lecture exam 1 (review questions) Flashcards
How many described species are on Earth?
2.3 million species
What percentage of species have gone extinct?
99%
What are the two general types of science?
discovery-based and hypothesis-based
What is discovery-based science?
aims to observe, explore, and discover
What is hypothesis-based science?
begins with a scientific question/problem and has a potential answer or solution that can be tested
What is a scientific hypothesis?
it leads to predictions that can be tested by observation or experimentation - can be falsifiable and must be testable
Who was Henry Bates?
he hypothesized that mimicry evolved in harmless species as an evolutionary adaptation that reduces their chances of being eaten
What does the Batesian Mimicry Hypothesis state?
a species mimics the warning signals of another species without having the characteristics that make it undesirable to their shared predator
What is a scientific theory and why is it so powerful?
a theory is broader than a hypothesis and can lead to a new testable hypothesis - it is supported by larger bodies of evidence in comparison
Why are fields dealing with supernatural phenomena considered either unscientific or pseudoscientific?
science cannot support or falsify supernatural explanations because they are outside the bounds of science
What are the (7) characteristics of life?
Order
Evolutionary adaptation
Response to the environment
Reproduction
Growth and development
Energy processing
Regulation/homeostasis
Why is the Theory of Evolution important to all biologists?
Evolution makes sense of everything we know about living organisms
List the three domains of life
domain Bacteria
domain Archaea
domain Eukarya
Starting with domain, list the main taxonomic groups, from the largest (most inclusive) down to species
domain
kingdom
phylum
class
family
genus
species
How do you write a genus name?
Genus names are uppercase and italicized
How do you write a species name?
Species names are lowercase and italicized
What were Darwin’s 2 main points in his book, “Origin of Species”?
- Species showed evidence of “descent with modification” from common ancestors
- Natural selection is the mechanism behind “descent with modification”
When did Darwin publish “Origin of Species”?
1859
Describe how natural selection can cause a population to change
Individuals will survive if they are best suited to their environment - the population will all have beneficial traits from adaptation
What’s a one-sentence definition of evolution?
Change in gene frequency in a population of organisms
Do individuals evolve?
No, populations evolve. Individuals in a population vary, though.
Can an individual undergo adaptation?
Yes, individuals can adapt to their environment if they have enough time to. The possess a mechanisms (sexual reproduction) that can generate variation.
What is speciation?
The origin of new species
What is microevolution?
Consists of adaptations that evolve within a population, confined to one gene pool.
What is macroevolution?
The cumulative effect of many speciation and extinction events over millions of years
What is the biological species concept?
It emphasizes reproductive isolation and that populations of a species have the potential to interbreed in nature and produce viable, fertile offspring; they do not breed successfully with other populations
What is gene flow?
The mating between two members of the same population
Why does gene flow matter?
It holds the phenotype of a population together
Why is reproductive isolation important?
It allows organisms to be different enough that they become a distinct species - also increases diversity
Why might Galapagos Tortoises from different islands show some differences?
Different eating habits - low, arid islands vs. high, lush islands
Why are the bones in our arms the same bones as those in a chicken?
We share a common ancestor that had the same bones in their arms
How does the Theory of Evolution explain the unity of life (shared characteristics of life)?
All life on Earth evolved from a single common ancestor, so all species are united in that way
Why do all mammals (whales, humans, bats, etc.) have fur at some point in their lives?
All mammals had shared a common ancestor that had fur at some point in their life
What are 5 pre-zygotic isolating mechanisms?
- temporal
- behavioral
- mechanical
- gametic
- reproductive
What is temporal isolation?
Species that breed at different times of the day, different seasons, or different years cannot mix their gametes
What is behavioral isolation?
Courtship rituals and other behaviors unique to a species are effective barriers
What is mechanical isolation?
Morphological differences can prevent successful mating
What is gametic isolation?
Sperm of one species may not be able to fertilize the eggs of another species
What are 3 post-zygotic barriers?
- reduced hybrid viability
- reduced hybrid fertility
- hybrid breakdown
What is reduced hybrid viability?
Genes of the different parent species may interact and impair the hybrid’s development
What is reduced hybrid fertility?
Even if hybrids are vigorous, they may be sterile (ex. mule)
What is hybrid breakdown?
Hybrids may seem viable but their offspring (second generation of hybrids) are not - mostly found in plants (for example: cotton)
How does allopatric speciation work?
Gene flow is reduced when a population is divided into geographically isolated subpopulations
Does allopatric speciation require natural selection?
No, but it may cause natural selection to arise in isolated populations
What happens if two isolated populations come back together and have NOT evolved reproductive isolation?
Interbreeding is prevented if speciation occurs
What is a population?
Organisms of the same species living in a particular area
T or F: Speciation may involve 1 gene or many
True
What is phylogeny?
The evolutionary history of a species/group of related species
What two things did Linnaeus give us?
- two-part names
- hierarchical classification
What is a taxon?
A group of one or more of an organism
Can phylogenetic trees (our hypotheses) change?
Yes
What’s a clade? What’s a monophyletic group?
They are the same thing, a group of species that includes an ancestral species and ALL its descendents
What is convergent evolution?
When two organisms look/behave the same, even though they are distantly related
What do convergent evolution and common ancestry have in common?
Both produce organisms with similarities
What does a systematist do?
Studies evolutionary relationships and classifies organisms
What is a grade?
A group of organisms based on similarity via convergent evolution (not common ancestry) is called a grade
What are the 7 descriptive characteristics of viruses?
- acellular
- no metabolism - cannot grow
- depend on host cells to reproduce
- collected nucleic acids from various sources
- can infect almost all forms of life
- are species-specific AND tissue-specific
- origin is uncertain
What sensory extension instrument verified the existence of viruses?
electron microscope
Why were viruses hard to visualize?
They don’t have fossils and the method they use to copy themselves in the host cell
What are three hypotheses for the origins of viruses?
- devolved from free-living cells
- nucleic acid molecule “escaped” from cells
- began as self-replicating molecules
What two things does every virion have?
nucleic acid and a protein capsid
What are the four shapes of viruses?
- filamentous
- icosahedral
- enveloped
- head and tail
What’s a bacteriophage?
Bacteriophages infect bacteria
What are the parts of a bacteriophage?
a DNA genome, head, tail, and tail fibers
What are the three main parts of an icosahedral virus, like adenovirus?
DNA, capsid, glycoproteins
What is a viral envelope good for?
Protects genetic material when traveling between host cells
What are glycoproteins good for?
Help the virus enter host cells
What are the 4 core classifications for viruses?
- DNA or RNA
- Single or double-stranded
- Circular or linear
- Non-segmented or segmented
An individual virus particle is called a ____________
virion
What are the 4 phases of a viral infection?
- attachment
- entry
- replication and assembly
- egress (release)
What are 3 main ways viruses replicate?
- transcribe mRNA
- mRNA makes viral proteins
- DNA incorporates into host genome
Explain the lytic cycle
virus hijacks a host cell, uses its components to manufacture more of the virus, destroys and exits the cell, and then goes on to infect other cells
Explain the lysogenic cycle
a viral reproductive stage where the virus’s DNA is replicated using the host cell’s DNA
Who discovered the CISPR system?
Doudna and Carpentier
What is an endogenous retrovirus?
A viral infection that has used reverse transcriptase to write its sequence into the host’s DNA IN THE SEX CELLS so that the viral DNA is now hereditary
List 4 methods of virus vaccine production
- attenuated “live” virus
- “killed” virus
- molecular subunits
- mRNA
