LS15 Mid-Term Flashcards
What are the steps of the scientific method?
1) Make observations
2) Formulate hypothesis
3) Make a prediction
4) Conduct an experiment
FiIl in the blank: Scientific thinking can tell you when you should ______.
change your mind
Is maze running influenced by genes? Explain.
- Yes, there is evidence that maze running in mice influenced by genes
- An experiment took “smart” mice (those good at maze running) & mated to have offspring. They did the same thing with “dull” mice. Then the best of the best mice were mated while the worst of the worst mice mated (top 20% and bottom 20%). They continued this over several generations and found that found that the bright mice did well and the dull mice did poorly.
How can you increase your experiment’s power?
1) Randomize subjects across control and experimental group
2) Control your study
3) Use a double-blind design
The better ______ your experiment is, the more _______ we should have in its results.
controlled, confidence
Should we let pseudoscience and anecdotal observations influence our beliefs?
No! (even though they can be almost unbearably appealing.)
Define scientific method/scientific thinking.
A highly flexible and often nonlinear process that can be used to explore a wide variety of thoughts, events, or phenomena, not only in science but in other areas as well
What are the 5 basic elements to scientific thinking?
Make observations.
Formulate a hypothesis.
Devise a testable prediction.
Conduct a critical experiment.
Draw conclusions and make revisions.
O-H-T-C-C!
Describe empirical knowledge.
It is based on experience and observations that are rational, testable, and repeatable.
What kind of process is scientific thinking?
Empirical process
What does scientific thinking always start with?
Observations (or noting apparent patterns or cause-and-effect relationships.)
What 2 things must a hypothesis accomplish to be useful?
- Establish an alternative explanation for a phenomenon
- Generate testable predictions
Can you prove that a hypothesis is 100% true?
No, but as more evidence accumulates, we can be more confident.
A good, testable prediction will have it so that, if our hypothesis is true, then our ________ will always be true.
Prediction
What is a critical experiment?
An experiment that makes it possible to decisively determine whether a particular hypothesis is better than the alternative hypotheses
What is an independent variable?
Some entity that can be observed and measured at the start of a process, and whose value can be changed as required.
What is a dependent variable?
One that can also be observed and measured, but whose response is created by the process being observed and depends on the independent variable.
What does controlling variables mean?
It means attempting to minimize any differences between a control group and an experimental group other than the treatment itself.
What is the placebo effect?
The frequently observed, but poorly understood, phenomenon in which people respond favorably to any treatment.
What is beneficial about blind experimental design?
Can reduce biases that may arise from the participants’ expectations
What does it mean for an experiment to be randomized?
The research participants are randomly assigned to the experimental and control group & thus no one has an influence on group composition
To draw clear conclusions from experiments, control and experimental groups should differ only with respect to the _______. Differences in outcomes between the groups can then be attributed to the ________.
treatment of interest, treatment
What is a hypothesis?
A proposed explanation for a phenomenon
What is a scientific theory?
An explanatory hypothesis for natural phenomena that is exceptionally well supported by empirical data
Which tends to be broader in scope: theories or hypotheses?
Theories
What is replication?
The process of repeating a study
What is positive correlation?
A relationship between variables in which they increase (or decrease) together.
What is pseudoscience?
Individuals make scientific-sounding claims that are not supported by trustworthy, methodical scientific studies
What are anecdotal observations?
Based on just one or a few observations, people conclude that there is or is not a link between two things
(i.e. lucky t-shirts, horoscopes, MMR vaccine causing autism)
Can scientific thinking give us insights into value judgments and other non quantifiable, subjective information?
No.
What characteristics are shared by all living organisms/living systems?
- Cellular structure
- Metabolism
- Sensitivity/responsiveness to the environment
- Homeostasis
- Growth, development, reproduction
- Evolutionary adaptation
What are the 5 central themes that recur throughout living things?
- Systems
- Pathways and transformations of energy and matter
- Information flow, exchange, and storage
- Evolution
- Structure and function
Why is the phrase “survival of the fittest” misleading?
“Survival of the fittest” is not even in the first 4 editions of The Origin of Species → it then is mentioned in the 5th a lot and it stuck
What is an evolutionary successful organism?
An organism with greater reproductive success than other individuals in the population
Fitness is measured…
- Relative to other genotypes/phenotypes
- In a specific environment
- By reproductive success
There is no _____ success. There is only _____ success.
absolute, relative
What is fitness?
a measure of the reproductive output of an individual with a particular phenotype relative to the reproductive output of individuals of the same species with alternative phenotypes
What do we expect fitness to do over time?
Increase
What is evolution?
- A change in allele frequencies in a population
What is a mutation?
A direct alteration of the base-pair sequence of an individual’s DNA so that one allele is changed to another (ex’s: power plant, UV radiation, chemicals)
Describe gene flow/migration.
Within a population some individuals leave or new individuals arrive, thus changing the overall allele frequencies.
What is genetic drift?
A random change in allele frequencies (in a population)
What are the 3 conditions for natural selection?
1) Variation of traits
2) Heritability
3) Differential reproductive success
What are the 4 agents of evolution?
- mutation
- migration (gene flow)
- genetic drift
- natural selection
List examples of traits that make an individual more likely to die, but also make them more likely to be selected by mates.
- Feer (males have big antlers → females choose males w/ largest rack of antlers even tho antlers make life difficult)
- Frigate bird males (females choose mates based on the size and color of the pouch → but the big sack makes it hard to blend in from predators)
- Peacocks (males w/ big feathers are more attractive but it makes it harder to fly)
Sexual selection leads to _______.
Trade off
What is the significance of snakes/guns regarding nature vs. nurture?
- Snakes have the same reaction everywhere/all ages (sweaty skin/increased heart rate) whereas guns cause no response in babies or many cultures.
- We have the wrong instincts because the world is changing so quickly.
Is the human brain a blank slate?
No. Some feelings and behaviors don’t need to be learned.
Define phenotype.
the observable qualities of an organism (morphology, behavior, etc.)
Define genotype.
the internal state of hereditary factors
What is a norm of reaction?
The set of all phenotypic expressions possible for a given genotype if raised under all possible different environmental conditions
What does it mean if the norm of reaction is steep?
A small change in environment causes a big change in phenotype
Species are not ________. We can watch them change in nature or even cause them to change.
immutable (flies living w/out food experiment shows this)
What is a gene?
A section of DNA instructing how to produce a trait
What is an allele?
one variant of a gene (several may exist)
Can an individual’s alleles change?
- No, DNA is inherited & remains the same.
- A population’s can though over time
What unexpected patterns did Darwin observe?
1) Finch variation
2) Similarity between fossils of extinct species & the living species in an area
How do you know if evolution by natural selection is occurring?
1) Variation
2) Heritable
3) Differential reproductive success
What is directional selection?
Certain variants/genes are getting cut out of the population (variation for the trait goes down overtime)
Ex’s:
- low-producing milk gene in cows
- mini horses being bred
- really big or small dog breeding
Give an example of stabilizing selection.
Birth weight (really tiny babies are unlikely to survive due to complications
Give an example of disruptive selection.
Coho salmon :
- Males fight for best territory → females come to lay eggs → male releases sperm to fertilize eggs → he guards/protects them until they hatch
- Big males typically win but sometimes a small one can sneak in while 2 others are fighting
Persistent selection can dramatically change the _____, _____, and ______ of the individuals in a population
Morphology, behavior, and physiology
What is a homologous pair?
A pair of chromosomes that at every equivalent point form 1 end to other, there is the same instruction set
(ex: hair color, eye color, gene for digesting lactase)
What is a karyotype?
a picture of all the chromosomes in a cell
The law of segregation points out that ________________.
a gamete receives only 1 allele from the pair of alleles possessed by an organism
What does a test cross allow you to determine?
It allows you to determine whether individuals showing dominant traits are homozygous or heterozygous.
Male-pattern baldness is a _______ trait.
sex-linked
What are some methods of sex determination?
- Male heterogamety
- Female heterogamety
- Ploidy
- Incubation temperature
What is “kindness”?
An action that 1 individual does at a cost to them for a benefit for the recipient of the action
Why are people “nice” to each other?
- Because an allele in you causes you to act in such a way that you increase the reproductive success of other ind’s carrying that allele (Shared genes/Kin selection)
- Because an allele in you causes you to help other ppl who will return the favor, thereby helping you (& the allele causing the kindness). The allele buffers itself from an uncertain future by sorting goodwill in others. (Reciprocal Altruism)
What are the 2 ways an allele can increase its market share?
Direct fitness and indirect fitness
What is direct fitness?
Increase the number of offspring I produce
What is indirect fitness?
Increase the number of offspring my kin produce. They also carry many of my alleles.
Inclusive fitness = ________ + _________
direct fitness + indirect fitness
What does inclusive fitness help us understand?
Much of the apparent altruism that we see in the world.
What is Hamilton’s rule and what do the letters represent?
B * r > C
B = Benefit to relative
R = coefficient of relatedness (0.0 - 1.0)
C = cost to me
Can you use Hamilton’s rule without exact numbers?
Yes, you can use it in practice.
What is the significance of Belding’s ground squirrels?
They are an example of Hamilton’s rule.
- Some (usually females) when a predator approaches
- Others hide when they hear a yell and go in burrows
- Male squirrels relocate to a different community at sexual maturity. Females don’t.
- The more kin a squirrel is likely to have neatby, the more it will act “altruistically.” Older females share more genes so they are more likely to yell.
What is “r” a measure of?
the proportion of our alleles we have in common with our relatives
How do you determine coefficients of relatedness?
1) Every connection between a parent and offspring is 0.5
2) Find every distinct way that 2 individuals could have inherited the same allele from an ancestor
3) For each path, calculate the probability
4) Add the probabilities for all of the possible paths
What is spatial association?
Treating those around you as kin
What is social association?
Treating those from childhood as kin
What is phenotype matching?
Treating those who resemble you as kin
Suppose you capture an old female ground squirrel and move her to a new neighborhood far away. Will she still make an alarm call?
Yes
Give an example of apparent altruism among unrelated individuals.
Vampire bats…
- suck blood for food but some often don’t get enough\
- others will sometimes regurgitate food for others
- A bat is significantly more likely to give food to bats that have previously helped it
- Those that don’t help are shunned
How often do we see cooperation among individuals in the animal kingdom?
Very rarely (vampire bats are an exception)
What conditions are conducive to reciprocal altruism?
1) Repeated interactions
2) High benefit to recipient relative to the cost to the actor
3) Ability to keep tabs on people (and to punish cheaters)
Why are our brains good at keeping track of social info?
Our brains were built for a world in which we encountered only a small number of people (~100) and we may have needed any one of them
What are our avenues of enhancing cooperation?
- Tinker with perceived costs and benefits
(reduce perceived cost to other person, accentuate the benefit that you’ll receive from the cooperation) - Distinguish cheaters and kind people
(ex: photocopier study) - Reduce the perceived vulnerability of partners
(make the first step: gifts)
Evolution is a(n) ________ process.
ongoing
Evolution occurs when the ____________ in a population change.
allele frequencies
What is an allele’s frequency?
the proportion in which it is present in a population relative to the other alleles of the same gene
What is the only way that new alleles can be created within a population?
Mutation
What is the founder effect?
A phenomenon by which genetic drift can occur. The isolation of a small subgroup of a larger population can lead to changes in the allele frequencies of the isolated population, because all the descendants of the smaller group will reflect the allele frequencies of the subgroup, which may differ from those of the larger source population.
What is the bottleneck effect?
A phenomenon through which genetic drift can occur; a sudden reduction in population size (often due to famine, disease, or rapid environmental disturbance) that can lead to changes in the allele frequencies of a population.
(example: cheetahs)
Are the effects of genetic drift more significant is small or large populations?
Small
What did Darwin mean by differential reproductive success?
From all the variation existing in a population, individuals with traits more suited to survival and reproduction in their environment generally leave more offspring than do individuals with other traits
Describe sexual selection and give an example.
- Some traits specifically confer greater reproductive success because they make the individual more attractive to the opposite sex
- male peacock’s brightly colored feathers
- large antlers of male red deer
Do recessive traits become rarer in a population?
No, a trait does not decrease in frequency simply because it is recessive.
What are chromosomes?
linear or circular strands of DNA comprising specific sequences of base pairs
Is binary fission asexual or sexual reproduction?
Asexual reproduction, because the daughter cells inherit their DNA from a single parent cell and thus are genetically identical to the parent.
Mitosis leads to _____ cells.
duplicate
What is mitosis?
the process by which cells duplicate themselves.
What happens in mitosis? (just the big idea)
It follows chromosome replication and leads to the production of two genetically identical daughter cells from one parent cell. This makes it possible for organisms to grow and to replace cells that die.
What is the ultimate result of mitosis and cytokinesis?
the production of two genetically identical cells.
Differentiate diploid and haploid cells.
- Diploid refers to cells that have two copies of each chromosome
- Haploid refers to cells that have one copy of each chromosome
____ and _____ are produced by meiosis.
sperm and egg
What are advantages and disadvantages of sexual reproduction?
Advantages:
- Combining alleles from two parents at fertilization.
- Crossing over during the production of gametes.
- Shuffling and reassortment of homologues during meiosis.
Disadvantages:
- Dangers associated with mating
- When an individual reproduces, only half of its offspring’s alleles will come from that organism. The other half will come from the other parent.
What are advantages and disadvantages of asexual reproduction?
Advantages:
- Fast and easy
- Efficient
Disadvantages:
- The more closely an offspring’s genome resembles that of its parent, the less likely it is that the offspring will be suited to the environment when it changes.
In humans, the sex of a baby is determined by its ______.
father
What are autosomes?
non-sex chromosomes
Mendel called the purple-flower trait _______, and he considered the white-flower trait to be the ________ trait.
dominant, recessive
What does it mean if someone is a carrier for a trait?
an individual that carries one allele for a recessive trait, and so does not exhibit the trait but can have offspring that do
What happens when “r” is really large?
Cooperation becomes extreme.
(ex’s: naked mole rats, queen bees)
Do we expect conflict when r < 1.0?
Yes, some conflict is likely.
Give an example of how reciprocal altruism can reduce conflict.
- Truces sprung up during WW1
- ## Individual units facing each other across trenches initiated mini-truces without formal exchanges
When does kin selection occur?
When an individual assists a close relative in a way that increases the relative’s fitness enough to offset the individual’s own decrease in fitness.
What is reciprocal altruism?
- a two-part interaction, beginning with one individual (a helper) assisting another (the recipient) in a way that initially decreases the helper’s fitness while benefiting the recipient.
- The recipient then becomes more likely to return the favor in the future.
What additional element did the scientific method add to observations/formulating hypotheses?
Testing of the predictions (specific to the hypothesis by a series of additional observations)
Give an example of evolution that is not also natural selection.
Change in allele frequencies in cheetahs when they went through a population bottleneck effect about 10,000 years ago.
What are the three explanations which, taken together, represent a “complete theory of kindness”? Give examples/
1) Kin Selection/Shared genes
Ex: murder should be less common among relative than non-relatives
2) Reciprocal altruism
Ex: vampire bats
3) Maladaptive behavior (due to mismatch)
Ex: older female Beldings squirrel will still call out if you a move her to a new environment w/ unrelated individuals
