Download AP bio midterm review 9

Allopatric speciation (define, steps, example)- speciation occurs
because of a physical/geological barrier; canyon/mountain
range/river etc separates a species, over time the separated
organisms adapt to their new environment and eventually
cannot interbreed
Speciation
a. biological species concept (Ernst Mayr)
population able to interbreed & produce viable, fertile offspring
b allopatric = geographically isolated populations
Sympatric speciation (define, steps example)-speciation occurs
without a geographic barrier; isolation is “by choice” and due
to environment factors/preference sympatric = populations in same environment adapt
to fill different niches
Adaptive speciation (define, why, benefits?) – ex.
Galapagos finches; evolution occurs to fill an
environmental niche and (can) result in new species; adds
to diversity of species, lowers competition for resources
Adaptive speciation occurs when biological interactions induce disruptive selection and the evolution of
assortative mating (nonrandom mating pattern where individuals with similar genotypes and/or phenotypes
mate with one another more frequently than what would be expected under a random mating pattern), thus
triggering the splitting of lineages.
Homologous structures?- same ancestral origin with different
function; ex. Human arm compared to sheep leg or bird wing
or seal flipper
Analogous structures? Different origin but similar function
because the environment chooses for that trait; ex sugar glider
vs flying squirrel; bee wings vs bird wings
Natural selection, evidence for and principles? A possible
mechanism for evolution; those with the preferred inheritable
traits are selected for survival and reproduction; genetic
variation, overproduction, competition (struggle to survive),
natural selection is always happening; fossils, biochemistry,
vestigial structures, homologous structures, analogous
structures, comparative embryology
Coevolution? Where the evolution of one species drives the
evolutionary change of another species (like cheetahs and
antelopes)
Hybrid vigor? Mix between two different species, beneficial
traits from both original species (usually infertile) ; An increase in the
performance of hybrids over that of purebreds outbreeding enhancement, is the improved or increased function of
any biological quality in a hybrid offspring.
Geographic isolation? (see allopatric speciation); isolated
species because of barrier, increase variability (within a
species), increase biodiversity (more species)
Convergent evolution? Similar traits evolve for different
organisms due to environmental selective pressures
Divergent evolution? Species with common ancestor become
new separate species (usually due to isolation)
Defensive adaptation? Like odors, toxins, cryptic coloration,
camouflage, warning coloration, aposematic coloring
Adaptive radiation? Where one species gives rise to several new
species (Galapagos finches); Adaptive Radiations can be a direct consequence of 4 of
the following 5 factors. Select the exception.
A. Vacant ecological niches
B. Genetic drift
C. Colonization of an isolated region that contains suitable habitat and few competitor species.
D. Evolutionary innovation
E. An adaptive radiation in a group of organisms(such as plants) that another group use for food.
It occurs when a variety of new forms—including new related species—adapts to and fills a variety of
ecological niches. Darwins Niches
Polymorphism? Many body forms (medusa/polyp of jellyfish;
this would be alternation of generations)
two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more
than one form or morph. In order to be classified as such, morphs must occupy the same habitat at the same time and belong
to a panmictic population (one with random mating).[
Describe the Miller/Urey experimentOrganic molecules may have been synthesized abiotically from
the early earth; he used inorganic compounds to create organic
by mixing CH4, NH3, H2 and attached voltage to it, over time
simple compounds like formaldehyde, hydrogen cyanide, and
complex molecules like amino acids and hydrocarbons were
made.
What is the endosymbiotic theory? There were prokaryotes (or
prokaryote like) that can generate their own energy that were
engulfed by other prokaryotes and eventually became
multicellular. Cyanobacteria (or photosynthetic bacteria) is
thought to be the 1st to be engulfed, then mitochondria.
Evidence: own DNA, their own membranes, their own
ribosomes, similar size to bacteria, similar structure to bacteria,
if we remove mitochondria/chloroplasts from cell they couldn’t
be replaced
Describe the early earth’s atmosphere?
Earth is 4.5 billion years old
b. abiotic origin
atmosphere of CO2, methane (CH3) & ammonia (NH3) energized by lightning & UV
rays
formation organic compounds in seas (Miller – Urey experiment)
formation of protobionts & then bacteria (3.5 bya)
Behavioral isolation? Isolation by choice, diurnal/nocturnal,
different breeding season, habits etc…
Genetic drift? Process by which chance determines fluctuations
in allele frequency (bigger effect on a smaller population); genetic
drift = effect of chance events; bottleneck effect (cheetahs); founder’s effect (European settlers in Americas); gene
flow
Polygenetic inheritance? Multiple genes determine inheritance
patterns
Heterozygote advantage? The heterozygote genotype is more
beneficial than either homozygote genotype, better
reproductive success, better survival rates, helps to maintain or
increase variability
Sexual selection? Intersexual: girl choosing guy; intrasexual:
competition for female; certain traits are favorable for
reproductive success; intrasexual selection, or competition between members of the same sex (usually
males) for access to mates, and intersexual selection, where members of one sex (usually females) choose members of the
opposite sex.
mechanisms:
pre-zygotic: habitat factors, temporal factors, behavioral factors, mechanical factors,
gamete factors
post-zygotic: reduced hybrid viability, reduced hybrid fertility
Sexual dimorphism?: secondary features that distinguish
between the sexes
Disruptive selection? The heterozygous genotype is selected
against resulting in the increase of both homozygous
genotypes
Stabilizing selection? Homozygous traits are selected against in
favor of heterozygous
Directional selection? Skewed toward either (not both)
extreme phenotypes (homo dom or homo rec)
Cryptic coloration?
allows an organism to match its background and hence become less vulnerable to predation or
recognition by prey.
Warning coloration?
(aposematism) is effectively the "opposite" of camouflage. Its function is to make the animal, for example a wasp or a
coral snake, highly conspicuous to potential predators, so that it is noticed, remembered, and then avoided.
C4 photosynthesis?

In this type of photosynthesis environmental CO2 is first incorporated into 4-carbon acids in cells
known as mesophylls. These acids are transported to other cells known as bundle sheath cells. In
these cells, the reaction is reversed, CO2 is released and subsequently used in the normal (C3)
photosynthetic pathway. The incorporation of CO2 into 3-carbon compounds is catalyzed by an
enzyme known as Rubisco.
In hot and dry environments C4 photosynthesis is more efficient than C3 photosynthesis. This is due to two
reasons. The first one is that the system does not undergo photorespiration, a process that runs counter to
photosynthesis (see below). The second one is that plants can keep their pores shut longer periods of
time, thus avoiding water loss
CAM photosynthesis?
crassulacean acid metabolism (CAM), exists in succulents such as cacti and other desert plants. These plants have the same
two carbon-fixing steps as are present in C4 plants, but rather than being spatially separated between the mesophyll and bundle
sheath cells, CAM plants have both carbon dioxide-fixing enzymes within the same cell.
These enzymes are active at different times, PEP carboxylase during the day and Rubisco at night. Just as Kranz anatomy is
unique to C4 plants, CAM plants are unique in that the stomata are open at night and largely closed during the day.
Glycolysis? Glucose 2 pyruvates, 2 ATP, 2 NADH
Krebs (TCA, Citric Acid cycle)? Pyruvate goes in (acetyl coa), 2
atp created, NADH, FADH2
Electron transport- gives the most ATP, oxygen is the final
electron acceptor, ATP synthase powers ADP->ATP; uses NADH
and FADH2 as the source of electrons for the ETC
Secondary consumer? Carnivores and omnivores
Primary consumer? herbivores
Detritovore? Decomposer, eats dead or decaying matter;
mushrooms bacteria worms
Symbiosis? Relationship between organisms
Commensalism? one benefits, the other neither benefits nor is
hurt
Mutualism? Both benefit
Parasitism? Benefits for one hurts the other
Predation? One organism consumes another
Law of tolerance? Certain range of environmental factors in
which organisms can survive
Ecological succession? Natural maturing process of an area;
primary succession: bare rock then pioneer plants leading to a
climax community; secondary succession: rebuilding after a
fire or farmland (already nutrient rich soil) then ultimately a
climax community
Net primary productivity?
NPP is a parameter used to quantify the net carbon absorption rate by living plants. NPP is the difference between
plant photosynthesis and respiration
Trophic pyramid? Energy flow (10% from each level reaches the
organisms above it), biomass, food chain
Biological magnification? A toxin gets magnified the higher up
the food chain, most concentrated toxin levels in the top
predators
Eutrophication? Premature aging of an environment
Trophic levels? See above
Organism? Anything that meets the 8 criteria of life; cells,
metabolism, homeostasis, reproduces, responds to stimuli,
growth and development, shows organization, adapts
Community? Any organisms and environment interacting
Habitat? The place where the organism normally lives (like
under a rock)
Ecosystem? Many communities interacting
Niche? your role in the environment
Tropical rain forest? Forest, humid, lots of biodiversity
Taiga? Cold,snowy, coniferous forests
Arctic tundra? Snowy, colder
Temperate grassland (you would call it a savannah)? Tall grass,
African animals, rainy season
Desert? Low precipitation, antartica, few trees
Exponential versus logistic growth? Exponential looks like a J
curve no limit to the population; logistic S curve because the
population can reach the carrying capacity
Cell cycle steps? Interphase (G1, S, G2) mitosis (P, M, A, T)
cytokinesis
Steps of interphase? G1- regular cell function; S-synthesis of
DNA, G2 getting ready for mitosis
What happens in cytokinesis? Cytoplasm divides; animals cell
divide at the cleavage furrow, plants divide at the cell plate
Mitosis steps? Prophase- chromosomes condense, nuclear
membrane dissolves, no nucleolus; Metaphase- lining up along
midline; Anaphase- sister chromatids separate toward the
poles; Telophase- separation starts, nuclear membrane starts
to reform
Big picture for mitosis? Make somatic cells; one parent cell
divides to create 2 daughter cells; clone of original cell
Binary fission? Bacteria reproduces this way; mitosis
Asexual versus sexual reproduction? Asexual- one parent, clone
of original; faster form of reproduction, no genetic variation ,
mitosis(unless by mutation), budding, binary fission,
parthenogenesis, regeneration
Sexual reproduction- meiosis, two parents, need sexual organs
(testis/ovum) fertilizes into zygote; increase genetic variation;
internal or external fertilization
Cell cycle checkpoints?
Cdk (cyclin dependent kinase, adds phosphate to a protein), along with cyclins, are major control switches for the cell
cycle, causing the cell to move from G1 to S or G2 to M.
What can occur because of faulty cell cycle?
MPF (Maturation Promoting Factor) includes the CdK and cyclins that triggers progression through the cell cycle.
p53 is a protein that functions to block the cell cycle if the DNA is damaged. If the damage is severe this protein can
cause apoptosis (cell death).
1. p53 levels are increased in damaged cells. This allows time to repair DNA by blocking the cell cycle.
2. A p53 mutation is the most frequent mutation leading to cancer. An extreme case of this is Li Fraumeni
syndrome, where a genetic a defect in p53 leads to a high frequency of cancer in affected individuals.
p27 is a protein that binds to cyclin and cdk blocking entry into S phase. Recent research (Nature Medicine 3, 152
(1997)) suggests that breast cancer prognosis is determined by p27 levels. Reduced levels of p27 predict a poor
outcome for breast cancer patients.
The sputum (fluid coughed up from the lungs) of many smokers contain cells with mutations (errors) in
the genes for p53. The smoking induced mutations appear to be an early signal showing that cancer of
the lungs will follow. What is the likely relationship between early p53 mutation and the development of
lung cancer?
A. p53 with a mutation directly stimulates the growth of cancer cells.
B. Mutations in p53 would prevent abnormal cells from dying by apoptosis.
C. Mutant p53 triggers the M phase of the cell cycle leading to abnormal cell division.
D. p53 causes a cell to enter G0, blocking cell division.
Cyclin/CDKs? See above
What can occur because of faulty cell cycle? See above
Big picture for mitosis (chromosome number before/after,
number of cells before/after)
Question: Prior to cell division, each chromosome replicates or duplicates its genetic material. The
products are connected by a centromere and are called:
A. sister chromosomes
B. homologous chromosomes
C. sex chromosomes
D. sister chromatids
Big picture for meiosis (same information as mitosis)?
Genetic variation; 1 diploid divides to make 4 haploid gametes
(men- 4 sperm; women 1 egg and 3 polar bodies)
Steps for meiosis?
Meiosis 1- tetrad forms (homologous chromosomes pair; cell cs
number is 4n); crossing over occurs in prophase (genetic
diversity, law of independent assortment); metaphase
homologs line up in middle; anaphase- homologous cs
separate into sister chromatids; telophase- start to divide along
cleavage furrow/cell plate (no nuclear membrane); cytokinesis
two cells form cell is now 2n
Major events that increase variation in a gamete?
Cleavage furrow?
Structure of cell membrane?
Diffusion?
Facilitated diffusion?
Active transport?
Osmosis?
Tonicity? measure of the osmotic pressure gradient (as defined by the water potential of the two solutions) of
two solutions separated by a semipermeable membrane
Hypertonic?
Hypotonic?
Isotonic?
Turgor pressure?
pushes the plasma membrane against the cell wall of plant, bacteria, and fungi cells as well as those
protist cells which have cell walls.
Water potential?
Water molecules move randomly.
When water is enclosed by a membrane some of the moving water molecules will hit the
membrane, exerting pressure on it.
o This pressure is known as water potential.
 It is measured in units of pressure, can be measured in kPa, MPa, bar.
 Pure water has a water potential of zero.
 A solution will have a lower concentration of water molecules so it will have a negative
water potential.
o
o
 We look at water movement in terms of water potential. (ψ psi)
 Two factors:
 Solute concentration and pressure
 Pure water ψ =0
 The addition of solute lowers the water potential. (negative number)
 Water potential determines the rate and direction of osmosis.
Signal transduction (generic) steps?
Enzyme that adds phosphate?
phosphorylases and kinases, which attach phosphate groups to their substrates by using energetic molecules like ATP.
Enzyme that removes phosphate?
phosphatase is an enzyme that removes a phosphate group from its substrate by hydrolysing
Density-dependent inhibition?
Mitochondria?
Nucleus?
Nucleolus?
Ribosomes?
Chloroplast?
Golgi apparatus?
Lysosome?
Plant cell traits?
Animal cell traits?
Hydrogen bonding?
Carboxyl group?
Carbonyl group?
Hydroxyl group?
Amino group?
Trace element?
Prokaryote cells?
Eukaryote cells?
Respiration processes (big pictures, steps, products/reactants,
energy use/production)?
Fermentation processes?
Photosynthesis processes ((big pictures, steps,
products/reactants, energy use/production)?
Coenzymes?
Allosteric inhibition?
Competitive inhibition?
Enzyme function?
Activation energy?
Exergonic reactions (exothermic)
An exothermic reaction is a chemical or physical reaction that is done by the release of heat. It gives out energy to its
surroundings. The energy needed for the reaction to occur is less than the total energy released.
Endergonic reactions (endothermic)
An endothermic process or reaction absorbs energy in the form of heat (endergonic processes or reactions absorb energy,
not necessarily as heat). Examples of endothermic processes include the melting of ice and the depressurization of a
pressurized can.
What is energy coupling?
a description of the energetic relationship between the reactants and products in an exergonic reaction
the use of an enzyme to reduce EA
a barrier to the initiation of a reaction
the use of energy released from an exergonic reaction to drive an endergonic reaction
the hydrolysis of ATP to ADP + P
Optimal foraging theory?
Optimal foraging theory is an idea in ecology based on the study of foraging behaviour and states that organisms forage in
such a way as to maximize their net energy intake per unit time. In other words, they behave in such a way as to find, capture
and consume food containing the most calories while expending the least amount of time possible in doing so.