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165 Cards in this Set

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What did Darwin say are the conditions needed for natural selection to occur?
(1) phenotypic variation (implying that the genotype is not the same)
(2) at least some of the phenotypic variation is inherited
(3) there os a differntial survival, reproduction, mating (all components of fitness)
(4) there is reproductive excess (greater than replacement)
Why is it that when you have repoductive excess, descendence may end up looking different from ancestors
When population density is low, the pop. growth rate is high. When pop. density is high, natural selection (competition for resources etc..) is also high
So, not all individuals survive. The ones that do are more fit.
(dN/dt) = rN [(k-N)/k] represents what growth modle?
what does k stand for?
What happends when N is large? small? what does this mean?
This is the equation for the logistical modle for growth. k= the carry capacity of th environment. At k the birth rate = death rate. (N is individ.) When N is large the [eqt] apprch 0 (meaning the growth rate apprchs 0)When N is small the [eqt] appr. 1 (meaning the growth rate is at a maximum)
This means that at places near K there is more intense natural selection
What is a discrete trait?
One that is located at 1 or a few loci
Hb blood type
What is a quantitative trait?
One that is represented by mant different loci
What is a loci?
an address for a trait
eye color loci
What are alleles?
alternative versions of a trait
blue eyes, green eyes
What is the original source of variation?
What are the different allels of the Hb blood type trait? How do they behave? What phenotypes do these allels represent?
Hb a, Hb s, Hb c are the diff alleles. They are codominant.

allele combo = genotype/phenotype
Hb a Hb a = normal genotype /no resistance
Hb a Hb s = sickle trait/ some malaria resistance
Hb s Hb s = sickle genotype/sickle disease
Hb s Hb c = normal /no resistance
Hb c Hb c = .../high resistance
When is natural selection weakest (in relation to a growth curve)? Why?
Natural selection is weakest when the population's growth rate is fastest, becuase most individulals will able to sucessfull reproduce.
When is natural selection strongest (in relation to a growth curve)? Why?
It is fewer when there are population size limits (like near the K or carry capacity of a logistical model), becuase fewer individuals will be able to reproduce many offspring.
What are density-dependent effects analogous to?
allele effects
When do density-dependent or allele effects take place?
In logistical growth, when there is a high or low density the population growth rate will be influenced.
ex: few mates at low density
ex: disease spreads faster at high density
What is an example of a discrete trait in humans?
ABO blood in humans
What is a discrete variation?
Phenotypic variation that comes in a few categories and is controlled by one or a few loci; discrete variation involves alleles that are dominant, recessive, or co-dominant
What is an example of a quantitative variation in humans?
What is a quantitiative variation?
phenotypic variation with many categories that are not easily sorted into a few categories; these traits are usually controlled by many loci, each with a small effect on the phenotype
Concepts of dominance, recessiveness, and co-dominence do not apply to quantitative variation
What is a single nucleotide polymorphism? SNP?*** look up and edit w/book***
a change in one nucleotide. It is quite common
What blood type is more resistant to malaria?
sickle trait HbA HbS
What blood type causes sickle cell disease?
Where is the HbA HbS blood type most common? why?
HbA HbS is most common in areas where malaria is common, becuase when in contact with malaria the hemoglobin of this blood type will sickle and be destroyed. The malaria doesn't have a chance to spread and there may exist differencial survival of individuals with this blood type, making it more likely that these individuals will mate and pass on this variation.
In an environment where malaria is NOT common why is the HbA HbS trait not selected for?
Having the HbS allele increases the chances for passing on sickle cell disease (forming a heterozygote HbS HbS) This is selected against becuase the heterozygote HbA HbS has no higher fitness in this enviroment thatn the normal HbA HbA
How could the dominance or recessiveness of an allele change depending on enviromental conditions?
Under some environmental conditions, a heterozygote has a distinctive phenotype that is favored (or not) by natural selection; in other environmental conditions, a heterozygote may have the same fitness and therefore the same phenotype as one of the homozygotes, which means one of the alleles is being masked by the other.
How do you calculate the frequency of an allele?
# specific allele/ total
What would be the allele frequency?:
AA= .33
Aa= .34
aa= .33
A= 50%
.33 + .5(.34)= .50
What causes non random mating?
Positive assortitive mating
nagative assortitive mating
What does random or nonrandom mating change?
Genotype and phenotype frequencies but NOT allele frequency
What is positive assortitive mating? Example?
When similar phenotypes mate with each other. HbA HbS mating with HbA HbS in an environment where malaria is prevelent b/c this genotype has a higher fitness and differentiable survival.
What is negative assotritive mating?
opposites attract
How do you determine if there is negative assortitive mating?
After calculating Hardy Weinberg genotype frequencies, if there are more heterozygotes than HW then there is evidence for negative assort.
How do you determine if there is positive assortitive mating or inbreeding?
It after calculating the Hardy weinberg frequencies the mumber of heterozygotes is less than HW there is evidence for positive assort. or inbreeding
What is genetic drift? How does it effect vartiation?
Sampling error sue to chance can cause a change in allele frequence especially in a SMALL POPULATION. This may cause the fizating of an allele and the loss of genetic variation
What is the frequency of a fixed allele?
What is a homologous chromosomes?
chromosomes that carry the same loci (address) an allele is what lives at the locus
What is polymorphism?
When there are 2 or more alleles at a locus
What prevents inbreeding in plants?
The S locus: only the S pollen the plant DOESN'T already have will pollinate the plant
What is gene flow?
What can gene flow do?
1) cause one time colonization (in this case genetic drinft opperates)ex: new isalands
2) ongoing gene flow can reduce differences in populations (mixing or homogenization)
3) ongoing gene flow can prevent adaptation to local environments ex: banded water snakes
When does natural selection occur?
1) zygotic natural selection
2) before reporduction
How are sexual selection and natural selection related?
Both change alolele frequency but sex selection is related to loci related to attracting a mate
Why is something recessive?
The allele that causes recessiveness is non functional or less functional.
An organism will use the functional allele
What is easier to eliminate via selection, a dominat or recessive allele?
Dominant alleles can be eliminated by selection. Recessive alleles can hide under the dominant phenotype
What is directional selection?
When one extreme of the curve greater fitness. As a result the curve shifts position in one direction.
what is stabilizing/normalizing selection?
With QUANTITATIVE traits, it causes the curve to get thinner EX: birth weight in babies
What is balencing selection?
A special case for discrete traits with Co-dominance when the heterozygote is favored becuase of a distinction from the two homozygotes
EX: Malaria resistance in HbA HbS
What is diversifying or disruptive selection?
When either extreme of a trait is adventagous.
EX: beak size in finches (big beak for certain seeds, small for others)
What is cyclical or seasonal selection?
depending on the season/environment selection goes back and forth
EX: insects and winter make J- growth curves
What is frequency-dependent negative selection?
The more rare an allele the more fit it is
EX: S locus in plants
What is frequency-dependent positive selection?
The more common a trait the more fit it is
EX: Mullarian mimicry
How is fitness and frequency related?
Fitness is positivly correlated to frequency; high frequency phenotypes have greater fitness
What types of selection reduce genetic variation?
directional, stabalizing/normalizing (birth weight), and positive frequency dependent
What types of selection increase or maintain genetic variation?
balancing (HbA HbS), disruptive/diversifying (beak size), cyclic/seasonal, negative frequency dependent
How does genetic drift affect variation?
Almost always reduces variation by causing fixation or loss of alleles due to sampling error; greates effect in small populations.
How does mutation affect variation?
it increases gen. var. by producing new alleles
How does gene flow affect variation?
usually increases variation by introducing new alleles
How does non-random mating effect variation?
It canges the genotype (and phenotype) freq but NOT allele freq.; may influence action of selection by changing freq. of phenotypes available for selection
How do selection and genetic drift interact?
In small pops, selection must be stronger to overcome the random effect of drift (to prevent smtng like founders effect); weak selection can opperate in large pops
How do selection and gene flow interact?
Gene flow mixes local pops so strong selection may be needed to overcome it
EX banded snakes
How do selection and mutation interact?
Selection removes harmful dominant mutations by selecting against heterozygotes; harmful recessive alleles cannot be removed until they accumulate high enough levels to form homozygotes.
How do selection and random or non-random mating interact?
see book
Give an example of when sexual selection and natural selection oppose one another
peacocks: bright display attracts mate but also attracts predators
Give an example of when selection pressures oppose each other at different parts of life
larvae vs. adults of perrpered moths: larvae that are dark absorb more heat and grow faster due to a higher metabolic rate. But, dark adults sitting on pale tree bark are more easily seen be predators
What is the type of mimicry in which a harmless species looks like a harmfull species to avoid predation?
Batesian mimicry
What is the type of mimicry in which all harmfull species converge on one advertisement to prevent predation?
Mullerian mimicry
Mullerian mimicry is an example of what type of selection? why?
positive freq. dependant selection b/c the more alike all of the harmful species look the more "trained" predetors are to avoiding them. (having the common phenotype makes you more fit)
What is the fitness effect of competition? short term impact? long term coevolution impact?
Fitness: -/-
Short term: Reduces pop size of both species: if competition is asymetric competitive exclusion reduces the range on one species
Long term: niche differentiation via selection to reduce competition
What are the fitness effects of parisitism? short term impact? long term coevolution impact?
fitness: +/-
short term: depends on parasite density and effectiveness of defenses
long term: strong selection on host for effective defenses; strong selection on parasite for traits that overcome defenses
What are the fitness effects of mutualism? short term impact? long term coevolution impact?
Fitness: +/+
short term: pop size of both species dependant on each other
long term: storng selection on both sepcies to maximize fitness benefits and minimize fitness costs
What does the term "red queen effect" refer to?
the coevolutionary arms race between predator and prey.
The change in rate of
What are the three types of mutualism?
defense mutualism
harvesting mutualism
mutualism for gamete transfer
What is an example of mutualism for defense?
ants the defend hycaenid catterpillars and pupa against predators in exchange for sugar
What is an example of a harvesting mutualism?
see book
What is an example of mutualism for gamete transfer?
flowers and bees
What is anagenesis?
change within a lineage
What is cladogenesis?
splitting one lineage to make two or more independently evolving lineages
What are the approaches to determining a species?
biological species concepts
phylogetic species concepts
What is the morphospecies copncept?
(change in form) if physical characteristics differ then the species differ
What is the Biological species concept?
pre/post zygotc seperation and reproductive isolation differenciate species
What is the phylogenetic species concept
Definintion of species is cased on shared ansestry
How do you define a species
There is a continuous exchange of genetic info among populations
What is homology? Example?
similarity due to shared ancestry. Ex: hom/hox genes
What is analogy? Example?
Similarity due to solution to same problem Ex: dolphin and ichthysaur (convergent evolution)
What do plants need water for?
To dissolve CO2
What is water potential? equation?
The tendency of a system to release water

wat pot= solute pot. x pressure pot
Is the solute potential (Psi S) in living cells usually positive or negative?
Is the pressure potentia (psi P) in LIVING PLANT CELLS usually positive or negative?
Is the pressure potential (Psi P) is xylem positive or negative? Whay
negative (1) Xylem is non living and (2)due to tension
Is the water in xylem under tension or pressure?
tension; it is like a rubber band being pulled up.
The evidence for this is that is you chop into a tree the water will retreat and air will rush in
What is the function of a guard cell?
When water is scarce the guard cell will close the pore in the leaf
What does a guard cell respond to?
Usually opens in light and responds to CO2 levels in leaf ( when CO2 is low, the guard cell will open)
How does a guard cell open?
When in light. potassium (K+) enters the guard cell, when this happends, The ΨS goes down, The Ψ goes down and the cell swells OUT to open. (The subsidiary cells provide to K+)
What are some systems a plant uses to prevent water loss?
a cuticle, leaf hairs, sunken guard cell
What is inside phloem?
sugar, some amino acids, auxins (it acts as sugar and signal transport)
What is the Ψs of phloem at leaves?
-1.7 (lots of solutes)
How does material is phloem move?
mass flow (pressure)
Where is the ΨP higher at source or at sink?
source (more solutes)
What are the structural characteristic od auxins?
unsaturated rings (dbl bonds)
acidic side chain (Cooh)
How do auxins work to enlarge cells?
Weaken cell wall and allow water to rush in, the cell volume increases, cell grows. When auxin leaves cell wall hardens and cell stays at new size
What is a flower made from?
The shoop apex (apical meristem)This is a determinate action and the plant cant go back
What signals a plant to flower? (the transplant experiment)
Once the tip becomes COMPETENT and there is an enviromental que the plant becomes DETERMINED and flowers
Why do Short Day Plants bloom?
becuase of long nights
What state is phytochrome in during daylight? dark?
Pfar red in light
decays slowely in darkness into P red
What are the ways in which a plant deals with drought?
During devolopment:
A. Leaf area adjustment ( leaf expression and leaf drop)**first line of defense (decreases need for water and evap surface)
B. Directed Root growth **second line of defence (enhances supply of water)

After development:
A. Stomatal closure (temporary or else plant will die)
What is the source of water that pressurizes phloem?
What is the definition of an auxin?
any molecule that induces coleoptile curvature by cell enlargement
What is the method by which auxin moves?
It is redistributed from the lighted side to the shaded side
What are the mechanisms by which plants promote outcrossing?
spacial (ie long stigma and short anthers)
temporal (differential maturation of gametes: egg fist, pollen second)
What is parthenocarpy?
seedless fruit (auxin production transfered to ovary wall instead of seed)
What chemical signals ripening?
What is an organism that produces its own heat from metabolism?
What is an orgaism that gets heat from the environment?
Per gram ______ have a higher metabolic rate than ____.
endotherms have a higher metabolic rate per gram than ectotherms
a solution that is hypotonic to another has a higher amount of solutes compared to the other solution
a soution that is hypertonic has a lower amount of solutes than the other
Is intrapleural pressure negative, positive, or both?
always negative
What is transpulminary pressure?
alveolar pressure - intrapleural pressure
What happends during inspiration?
1. intrapleural pressure drops (becomes more negative)
2. transpulmonary pressure increases
3. alveolar volume increases
4. alveolar pressure decreases
5. air rushes in
What happends during expiration?
1. intrapleurual pressure rises (becomes less negative)
2. transpulminary pressure decreases
3. alveolar volume decreases
4. alveolar pressure increases
5. air rushes out
What is the resistance to breathing?
the elasticity of the lung tissue and surface tension
What is complience?
change in volume/change in pressure
If you have a high PO2-50, what is your affinity for oxygen?
it is LOW
What are the cortical nephrons?
Short, 2/3 of nephrons, make high volume low concentration urine
What are the juxtamedullary nephrons?
longer, in medula, allow for high concentration urine
What does the proximal tubual do?
reabsorbs 2/3 of the filtrate
The decending loop of Henle does what?
it is permiable to water and not salt (passsive)
The ascending loop of Henle does what?
it pumps out solutes and is impermiable to water
What does the collecting duct do?
it controls the concentration of urine by being variable permiable to water
What is Mean Arterial Pressure (MAP)
difference in blood pressure between left ventricle and right atrium
How much blood is stored in the veins?
2/3 in veins (capacators)
What is the average blood pressure of the pulminary circulitory system? Why?
24/8 because it is a shorter system (with less resistance)
What is the average blood pressure of the systemic circ. system? Why?
120/80 because it is longer (with more resistance)
What is the right valve between the artium and ventricle called?
right atrioventricular or TRIcuspid valve
What is the left valve called?
bicuspid or mitral valve
What prevents valves from becoming everted?
papillary muscles
What is systole?
ventricles contracted
What is diastole?
ventricles relaxed
What is longer systole or diastol? Why?
diastol is longer in time becuase it allows time for ventricles to fill with blood
What blood vessles are most important for maintaining blood pressure during diastol? How do they do this?
The large arteries baloon out during systol creating potential energy. During diastol they rebound and put energy back into the system
What blood vessles are important for maintaining resistance in the circulatory system?
What blood vessles help redirect blood to where it is needed?
What is important to know about resistance?
resistance is inversly proportional to the radius raised to the fourth power!!!
what is the role of venules?
they are the primary site for chemotaxis (where white cells leave blood and enter infected tissues)
How much blood is stored in systemic circulation? pulminary? heart?
83% in systemic
12% in puliminary
5% in heart
What is important to know about the velocity of the blood?
The velocity of blood is inversly proportional to the cross sectional area of a blood vessle
What is Bernuli's principle? How does it apply to capillaries?
If the flow rate of a liquid is kept constant, a tube of larger area will have a slower velocity than a tube of a smaller area (small is fast)
However, becuase the COMBINED cross-sectional area of cappilaries is HUGE compared to the aorta the velocity of blood in ONE capillary is much sloer than the aorta
What happends in systole?
1. AV valves close (b/c pressure in venticle exeeds that of atrium) and isovolumetric contraction begins
during IVC there is a build up of force (rapid rise in ventric. press. but no change in volume)
2. when pressure of ventricles exceeds aortic/pullminary atery pressure the aortic/pulminary valves opens
3. there is rapid ejection of blood into the aorta/pul artery
4. when momentum of ventr is slower than aorta/pul artery the aortic/pul valve closes
**during systole the atrial pressure rises slowely b/c blood is returning to the atriums
What happends in diastole?
1. Aortic and pulminary valves close and isobaloonic relaxation begins
during IBR there is rapid relaxation of ventricle.
2. when pressure in atria excceds ventricles the AV valves open and blood flow in passivly
3. at end of diastole, atria contract and add 1/3 more blood to End Dias Vol
4. AV valves close
When are alle 4 valves closed?
AT begining of systole (iso vol cont) and begining of diastole (iso balo relax)
What does Starlings law say?
The larger the end diastolic volume the larger the subsequent systole stroke volume will be.
Why does Stroke volume increase during exercise?
The sympathetic nervous system causes the heart to he hyperdynamic (more powerful) because of norepinephrin
What is the most important mechanism for increasing cardiac output during exercise?
increased heart rate (also altered by norepi)
What does norepinephrin do?
1) increases stroke volume by increasing release of calcium into heart cells (which makes the heart more powerful)
2. increases heart rate by increasing activity of pacemaker cells in sinoatrial node
What does the AVN do?
resists elctrical activity and delays pacemaker signal from reachinf the ventricales
It prevents artia and ventricles from cotracting simultaniously and allows time for siastole
Explain SAN pacemaker potential
-pacemaker cells are self stimulatory due to inward leak current of sodium (funny current)
-inward current of calcium at rapid depolarization
-repolarization due to potassium outward current
How does norepin change the discharge of pacemaker cells?
causes more socium to leak in so it is easier to reach threshold
How does the parasympathetic NS decrease heart rate?
By allowing more potassium to leak out of pacemaker cells so it is harder to reach threshold
What is the importance of the plateau in muscle action potential?
prevents tanic contraction and allows sufficient Calcium to enter heart muscles cell to activate contraction
Why doesn'e EDV increase significantly during exercise?
a higher heart rate leads to less diastolic filling time but because flow rate of blood is higher the ventricles fill up with approx the same amount of blood
What factors by themselves cannot cause evolutionary change in a population
positive assortive mating and inbreeding (they dont change allele freq)
What will a phytoalexin degrading enzyme do to a plant?
plants that were normally resistant will be infected
What part of a plant recognizes the light signal to flower
leaves (organs responsible for water loss)
climacteric means?
What is a plant hormone that is a gas
What synthysizes ADH?
What does the sympathetic stimulation of excitatory cells in the SAN do?
increase conductance to sodium