Biology: Scientific Method and Cell Structure

Scientific Method and Microscopy

• The scientific method involves a series of steps: observation, question, hypothesis, prediction, experiment, analysis, and conclusion.
• Microscopy uses lenses to magnify samples. Focusing involves adjusting the coarse and fine focus knobs to achieve clarity.

Cell Structure and Function

• Diffusion is the movement of molecules from high to low concentration.
• Osmosis is the diffusion of water across a selectively permeable membrane.
• Prokaryotic cells lack a nucleus and membrane-bound organelles; eukaryotic cells possess both.
• Plant cells contain chloroplasts and a cell wall; animal cells do not. Organelles have specific functions.
• Isotonic solutions have equal solute concentrations inside and outside the cell.
• Hypertonic solutions have a higher solute concentration outside the cell, water moves out.
• Hypotonic solutions have a lower solute concentration outside the cell, water moves in.
• The pH scale measures acidity and alkalinity.

Chemical Composition of Cells

• Biuret reagent tests for proteins (purple/violet = positive); iodine tests for starch (dark purple/blue-black = positive); Benedict's reagent tests for sugars (green/yellow/orange/brick red = positive).

Enzymes

• Enzymes are biological catalysts that speed up reactions.
• Enzymes catalyze both synthesis (building) and degradation (breaking down) reactions.
• The active site is where the substrate binds to the enzyme.
• Enzyme-substrate complexes form during reactions.
• Enzyme activity is affected by concentration, temperature, and pH.

Cellular Respiration

• Cellular respiration is the process of breaking down glucose to release energy. It produces ATP (energy).
• Sugar fermentation rate correlates with CO2 production over time.

Photosynthesis

• Photosynthesis uses light energy to convert carbon dioxide and water into glucose and oxygen.
• Photosynthesis takes place in chloroplasts within the plant cell.
• Photosynthesis produces glucose and oxygen.
• The Calvin cycle is a part of photosynthesis, converting carbon dioxide to sugars.

Animal Organization

• Epithelial tissue covers body surfaces; nervous tissue transmits signals; muscle tissue contracts; connective tissue supports and connects.
• Muscle tissue types include skeletal, cardiac, and smooth.

Cardiovascular System

• The heart's components include chambers (atria and ventricles) and valves.
• Blood flows through the heart in a specific pattern, oxygenated and deoxygenated.
• Directional terms (anterior, posterior, ventral, dorsal) describe body positions.

Urinary System

• The urinary system (kidneys, ureters, urethra, bladder) filters blood and produces urine.
• Kidneys filter waste from the blood.

Reproductive System

• The male reproductive system includes the testes, epididymis, vas deferens, seminal vesicles, prostate gland, urethra, and penis. The parts play distinct roles in reproduction.
• The female reproductive system includes the ovaries, fallopian tubes, uterus, and vagina. The parts play distinct roles in reproduction.

Nervous System

• The nervous system has central (brain and spinal cord) and peripheral (nerves) divisions.
• The brain has lobes (frontal, parietal, temporal, occipital) with specific functions.
• The cerebellum coordinates movement; the thalamus relays sensory information; the corpus callosum connects the brain hemispheres.

Special Senses (Eyes and Ears)

• Rod cells in the eye detect light; cone cells detect color.
• Visual information travels from the eye to the brain for processing.
• Hair cells in the ear vibrate, transferring sound vibrations.
• Auditory information is processed in the temporal lobe of the brain.