Biology practicals and Meiosis

General Practicals

• Students should be in the laboratory at least 5 minutes before practical sessions commence
• At the end of most practical sessions, students will be required to produce line diagrams of specimens viewed using microscopes or slides
• Marks are determined by the practical coordinator based on nature and workload
• All students are expected to comply with biology practical rules, regulations, and guidelines

Diagrams

• Diagrams should have a heading, straight labels that run parallel, and a description
• Marks will be deducted if these elements are missing

Class Test Sheet

• Ensure you fill in the correct name, surname, student number, seat number, and computer number before assessment.
• Indicate at the top of your script which test you are writing (Even or Odd) according to your seat number

Microscope

• The microscope is an essential tool in most sciences, discovering objects not visible to the naked eye
• Microscopes range from simple magnifying glasses to electron microscopes
• The light microscope is commonly used in education, containing two lenses and knobs to resolve focus

Practical 1: Microscope I

• To develop a theoretical knowledge on the structural components and functions of a microscope and its uses.
• Objectives include inspiring interest and ensuring adequate understanding of the function of the microscope
• Materials used are a laptop computer and multimedia projector

Components of the Microscope

• Binocular lenses/eyepieces magnify the image, consisting of two or more internal lenses, usually at 10X magnification
• Simultaneous use of both eyes allows a depth of field for the microscope
• The binocular tube holds ocular lenses in the correct position, maintains distance, and connects ocular to the objective lens
• The headpiece adjusts the distance between the user's eyes and rotation of the binocular unit
• The Neck piece/ handle of the frame provides a horizontal piece to carry the instrument and attaches the frame
• The stem provides the vertical frame, linking the stage and main focus mechanisms
• Coarse focus allows rapid up and down movements of the stage, giving initial focus to the specimen
• The Fine Focus Knob allows slow movement of the stage to increase the detail of the specimen
• The Electric Cable is an attachment conducting electricity from a 250 AC supply
• The Nose Piece attaches the objectives, rotating to allow different power objectives
• The Objectives magnify at 4x, 10x, 40x, and 100x with optical differentiation
• The Mechanical Stage features a clip to hold the slide and allows adjustment of the object in the field of view
• The Solid Stage Platform holds the object (slide) and could be moved by focus knobs into view
• The Aperture is a hole in the middle of the stage that allows light to reach the specimen
• Iris Adjustment controls the amount of light passing through the slide, thus contrasting the image
• The Condenser Lens System focuses the light from the light source onto the specimen being viewed
• Adjustment knobs allow vertical and horizontal movement of the slide
• The Adjustment Knob moves condenser lenses to focus the light source
• The Riostat Adjustment Knob controls the amount of electricity to the light bulb, thus giving brightness and switching on/off
• The Light Source is provided by a bulb with a lens sending light to the condenser
• The Base provides a firm base, holds the electricity supply (AC/DC), and supports the illuminator

Care of the Instrument

• Microscopes represent considerable investment and can be easily damaged without precautions
• Carry the microscope with both hands, grasping the arm with one hand and placing the other under the base for support
• No circumstances should one attempt to carry two microscopes at one time
• Keep your workstation uncluttered while doing microscopy
• Don't let the light cord dangle in such a way as to hazard foot entanglement
• Check at the beginning of each laboratory that the lenses are clean using lens paper to clean them
• Cover the microscope when not in use
• Remove the slide from the solid stage
• Wipe off immersion oil with lens tissue and rotate the 4x objective into position
• Return the microscope to an erect position and raise the lamp to its highest position
• The electric cord should wrap around the base, and the mechanical stage adjusted so it doesn't project
• Check that no parts are loose or missing, and immediately contact the demonstrator if there is any problem
• Always place the dustcover and return the microscope to its correct place and do not leave it on the lab bench

Practical 2: Microscope II

• The aim is to provide the necessary practical skills required for the effective use of the microscope
• Objectives include ensuring students know how to set up for ready use, distinguish between Phases, manipulate the microscope as prescribed in the phases, and enforce knowledge
• Materials include light microscope, PA System, Monitors, Microphone, Blank microscope slide, Piece of white paper and pen
• Phase one involves starting the microscope, adjusting light, placing and clipping the slide, before aligning the specimen with the objective
• Phase two involves continuing to magnify the specimen to ten times bigger with the 10 times clip lens, and fine tuning with the fine focus knob
• Phase three involves magnifying the object 40 times using the 40x objective lens, using only the fine focus knob to prevent slide damage

Viewing the Specimen

• Start with the lowest power and move the stage to the highest point
• Inter-pupillary distance while looking through the eyepieces allows a singular image
• Diopter adjustment allows compensation of vision between two eyes

Light Control

• Light intensity is essential
• Adjust the intensity switch while looking through the eyepieces, filling the viewing area with light or contacting the instructor
• Locate the iris lever dial and adjust to medium/low level, adjusting as the magnification increases

Common Problems

• Field is dark, ensure the light is on, securely clicked, and if the slide is flat
• You are not sure if you are looking at dirt use the mechanical stage knobs or rotate the ocular gently between your fingers
• You cannot find the specimen, adjust the stage, light, and ensure the slide is secure
• You are having trouble focusing start on the low power objective carefully
• You lose the specimen when switching from the 40X objective to the oil immersion, ensure the exact center and lens is clean
• Double vision persists after adjusting the width of the eyepieces, open the iris, and refine then rotate again

Care when Using Oil

• One of the most common problems when switching objectives after using oil is RE-CLEANING, refocusing with the 10X objective
• The 100 times objective lens use is strictly prohibited in that it requires expertise
• The oil immersion derives its name from the fact that a special mineral oil is interposed
• The use of oil enhances resolving power in the microscope with a high point Condenser

Practical 3: Ecology and Environmental Health

• Aim to enhance and theoretical knowledge of ecology and environmental health
• The objectives is understanding issues that affect our environment, the impact and consequences
• Following presentation sessions, a DVD titled “An Inconvenient Truth” shall be presented in class on global film documentary
• Students are expected to report back on what they have gathered from the movie in terms of their views, beliefs, and preconceptions
• They need to ensure that they pay close attention during the movie and listen more than they write

Practical 4: Ecology: Water Conservation

• The objectives are that students will understand how even moderate water shortages can impact daily life and explore methods to reduce water
• Drought happens when naturally occurring moisture, in the form of rain or snow, is less than normal
• When water evaporates, it takes the form of vapor when it escapes and rises into the atmosphere
• Water shortages are occurring in Africa and all over the world the water table and aquifers are dropping at a rate of up to 5 feet a year
• Salt water is contaminating the water table.
• Eventually contaminants will damage the source like landfills

Practical 5: Cytology I

• The aim of this lesson is provide students with the necessary knowledge and practical skills in the field of cytology
• Objectives include preparing animal and plant cells to concretize student's microscope knowledge that students should bring with them
• The class will cover making lip scrapes and onion slides
• Follow a drawing of the cells following the rules that apply in biology
• Ensure everyone has clean equipment for drawing and cleaning

Practical 6: Cytology II

• This lesson's focus cells reproduce, develop and maintain themselves, you will focus on mitosis and meiosis to understand the cytological principle
• The title “Mitosis and Meiosis” shall be screened, accompanied Bio-viewer B4 and M40
• The bio-viewer namely B4 which touches on aspects and processes involved in plant mitosis while M40 is on Human meiosis

Practical 7: Genetics

• Emphasis is mainly directed to aspects of bringing about relationships between the genes, the DNA and the transmission of genetic traits
• Materials: Videotape titled “The living Cell - DNA" and viewer Set 81 titled “Chromosomes and Genes in Action”

Practical 8: Evolution I

• Macro-evolutionary change is demonstrated with film and discussion on evolution of mammals and humans
• Assessment focused mainly on information from the videos

Practical 9 – Evolution II

• The phenomena characteristic and depictive of micro-evolutionary patterns that cause evolutionary changes are investigated
• The beans that represent human alleles are selected from the gene pool

Allele Frequency and Sickle Cell Lab

• Place the 75 red and 25 white beans in the Gene Pool container and mix the beans up
• Simulate fertilization by PICKING OUT two alleles (beans) WITHOUT LOOKING.
• For every two beans, a COIN is flipped to determine if the individual is infected with malaria
• the individuals is not infected with malaria to put the appropriate mark onto total surviving alleles
• At the end of the round, COUNT the number of all alleles of the first generation on a data sheet
• Do it again for a second generation.

Practical 10: Taxonomy I

• Intended to illustrate classification, how to do this via a video format
• Focus on classing organisms with binomial nomenclature by Carolus Linnaeus, understanding basic scheme principles and ensure better learning.

Practical 11: Taxonomy II

• Practical lesson shall focus on the organisms (from the kingdom) Algae, Fungi, Plantae, Protozoa
• To understand systematic and diagramatic nomenclature, enchance light microscope usage, handling of specimens and ability to diagram the specimen under microsope
• Include Spirogyra, Rhizopus, moss, (plant)Plasmodium, falciparum, Giardia, lamblia and Vorticella

Practical 12 Taxonomy III

• Practical lesson focuses on Kingdom Animalia
• To understand systematic and diagrammatic nomenclature, enchance light microscope usage, handling of specimens and ability to diagram the specimen under microsope
• Draw the label, abelia polyps, Paramecium and fasciola hepatica

Practical 13 – Embryology

• From Gamatogenesis to embronic development. With the focus on fertilization, approach of the sperm to the egg agglutination, penetration of sperm.
• Understand the concepts and practices of fertilization. Follow media.