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Biology 311D Final Exam Study Guide
Terms in this set (111)
Meiosis and Mitosis Week 1
- if chromosomes are close together, they are paired up in the process of meiosis
- replicated chromosomes: contains 2 identical double stranded DNA- molecules, the chromatids, that are joined at their centromere, in "s" phase of meiosis
- Haploid: a cell or organism with only one set of chromosomes (n)
- Metaphase in Mitosis: anaphase is happening and chromatids separate
- Metaphase 1 of Meiosis: tetrads align randomly (independent assortment) of chromosomes
- cells undergo cell division as part of the cell cycle
- Mitosis and Meiosis are preceded by replication of chromosome but w/ Meiosis, there are 2 splits
- Recombination: when the alleles from maternal and paternal pairs mix and trade DNA through crossing over that happens during prophase 1
- homologous portions of 2 non-sister chromatids trade places
- recombination chromosomes is what crossing over produces which combine DNA from each parent (they are NEW combos of genes and contribute to genetic variation in gametes)
- Independent Assortment: maternal/paternal chromosomes randomly lining up in metaphase 1
EX: 3 homologous pairs- 2^n=2^3=2x2x2=8
Mendelian Genetics Week 2
- The pattern of inheriting characteristics that follows the laws formulated by Gregor Mendel
- Punnett Square: predict the ratio of offspring genotypes and phenotypes when given info about parental phenotypes and the dominance pattern
- Chiasma: the crossing over point where breaking of chromatids happen
- Phenotypes: appearance of genetic composition
- True Breeding Parents: homozygous, offspring are always going to have the same offspring bc of a homozygous dominant trait (P generation)
- F1 generation is the offspring of P generation, the offspring self/cross pollinated and made F2 generation
- Law of Segregation: 2 alleles for a heritable character segregate (separate from each other) during gamete formation and end up in different gametes
- Diploid cell: an organism inherits 2 copies (2 alleles) of a gene, one from each parent
EX: if a cell is 2n=8...diploid
after S: 2n=8 (replicated)... diploid
after MI: n=4 (replicated)... haploid
after MII: N=4 (normal chromosomes)... haploid
- Gamete: sex cell, egg/sperm, gets only one of the 2 alleles that are present in somatic cells of the organism making the gamete
- Genotype: allele genetics of an organism\
- Law of Independent Assortment: 2 or more genes assort independently, each pair of alleles segregates independently of any other pair during gamete formation
- Allele: version of a gene
- meiosis explains laws of allele segregation: separation of homologs during anaphase 1 accounts for the segregation of the 2 alleles of a gene into separate gamete; each haploid gamete gets only one allele of each gene
- meiosis explains independent assortment: random arrangement of chromosome pairs at metaphase 1 accounts for independent assortment of the allele for 2 or more genes located on different homologous pairs. The destination of one allele is independent from one of the other alleles
- Sex-linked genetics: pattern of inheritance from that produced by genes located on autosomes
- Dominant alleles: both dominant homozygotes and heterozygotes show the disorder (ex: achondroplasia, Huntington's disease)
- Recessive alleles: disorder shows up only in people that are homozygous for the recessive allele (ex: Cystic fibrosis, sickle-cell disease)
- Complete dominance: the phenotypes of the heterozygote and the dominant homozygote in F1 hybrids are indistinguishable
- Incomplete dominance: F1 hybrids have a phenotype somewhere between those of the 2 parental varieties
- Co-dominance: the 2 alleles each affect the phenotype in separate, distinguishable ways
- Epistasis: the phenotypic expression of a gene at one locus alters that of a gene at a second locus
- Polygenic inheritance: when 2 or more genes have an additive effect on a single phenotypic character
homozygous recessive= aa, bb
homozygous dominant= AA
heterozygous= Aa, Bb
- Each allele codes for a version of a protein (allele NOT= gene NOT= allele)
- the enzyme that codes for the recessive gene is not functional
EX: albinism in humans occurs when both allele at a locus produce defective enzymes in the biochemical pathway leading to melanin
- Evolution and Population genetics
- Natural Selection
Natural Selection: process of differential survival and reproduction
- occurs when, due to genotype, some individuals have phenotypes better suited to their environment (better adapted)
- more likely to survive and reproduce
- over time, as better-suited individuals in each generation have offspring, the allele frequencies can change
Microevolution: allele frequencies changing from generation to generation
Population: group of individuals of the same species living in the same area that can interbreed and produce fertile offspring
- genetic makeup can be characterized by its gene pool, every copy of every type pf allele at every locus for all the members of a population
Directional Selection: shifts the overall makeup of the population by favoring variants that are at one extreme of the distribution
Disruptive Selection: favors variant at both ends of the distribution
Stabilizing Selection: removes extreme variants from the population and preserves intermediate types
- Adaptation: an inherited characteristic that enhances an organism's survival and reproduction
- Darwin discussed descent with modification in which shared ancestry and an accumulation of difference over time resulted in a changing population
-Adaptive Evolution: evolution by natural selection; as long as there us genetic variation in a population, some members of the population will be better adapted for their environment and can pass that on to their offspring
INDIVIDUALS DO NOT EVOLVE: populations evolve over time as certain individuals live and reproduce or die
- for a gene/ locus with 2 alleles, "p" is often used to represent the frequency of 1 allele, while q represents the frequency of the other allele
- if a locus has more than 2 alleles, the frequencies of all of them must still add up to 100% or 1
Hardy-Weinburg Equation: p^2 + pq + q^2 =1
Species concepts and processes of speciation Week 5
Briefly describe the biological, morphological and phylogenetic species concepts, listing pros and cons. Outline the role of reproductive isolation in speciation.
Biological Species Concept:
- species is defined as a group of populations where the members can interbreed and produce viable, fertile offspring
- DO NOT breed successfully with other populations
Morphological Species Concept:
- defines just by structural features
- can apply to sexual and asexual species
Phylogenetic Species Concept:
- smallest group of individuals that share a common ancestor on phylogenetic tree
- difficult to determine degree of difference
- applies to sexual and asexual species
Speciation starts by...
- barrier to gene flow needed for speciation
- then the 2 populations might accumulate enough mutations to make them different
- genetic differences that impede members of 2 distinct groups from producing viable, fertile offspring
- Pre-zygotic barriers- barriers before fertilization
- Post-zygotic barriers- barriers after fertilization
- prevent members of different species from producing offspring, or ensure that any offspring are sterile (role in speciation)
Phylogenetics Week 6
Interpret and use a phylogenetic tree to provide evidence for or against a hypothesis.
- the analysis of evolutionary, or ancestral, relationships between taxa
Taxon: biggest -> smallest
species (Panthera pardus) => Genus (Panthera) => Family (Felidae) => Order (Carnivora) => Class (Mammalia) => Phylum (Chordata) => Kingdom (Animalia) => Domain (Bacteria, Eukarya, Archaea)
make phylogenetic tree to show relationships or show hypotheses of relationships
Practical Phylogenetic Species Concept: individuals considered the same species should NOT be more than closely-related to members of the other species than to their own
Phylogenetic tree is a visual representation of a hypothesis about evolutionary relationships
- each branch point is called a node and it represents a divergence of 2 lineages (the simplest tree has 3 taxa)
- The three taxon statement: "Species 1 and 2 are more closely related to each other than either is to species 3"
- sister taxa: groups that share an immediate common ancestor
Pertaining to a taxon derived from a single ancestral species that gave rise to no species in any other taxa.
Evolution of plants and their major traits Week 7
Explain how plants adapted to life on land new features (roots, vascular tissue, leaves, pollen, seeds, flowers & fruit) arose through time.
- Multicellular eukaryotes evolved diverse adaptations to survive in different habitats
- 3 lineages evolved multicellularity independently: animal, plant, fungi
- symbiotic relationship btwn prokaryotes gave rise to eukaryotes
Serial Endosymbiosis: ancestor engulfed another prokaryote, but it survived and developed mutual relationship
- evolved to mitochondria through the endosymbiosis-> ancestral heterotrophic eukaryote
- photosynthetic prokaryotes were engulfed -> ancestral photosynthetic eukaryote
Advantages to Multicellularity:
- cell specialization: different tissues, different roles/ jobs
- take advantage of different environments, more adaptable?
- predator/prey survival
- cells can die and be replaced
- more complex in general, more diverse in abilities
Disadvantages in Multicellularity:
- higher energy needs
- complexity: interdependence on tissue/ organs
- complex cell division: difficult or slow to regenerate
- complexity: long time to reach maturity
- infection from smaller cells
How did multicellularity evolve?
- changes to evolve multicellularity
- cell specialization: differentiation into different cells (cell fate)
- cell communication/ coordination: especially for reproduction
- new energy/ nutrient requirements
Evolution of animals and their major traits Week 8
Describe the evolution of animals in the ocean from a single-celled common ancestor and how diversity in animals increased dramatically in the Cambrian (possibly due to evolution of predator and prey adaptations, or to the rise in O2 or to the evolution of new regulatory genes like Hox, or maybe all three!). Describe some features that allowed some lineages (like insects ortetrapods)to transition and diversify on land.
In general terms describe the trends of evolution in the hominin lineage and describe when and where our own species evolved.
Cambrian Explosion: Period of time during the Cambrian period (535-525 MYA) in which there was a rapid increase in the diversity of large animals
- most of the fossils recovered from the period belonged to bilaterians, whose members are bilaterally symmetric (like us) and have complete digestive traits
Hypothesis 1: Predators started acquiring adaptations for hunting, like claw, which led to prey species developing defenses, like hard shells (natural selection) - new predator/ prey relationships caused a decline in soft-blooded pre-Cambrian species
Hypothesis 2: Before the Cambrian explosion, there was a great increase in atmospheric oxygen
- this enabled animals w/ larger body sizes and higher metabolic rates to survive, and harmed those species who did not have these things
Hypothesis 3: the origin of Hox genes and other genetic changes that affected the regulation of development genes allowed for the evolution of new body forms
Hominin: the group of closely-related humans and extinct species
The process by which a blastula develops into a gastrula with the formation of three embryonic layers
Animal homeostasis &hormones Week 9
Describe the process of homeostasis, including the role of negative feedback.
Give brief examples of how the nervous system and endocrine system allow for coordination and control of animal bodies.
Tissues and organ systems need to work together in an animal's body meaning they need to be coordinated and controlled
1. Endocrine System: signaling molecules (hormones) released into the bloodstream by endocrine cells are carried to all locations in the body
- receptor cells respond to endocrine stimulus
- cell-surface receptors (for non lipid-soluble hormones) - hormones-receptors interaction will trigger changes at the plasma membrane that will be converted into a cellular response (signal transduction pathway)
- cytosolic receptors (lipid-soluble hormones) - hormone-receptor complex moves from the cytosol into the nucleus where it alters transcription of particular genes
2. Nervous System: nerve signal travels along neuron axons to the target cells (the ones that are connected with axons). It involves 2 types of signals:
1. Electrical Signal: change in voltage along axons
2. Chemical Signal: btwn neurons and neurons and target cells
Homeostasis: the capability of animals to maintain a relatively constant internal environment even when the external environment changes significantly
- animals that control their internal state and keep it constant independently from external fluctuations are called regulator (vs conformer - they change their internal state in accordance w/ the external environment)
- internal physical and chemical properties are generally maintained w/in a range of values or around a specific value (set point)
- set points and normal ranges for homeostasis are usually stable, however there can be changes associated to life stage (change in hormone balance during puberty) and some fluctuate cyclically (female hormone responsible flor menstrual cycle)
Negative Feedback: occurs when some function of the output of a system, process, or mechanism is fed back in a manner that tends to reduce the fluctuations in the output, whether caused by changes in the input or by other disturbances
Ex: insulin released if blood sugar rises. insulin triggers liver to take up glucose
Energy & nutrient acquisition, transport, & waste Week 10
Give brief examples of specialized cells and tissues that allow multicellular organisms to get the nutrients they need and transport it throughout their bodies.
- Water and Mineral Transport through the Xylem
- Sugar Transport through the Phloem
Feeding Mechanisms of Animals?
Open/ Closed Circulatory systems?
Single circulation and double circulation?
Response to stimuli Week 11
Compare and contrast the pathways by which animals and plants respond to external stimuli.
Describe innate and adaptive immunity, including the role of B cells and T cells recognizing unique pathogens and responding to them (and "remembering" them) after clonal selection.
"Etiolation" - morphological adaptations from growing in the dark
- common in plants that sprout underground
- small leaves
- focus on elongation of stems
"De-etiolation" - greening response once shoot reaches sunlight
- leaves expand
- stem elongation slows down
- roots start to elongate
- shoots and leaves produce chlorophyll
Animals Response to Stimuli:
Neurons: specialized cell for transmitting electrical signal (membrane potential)
- inside neuron has negative charge, K+ ions
- outside neuron has positive charge, Na+ ions
- difference between inside and outside charge is the resting potential
Depolarization of membrane: when this charge difference is reduced
Cellular Innate Defenses
- toll- like receptors (TLRs) - toll describes characteristics fragments found on many pathogens
- Ex: TLR 3 binds dsDNA of viruses, TLR 4 binds lipopoly saccharides on bacteria
- Neutrophils - infected tissue signals, then neutrophils move from blood to engulf pathogen
- Macrophages - larger phagocytic cells
Pathogen - specific recognition also immune "memory"
- Lymphocytes (type of white blood cell) - Tcells and B cells
Antigen: any substance that elicits a B or T cell response
- B or T cells binds to an antigen via its antigen receptor
- recognizes the bacterial or viral protein
T cells: Lymphocytes migrate from bone marrow to the thymus, mature into T cells
B cells: Lymphocytes stay in bone marrow and mature into B cells
Animal behavior & population growth (pop ecology) Week 12
Explain how finite resources contribute to a carrying capacity of the environment for each species. Logistic growth is growth that slows as the population reaches its carrying capacity.
Logistic Growth (s-shaped curve):
- in natural world resources are not unlimited and there is a limit to the number of individuals that can occupy a habitat
- as the size of a population increases, each individuals has access to fewer resources -> population growth slows and eventually becomes stable at the carrying capacity
Carrying Capacity (K): maximum population size that a particular approx half K and then decreases; population stops to grow when N=K
Species interactions& community ecology Week 13
Explain interspecific interactions and trophic levels. Explain how atrophic cascade can occur if a keystone species is removed from an ecosystem
Use the concept of an ecological niche to explain "competitive exclusion" and "resource partitioning".
Competition: 2 members of different species compete for the same limiting resource (-/-)
- Competitive Exclusion: 2 species competing for the same resource can't permanently coexist in the same place
- Resource Partitioning: as long as at least 1 significant difference btwn 2 niches arises, 2 species w/ similar niches will be able to coexist
Exploitation: 1 species benefits by feeding on another species (+/-)
- predation: killing and eating a member of a different species
- parasitism: 1 organism gets nourishment from another organism that is harmed in the process
Positive Interactions: at least one organism benefits and neither is harmed (+/+) or (+/0)
- includes mutualism (both benefits) and commensalism (one benefits)
Trophic Levels: describes the feeding relationships of its organisms, most commonly represented by a food chain or groups of food chains called a food web
- both describe the transfer of energy from the primary producers all the way up to tertiary and quaternary consumers
- less energy is available as you move through the trophic levels- that's why plants are more numerous than carnivores- you don't see oceans overrun w/ giant sperm whales
Keystone species removed/ disappeared from the ecosystem=
- no other species would be able to fill its ecological niche
- the ecosystem would be forced to radically change, allowing new and possibly invasive species to populate the habitat.
Systems ecology and energy flow Week 14
Make a diagram showing how energy flows and matter cycles through different trophic levels in an ecosystem(including decomposers/ detrivores).
Energy flow in notes and on phone on WEEK 14
Trophic Efficiency: all the production efficiencies multiplied over the length of the food chain
- average of 10% energy of one trophic level goes to the next level
Biodiversity Week 15
Biological Diversity - variety of life on Earth
THREE LEVELS OF BIODIVERSITY:
Genetic Diversity: genetic variation w/in a population and between populations; extinction of a population decreases the genetic diversity of a species > less variation for adaptations and evolution
Species Diversity: number of species in an ecosystem or across the biosphere; interest in endangered species and threatened species (likely to become endangered in near future)
Ecosystem Diversity: variety of ecosystem on Earth; the local extinction of one species can have a negative impact on other species in the ecosystem
- human activities impact biodiversity and the effects can be local, regional, global
HUMAN ACTIVITIES IMPOACT ECOSYSTEMS -
- reduction or disappearance of natural habitats because of agriculture, urbanization, forestry, mining, pollution
- it can occur as:
- habitat destruction: a habitat is destroyed and not able to support its native species
- habitat fragmentation: a habitat is split into smaller pieces limiting capability of species to move and reducing their ranges
- it can lead to species displacement or species extinction if no alternative habitat is available or a species is not able to move
- harvesting of wild species at rates that exceed ability of populations to rebound or species reproductive rate
- outcome of exponential increase in human population and in the use of sophisticated tools
- can cause extinction of a local population or extinction of the whole species
- intentionally or accidentally (by ships, airplanes) introduction of non-native species in a new area by humans
- can spread rapidly because not subject to same parasitism or predation pressure at native species
- competition for resources with native species or predation on native species may lead to reduction/extinction of the latter
- addition of nutrients in the environment as a result of farming and agricultural activities (waste products and fertilizers)
- Negative effects on ecosystems when nutrient levels exceed the critical load - amount of nutrients that can be used by organisms w/out damages on ecosystems
- can cause extinction of a local population or extinction of the whole species
- introduction in the environment of chemical compounds (synthetic compounds, pharmaceuticals)
- can have negative effects on organisms (endocrine system disruptor)
- accumulate in organisms' tissues and undergo biological magnification (increases of toxin concentrations as we move up in the trophic chain)
- changes in the Earth's ecosystems and processes that govern the biospheres functioning
- result of many human activities such as emission of greenhouse gases, deforestation, introduction of toxins, pollution, etc... that affect the biosphere at a global scale
*Climate Change: one of the ongoing global changes: its the result of emission of greenhouse gases in the atmosphere and deforestation
- increase in global temperature
- changes in wind and rain patterns
- increase in severe weather events (drought, storms)
- melting of ice
- ocean acidification
EFFECTS ON CLIMATE CHANGE:
- alteration of key cellular process (enzymatic rates, cell division)
- heat stress on plants and animals: physiological and metabolic effects
- low resistance to diseases and pathogens
- shift in timing of migration. reproduction, blooming
- effects on survival and reproductive success
- changes in population's size
Community and ecosystem level:
- shift in geographical ranges of species
- habitat loss (ex: melting of ice in Artic regions)
- disruption of food webs and ecosystem's dynamics
CONSERVATION EFFORTS -
- efforts with the goal of protecting ecosystems and species diversity and maintaining/restoring habitats
- balance between science, technology, economy and society
-applied to different levels - form single species to ecosystems
Population Conservation: aims at safeguarding small populations or declining populations
- Small-population approach focuses on the processes that bring a small population to extinction ("extinction vortex"): efforts aim at increasing genetic diversity of a population
- Declining-population approach studies the environmental factors that cause the decline of a population and aims at restoring the species habitat
Ecosystem Conservation: aims at protecting communities and their physical environment
- Movement Corridors: connections between fragmented habitats
- allow species to cross barriers made by humans
- increase species dispersal and reduce inbreeding
- Protected Areas: areas of ecological and natural value, often hotspots of biodiversity
- zoned reserves: region with pristine areas surrounded by areas subject to human activities which don't harm core protected areas
IMPORTANCE OF BIODIVERSITY CONSERVATION:
- moral value: Earth is our home and we're connected to nature and species surrounding us
- interest in protecting single species w/ economical or medical value
- Ecosystems sustain human's life
- purify air and water
- detoxify and decompose wastes
- provide food, fuels, energy, and materials used in daily life
- cycle nutrients and maintain the soil
- regulate climate
- Ecosystem Services: all the processes mediated by ecosystems and the benefits that humans receive from the nature
- couldn't live without them
Consider a tomato plant that is heterozygous at the leaf texture locus. When this plant makes gametes, each one will get either the dominant allele or the recessive allele, but not both alleles for texture. What is this law know as?
Law of Segregation
Mendelian inheritance of recessive X-linked diseases differ from typical Mendelian inheritance patterns in that ___.
males with just one recessive allele will show the recessive phenotype
Fairy shrimp can have either red legs or white legs. The allele that leads to red legs (R) is dominant over the allele that leads to white legs (r). Fairy shrimp can have either frilly antennae or plain antennae. The frilly allele (F) is dominant over the plain (f) allele. In a crossing between two shrimp that are heterozygous for both traits, what is the expected ratio of RRFF offspring to offspring of all other genotypes?
Consider a character of wing shape on a cerulean warbler. Wings are blunt or pointy, with blunt being the dominant trait. A warbler with blunt wings could have the genotype of BB or Bb. Warblers have, on average, 3 eggs per nest. Which test-cross below would be most efficient at helping you find out the genotype of the mystery warbler?
Mate this warbler with a pointy-winged warbler and see what phenotypes the offspring have.
Color blindness is an X-linked recessive disorder. If a man who is colorblind has kids with a woman who is not colorblind (but whose mother was colorblind),______ percent of their children will be colorblind,_____ percent of their daughters will be color blind,_____ percent of their daughters will be carriers, and _____ percent of their sons will be colorblind.
Imagine you are studying the genetics of plant traits and are using flower shape (tubular or campanulate) and leaf texture (glossy or fuzzy).
Tubular is dominant over campanulate flowers, and
Glossy is dominant over fuzzy leaves.
You initially crossed truebreeding tubular glossy plants to get heterozygous offspring. Then you cross those heterozygotes together.
According to normal Mendelian inheritance patterns, what percent of the offspring from the heterozygote crossing should have tubular flowers and glossy leaves?
A Cumberland elktoe (mussel) has two unlinked genes, one for shell color (C) and one for shell length (L). Its genotype is CcLl. Which of the following genotypes for these two genes is possible in a gamete from this organism?
P_ pea flowers are purple and pp pea flowers are white. Which of the following explains Mendel's pea plants' color dominant/recessive phenotypes on a molecular level?
The amount of protein produced by plants with just one "P" allele is sufficient to make their flowers look purple.
When Thomas Hunt Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and white-eyed flies. All the white-eyed flies were male. What was the explanation for this result?
The gene involved is on the X chromosome.
A skin cell of a whistlegig contains 48 chromosomes. Write in the appropriate number for each of the following whistlegig cells: a bladder cell has_____ chromosomes, sperm have ______chromosomes, a bone cell just after S-phase of mitosis has _____ chromosomes, a liver cell has_____ homologous pairs of chromosomes, and a zygote has_____
Consider a diploid cell for which 2n=36 that undergoes meiosis. When you sample the chromosome content of a daughter cell after meiosis I you find that the maternal copy of chromosome #12 and the paternal copy of chromosome #17 are in the same daughter cell. What led to this pairing of #12 maternal with #17 paternal? Choose all correct answers and no incorrect answers.
- independent assortment of chromosomes
After cytokinesis of meiosis I, there are two cells from the original one cell. What can be said about each of these two cells? Choose all correct answers.
- They are identical to the parent cell
- They contain replicated chromosomes.
- They are haploid.
- They have two chromatids per chromosome.
Which of the following describes a pair of homologous chromosomes? (choose all that apply)
- 2 copies of the same chromosome in a nucleus: one copy originally donated by the sperm and the corresponding copy originally donated by the egg
- in a diploid organism, two chromosomes of the same length, containing the same genes in the same order.
Which of the following is/are NOT a source of variation due to sexual reproduction?
- Adapting to new environmental conditions
- Organisms can sometimes take up DNA from external sources
- Random mutations during DNA replication
Which aspect of meiosis has the greatest effect in maintaining genetic variation in a population?
independent assortment of chromosomes
What is true of natural selection?
Natural selection can lead to beneficial mutations increasing in frequency in a population.
A lemur specialist travels to a remote island and finds a population of lemurs that she does not recognize as a known species. She takes photographs and audio recordings of lemurs performing mating calls. From analysis of the data she gathered, she determines that the island group is a new species of lemurs! Given that she used only this data, what species concept is this biologist using when she asserts these are new species?
- morphological species concept
- biological species concept
Consider two very closely-related subspecies of snakes. One subspecies feeds on frogs and small fish that live on the edge of a creek in a forest. The other snake subspecies feeds on rodents that live in the roots of trees of the forest. They can mate and produce offspring, but they do not. Which one of the following is preventing these snakes from mating and producing offspring?
Bunny Rabbits have either brown or white fur and the brown trait is dominant over white. You collected data on a RB population of 900 rabbits and calculated q to be 0.65. Assuming Hardy-Weinberg equilibrium at this locus, how many of this population had brown fur?
close to 520
Consider a crossing between a horse species "X" (2n=64) and donkey species "D" (2n=62). The F1 offspring are mules (healthy and vigorous), but mules do not reproduce sexually. Why is this?
Mule cells contain a chromosome without a homolog, so meiosis cannot proceed reliably.
Organize the events (in time) in the sequence that would be most likely to promote speciation.
Earlier in time (1 species)
1. Two overlapping populations of "prairie dogs" (pop A and pop B) occupy the prairie grassland of Kansas and there is occasional gene flow between them.
2. An earthquake separates population A from population B.
3. Pop A and pop B are genetically different because of genetic drift.
4. Different random mutations accrue in each population and do not spread to the other population.
5. Because each population has its own combination of deleterious mutations, any potential matings between dogs from A and dogs from B result in a lethal combination of harmful alleles.
The present (2 species)
Sympatric speciation requires ___.
reproductive isolation between members of a single population
In a population of Katz, there is variation in whisker texture, and this character is controlled by 1 gene. The "W1" allele confers straight whiskers, and the "W2" allele confers tightly curled whiskers. Individuals that are heterozygous at this locus have whiskers that are slight wavy. You have carefully recorded data on this fox population, and you think you have counted them all. There were 73 straight-whiskered individuals, 375 wavy-whiskered individuals, and 87 curled-whiskered individuals. What is the frequency of the W2 allele in this population?
Which of the following observations influenced Darwin's reasoning on the mechanism of natural selection? Choose all that apply and none that do not.
- Each generation produces more offspring than are able to survive and reproduce.
- There is heritable phenotypic variation between members of a population
A population of glowbugs has 126 individuals with short antennae and 24 individuals with long antennae. Antennae length is inherited in a complete dominance pattern, with "short antennae" dominant over "long antennae".
Consider the Rock Pocket Mice in the American Southwest. At one point in the past, most of the mice had light tan fur, but many areas now have predominantly dark furred mice. Which of the following is the best explanation for this?
Random mutations naturally occur, and some mutations change fur color. At some point in time, the environment changed, causing dark mice to have more offspring than light mice, and the dark allele increased with each generations.
Which of the processes will NOT alter allele frequencies in a population from one generation to the next? Select all that apply.
- Recombination (crossing over) due to sexual reproduction
- Random mutations to somatic cells
- Individuals in a population gaining new skills in their lifetimes
Studies have shown that as individuals struggle to achieve a skill or solve a problem, their neurons make new connections and they become more intelligent over time! Would this be considered microevolution?
No, because evolution is not measured at the level of an "individual".
Given your understanding of how evolution by natural selection works, which conditions foster evolution by natural selection in a population? Select all that apply and none that do not.
- Resources are limited
- New mutations appear in each generation
- Competition for food keeps some phenotypes from surviving
Many scientists believe that in the very early evolution of prokaryotes, DNA was routinely swapped between individual cells, giving them whole suites of new traits. Which of the following are implications for this scenario of ubiquitous horizontal gene transfer? Select all that apply.
- The base of the tree of life would be better depicted as a net than a tree with bifurcating branches.
- Acquisition of new traits did not depend solely on random mutation.
- Species concepts would be difficult to apply to these populations.
By reference to the tree above, which of these groups are monophyletic?
Lion, Sand Cat, Domestic Cat
Which of the following are traits that most land plants share, but that set them apart from their closest green algae relative? Select all that apply.
- Waxy cuticle covering on epidermis
- Embryos dependent on parent
- Apical meristems
In the life cycle of a mushroom, certain cells in the gills under the mushroom cap undergo _______, leading to a diploid ________.Then the process of ________ leads to the formation of haploid spores. After mitosis, cells of different mating types undergo _______, forming _______ cells, which may later form a fruiting body.
For which of the following reasons is self-fertilization evolutionarily beneficial?
Some genetic diversity among offspring and very high likelihood of successful fertilization and seeds.
Your friend buys you a plant from a nursery, but cannot remember what it is called. You examine the plant the first thing you notice is that it's of medium height (24 inches). This tells you that it is a probably a/an _______ plant. The salesperson also told your friend that this plant disperses spores, but not seeds. This tells you that it is probably a/an ______ .
The transition from an aquatic lifestyle to a terrestrial lifestyle was a major event for both plants and animals. It opened up an entirely new world and was a catalyst for further diversification. Which of the following traits of plants can be seen as an adaptation to life on land? Choose all that apply.
In the life cycle of land plants, a ______ ________ creates _______ via meiosis. These grow through mitosis into a ________ multicellular ________ . This stage makes gametes via mitosis. Gametes fuse via _______ , and a diploid zygote grows by mitosis into the adult sporophyte.
The following plant structures are listed with their function in flowering plant reproduction. Choose the TWO relationships below that are INACCURATE.
- Fruits provide nutrition for the growing embryo
- Sepals advertise an incentive for seed dispersers
The cactus family of plants are adapted to very dry environments.
The euphorbia family of plants is diverse and widespread, with members that live in many different habitats ("Poinsettias" are in this family - see picture below!)
Euphorbias and cacti are not closely-related, and their most recent common ancestor does not have spines and a thick, fleshy base. The similar morphology of Euphorbia horrida and Stenocereus thurberi shown above is an example of ______.
Which of the following are derived traits of amniotes that allow them to be better adapted to life on land? Choose all the apply.
- a fluid-filled egg protected by a shell
- lungs ventilated via rib cage
Under which circumstance would simultaneous hermaphroditism be advantageous for a particular species?
Population density for this species is very low
Which of the following characters are unique to animals? Select all that apply and none that do not.
- muscle cells
- nerve cells
Which of the following is a derived trait that distinguishes (separates) the Eumetazoa from Porifera?
The process of gastrulation
Which of the following trends are seen in hominin evolution? (select all that apply)
- increasing complexity of tool manufacture and use
- increasing bi-pedalism
- greater brain size to body size
Which arthropod characteristic facilitated some lineages to transition to life on land?
Spider monkeys are common to tropical areas from Mexico to South America. To which category do spider monkeys belong?
Increased terrestrial insect diversity is correlated with (choose all that apply)
- The appearance and radiation of angiosperms
- The evolution of flight
The oldest known fossil of a taxon that has been classified as belonging to the hominin group lived approximately ___ years ago.
From the list below select 3 proposed hypotheses for the burst of biodiversity in the Cambrian period.
1. Changes in regulatory genes
2. Increased oxygen levels allowing larger size / increased metabolism
3. Evolution of hard body parts useful in offense and defense
In humans, chemical digestion begins in the mouth, but mostly occurs in ___.
the small intestine
In order of action, the three glands involved in the hormone cascade pathway that leads from a stimulus of an infant "feeling cold" to a response of "increased metabolism" (and therefore heat) in body tissues.
Hypothalamus ->Anterior pituitary ->Thyroid
How does countercurrent exchange in fish gills allow for efficient O2/CO2 exchange?
As water meets an oxygen-poor gill capillary, it loses oxygen to the capillary. Although it doesn't have as much oxygen as it did before, the water will always be more oxygen-rich than the capillary it meets as it continues across the gills, so O2 continues to enter the blood.
Pepsin is a protein-digesting enzyme that works in the lumen of the stomach. How is pepsin kept from digesting the protein of the cells that produce it? Choose all that apply.
It works best at low pH, so is not functional in the regular environment of a cell.
Compared to carnivores, herbivores often have adaptations such as ________.
a relatively large cecum with bacterial mutualists
An example of the interconnection between the endocrine and the nervous systems is seen in ____.
a neurosecretory cell in the hypothalamus stimulating the anterior pituitary
Increasing surface area is an important quality to improve exchange of nutrients and waste. Which of the following examples are adaptations that increases the surface area to volume ratio? Select all that are correct.
- villi in the small intestine
- root hairs of plant roots
- branching of fungal mycelium
The force underlying the bulk flow of xylem sap begins with ____.
transpiration of water from the leaf stomata
For most plants, the sufficient acquisition of nitrogen includes all but _____.
gas exchange at the stomata
In a physiological system operating with positive feedback, _____.
the response to a stimulus will amplify the stimulus
In a general excretory system, blood or hemolymph under the force of hydrostatic pressure is forced through a filter of ______.
Animals stand to lose a lot of water when they excrete nitrogenous waste. For a body to counter this loss by reabsorbing water from the excretory tubule (the tube that contains the filtrate), the excretory tubule must pass through an area that is ____.
hyperosmotic to the filtrate
Why is uric acid (as opposed to urea or ammonia) an appropriate adaptation for birds? (only one correct answer)
- It's non-soluble. Soluble wastes like urea or ammonia would be trapped within a shelled egg of a bird or reptile and would accumulate to dangerous levels.
If you were able to record the pressure of a sieve tube (the column of phloem tissue) at different parts of a flowering plant, which of the following would you predict?
The phloem would be under positive pressure, and the pressure of flower petal phloem would be lower than the pressure of phloem in nearby leaves.
An animal that is an osmoconformer will have body fluids that are isosmotic with their surroundings. Osmoregulation for these animals requires much less energy than for osmoregulators. Yet osmoconformers still spend energy on regulating solutes. How can this be explained?
All animals need specific concentrations of particular solutes, concentrations that are typically different from that of their surroundings even while their overall osmolarity may match that of their surroundings.
Animals maintain relatively stable internal states for many variables through the process of homeostasis. The control and communication required is facilitated largely by the __ and __ systems.
In what types of species should natural selection favor monogamy over polygyny?
animals for which the male will have more viable, fertile offspring if he stays with one mate than he would if he had multiple mates that he did not stay with.
Imagine a hypothetical follow-up experiment in which, after 74 generations, 1/2 the R1-R3 population is put into a small enclosure, and they are kept at a high density environment for the next 20 generations.
In this new high-density R1-R3 population, what would you expect to see with regard to the allele frequencies between the 75th and 95th generations?
The ForR allele would increase in frequency.
When looking at a variety of life history traits, we see that some species have a lot of offspring, spending little energy on each individual offspring. Such species typically have very high rates of juvenile mortality. If fitness is measured by how many viable, fertile offspring an individual leaves, why does natural selection not lead to parents spending more energy on each individual offspring, thereby ensuring a higher survival rate in their young? Select all that apply.
- When there are so many offspring, mortality can be quite high, yet still many offspring survive to reproductive age. Thus the small amount of energy their parents spent per individual is not selected against.
- Energy is limited. If such an individual puts more energy into each offspring, they will have less energy for subsequent survival and reproduction, thus will have fewer viable offspring in the future. Over the lifespan of this individual, there is no fitness advantage to spending more energy per offspring.
A plant can stop the spread of a pathogen by forming lignin in the cell walls of the infected cells. What is necessary for this response?
The plant must have the specific "S protein" capable of recognizing specific effector proteins made by the pathogen
Animal response to stimulus involves sensory receptors, some of which are neurons. Those which are not neurons must ___.
stimulate the opening of ion channels in neurons.
Each spring, Neotropical migratory warblers fly north to their breeding grounds, where they feed on insects in shrubs and trees. What are standard ways for ornithologists to learn the size of the populations once they've reached their breeding grounds? Choose all that apply.
- Estimate the size by counting the number of nests in a given area and use it as a proxy for the number of breeding birds
- Estimate the size through a mark and recapture program (bird banding).
Male meadow voles are solitary and do not bond with or stay with a female after mating. If you were to experimentally modify male meadow voles to increase pair-bonding behavior, which modification would yield the most promising results?
Increase expression of ADH receptors in the brains of male meadow voles
You are studying the genetics of a population of jackalopes in Wyoming. Their range is an area of grassland bordered by forests, so it's easy to get an accurate count of this population. In July 2019 the population was 840. In July 2020 the population was 966. If the growth rate stays the same, what do you predict the population size will be in July 2021? Round to the nearest jackalope.
Which of the following is a characteristic of adaptive immunity?
It has the ability to detect very specific pathogens.
Why do populations grow more slowly as they approach their carrying capacity?
Density-dependent factors lead to fewer births and increased mortality.
Natural selection should favor foraging behavior that ______.
minimizes the costs and maximizes the benefits of foraging
In their response to gravity, both plants and animals ___.
rely on cells that detect dense particles
At certain low concentrations, auxin stimulates growth, but at high concentrations, auxin inhibits growth. An example of this inhibition is in ___.
The higher concentration of auxin on the "down" side of a root cells, leading to bending down.
In a local inflammatory response, mast cells release ________
which make blood vessels dilate. Macrophages and neutrophils release ________ , which increase blood flow (which also brings more neutrophils). A systemic inflammatory response will cause a fever.
The idea behind vaccination is to induce ___ without requiring the vaccinated individual to get sick.
clonal selection in B and T cells
It takes a great mass of primary producers to support a healthy ecosystem that includes tertiary consumers. This is because ___.
the trophic efficiency is only about 10%
Fly fishing is popular in Texas and brings tourism money into local economies. White trout are native fish often caught in Central Texas rivers. In 2015, non-native pink trout were introduced to three Texas rivers to make fishing even more interesting. These fish were chosen because they eat the same food source as white trout, so it was thought they would be able to survive.
What process explains why these three rivers no longer have white trout?
Net primary production per unit area is likely to be highest in which of the following ecosystems?
Consider this scenario: After a massive forest fire, the landscape is mostly barren. Lupines, members of the pea (legume) family, are able to colonize the area before most other plants. Their presence increases the nitrogen content of the soil. The best description of the relationship between lupines and the plants that become established later is ___.
Detrivores and decomposers are essential to ___. (choose all that apply)
- remove dead organisms and feces
- move nutrients from non-living matter to living organisms
Merry warblers feed on grubs (insect larvae) that crawl on willow trees along a river. Sprite sparrows feed mostly on flying insects but supplement their diets with grubs. Sprite sparrows typically lay 3-6 eggs per nest. In areas where they co-occur with merry warblers, sprite sparrows lay 3-5 eggs per nest.
The "interspecific interaction" between merry warblers and sprite sparrows is ___.
After some dramatic geological activity, a new volcanic island emerges in the Hawaiian Islands! Bacteria and other unicellular organisms colonize the area first. Because this area is quite dry, it will take a long time (many decades) before the first tiny plants are able to grow.
This is an example of ___.
Which of the following best depicts the effects of a limiting nutrient?
In a marine system, plant growth is limited to the availability of nitrogen and phosphorous.
In ecosystems, why is the term cycling used to describe material transfer, whereas the term flow is used for energy exchange?
The same materials are continually moving between biotic and abiotic sources, but new energy enters an ecosystem, moves through biotic and abiotic sources, and is eventually lost as heat.
Invasive species often have complex effects on a community. There is a term, "hyperpredation", which describes a situation in which a non-native predator has ample access to small and easy non-native prey. Given the access to ample food, the predator population grows, and subsequently begins to branch out to secondary native prey items.
This scenario closely matches the scenario that unfolded in the Santa Cruz Island community after the decline of the native Bald Eagle population. In this case, the non-native predators were ___ and their non-native prey were ___.
Golden eagles ; pigs
Choose the example(s) of common defenses against herbivory.
The carrying capacity of Yellowstone National Park for elk is heavily influenced by the amount of forage material for the elk (grasses, aspens, willows). However, when wolves were reintroduced to the park, it became clear that they also influenced the carrying capacity of the park for elk.
The influence of wolves is explained by ___.
the trophic cascade (top-down) model
You are part of a team analyzing various soils in different biomes. Given what you know about the role of decomposition in nutrient cycling, which location do you predict the soil to have the highest carbon content?
a boreal forest
An organism's production efficiency can be described as ___.
the amount of energy that the organism consumes and uses to build its body
Which of the following defense mechanism(s) allow(s) prey to go undetected? Select all that apply.
ability to change coloring to that of surroundings
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