Systematics and Phylogeny Quiz

Systematics and Phylogeny

• Systematics classifies organisms and determines evolutionary relationships.
• Phylogeny is the evolutionary history of a species or group of species.
• Systematists use fossil, molecular, and genetic data to infer relationships.
• A clade includes a common ancestor and all descendants.

Phylogenetic Trees

• A phylogenetic tree represents a hypothesis about evolutionary relationships.
• Each branch point represents the divergence of two species.
• Sister taxa share an immediate common ancestor.
• A rooted tree includes a branch representing the last common ancestor of all taxa.
• A polytomy is a branch where more than two groups emerge.

What Phylogenetic Trees Show

• They show patterns of descent.
• They do not indicate when species evolved or the amount of genetic change in a lineage.
• It’s incorrect to assume that a taxon evolved from the taxon next to it.
• Phylogeny provides information about similar characteristics in closely related species.

Biosphere and Taxonomy

• The biosphere includes all areas of Earth with life.
• An ecosystem consists of living and non-living components.
• A community is the different species in an ecosystem.
• A population is all individuals of a species in a given area.
• Organisms are the individuals of a population.

Levels of Organization

• Organ systems have specialized functions.
• Organs are structures with specialized functions.
• Tissues are composed of cells, the fundamental units of life.
• Organelles are structures within cells with specialized functions.
• Molecules are made up of atoms that can join to form larger structures.

Prokaryotic vs. Eukaryotic Cells

• Prokaryotes lack a membrane-bound nucleus and organelles.
• Eukaryotes have a membrane-bound nucleus and organelles like mitochondria and chloroplasts.
• Prokaryotes have a small cell size.
• Eukaryotes have a larger cell size.
• Prokaryotes have peptidoglycans in their cell wall (bacteria).
• Eukaryotes lack peptidoglycans in their cell wall.

Animal Cells

• The plasma membrane controls what enters and exits the cell.
• Lysosomes contain enzymes for digesting organic particles.
• Mitochondria produce ATP by cellular respiration.
• Ribosomes produce proteins.
• The endomembrane system includes the endoplasmic reticulum and Golgi apparatus.
• The rough endoplasmic reticulum (RER) is involved in protein transport.
• The smooth endoplasmic reticulum (SER) participates in detoxification and steroid production.
• The Golgi processes and packages material for export or use within the cell.
• The nuclear envelope encloses the genetic material and controls entry and exit.
• The nucleolus is involved in the synthesis of ribosomes and RNA.

Three Domain System

• Early classification recognized two kingdoms: plants and animals.
• Later, five kingdoms were recognized: Monera, Protista, Plantae, Fungi, and Animalia.
• The three-domain system (Bacteria, Archaea, and Eukarya) is now widely accepted.

Mechanisms of Evolution

• Gene flow involves the movement of alleles among populations.
• Natural selection leads to differential survival and reproduction based on environmental influences.
• Genetic drift involves random changes in allele frequencies due to chance factors.

Gene Flow

• Gene flow reduces differences between populations over time.
• It is more likely than mutation to directly alter allele frequencies.

Genetic Drift

• Smaller sample sizes have a higher chance of deviating from predicted results.
• Genetic drift causes unpredictable fluctuations in allele frequencies.
• It tends to reduce genetic variation by eliminating alleles.

Founder Effect

• A few individuals become isolated from a larger population.
• Allele frequencies in the small founder population may differ from the parent population.

Bottleneck Effect

• A sudden reduction in population size occurs due to environmental changes.
• The resulting gene pool may no longer reflect the original population.
• Small populations are susceptible to further genetic drift.

Test your knowledge of systematics and phylogeny with this quiz. Explore the classification of organisms, evolutionary relationships, and the structure of phylogenetic trees. Understand key concepts such as clades, sister taxa, and patterns of descent.