Biology Honors Evolution

What is a scientific fact?

An observation that has been repeatedly confirmed and for all purposes is accepted as true.

What is a hypothesis?

A proposed explanation for a phenomenon

What is a scientific law?

Predicts the result of certain initial conditions

What is a scientific theory?

Tries to provide the most logical explanation of why things happen as they do and has been supported many times through testing. This can be revisable and subject to change.

What is evolution?

The slow, gradual change in a population of organisms over time (populations evolve, individuals do not)

Who was Charles Darwin? What led him to propose evolution?

Charles Darwin was a naturalist, or a biologist that studies the impact of living things on their environment and each other. His observations he found while on a voyage on the Beagle led him to propose the evolution theory.

What were Hutton and Lyell’s theories?

Concluded that the Earth is very old.

Hutton- Made connections that forces beneath the Earth’s surface can push rock layers up, creating mountains.

Lyell- Slow and steady processes that happened long ago are happening today (ex. rivers carving valleys)

What was LaMarck’s evolution hypothesis?

Organisms can change during lifetime by selectivity using body parts (used parts became bigger and better, unused parts disappeared), and acquired traits during lifetime could be passed down to offspring.

What was Malthus’ theory? How did Darwin apply this to evolution?

Malthus’ theory was that population grows exponentially while food grows arithmetically, leading to inadequate space and food. Darwin applied this to other organisms as most organisms don’t survive long enough to reproduce.

What were some examples of evolution Darwin saw on his voyage?

He saw finches with different beaks evolved for their different food sources, iguanas who had evolved to eat a seaweed diet and swim, and tortoises with different shell shapes to access their different food sources.

What are fossils? What can they form in?

Remains or imprints of organisms that once lived. Fossils can form in amber (hardened sap), sedimentary rock (rock layers), and ice (may preserve their fur or hair).

How did horse anatomy change? Why?

Teeth evolved for grazing, and became extended into the jaw and more bumpy. The skull grew substantially to accommodate the new teeth shapes. The reason for the change in anatomy was changing environmental conditions.

What is molecular biology?

The field of biology that studies the composition, structure, and interactions of cellular molecules (like RNA/DNA) that carry out biological processes necessary for cell function and maintenance.

Why is cytochrome c used?

Cytochrome c is used to study evolutionary relationships because it is universal (found in mitochondria), so differences/similarities can indicate common ancestry between different species.

What organism is most closely related to humans and why?

The monkey is most closely related to humans because we evolved from them, so there are similar amino acid sequences in cytochrome c.

What is biogeography?

The study of where organisms live now and where their ancestors lived in the past.

Why do similar species flourish in very different climates and continents?

Species once coexisted on Pangea, but were separated when Pangea separated, so they evolved to adapt to their own environments.

What two patterns of biogeography can be observed?

1. Closely related species differentiate in slightly different climates
2. Very distantly related species develop similarities in similar environments

What is embryology?

The branch of biology that studies embryos and their development

What is an embryo?

An organism in the earliest stages of development before born or hatched.

What are homologous features? How does a higher number indicate how closely related different species are?

Structurally similar anatomical features that two species share that indicate that the species share a common ancestor. A higher number of homologous features shared by different species means that they recently driver from a common ancestor and are closely related to one another.

What do pharyngeal arches develop into for fish, humans, and elephants?

Fish- Gill structures

Humans and elephants- Ear and jaw structures

What is a common ancestor?

An ancestral organism shared by two or more descendants

What is homology?

Traits inherited by two different organisms from a common ancestor.

What is convergent evolution?

A process in which two distinct lineages evolve a similar characteristic independently from one another.

What must structures have to be homologous? Give an example of non-homology.

Structures must have a common ancestor to be homologous. Octopuses and tetrapods have similar limbs but evolved independently.

Homologous structures are (similar/different) structures from (similar/different) organisms with (same/different) functions.  These are seen in organisms that are (closely/distantly) related.

Similar, different, different, closely.

What are analogous structures?Why are they important?

Anatomically different structures with similar functions. They are important to understand convergent evolution.

What are vestigial structures?

Structures left over from evolution that are now useless.

What are the original functions of goosebumps, tailbones, wisdom teeth, and appendix?

Goosebumps- Used to make one warm when cold or appear larger when threatened

Tailbones- Used to be a tail used for mobility and balance

Wisdom teeth- Used to eat ancient meat

Appendix- Held onto gut bacteria, which aided with digestion

What is the key difference between cave fish and minnows? Why did cave fish evolve to not have this feature? What sense might be enhanced?

Cave fish do no have eyes. Cavefish have evolved to not have eyesight because it is redundant to have in dark cave locations. They have enhanced touch to sense its surroundings.

Why are vestigial structures evidence of evolution?

They show structures that species have evolved to no longer need/use.

What is fitness?

Organisms that survive can reproduce and leave more beneficial traits or adaptations

What are the 4 natural selection principles?

1. More offspring are produced than can survive
2. Genetic variation
3. Variations are inherited
4. Descent with modification over time

What are the 4 types of natural selection?

Normal, stabilizing, directional, and disruptive

What is stabilizing selection? What is an example?

Selected for moderate trait, selected against both extreme traits. An example is peacocks

What is directional selection? What is an example?

Selected for one extreme trait, selected against moderate and other extreme trait. An example is peppered moths.

What is disruptive selection? What is an example?

Selected for both extreme traits, selected against moderate trait. An example is pocket mice.

What is speciation?

The formation of a new, distinct species in the course of evolution.

What are species?

Organisms that interbreed in nature and produce fertile offspring.

What are examples of species? What are examples of not species?

An example of a species is dogs, which all have 78 chromosomes. An example of a not species is mules as they are infertile.

What are limitations to the definition of a species? Why?

Asexually reproducing organisms because species are assigned based on appearance and metabolic structures. Extinct organisms because they are grouped together by appearance and location. There may be unclear gene pool, infertility, and species are far apart.

What are the classification groups of organisms in order?

Domain, kingdom, phylum, class, order, family, genus, species.

What is binomial nomenclature?

A two-word naming system for all different special, made up of an organism’s genus and species.

How do you properly write a scientific name?

The first letter of the Genus name is capitalized, while species name is written in lowercase. Name is either italicized or underlined.

How old is the Earth?

Over 4 billion years

What organism is responsible for adding oxygen into the atmosphere? What was life like before this?

Cyanobacteria. Life consisted entirely of bacterias before this.

What are cladograms?

A branching diagram that shows the evolutionary relationship between organisms.

What is phylogeny?

The study of evolutionary relationships

What are derived characteristics?

Characteristics of an organism that was not present in its ancestors. These serve some sort of purpose. Ex. mammal ancestors didn’t have fur

Where are the organisms that first evolved located on cladograms? Where are the ones that evolved later?

The organisms that first evolved are farthest to the left, and those that evolved later are on the right.