BIO 206 Past Questions and Answers

Welcome to Studentsdash Study BIO 206 Past Questions and Answers

Table of Contents

SOLUTIONS TO 2021

SECTION A

1a. What is a microtome?
A microtome is an instrument used to cut thin sections of tissue specimens for microscopic examination. It allows for the precise slicing of samples, enabling the study of cellular structures.

1b. Describe the different types of microtome.

Rotary Microtome: It has a rotating arm that holds the specimen. It’s commonly used for paraffin-embedded tissues.
Cryostat Microtome: Used for cutting frozen tissue sections. It maintains low temperatures to preserve the sample.
Ultramicrotome: Designed for slicing very thin sections for electron microscopy. It uses glass or diamond knives.
Sliding Microtome: The specimen moves back and forth in a fixed blade, often used for larger samples.

2. Describe the different techniques of data presentation, stating the advantages and disadvantages.

Tables:

Advantages: Easy to read; allows for comparison of data.
Disadvantages: Can become cluttered with too much data.

Graphs (Bar and Line):

Advantages: Visual representation makes trends easy to identify.
Disadvantages: Misleading if scales are manipulated.

Charts:

Advantages: Good for summarizing information and showing proportions.
Disadvantages: Can oversimplify data.

SECTION B

3a. Define the term “Spectrophotometry.”
Spectrophotometry is a quantitative analytical method used to measure the amount of light absorbed by a sample at a specific wavelength. It is widely used in chemistry and biology to determine the concentration of solutes.

3b. State sequentially the procedure for operating a spectrophotometer using an unknown sample.

Turn on the spectrophotometer and allow it to warm up.
Set the desired wavelength for measurement based on the sample characteristics.
Prepare a blank solution (usually the solvent used) and place it in the sample holder to calibrate the instrument.
Set the instrument to zero absorbance using the blank.
Prepare the unknown sample and place it in the sample holder.
Record the absorbance reading.
Use the absorbance to calculate the concentration of the unknown sample using Beer’s Law.

3c. A researcher was to determine the level of Lead (Pb) in Talinum triangulare planted samples collected at different locations. Using Y = 0.32x – 0.02, calculate the concentrations of Lead (Pb) in the samples.
Given the absorbance values:

Sample 1: 0.31
Sample 2: 0.24
Sample 3: 0.05
Sample 4: 0.18 Using the formula ( Y = 0.32x – 0.02 ):
For Sample 1:
( 0.31 = 0.32x – 0.02 )
( 0.33 = 0.32x )
( x = \frac{0.33}{0.32} \approx 1.03 \, \text{mg/L} )
For Sample 2:
( 0.24 = 0.32x – 0.02 )
( 0.26 = 0.32x )
( x = \frac{0.26}{0.32} \approx 0.81 \, \text{mg/L} )
For Sample 3:
( 0.05 = 0.32x – 0.02 )
( 0.07 = 0.32x )
( x = \frac{0.07}{0.32} \approx 0.22 \, \text{mg/L} )
For Sample 4:
( 0.18 = 0.32x – 0.02 )
( 0.20 = 0.32x )
( x = \frac{0.20}{0.32} \approx 0.63 \, \text{mg/L} )

Concentration results:

Sample 1: 1.03 mg/L
Sample 2: 0.81 mg/L
Sample 3: 0.22 mg/L
Sample 4: 0.63 mg/L

4a. What is microscopy?
Microscopy is the science of using microscopes to view samples and objects that cannot be seen with the naked eye. It allows for the magnification and detailed observation of small specimens.

4b. State sequentially and describe briefly the procedure for a permanent slide preparation.

Selection of Specimen: Choose a small piece of tissue or sample.
Fixation: Use a fixative (like formalin) to preserve the specimen.
Embedding: Place the fixed sample in a medium (like paraffin wax) to provide support.
Sectioning: Cut thin slices of the embedded specimen using a microtome.
Mounting: Place the slices on glass slides and add a mounting medium.
Cover Slip: Apply a cover slip over the sample to protect it and facilitate viewing.

SECTION C

5a. What is a herbarium?
A herbarium is a collection of preserved plant specimens used for scientific study. It serves as a reference for plant identification and classification.

5b. Outline the needs for having a herbarium in Ebonyi State University.

Biodiversity Research: Support research on local flora and promote understanding of plant diversity.
Education: Serve as a learning resource for students studying botany and related fields.
Conservation: Help in documenting and conserving endangered plant species.
Cultural Significance: Preserve the knowledge of traditional uses of plants in local communities.

5c. Discuss how to write a final report to accompany the collected specimens.

Title Page: Include the title, your name, date, and institution.
Introduction: Briefly explain the purpose of the collection and study.
Materials and Methods: Describe how specimens were collected and prepared.
Results: Present the findings, including any data, photographs, or observations.
Discussion: Analyze the significance of the results and compare with existing literature.
Conclusion: Summarize key findings and suggest areas for future research.
References: List any literature or sources cited in the report.

6. Define the following terms:
(i) Specimen Preservation: The process of protecting biological specimens from decay or deterioration, often using preservatives like formaldehyde or ethanol to maintain their physical and chemical properties for future study.
(ii) Chromatography: A laboratory technique for separating mixtures into their individual components. It involves passing a mixture through a medium where the components travel at different rates, allowing for their separation and analysis.

SOLUTION TO 2022 Question paper

Question 1a: Define the term ‘Microscopy’.

Microscopy refers to the use of microscopes to view objects that are too small to be seen by the naked eye. It allows for the magnification of minute structures, including cells and microorganisms, enabling detailed observation and study.

Question 1b: State in a stepwise manner, the steps in operating a modern microscope.

Place the microscope on a stable surface and plug it into a power source if it is an electric microscope.
Turn on the light source (if using a light microscope) by adjusting the light intensity to suit your vision.
Prepare the slide with the specimen to be viewed and place it on the stage.
Secure the slide using the stage clips to keep it in place.
Select the lowest magnification objective lens (e.g., 4x or 10x).
Adjust the coarse focus knob to bring the specimen into view.
Fine-tune using the fine adjustment knob to get a clear image.
Increase magnification by switching to a higher objective lens (e.g., 40x or 100x) and refocus if necessary.
Adjust the diaphragm for better contrast and clarity.
Once done, turn off the light source, lower the stage, and clean the lenses and slides.

Question 2a: List and state the functions of the two major devices in spectrophotometry.

Monochromator: A device that isolates a specific wavelength of light from the light source. It helps select the wavelength at which the sample’s absorbance will be measured.
Photodetector: A sensor that measures the intensity of light that passes through the sample. It detects the absorbance of the sample and converts it into an electrical signal, which is then displayed as an absorbance value.

Question 2b: Calculate the phosphate concentrations using the given absorbance data and the equation Y = 0.223X – 0.08

Using the absorbance values in the table, we can compute the phosphate concentration for each sample.

Let’s calculate the phosphate concentrations one by one:

Question 3a: What is a stain?

A stain is a substance used in microscopy to enhance the contrast of microscopic specimens. Stains bind to specific structures in cells or tissues, making them more visible and easier to examine under a microscope.

Question 3b: Steps involved in permanent slide preparation

Fixation: The specimen is treated with chemicals (e.g., formaldehyde) to preserve its structure.
Dehydration: Water is removed from the specimen using increasing concentrations of alcohol.
Embedding: The specimen is embedded in a medium (e.g., paraffin wax) to provide support for sectioning.
Sectioning: The embedded specimen is sliced into thin sections using a microtome.
Staining: The sections are stained with dyes to highlight different structures.
Mounting: The stained specimen is mounted on a glass slide with a coverslip using a mounting medium.

Question 4a: Outline the invaluable contributions of a herbarium to biodiversity of plants.

Conservation: A herbarium serves as a repository for plant specimens, preserving species that might be endangered or extinct in the wild.
Research: It provides valuable reference material for scientific research, helping in the identification and classification of plant species.
Documentation: Herbariums maintain historical records of plant species, helping scientists track changes in plant biodiversity over time.
Education: They serve as educational resources for teaching botany, taxonomy, and biodiversity to students and the public.
Species Distribution: Herbariums document the geographical distribution of plant species, aiding in biogeographical studies.
Taxonomy and Classification: They contribute to plant taxonomy by helping botanists describe and classify new species.
Biodiversity Assessment: Herbariums help in assessing regional biodiversity and identifying areas with high plant diversity for conservation.
Reference for Medicinal Plants: Specimens in herbariums can be used as references in studies of ethnobotany and medicinal plants.
Environmental Monitoring: Herbariums can track changes in plant populations due to climate change, pollution, or habitat destruction.
Supporting Floristic Studies: They provide baseline data for floristic studies, which document the plants of a particular region.

Question 4b: Outline any ten (10) equipment and materials needed in collection of plant specimens.

Plant Press: Used to flatten and dry collected plant specimens.
Secateurs: A cutting tool for clipping plant stems, leaves, or flowers.
Field Notebook: For recording important information about the plant and its location.
GPS Device: To record the precise geographical location of the specimen.
Plastic Bags: For temporarily storing freshly collected specimens.
Trowel: For digging up plants, especially for collecting roots.
Labels: To identify and mark each specimen with relevant details.
Camera: To photograph the plant in its natural habitat before collection.
Newspapers: For pressing and drying specimens between sheets.
Mounting Paper: Used to permanently mount dried specimens for herbarium storage.

Question 5a: Explain the following terms:

Chromatography: A laboratory technique used to separate mixtures of substances into their individual components. It relies on the differential movement of the components through a stationary phase under the influence of a mobile phase.
Chromatogram: The visual output or result of a chromatography process, showing the separated components of a mixture as peaks or bands.
Resolution: In chromatography, resolution refers to the ability to clearly distinguish between two closely eluting components. Higher resolution means better separation of components.
Reverse Phase: A type of liquid chromatography in which the stationary phase is non-polar (hydrophobic) and the mobile phase is polar. This technique is often used for separating compounds that are hydrophobic.
Mobile Phase: In chromatography, the mobile phase is the solvent or mixture of solvents that carries the sample through the stationary phase. It interacts with the sample and plays a key role in separating the components.

Question 5b: Discuss the term ‘liquid chromatography’.

Liquid chromatography is a technique used to separate and analyze compounds in a liquid sample. It involves passing a liquid (mobile phase) containing the sample through a stationary phase, usually a column packed with a solid material. As the sample moves through the column, the components are separated based on their interactions with the stationary phase. This method is widely used in biochemistry, pharmaceuticals, and environmental testing to analyze complex mixtures.

Question 6a: Discuss the various preservatives used in storage of animal specimens.

Formaldehyde (Formalin): Commonly used to preserve animal tissues and entire specimens. It prevents decomposition by cross-linking proteins and other biological materials.
Alcohol (Ethanol or Isopropanol): Alcohol is widely used to preserve smaller specimens. It prevents the growth of bacteria and fungi, slowing down decay.
Freezing: Specimens can be preserved by freezing, especially when future genetic analysis is needed. Freezing halts biological processes, preserving tissue integrity.
Glycerin: Sometimes used in combination with alcohol or formaldehyde, it helps maintain flexibility in soft tissue specimens.
Phenol: A less commonly used preservative, phenol can be added to solutions to enhance preservation by inhibiting microbial growth.
Vacuum Sealing: Specimens can be vacuum-sealed to reduce exposure to air and moisture, which slows decomposition.
Borax Solution: Used in combination with other chemicals, borax helps prevent bacterial growth and preserve animal specimens.

Question 6b: List the various types of animal specimen.

Whole Animal Specimens: Entire animals preserved for educational or research purposes.
Tissue Samples: Specific parts of animals, such as muscles, organs, or bones, preserved for scientific study.
Skeletons: Bones of animals that have been cleaned and preserved for anatomical study.
Mounted Specimens: Taxidermy animals used for display, often in museums.
Blood Samples: Preserved blood used in biological and medical research.
Insect Collections: Insects preserved and mounted on pins for identification and study.
Eggs or Larvae: Early developmental stages of animals preserved for research.
Slides of Animal Tissues: Thin slices of tissue mounted on microscope slides for histological examination.
DNA or RNA Samples: Preserved genetic material from animals used for molecular studies.
Preserved Specimens in Jars: Small animals or organs preserved in liquid solutions such as formalin or alcohol.