BIO 102 Exam 1 Flashcards

How did the environment of early Earth contribute to the formation of simple organic molecules?

Early Earth had water and energy sources such as volcanic activity and other environmental energy. These conditions could drive chemical reactions that allowed inorganic substances to form simple organic molecules.

What is the chemical evolution hypothesis?

The hypothesis that chemical processes on early Earth produced increasingly complex organic molecules that eventually contributed to the origin of life.

What theory explains how eukaryotic cells formed?

The endosymbiotic theory.

What is the endosymbiotic theory?

It proposes that an ancestral cell engulfed smaller prokaryotic cells. Instead of digesting them, the cells formed a mutually beneficial relationship and eventually became organelles such as mitochondria and chloroplasts.

What evidence supports the endosymbiotic theory?

Mitochondria and chloroplasts have their own DNA and ribosomes, are similar to bacteria in several characteristics, have membranes, and can reproduce/divide independently to some degree.

Which organelles are thought to have originated through endosymbiosis?

Mitochondria and chloroplasts.

What is biogeography?

The study of the geographic distribution of organisms.

How can biogeography help us understand evolutionary history?

The geographic distribution of organisms provides clues about where ancestors lived, how populations migrated, how geographic barriers separated populations, and how isolated populations evolved.

How does the distribution of marsupials demonstrate biogeography?

Marsupials originated in the Americas, and some migrated toward Australia. Geographic isolation of Australia allowed populations there to evolve separately, contributing to Australia's many unique marsupial species.

Why is it difficult to determine the number of microbial species?

Microorganisms are extremely diverse and numerous, many are difficult to observe or culture in laboratories, and defining and classifying microbial species can be difficult.

Which group has more species: mammals or vertebrates? Why?

Vertebrates have more species because mammals are only one subgroup within the larger vertebrate group.

What is a homologous structure?

A structure that is similar because it was inherited from a common ancestor, even if it has a different function.

Give an example of homologous structures.

The forelimbs of humans, bats, and whales.

What is an analogous structure?

A structure that performs a similar function but evolved independently rather than being inherited from a common ancestor with that particular structure.

Give an example of analogous structures.

Bird wings and insect wings.

What is the easiest way to remember homologous vs. analogous?

Homologous = common ancestry. Analogous = similar function, independent origin.

What is convergent evolution?

When unrelated or distantly related organisms independently evolve similar traits because they experience similar environmental or selective pressures.

What situations can result in convergent evolution?

Similar environmental conditions or selective pressures can favor similar adaptations in organisms that are not closely related.

How are convergent evolution and analogous structures related?

Convergent evolution can produce analogous structures because unrelated organisms independently evolve similar traits or functions.

What is the root of a phylogenetic tree?

The root represents the common ancestor of all the organisms shown above it.

What is a branch on a phylogenetic tree?

A branch represents an evolutionary lineage.

What is a node on a phylogenetic tree?

A node is a branching point that represents a common ancestor.

What is a tip on a phylogenetic tree?

A tip represents a descendant organism or group.

How do you determine which organisms are most closely related on a phylogenetic tree?

Find the organisms that share the most recent common ancestor.

Does physical distance between organisms on a phylogenetic tree determine how closely related they are?

No. Their evolutionary relationship is determined by their most recent common ancestor, not how close their names appear on the page.

Why might different groups of organisms share a character trait?

They may have inherited the trait from a common ancestor, or unrelated organisms may have independently evolved similar traits because of similar environmental pressures.

What is biology?

The scientific study of life.

What is a hypothesis?

A testable and falsifiable explanation or prediction.

What does falsifiable mean?

A hypothesis is falsifiable if there is a possible observation or result that could show it is wrong.

What is an independent variable?

The variable that the researcher manipulates or changes.

What is a dependent variable?

The variable that the researcher measures.

How can you remember independent vs. dependent variables?

Independent = I change it. Dependent = the result depends on it.

What is an experimental group?

The group that receives the experimental treatment or manipulation.

What is a control group?

The group that does not receive the experimental treatment and provides a comparison.

What is a placebo?

An inactive treatment designed to resemble the experimental treatment.

Why is a control group important?

It provides a comparison that helps researchers determine whether the experimental treatment caused a change.

What is random assignment?

Assigning participants to groups by chance to help reduce systematic differences between groups.

What is replication?

Repeating an experiment or study to determine whether the results are reliable and repeatable.

Why is replication important?

Similar results from repeated experiments increase confidence that the finding is reliable.

What is anecdotal evidence?

Evidence based on personal experiences, stories, or individual observations.

Why is scientific evidence generally stronger than anecdotal evidence?

Scientific evidence is collected systematically using measurable data, controlled methods, analysis, and often replication.

What is correlation?

An association between two variables.

Does correlation prove causation?

No. A third variable may influence both variables.

What is causation?

When a change in one variable directly produces a change in another variable.

What does statistical significance mean?

It indicates that a result is unlikely to have occurred simply by chance under the statistical assumptions being tested.

What does p < 0.05 mean?

Assuming the null hypothesis is true, the probability of obtaining a result at least as extreme as the observed result is less than 5%.

Does statistical significance automatically mean a result is biologically important?

No. A result can be statistically significant without having a large or practically important effect.

What are the three domains of life?

Bacteria, Archaea, and Eukarya.

What is a prokaryotic cell?

A cell that does not have a nucleus or membrane-bound organelles.

What is a eukaryotic cell?

A cell that has a nucleus and membrane-bound organelles.

Which domains contain prokaryotes?

Bacteria and Archaea.

Which domain contains eukaryotes?

Eukarya.

What is the major difference between prokaryotes and eukaryotes?

Prokaryotes lack a nucleus; eukaryotes have a nucleus.

What do ribosomes do?

Ribosomes make proteins.

What is the function of the nucleus?

It contains most of the cell's DNA.

What is the function of mitochondria?

They are involved in cellular energy production and ATP production.

What is the function of chloroplasts?

They carry out photosynthesis in plants and algae.

What does the cell membrane do?

It controls what enters and leaves the cell.

What are the three major statements of cell theory?

1. All living things are made of cells. 2. Cells are the basic unit of life. 3. All cells come from preexisting cells.

What was early Earth like compared with Earth today?

It had different atmospheric and environmental conditions, abundant water, volcanic activity, and different available energy sources.

What did the Miller-Urey experiment investigate?

Whether organic molecules could form under conditions designed to resemble early Earth.

What did the Miller-Urey experiment demonstrate?

It demonstrated that organic molecules could form from simpler substances under certain early-Earth-like conditions.

Did the Miller-Urey experiment create life?

No. It provided evidence that some organic molecules could form under appropriate conditions.

Where did life begin according to the notes?

In water.

What were the earliest organisms like?

They were simple prokaryotic organisms.

What was the atmosphere like before oxygen accumulated?

Early Earth had little or no oxygen in the atmosphere compared with later periods.

What organisms contributed to increasing atmospheric oxygen?

Cyanobacteria and other photosynthetic organisms.

How did cyanobacteria affect Earth?

Through photosynthesis, they released oxygen, contributing to increasing atmospheric oxygen.

What was the Great Oxygenation Event?

A major increase in Earth's atmospheric oxygen associated with the activity of photosynthetic organisms such as cyanobacteria.

Why was increasing oxygen important?

It changed Earth's environment and made aerobic metabolism possible and increasingly important.

What is a fossil?

Preserved evidence of past life.

What is the fossil record?

The collection of fossils and their distribution through geological time.

Why is the fossil record incomplete?

Fossilization requires specific conditions, and many organisms—especially soft-bodied organisms—are unlikely to be preserved.

What is a body fossil?

Preserved physical remains of an organism, such as bones, teeth, or shells.

What is a trace fossil?

Preserved evidence of an organism's activity, such as footprints or burrows.

What is relative dating?

Determining whether something is older or younger than something else.

What is radiometric dating?

A method that uses radioactive decay to estimate the age of rocks or fossils.

What is a half-life?

The amount of time required for half of the radioactive parent isotope in a sample to decay.

How much parent isotope remains after one half-life?

50%.

How much remains after two half-lives?

25%.

How much remains after three half-lives?

12.5%.

How much remains after four half-lives?

6.25%.

What is the Hadean?

A very early period in Earth's history.

What is the Archean?

An early period when simple life was present.

What is the Proterozoic?

A period associated with increasing oxygen and the development/diversification of more complex life.

What is the Phanerozoic?

The period associated with abundant visible fossil life.

What was the Cambrian explosion?

A major increase in the diversity of animal life during the Cambrian period.

What major event is associated with the end of the Permian?

A major mass extinction.

What major evolutionary event is associated with the end of the Cretaceous?

A major extinction event that eliminated non-avian dinosaurs.

What is a mass extinction?

An event during which a large proportion of Earth's species become extinct over a relatively short geological period.

What is evolution?

Change in populations over generations.

Do individual organisms evolve?

No. Evolution occurs in populations over generations.

What is natural selection?

Differential survival and reproduction based on heritable traits, causing advantageous traits to become more common in a population over generations.

What is an adaptation?

A heritable characteristic that increases an organism's ability to survive and reproduce in a particular environment.

Do organisms develop adaptations because they "need" them?

No. Existing heritable variation is acted upon by natural selection.

What is required for natural selection to cause evolutionary change?

Heritable variation in traits and differences in survival or reproductive success associated with those traits.

What is the relationship between variation and natural selection?

Variation provides differences among individuals, and natural selection can cause advantageous heritable traits to become more common over generations.

What is taxonomy?

The naming and classification of organisms.

What is the taxonomic hierarchy from broadest to most specific?

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

What is the broadest taxonomic category?

Domain.