Biology Lab Midterm

Microscopy Important Terms:

• Magnification: How much an image is enlarged.

• Resolution: The ability to distinguish two close objects as separate.

• Contrast: The difference in brightness between different parts of a specimen.

Microscope Parts and Functions:

• Ocular Lens (10x) – Magnifies the image.

• Objective Lenses – Further magnifies (4x, 10x, 40x, 100x).

• Stage & Stage Control Knobs – Holds and moves the slide.

• Illuminator – Light source.

• Coarse Adjustment Knob – Moves the stage; NEVER use on high power.

• Fine Adjustment Knob – For precise focusing.

• Condenser Lens & Iris Diaphragm – Focuses and adjusts light.

Microscope Storage Checklist:

1. Remove slide.

2. Set to low power.

3. Reduce light dial.

4. Turn off light.

5. Wrap cord, tuck plug, and replace dust cover.

6. Return to the correct numbered shelf.

Biological Molecules and Properties of Water (Exercise 4)

Major Biological Molecules: 

*Monomers into 

1. Carbohydrates:

   • Monomer: Monosaccharides (glucose, fructose).

   • Polymer: Polysaccharides (starch, glycogen, cellulose)

     • Polysaccharides:

     • Plants - starch & cellulose

     • Animals  - glycogen

   • Function: Quick energy and structural support.

   • Carbohydrates

     • Monosaccharide → disaccharide → polysaccharide 

     • Common Form: CH₂O

2. Proteins:

   • Monomer: Amino acids (20 types).

   • Polymer: Polypeptides.

   • Functions:

     • make up enzymes

     • structural

     • movement 

     • cell recognition

     • channels/pores in membranes

   • Collagen is an example of proteins

   • Most proteins end in -ase

3. Lipids:

   • Types: Triglycerides, phospholipids, steroids, waxes.

   • Function: Long-term energy storage, cell membranes, hormones.

   • Hydrophobic

   • Examples: fats, oils, testosterone/estrogen, cuticle (plants) 

Experiment Components:

• Positive Control: Expected to show a reaction.

• Negative Control: Should show no reaction.

• Variables: Independent (changed), Dependent (measured), Controlled (kept constant).

Indicator Reagents Used:

1. Benedict’s Test – Detects reducing sugars (glucose).

2. Iodine Test – Detects starch (turns blue-black).

3. Biuret Test – Detects proteins (turns purple).

4. Sudan IV Test – Detects lipids (stains red).

Properties of Water:

1. Surface Tension – Cohesion between water molecules.

2. Solvent of Life – Dissolves many substances.

3. Evaporative Cooling – Sweating cools organisms.

4. Expansion upon Freezing – Ice is less dense than liquid water.

Structure and Function of Living Cells (Exercise 5)

Cell Theory:

• All living things are made of cells.

• Cells are the basic unit of life.

• Cells arise from pre-existing cells.

• Cytology began in 1665 when Robert Hooke observed cork cells

Cells - unit of structure, function, and reproduction in living organisms.

• unicellular (one) multicellular (many)

• ALL Cells Contain:

  • plasma membrane

  • region of DNA

  • cytoplasm

  • ribosomes

    Types of Cells:

1. Prokaryotic Cells (Bacteria, Archaea):

   • No nucleus.

   • Single circular DNA.

   • Small ribosomes.

   • Simple structure.

2. Eukaryotic Cells (Plants, Animals, Fungi, Protists):

   • Have a nucleus.

   • Multiple linear DNA.

   • Large ribosomes.

   • Complex structure.

Common Cell Structures:

• Plasma Membrane – Controls what enters and exits the cell.

• Cytoplasm – Jelly-like substance where reactions occur.

• Ribosomes – Protein synthesis.

• DNA Region – Contains genetic material.

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Organelles in Eukaryotic Cells:

• Nucleus – Contains DNA, controls the cell.

• Rough ER – Ribosome-covered, makes proteins.

• Smooth ER – Makes lipids, detoxifies.

• Golgi Apparatus – Modifies and packages proteins.

• Lysosomes – Digestive enzymes (only in animal cells).

• Vacuoles – Storage (large central vacuole in plant cells).

• Mitochondria – Powerhouse, makes ATP.

• Chloroplasts – Photosynthesis (only in plant cells).

Cell Wall – Structure and support (only in plant cells).