Linnaean Taxonomy

Linnaean Taxonomy

• Carolus Linnaeus developed a hierarchical classification system.
• The system assigns a scientific name to each organism type.

Linnean System of Classification

• Linnaeus grouped organisms into a hierarchy of categories.
• Categories range from domain (most inclusive) to species (least inclusive).
• The order of the classification is: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.
• "Did King Philip Come Over For Good Soup?" is a mnemonic for remembering the order.

Taxonomic Levels

• The most inclusive levels are: Archaea, Bacteria, and Eukarya (domains).
• Each domain divides into kingdoms, then phyla, classes, orders, families, genera, and species.
• A taxon is a group at any rank.

Binomial Nomenclature

• It's a two-part format of scientific names, created by Carolus Linnaeus in the 18th century.

Dichotomous Key

• It's a method of identification.
• Organisms divide into two categories repeatedly to narrow down identification.
• It can be a series of paired statements in a numbered sequence.
• Alternatively, can be a branching flowchart.

Phylogeny

• It's the evolutionary history of a species or group of species.
• A phylogenetic tree is a diagram that indicates common ancestors and lines of descent.

Cladistics

• It's a phylogenetic system.
• It defines groups by distinguishing between ancestral and derived characters.
• It's a method of classifying organisms of species called clades.

Ancestral and Derived Characters

• Ancestral characters resemble those of a group's ancestor.
• Derived characters are features different from those found in the group’s ancestors.

Reading a Cladogram

• A cladogram is a tree-like diagram built using shared derived characters.
• The root is the initial ancestor common to all organisms in the cladogram.
• A node is a common ancestor that speciated to give rise to two or more daughter taxa.
• An outgroup is a distantly related species and functions as a reference group.
• Clades are a common ancestor and all of its descendants.

Monophyletic Grouping

• Contains a single common ancestor and all of its descendants.

Paraphyletic Grouping

• Contains a common ancestor and some, but not all, of its descendants.

Polyphyletic Grouping

• Involves a grouping with no recent common ancestor.

Phylogeny Based on Morphology

• Homologous structures are body parts that appear similar in separate lineages due to a common ancestor.
• Analogous structures are body parts with the same function in different groups but without common ancestry.

Phylogeny Based on Molecular Data

• DNA sequence comparisons align DNA sequences to determine evolutionary relationships.
• Protein sequence comparisons use differences in amino acid sequences to measure relatedness.

Water Transport in Xylem

• Transpiration is water loss to the environment, mainly through evaporation from leaf stomata.
• Cohesion is water's ability to stay linked in a chain.
• Adhesion is water's ability to stick to the inside of a xylem tube.
• Stomata close when a plant is under stress to prevent water loss.

Sugar Transport in Phloem

• The source is where sugar is made or stored (leaves).
• The sink is where sugar will be used (roots).
• Sugar solution moves from source to sink (lower pressure areas).

Open Circulatory System

• Fluid bathes tissues directly in open spaces before returning to the heart.

Closed Circulatory System

• The heart pumps blood through a continuous system of vessels (no gaps/open spaces).

One-Circuit Circulatory Pathway (Fishes)

• The heart has a single atrium and ventricle.
• Blood pumps only to the gills.

Two-Circuit Circulatory Pathways

• The pulmonary circuit moves blood to the lungs.
• The systemic circuit moves blood to tissues.
• Amphibians have two atria and one ventricle.
• Birds and mammals have two atria and two ventricles.

The Human Heart

• The septum separates each side of the heart.
• The atrium receives blood.
• The ventricle pumps blood.
• Valves keep blood moving in the correct direction.
• Arteries move blood away from the heart.
• Veins move blood towards the heart.

Two Major Circular Pathways

• The pulmonary circuit carries O2-poor blood from the heart to the lungs through pulmonary arteries.
• Pulmonary veins return oxygenated blood to the heart.
• The systemic circuit carries oxygenated blood from the heart through the aorta and branching arteries to capillaries throughout the body.
• It returns O2-poor blood to the heart via veins.

Tracing the Pathway of Blood

• The right ventricle pumps blood to the lungs via pulmonary arteries.
• Blood flows through lung capillaries, loading O2 and unloading CO2.
• Oxygen-rich blood returns from the lungs via pulmonary veins to the left atrium.
• O2-rich blood flows into the left ventricle, which pumps it out to body tissues.
• Blood leaves the left ventricle via the aorta, leading to arteries throughout the body.
• Blood is supplied to capillary beds in the head, arms, abdominal organs, and legs.
• O2-poor blood from the head, neck, and forelimbs enters the superior vena cava.
• The inferior vena cava drains blood from the trunk and hind limbs.
• The venae cavae empty into the right atrium.
• From there, O2-poor blood flows into the right ventricle.

Two Types of Blood Vessels

• Arteries have thick walls and carry blood away from the heart to arterioles, then to capillaries.
• Capillaries have thin walls composed of epithelial cells.
• Venules take blood from the capillaries and merge to form veins.
• Veins have thinner walls than arteries.

Gas Exchange

• Gas exchange is the uptake of molecular O2 from the environment.
• It includes the discharge of CO2 to the environment.

Types of Respiration

• External respiration is gas exchange between air and blood in the lungs.
• Internal respiration is gas exchange between blood and interstitial fluid.

Respiratory Surfaces

• Each surface consists of a thin, moist membrane.
• The surface area must be relatively large.
• The rate of diffusion varies in air and water.

Respiratory Structures in Different Organisms

• Hydras' outer cell layer contacts the environment, and the inner layer exchanges gases with the gastrovascular cavity.
• Earthworms use their body surface (skin) for respiration.
• Insects have tracheae that deliver oxygen directly to cells without entering the blood.
• Aquatic vertebrates have gills to extract oxygen from water.
• Vertebrate lungs contain a moist internal respiratory surface, and the circulatory system aids in gas exchange.

Respiratory Medium

• The medium can be air or water.
• Air is a more efficient medium since water is more viscous.
• Fish kill describes sudden death of aquatic animals in a short period.

Ventilation

• Ventilation is the process of air flowing into the lungs during inhalation.
• It is also the flow of air out of the lungs during exhalation.

Breathing Mechanisms

• Positive pressure breathing involves a frog forcing air into its lungs.
• One-way ventilation in birds increases the efficiency of gas exchange.
• Negative pressure breathing involves lowering the pressure in the lungs to draw air in.

The Respiratory Cycle in Humans

• During inhalation, the chest cavity and lungs expand.
• During exhalation, the chest cavity and lungs resume their original positions and pressures.

Respiratory Proteins

• A respiratory pigment is any molecule that increases the oxygen-carrying capacity of blood.
• Examples: hemoglobin, hemocyanin, chlorocruorin, hemorythrin.
• Hemoglobin contains four polypeptide chains, each folded around an iron-containing heme group.

Human Respiratory System (Parts and Functions)

• The lungs exchange oxygen (O2) and carbon dioxide (CO2) with blood.
• Breathing moves air across the nose’s olfactory epithelium.
• This detects odors.
• Movement of air across the vocal cords in the larynx produces sounds.
• Breathing volume and rate determine blood CO2 concentration, which affects blood pH.

Respiratory Tract

• Air enters through the nose or mouth.
• It flows through the pharynx (throat) and larynx (voice box) to the trachea.
• The trachea branches into two bronchi, one to each lung.
• Inside each lung, airways deliver air to alveoli.
• Gases are exchanged with pulmonary capillaries in the alveoli.

Gas Exchange and Circulation in Humans

• The right ventricle pumps blood to the lungs to load O2 and unload CO2.
• Oxygen-rich blood from the lungs enters the heart at the left atrium.
• It is pumped to the body tissues by the left ventricle.
• Blood returns to the heart through the right atrium.

Food Uptake in Cells

• Phagocytosis involves the cell engulfing a particle by extending pseudopodia around it.
• Pinocytosis involves vesicles forming around a liquid.
• Receptor-mediated endocytosis involves receptor proteins on the cell surface capturing molecules.

Animal Feeding Mechanisms

• Substrate feeders live in or on their food source.
• Bulk feeders ingest large chunks of food.
• Fluid feeders suck fluids containing nutrients from a living host.
• Suspension feeders strain particles from water.

Intracellular Digestion

• It's the breakdown of complex food to simpler forms from inside cells.
• It's characteristic of animals devoid of digestive tracts.
• Lysosomes and food vacuoles are responsible for the process.

Extracellular Digestion

• Food particles break down chemically outside the cell or in the digestive system spaces.

Types of Digestive Systems

• A complete digestive tract has two openings.
• The mouth is the entrance, the anus is the exit.
• The tubelike digestive cavity is called the alimentary canal or gastrointestinal (GI) tract.
• An incomplete digestive tract has only one opening.
• The mouth ingests food and ejects wastes.
• Cnidarians have incomplete digestive tracts, it's also called a gastrovascular cavity.

Flow of Human Digestive System

• Digestion begins in the mouth.
• Mechanical digestion involves chewing to break food into smaller pieces.
• Chemical digestion involves salivary amylase (saliva) breaking down carbohydrates.
• The tongue mixes chewed food with saliva to form a bolus.
• The epiglottis covers the glottis to prevent food from entering the trachea.
• When swallowing, the soft palate closes the pharynx, and the epiglottis covers the glottis.
• Peristalsis involves waves of smooth muscle contraction pushing food along the esophagus.
• The stomach receives food from the esophagus, stores food, and starts protein digestion.
• It contains 3 muscle layers, separated by 2 sphincters.
• A sphincter is a muscle that surrounds a tube and closes or opens it by contracting and relaxing.
• Gastric juice is a mixture of water, mucus, hydrochloric acid, and enzymes (pepsin digests protein).
• The small intestine completes digestion and absorbs nutrients and water.
• The duodenum secretes mucus.
• The jejunum absorbs carbohydrates and proteins.
• The ileum absorbs water, fats, vitamins, and minerals.
• The pancreas produces insulin and glucagon, regulating blood glucose levels.
• It secretes pancreatic juice into the small intestine, digesting carbohydrates, proteins, fats, and nucleic acids.
• The liver produces bile.
• Bile breaks down fat into droplets.
• The gallbladder stores bile.
• The large intestine absorbs water and salts and eliminates wastes.
• The colon has sections like the cecum, ascending, transverse, descending, and sigmoid colon.
• The rectum stores remnants of digestion (feces).
• The anus eliminates feces.

Disorders of the Digestive System

• Acid reflux occurs when stomach acid goes back up the esophagus.
• Constipation is difficulty defecating.
• Diarrhea is loose and watery stool.
• Foodborne viruses, bacteria, and protists commonly cause diarrhea.
• A peptic ulcer is an open sore in the lining of the stomach or intestine.
• Colon cancer involves cells in the colon growing out of control.
• Hemorrhoids are swollen veins in the lower rectum or anus causing painful defecation and bleeding.
• Hepatitis is liver inflammation caused by viral infection, alcohol consumption, health conditions, or medications.
• Appendicitis is inflammation of the appendix due to a blockage causing an infection.