Both types are very effective photoreceptors due to their alternating single and double bonds which allow for delocalization of electrons, increasing stability and absorption of light.

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How does the structure of chlorophyll affect its absorption spectrum?

The slight structural differences between chlorophyll a and b result in different absorption spectra. Chlorophyll a absorbs mainly red and blue light, while chlorophyll b absorbs mainly blue and orange light. This creates a wider range of light absorption for photosynthesis.

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What are some applications of chlorophyll?

Chlorophyll is registered as a food additive and colorant with the E number E140. It is also a valuable source of magnesium, a micronutrient.

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How is chlorophyll extracted?

The process of extracting chlorophyll involves grinding leaves, adding acetone (a solvent) to extract the pigment, centrifuging the mixture to separate the chlorophyll, and measuring the absorption using a spectrophotometer.

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How is the absorption spectrum of chlorophyll determined?

The absorption spectrum of chlorophyll can be measured using a spectrophotometer, which shines light through a solution containing chlorophyll and measures the amount of light that passes through. This provides information about the wavelengths of light absorbed by chlorophyll.

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What is the role of chlorophyll in photosynthesis?

Chlorophyll plays a crucial role in photosynthesis by capturing light energy and converting it into chemical energy stored in glucose. This process is essential for plant growth and survival.

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What are some health benefits of chlorophyll?

Chlorophyll is a powerful antioxidant and anti-carcinogenic agent, helping to protect cells from damage caused by free radicals. It can also support detoxification processes, reduce the risk of kidney stones, and minimize chemotherapy side effects.

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Standard Glucose Solution

A solution with a known concentration of a substance. It is used in experiments to calibrate instruments and compare results.

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Test Tubes

A tube used for conducting experiments, especially in the laboratory. In this context they are used to prepare solutions for calibrating the ocular micrometer.

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Distilled Water

A colorless and odorless liquid that is very important in several scientific procedures, such as calibrating, dissolving and cleaning.

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Chromatogram

A visual representation of the separation of components in a mixture by chromatography, showing distinct bands or spots corresponding to different substances.

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Ninhydrin reaction

A chemical reaction where the amino group of an amino acid reacts with ninhydrin, producing a purple-colored compound called Ruhemann's purple. This reaction is used to detect amino acids on a chromatogram.

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Chromatography

A technique used to separate and identify components of a mixture based on their different affinities for a stationary phase and a mobile phase.

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Rf value

The distance traveled by the analyte (amino acid) from the origin line to the center of its spot on a chromatogram, divided by the total distance traveled by the solvent front.

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Mobile phase

A solution that is used to move the analytes up the chromatography paper in a chromatographic separation.

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Stationary phase

The material that is stationary on the chromatography paper, such as filter paper, and interacts with the analytes to cause their separation.

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Origin line

The starting point on the chromatography paper where the samples are applied.

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Solvent front

The point on the chromatogram where the mobile phase has traveled the furthest.

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Study Notes

Laboratory Manual for Biology Laboratory BIO F110

  • This manual provides details for laboratory activities in a biology course.
  • It includes exercises that require basic biology knowledge and skill.
  • The manual offers detailed recipes for preparing solutions.
  • Students are encouraged to work independently and in small groups.

General Laboratory Instructions

  • The laboratory exercises aim to teach techniques and measurements in biology.
  • Each session is two hours long.
  • Students must complete the experiment on time.
  • Students must bring a journal, lab coat, stationary, and calculators.
  • Students must report any breakage to the instructor promptly.
  • Results must be presented neatly in the journal.

Experiment 1: Microscopy and Identification of the Specimen Slide

  • Objective: Study the microscope parts and their uses, and identify specimen slide characteristics.
  • Theory: Microscopes are optical instruments used to view microorganisms and their structures.
  • Principle: Magnification, resolving power (ability to distinguish between points), and contrast are key to microscopy.
  • Materials: Microscope, specimen slides.
  • Procedure: Sit, switch on the light source. Adjust light and focus with rheostat/iris diaphragm lever. Focus on a slide; describe the characteristics using 4X, 10X, 40X, 100X objective lenses and oil immersion, if needed.

Experiment 2: Stomata Density

  • Objective: Observe and compare stomata (pores on leaves), study structure in different plants.
  • Theory: Stomata are pores in leaves with guard cells, regulating gas exchange.
  • Principle: Stomata density is the numbers per square millimeter of leaf.
  • Materials: Leaves (monocot and dicot), scalpel, microscope, glass slides/cover slip, water.
  • Procedure: Tear a leaf to expose the lower epidermis. Mount on slide to observe. Count stomata from multiple fields. Calculate average per field and then total stomata per mm².

Experiment 3: Calculation of Mitotic Index

  • Objective: Prepare onion root squash for mitosis study and determine mitotic/interphase ratio.
  • Theory: Mitosis is a stage in cell division, important for growth and cell repair.
  • Materials: Onion bulbs, 10% HCl, microscope slides, cover slips, staining solution.
  • Procedure: Cut root tips. Treat tips with HCl to stimulate cell division. Stain tips and observe various mitotic stages on a slide. Calculate the proportion of dividing cells.

Experiment 4: Micrometry

  • Objective: Calculate the calibration constant of ocular micrometer scale and calibrate measurements of microscopic objects.
  • Materials: Microscope, ocular and stage micrometers, slides/specimens.
  • Procedure: Place calibration slides. Calibrate the ocular scale against a known stage scale. Calculate calibration constant using the formula: (no. of ocular divisions/no. of stage micrometer divisions).

Experiment 5: Total White Blood Cell Count

  • Objective: Learn about WBC counting chambers.
  • Theory: WBCs play a crucial role in immune response.
  • Materials: WBC sample, Thoma pipette, Neubauer hemocytometer, diluted Methylene Blue, microscope.
  • Procedure: Dilute blood. Prepare a blood smear. Count the WBCs in the ruled counting chamber grid of a hemocytometer.

Experiment 6: Counting of Red Blood Cells

  • Objective: Understand red blood cell counting chamber techniques.
  • Theory: Red blood cells transport oxygen.
  • Materials: Blood sample, Hayem's solution, Thoma pipette, Neubauer hemocytometer, microscope.
  • Procedure: Mix blood with Hayem's solution, and distribute the mixture to the chamber grids. Observe, count under microscope. Calculate the ratio and number of RBCs per µL.

Experiment 7: Determination of Blood Group by Slide Agglutination Test

  • Objective: Determine blood types (A, B, O, AB).
  • Theory: Antibodies and antigens determine blood types, crucial in blood transfusions.
  • Materials: Blood sample, antisera (A, B, D), glass slides.
  • Procedure: Mix blood with antisera on the slides; if agglutination (clumping) occurs, a blood group is identified.

Experiment 8: Quantitative Estimation of Chlorophyll

  • Objective: Understand spectrophotometer and quantify chlorophyll.
  • Theory: Chlorophyll is a pigment essential for photosynthesis.
  • Materials: Leaves, acetone, mortar and pestle, spectrophotometer, and cuvette.
  • Procedure: Extract chlorophyll from leaves. Use a spectrophotometer to measure chlorophyll concentrations.

Experiment 9: Quantitative Estimation of Protein by Biuret Method

  • Objective: Measure protein concentration using a spectrophotometer and the Biuret method.
  • Theory: The Biuret method measures protein concentration based on color change.
  • Materials: Protein sample, Biuret reagent, spectrophotometer, test tubes.
  • Procedure: Prepare protein solutions and dilutions, add reagent to all solutions, and determine the unknown sample concentration using a standard curve.

Experiment 10: Quantitative Estimation of Glucose by DNSA Method

  • Objective: Quantitatively determine glucose concentration using a spectrophotometer.
  • Theory: Glucose is a primary energy source, with the DNSA method revealing its concentration.
  • Materials: Glucose sample, DNSA reagent, spectrophotometer, test tubes.
  • Procedure: Prepare known and unknown glucose solutions; measure absorbance of each solution at a specific wavelength for a standard curve analysis.

Experiment 11: Qualitative Analysis of Different Plant Pigments

  • Objective: Analyze plant pigments via paper chromatography.
  • Theory: Different plant pigments create various colors.
  • Materials: Leaves, acetone, chromatography paper, chamber, pencil, solvent (e.g., petroleum ether/acetone).
  • Procedure: Extract pigments, apply to paper, develop it in a chamber, measure traveled distances to determine Rf values for each pigment.

Experiment 12: Isolation and Quantitation of Eukaryotic Genomic DNA

  • Objective: Isolate and estimate DNA concentration.
  • Theory: DNA is genetic material, essential for life processes.
  • Materials: Banana, SDS, NaCl, sodium citrate, EDTA, ethanol, centrifuge.
  • Procedure: Homogenize tissue, extract DNA, precipitate DNA with ethanol, then purify and determine concentration.

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Biology Laboratory Manual BIO F110 PDF 2024-2025

Description

Test your knowledge on various biochemistry lab techniques and concepts related to measurements, micrometers, and spectrophotometry. This quiz covers calibration, absorbance readings, and the preparation of test solutions involving glucose concentrations. Perfect for students studying laboratory methods in biochemistry.

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