BIO 181: Introduction to Biology, Evolution, and Symbiosis

Comprehensive practice flashcards for BIO 181 covering the foundations of biology, spontaneous generation, chemistry of life, experimental design, microevolution, the Mc1r gene and coat color in beach mice, speciation modes, species concepts, gradualism vs. punctuated equilibrium, endosymbiosis, the hologenome theory, and convergent vs. divergent evolution.

According to the BIO 181 course syllabus, what are the four grading components and their respective percentage weights?

Teamwork and discussions: $20\%$, Midterm exam: $20\%$, Final exam: $20\%$, and Laboratory: $40\%$.

What does it mean that a living system is autopoietic?

It continuously self-maintains, repairs, and re-creates itself (for instance, producing a new stomach lining every 5 days, new skin every 6 weeks, a new liver every 2 months, and replacing $98\%$ of bodily atoms every 2 years).

How does life maintain its low internal entropy in accordance with the second law of thermodynamics?

It preserves and increases its internal order only by exporting heat and metabolic wastes into the environment, thereby increasing the disorder (entropy) of the external world.

What major evolutionary milestones occurred during the Archaean era ($4.0\text{--}2.5$ billion years ago)?

The emergence of the first bacteria at $3.8$ bya ($11$ fossil types in Australian rock), first anoxygenic phototrophs at $3.5$ bya, first oxygenic phototrophs (cyanobacteria) producing $O_2$ at $3.0$ bya, and first aerobic bacteria at $2.9$ bya.

How did Louis Pasteur experimentally disprove the hypothesis of spontaneous generation?

By boiling nutrient broth in swan-necked flasks; the curves allowed air entry while trapping dust and airborne bacteria in the bend, keeping the broth sterile indefinitely until tilted so broth contacted the trapped microbes.

What were the primary organic products synthesized by Stanley Miller and Harold C. Urey in their 1953 origin-of-life experiment?

Amino acids, specifically alanine and glycine, generated by circulating a mixture of $H_2O$, $CH_4$, $NH_3$, and $H_2$ through electrical sparks simulating lightning.

According to the global biomass census by Bar-On et al. (2018), which kingdom constitutes the vast majority of biomass on Earth?

Plants, accounting for approximately $450\text{ Gt C}$ of total global biomass, followed by bacteria with $70\text{ Gt C}$.

What is the structural and functional difference between a scientific hypothesis and a prediction?

A hypothesis is a general proposed explanation of how something works that can be tested, whereas a prediction is a specific, measurable outcome stating what will happen in an experiment if that hypothesis is correct.

What key distinction separates pseudoscience from junk science?

In pseudoscience, hypotheses and predictions cannot be empirically tested or falsified; in junk science, data are biased (e.g., extremely small sample size), evidence is unconfirmed or cherry-picked, and methodology is flawed, yet findings are widely publicized.

In evolutionary biology, what is the distinction between a proximate question and an ultimate question?

Proximate questions ask 'how/what' regarding the genetic, physiological, or developmental mechanism of a trait; ultimate questions ask 'why' regarding the adaptive value and evolutionary fitness provided by the trait.

What morphological differences distinguish mainland oldfield deer mice (Peromyscus polionotus) from beach mouse subspecies?

Mainland mice have a dark brown dorsal coat, light grey belly, and striped tail, whereas beach mice feature a lightly colored dorsal coat and no pigment on their face, belly, and tail.

In Dr. Hopi Hoekstra's field experiments testing predation on oldfield deer mice, how were behavioral and olfactory variables controlled?

By deploying $250$ motionless, soft Plasticine models painted to represent either camouflaged or non-camouflaged coats along transects in beach and mainland grassy field habitats.

What biochemical pigment switch occurs in Santa Rosa Island beach mice to give them a blond coat?

Their melanocytes switch from synthesizing dark brown/black eumelanin to producing blond/red pheomelanin.

What specific point mutation in the Mc1r gene causes blond fur in Santa Rosa Island beach mice (Peromyscus polionotus)?

A single base pair mutation (C to T) that substitutes an uncharged cysteine for a positively charged arginine at amino acid position 65 ($\text{Arg}^{65}\text{Cys}$) in the Mc1r transmembrane receptor protein.

What are the four primary mechanisms driving microevolution in populations?

Mutation, gene flow, genetic drift, and selection (both natural and artificial).

What are the two major forms of genetic drift, and how do they differ?

The bottleneck effect (severe population reduction caused by environmental events or disasters, leaving a random sample of survivors) and the founder effect (loss of genetic variation when a small group colonizes a new location).

What geographic barrier drove allopatric speciation in the antelope ground squirrels shown here?

The formation of the Grand Canyon, which geographically isolated populations into the Harris Antelope Squirrel (Ammospermophilus harrisii) on the south rim and the White-Tailed Antelope Squirrel (Ammospermophilus leucurus) on the north rim.

How did sympatric speciation initiate in North American apple maggot flies (Rhagoletis pomonella)?

Through a host shift from native hawthorns (Crataegus) to introduced domesticated apples (Malus domesticus), leading to behavioral host-mating preferences and temporal reproductive isolation due to differing fruit ripening schedules.

How does the ecological species concept distinguish biological species?

It defines a species as a set of organisms exploiting a single ecological niche, relying on specific resources and environmental roles rather than solely reproductive compatibility.

What is a ring species, as exemplified by Ensatina salamanders around California's Central Valley?

A connected chain of geographically adjacent populations encircling an uninhabitable barrier, in which neighboring forms interbreed, but the two terminal ends overlap without interbreeding, acting as distinct species.

What transitional morphological features are present in the Devonian fossil Tiktaalik roseae?

Fish traits (fins, scales) combined with tetrapod traits (a flat head with eyes on top, expanded ribs, and a movable neck).

How does phyletic gradualism contrast with the theory of punctuated equilibrium proposed by Gould and Eldredge?

Phyletic gradualism posits that species arise via the slow, steady accumulation of small changes over vast periods, whereas punctuated equilibrium posits that species remain in long periods of evolutionary stasis interrupted by rapid bursts of speciation.

What were the consecutive endosymbiotic events described in Lynn Margulis's Serial Endosymbiosis Theory (SET)?

1. Archaean host joined with a spirochete (motility/membranes); 2. Engulfment of an $\alpha$-proteobacterium (mitochondrion); 3. Engulfment of a cyanobacterium (chloroplast); 4. Engulfment of an $N_2$-fixing cyanobacterium (nitroplast).

What is a nitroplast, and in which organism was it recently described?

A specialized nitrogen-fixing organelle derived from the endosymbiotic cyanobacterium Candidatus Atelocyanobacterium thalassa (UCYN-A), integrated into the marine alga Braarudosphaera bigelowii via the import of algal-encoded proteins.

What genetic and antibiotic evidence proves the bacterial origin of mitochondria and chloroplasts?

Both contain single circular DNA genomes lacking histones, carry bacterial-like $70\text{S}$ ribosomes, and have protein synthesis blocked by bacterial antibiotics (e.g., streptomycin, rifampicin) but not eukaryotic ribosomal inhibitors (e.g., diphtheria toxin).

What is the holobiont and hologenome according to the Hologenome Theory of Evolution?

The holobiont is the host eukaryote together with its entire symbiotic microbiota; the hologenome is the collective genetic sum of both the host and microbial genomes, acting together as a primary unit of natural selection.

What defensive mutualism exists between leafcutter attine ants and the bacterial symbiont Pseudonocardia?

Pseudonocardia growing on the ants' cuticle synthesizes an antifungal agent that kills parasitic fungi threatening the colony without harming the ants' cultivated fungal gardens.

What is dysbiosis in the context of the human microbiome?

A state of microbial imbalance or maladaptation on or inside the body (an impaired microbiota) linked to inflammatory, metabolic, and autoimmune diseases.

How does artificial selection in wild mustard (Brassica oleracea) demonstrate microevolutionary diversification?

Selective breeding of a single wild ancestor modified different anatomical traits into distinct cultivars: lateral buds into Brussels sprouts, terminal buds into cabbage, stems into kohlrabi, leaves into kale, and flower buds into broccoli and cauliflower.

Why are the streamlined body forms of sharks, ichthyosaurs, and dolphins categorized as analogous structures resulting from convergent evolution?

They evolved independently in completely different taxonomic lineages (a fish, an extinct marine reptile, and a marine mammal) due to identical selective pressures for locomotion in aquatic environments, not from a shared streamlined ancestor.