Evolution Test Final

Question 1

Outline the parts of natural selection & give examples

Answer 1

1) Heritable Variation - difference in alleles and phenotypes in a population
2) Struggle for existence - based on the environment not everyone survives to reproduce
3) Survival of the fittest - those with an advantageous trait are more likely to survive and reproduce
4) Adaptation - over time the population shifts to that over generations an advantageous trait becomes more common (or a trait/allele that puts you at a disadvantage becomes less common)

Question 2

Historical and modern evidence of evolution

Answer 2

Fossils
Anatomy
molecular evidence
Biogeography

Question 3

Fossils

Answer 3

Radioactive dating
Geologists use radioactive rock to date the Earth, and found it is about 4.5 billion years old. Plenty of time for evolution.

REcent fossil finds
Many recently discovered fossils form series that trace the evolution of modern species from extinct ancestors.
Ex: the many intermediates from a land walking tetrapod to modern whales & dolphins

Question 4

Anatomy

Answer 4

Homologous structures - structures with some similarities due to shared ancestry, but may have been modified over time to serve different functions
structures inherited from a shared common ancestor
Evolutionary theory explains the existence of homologous structures adapted to different purposes as the result of descent with modification from a common ancestor.

Analogous structures - similar use, but not similar structure
May look superficially similar, but due to coincidence of having same function
Ex: Bee wing & bird wing

Vestigial structures
inherited from ancestors but have lost much or all of their original function due to different selection pressures
Ex: hip bones on whale or dolphin, legs on some skinks, appendix, tailbone on people

Embryology
Similar patterns of embryological development provide evidence that organisms have descended from a common ancestor.
Many vertebrates look very similar in develop initially.
Some shared structures include gill slits and tails.

Question 5

Molecular evidence

Answer 5

Similarities in DNA
At the molecular level, the universal genetic code & homologous molecules provide evidence of common descent.
All life use information coded in DNA
DNA has the same structure in all life
nitrogenous bases A,C,T,G, double helix, etc.
The flow of information is DNA → RNA → protein
DNA is shockingly similar across all organisms
Homologous molecules
Certain molecules appear homologous, nearly identical across species, because of a shared ancestry
Ex: cytochome c, protein involved in cellular respiration, is in all living organisms
Hox genes, involved in head to tail orientation of embryo development found in almost all multicellular animals from fruit flies to humans

Question 6

Biogeography

Answer 6

Patterns in the distribution of living and fossil species tell us how modern organisms evolved from their ancestors
Closely related but Different
Closely related species differ due to natural selection due to slightly different climates/habitats
Ex: Galapagos finches, tortoises, mockingbirds, etc.
Distantly related but Similar
Similar environments sometimes result in similar adaptations, in spite of being distantly related
Ex: large flightless birds in grasslands (emus, ostriches, and rheas)

Question 7

Three sources of genetic variation

Answer 7

Mutation
genetic recombination during sexual reproduction
lateral gene transfer

Question 8

Genetic variation: mutation

Answer 8

Any change in the genetic material of a cell, resulting from changes within individual genes or in larger pieces of chromosomes
Some are neutral, some harmful, some beneficial
Make genetic variation through mistakes in genetic code

Question 9

genetic variation: genetic recombination during sexual reproduction

Answer 9

Each chromosome in a pair moves independently during meiosis
23 pairs of chromosomes can produce 8.4 million gene combinations
Crossing over also creates genetic variation

Question 10

genetic variation: lateral gene transfer

Answer 10

Some organisms pass genes from one individual to another (outside of parents to offspring), or even from individuals of one species to another
Lateral gene transfer is the passing of genes from one organism to another organism that’s not its offspring
Can increase genetic variation in any species that picks up “new” genes
Common and important in single-celled organisms during the history of life

Question 11

how pesticide or herbicide resistance develops

Answer 11

At first individual pesticides kill almost all insects exposed to them, though a few individual insects usually survive because insect populations often contain enough genetic variation that a few individuals are resistant by chance to a particular pesticide
By killing most of the susceptible individuals, farmers increase the relative fitness of the few individuals that can resist the poison
Those insects survive and reproduce, passing their resistance on to their offspring
After a few generations, the descendants of the original, resistant individuals dominate the population
Happens through natural selection

Question 12

how a new species developed, such as with Galapagos finches

Answer 12

Two populations become separated geographically and undergo enough change in their respective habits that if or when they come into contact again they don’t mate. For Galapagos finches, song and appearance play a role in keeping different species from mating. So when populations of the same species are separated, changes in these traits set the stage for new species.A single finch population arrived from the mainland, when descendants reached other islands, they adapted to new conditions and changed so much that they eventually became separate species.

Question 13

What was early Earth like?

Answer 13

Earth’s early atmosphere had little oxygen and likely contained water vapor and compounds released by volcanic eruptions
For example, nitrogen, nitrogen oxides, carbon dioxide, methane, ammonia, and hydrogen
As Earth cooled, water vapor condensed into oceans, and most hydrogen escaped into space

Question 14

Miller & Urey’s experiments and what it suggest

Answer 14

1953, Stanley Miller and Harold Urey showed experimentally that synthesis of organic molecules was possible in an atmosphere similar to that of Early Earth

Question 15

How oxygen developed in the atmosphere

Answer 15

early microorganisms produced it using photosynthesis

Question 16

What is the evidence for endosymbiotic theory?

Answer 16

Endosymbiotic theory
Mitochondria and chloroplasts may once have been independent organisms that became incorporated into cells.

3 pieces of evidence to support endosymbiotic theory
They each have their own DNA! (single circular chromosome)
They replicate without the help of the cell and are the only organelles to do so.
They each perform their own metabolic processes:
Chloroplasts do photosynthesis
Mitochondria do cellular respiration
They each have their own membrane, similar to the cell membrane.

Question 17

PCR

Answer 17

machine used is allied an automated thermocycler, heats and cools reaction tubes quickly
can produce many copies of a specific target segment of D N A
A three-step cycle brings about a chain reaction that produces an exponentially growing population of identical D N A molecules
The key to P C R is an unusual, heat-stable D N A polymerase called Taq polymerase
During each P C R cycle the reaction mixture is heated to separate the D N A strands
Then it is cooled to allow annealing of short, single-stranded D N A primers complementary to sequences at the ends of the target segment
A D N A polymerase extends the primers in the 5′ to 3′ direction
P C R amplification alone cannot substitute for gene cloning in cells
Instead, P C R is used to provide the specific D N A fragment to be cloned
P C R primers are synthesized to include a restriction site that matches the site in the cloning vector
The fragment and vector are cut and joined together

Question 18

Gel electrophoresis

Answer 18

To see the fragments produced by cutting D N A molecules with restriction enzymes, researchers use gel electrophoresis
This technique separates a mixture of nucleic acid fragments based on length
DNA is cut using a restriction enzyme (see right).
This restriction enzyme is very specific as to where it will cut in the DNA, creating different lengths of segments of DNA
DNA is then put into a gel and ‘run’ using electric current.
Those longer DNA fragments will not be able to be pulled as far as the shorter fragments
Gels can be used for comparison in paternity, forensics and other comparative DNA analyses

Question 19

Charles Darwin’s observations aboard the Beagle and how that led to his theory of evolution by natural selection

Answer 19

Species vary globally
Noticed that different, yet eecoogicallly similar, animals species inhabited separated by ecologically similar, habitats around the globe
Species vary locally
Noticed that different, yet related, animal species foten occupied different habitats within a local area
Species vary over time
Noticed that some fossils of extinct animals were similar to living species

Putting it together
Galapagos mockingbirds turned out to belong to three separate species found nowhere else
Little brown birds that Darwin thought were wrnes, warblers, and blackbirds were actually all species of finches
They too were found howether else, though they resembled a South American finch species
Same was true of Galapagos tortoises, marine iguanas, and many plants that Darwin collected on the islands
Darwin began to wonder whether different Galapagos species might have evolved from South American ancestors
Spent years actively researching and filling notebooks with ideas about species and evolution
Evidence suggested that species are not fixed and that they could change by some natural process

Question 20

Ideas and key people who influenced Darwin & HOW they influenced, (and how they are different)
Hutton & Lyell

Answer 20

Concluded that Earth is extremely old and that the processes that changed Earth in the past are the same processes that operate in the present
Many Europeans in Darwin’s day though Earth was only a thousand years old, hadn’t changed much, Hutton and Lyell proved this wasn’t true
Hutton - idea that Earth was old meant that Darwin’s theory could be true
Lyell - idea of uniformitarianism (same process that we see in action today must have been ones that shaped Earth millions of years ago) led Darwin to question whether if Earth could change over time, could life too

Question 21

Ideas and key people who influenced Darwin & HOW they influenced, (and how they are different)
Lamarck (what was right and wrong, and how Darwin’s ideas are different)

Answer 21

Lamarck suggested that organisms had inborn drive to be perfect, could change during their lifetimes by selectively using or not using various parts of their bodies
Individuals could pass these acquired traits on to their offspring, enabling species to change over time ex. Giraffe’s necks used to be short but they stretched them out to reach leaves on taller trees, this trait was then passed down
Incorrect - organism don’t have inborn drive to become perfect, evolution doesn’t mean that species become better and doesn’t progress in predetermined direction, traits acquired by individuals during their lifetime can’t be passed on to offspring
Correct - one of the first naturalists to suggest that species are not fixed, among the first to try to explain evolution scientifically using natural process, realized there is a link between an organism’s environment and its body structures
Paved the way for later biologists including Darwin

Question 22

Ideas and key people who influenced Darwin & HOW they influenced, (and how they are different)
Malthus

Answer 22

Malthus said that if the human population grew unchecked, there wouldn’t be enough living space and good for everyone
Forces that work against population growth, he suggested, included war, famine, and disease
Darwin realized that Malthus’s reasoning applied even more t other organisms than it did to humans
If all the descendants of almost any species survived for several generations, they would overrun the world, doesn’t happen because most offspring die before reaching maturity, and only a few of those that survive reproduce
Darwin had become convinced that specie evolved, but he needed a scientific explanation based on a natural process to explain how and why evolution occurred
When Darwin realized that most organisms don’t survive and reproduce, he wondered which individuals survive and why