BISC 102 — Group 1: Diversity and History of Life (Lectures 1–3)

Flashcards testing core concepts from SFU BISC 102 Lectures 1 to 3, covering the diversity of life, cellular forms, reproduction, nutritional types, phylogenetics, taxonomy, species concepts, and Earth's evolutionary history.

What are the five fundamental characteristics shared by living organisms?

Cells, reproduction, energy and nutrients, genetic information, and evolution.

Why is fire not classified as a living organism despite requiring energy and spreading?

Fire lacks membrane-bound cells and genetic information.

According to the genetic information characteristic of life, how does information flow within an organism?

Hereditary information stored in DNA is transcribed into RNA, and RNA is translated into proteins.

How do prokaryotes and eukaryotes differ in terms of their nucleus and chromosome organization?

Prokaryotes lack a membrane-bound nucleus and typically have circular chromosomes, whereas eukaryotes possess a membrane-bound nucleus and multiple linear chromosomes.

What are the three domains of life, and which two share a more recent common ancestor?

Bacteria, Archaea, and Eukarya; Archaea and Eukarya share a more recent common ancestor with each other than either does with Bacteria.

What type of asexual reproduction involves an unfertilized egg developing into an embryo?

Parthenogenesis.

How do vegetative reproduction and fragmentation differ as asexual reproductive strategies?

Vegetative reproduction occurs when a new plant develops from an existing plant structure, whereas fragmentation occurs when a separated piece of a multicellular organism develops into a new individual.

In sexual reproduction, what are the roles of meiosis and fertilization with respect to ploidy?

Meiosis reduces chromosome sets from diploid ($2n$) to haploid ($n$), while fertilization fuses haploid gametes to restore a diploid ($2n$) zygote.

What distinguishes a diploid-dominant sexual life cycle from a haploid-dominant life cycle?

In a diploid-dominant cycle (e.g., humans and most animals), the multicellular organism is diploid and the haploid phase is limited to gametes; in a haploid-dominant cycle (e.g., some fungi), the organism is primarily haploid and the diploid stage is brief (typically the zygote).

What characterizes the alternation of generations life cycle?

Both the haploid stage (gametophyte) and diploid stage (sporophyte) are multicellular, alternating throughout the life cycle (e.g., plants and some algae).

What prefixes designate an organism's energy source, electron source, and carbon source?

Energy: Photo (sunlight) or Chemo (chemical energy); Electrons: Litho (inorganic) or Organo (organic); Carbon: Auto (inorganic, such as $CO_2$) or Hetero (organic).

What nutritional strategy defines green plants versus animals and fungi?

Green plants are photo-litho-autotrophs, whereas animals and fungi are chemo-organo-heterotrophs.

What are the key structural and physiological traits that distinguish animals from plants?

Animals are multicellular eukaryotes with no cell walls, diploid-dominant life cycles, and innovations like muscles and neurons; plants are multicellular eukaryotes with cellulose cell walls, chloroplasts, and an alternation of generations.

What are the primary characteristics of fungi regarding cell wall composition and nutrition?

Fungi possess chitin-containing cell walls, absorb nutrients, are chemo-organo-heterotrophs, and often have haploid-dominant life cycles.

What are the three mechanisms of horizontal DNA exchange in prokaryotes?

Transformation (uptake of environmental DNA), transduction (transfer of DNA via viruses), and conjugation (direct transfer of DNA between cells).

In a phylogenetic tree, what do a branch, node, and clade represent?

A branch represents an evolutionary lineage; a node represents a common ancestor where lineages diverge; a clade represents a common ancestor and all of its descendants.

How are monophyletic, paraphyletic, and polyphyletic groups distinguished?

A monophyletic group (clade) includes a common ancestor and all descendants; a paraphyletic group includes a common ancestor but excludes some descendants; a polyphyletic group combines taxa from separate lineages while excluding their relevant recent common ancestor.

What is a synapomorphy, and what example is associated with opisthokonts?

A synapomorphy is a shared derived trait found in a group and its common ancestor but absent from more distant ancestors; an example is the rear-positioned flagellum in opisthokonts.

What is the correct sequence of the major taxonomic ranks from broadest to most specific?

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

What rules govern binomial nomenclature introduced by Carl Linnaeus?

It consists of a two-part scientific name where the genus is capitalized, the species epithet is lowercase, and both are italicized (e.g., Homo sapiens).

What is the biological species concept, and what are its main limitations?

It defines a species as groups of interbreeding natural populations that produce viable, fertile offspring and are reproductively isolated; its limitations include inapplicability to fossils, asexual organisms, and populations where breeding compatibility cannot be directly observed.

How do the morphological, ecological, and phylogenetic species concepts define species?

Morphological: based on physical similarities and differences; Ecological: based on ecological niches and resource use; Phylogenetic: based on evolutionary relationships as the smallest distinguishable monophyletic lineages.

What is the difference between prezygotic and postzygotic reproductive isolation barriers?

Prezygotic barriers prevent mating or fertilization (e.g., differences in behavior, timing, habitat, or gametic incompatibility); postzygotic barriers reduce offspring survival or fertility after fertilization (e.g., hybrid inviability, hybrid sterility, reduced hybrid fitness).

Are fungi more closely related to plants or to animals?

Fungi are more closely related to animals than to plants.

How do permineralized fossils differ from compression fossils?

Permineralized fossils form when minerals precipitate into or replace organic tissues to preserve internal structure; compression fossils form when organisms are flattened under sediments, leaving a thin carbon film.

What are trace fossils and transitional features?

Trace fossils are indirect evidence of organism activity (such as footprints, burrows, or coprolites); transitional features are intermediate traits that bridge ancestral and more derived forms.

How do relative dating and radiometric dating differ in determining fossil age?

Relative dating determines whether a rock layer or fossil is older or younger relative to others; radiometric dating estimates absolute ages by measuring the decay of radioactive isotopes.

What four biases distort representation in the fossil record?

Habitat bias, taxonomic and tissue bias, temporal bias, and abundance bias.

Approximately when did life originate on Earth, and what dominated early Earth history?

Life originated approximately $3.7\text{ billion years ago}$, and early Earth was dominated by unicellular organisms.

What are the four stages involved in the origin of life?

Chemical evolution, the RNA world hypothesis, formation of protocells, and natural selection.

What is LUCA, and how is it characterized?

LUCA (Last Universal Common Ancestor) is the common ancestor of all extant living organisms; it is characterized as a unicellular prokaryote-like organism, but was not the very first life form.

What geological and biological structures provide evidence for the evolution of oxygenic photosynthesis?

Banded iron formations (formed when generated oxygen reacted with dissolved iron) and stromatolites (layered mineralized microbial mats containing cyanobacteria).

What structural and genetic lines of evidence support the Endosymbiosis Theory for mitochondria and chloroplasts?

They have their own DNA, possess bacteria-like ribosomes, replicate via binary fission-like division, are similar in size to bacteria, have double membranes, and show molecular similarity to bacterial lineages.

How do adaptive radiation and mass extinction oppositely affect species diversity?

Adaptive radiation rapidly increases species diversity as a lineage diversifies into varied ecological niches; mass extinction rapidly decreases species diversity through widespread biodiversity loss over a short geological period.

What major evolutionary milestones distinguish the Precambrian from the Phanerozoic eon?

The Precambrian spans the origin of life, oxygenic photosynthesis, eukaryotes, and early multicellularity; the Phanerozoic is defined by extensive animal diversification, major adaptive radiations, and five major mass extinctions.