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Biology Exam
| Term | Definition |
|---|---|
| Evolution | Change in one or more heritable characteristics of a population from one generation to the next. |
| Empirical thought | Relies on observation to form an idea or hypothesis. |
| George Buffon | Proposed that populations of living things change over time. |
| Jean-Baptiste Lamark | Examined fossils and realized that some animals remained the same while others changed over time. |
| Erasmus Darwin | Contemporary of Buffon and Lamarck and an advocate for evolutionary change; he noted how breeders changed the traits of domesticated plants and animals. |
| Darwin's thinking was influenced by | Work in other fields and his own observations on the Beagle's 5 year journey. |
| James Hutton and Charles Lyell supported which hypothesis? | Uniformitarianism hypothesis. |
| Uniformitarianism hypothesis | Slow geological processes lead to substantial change over time which implied that the Earth was much older than 6k years. |
| Thomas Malthus | Wrote about limits to population growth and that not all members of a population will survive and reproduce. |
| Darwin noted distinctive traits of island species which | Allowed them to better exploit their environment. |
| Darwin suggested that existing species are | Derived from pre-existing species. |
| Darwin expressed his ideas about evolution as | Theory of descent with modification through variation and natural selection. |
| Variations in traits | May occur among individuals of a given species; variations are based on genetic differences and are heritable (passed from parents to offspring). |
| In Natural Selection, | Individuals with heritable traits that make them better suited to their native environment tend to flourish and reproduce whereas other individuals are less likely to survive and reproduce. |
| As a result of natural selection, | Certain traits that favor reproductive success become more prevalent in a population over time. |
| Evidence that reflects the process of evolution | Studies of natural selection, fossil record, biogeography, convergent evolution, selective breeding, anatomical, developmental, molecular. |
| Fossils | Preserved remains of past life; the fossil record provides evidence of the history of life on Earth. |
| Transitional form | Displays an intermediate state between the ancestral form and the form of its descendants. |
| T. Rosaea had what features? | Broad skull, flexible neck, eyes on top of head, primitive wrist, and five finger-like bones. |
| Biogeography | Study of the geographic distribution of extinct and living species. |
| Endemic species | Species naturally found only in a particular location. |
| Convergent evolution | Occurs when two species from different lineages have independently evolved similar characteristics because they occupy similar environments. |
| What are similar characteristics called? | Analogous structures. |
| Selective breeding | Programs and procedures designed to modify traits in domesticates species. |
| What is selective breeding also known as? | Artificial selection. |
| What do humans do in selective breeding? | Human breeders select which individuals will reproduce based on desirable traits. |
| What makes selective breeding possible? | Genetic variation, humans have employed selective breeding for centuries. |
| What crop plants have been developed by selective breeding of the wild mustard plant? | Kohlrabi, Kale, Broccoli, Brussel sprouts, cabbage, cauliflower. |
| Homology | Similarity that occurs due to descent from a common ancestor; homologies may involve anatomical, developmental, or molecular features. |
| Provide an example of anatomical homology. | The arm bones of any mammal. Human, bat, turtle, whale. |
| Vestigial structures | Anatomical features that have no current function but resemble structures of presumed ancestors. |
| Developmental homology | Similarities that occur during development. Human embryos have gills even though they are supplied oxygen through the umbilical cord, human embryos have boney tails. |
| Molecular homology | Similarities that occur at the molecular level. Genetic sequences. |
| Gene pool | All of the alleles for every gene in a population. |
| Population genetics | Study of the genetic variation within a gene poll and how variation changes from one generation to the next. |
| Population | Group of individuals of the same species that occupy the same environment at the same time and can interbreed with one another. |
| Adaptation | A population becomes better suited to its environment. |
| Polymorphism | Presence of two or more variants for a given character within a population. |
| Polymorphic gene | Two or more alleles in a population. |
| Monomorphic gene | Exists predominantly as a single allele in a population. |
| How can genes become polymorphic? | Deletion, duplication, or change in a single nucleotide. |
| Single-nucleotide polymorphism (SNP) | Smallest type of genetic variation that can occur within a gene and is most common. |
| Large, healthy populations exhibit a ____ level of genetic diversity. | High. |
| Allele frequency formula | Number of copies of a specific allele in a population divided by total number of all alleles for that gene in the population. |
| Genotype frequency formula | Number of individuals with a particular genotype in a population divided by total number of individuals in the population. |
| For diploid species, | Homozygotes have 2 copies of a given allele and heterozygotes have 1 copy. |
| Hardy-Weinberg equation describes? | Relationship between allele and genotype frequencies when a population is not evolving. |
| For genes that exist in 2 alleles, | p+q=1, where p is the frequency of one allele and q is the frequency of the second allele. |
| For the Hardy-Weinberg equation to predict the allele and genotype frequencies, the population must be in | Equilibrium. |
| Hardy-Weinberg equation | p^2+2pq+q^2=1, where p2 is dominant homozygotes, 2pq is heterozygotes, and q2 is recessive homozygotes. |
| In a population, the frequency of a gamete carrying a particular allele is | Equal to the allele frequency in that population. |
| To be in equilibrium, | Evolutionary mechanisms that can change allele and genotype frequencies are not acting on a population. |
| What are the conditions for Hardy-Weinberg Equilibrium? | No new mutations, No natural selection, Population is so large, No migration, Random mating. |
| Microevolution | Changes in a population's gene poll from generation to generation. |
| How does microevolution happen? | Introduction of new genetic variation and evolutionary mechanisms that alter the frequencies of existing genetic variation. |
| Natural selection | Process by which individuals with certain heritable traits tend to survive and reproduce at higher rates than those without those traits. |
| Reproductive success | Likelihood of an individual contributing fertile offspring to the next generation. |
| Reproductive success is commonly attributed to 2 categories | Characteristics that make organisms better adapted to their environment and therefore more likely to survive and reproduce. And Traits that are directly associated with reproduction such as finding a mate. |
| Fitness (w) | Relative likelihood that one genotype will contribute to the gene pool of the next generation compared with other genotypes; fitness is a measure of reproductive success. |
| Genotype with the highest reproductive success is assigned a fitness value of what? | 1.0. |
| Different patterns of Natural selection | Directional, Stabilizing, Diversifying/Disruptive, and Balancing. |
| Directional selection | Individuals at one extreme of a phenotypic range have greater reproductive success in a particular environment. |
| Example of directional selection? | Mouse with light hair eventually fade within the population because mouse with brown hair is better suited to the environment. |
| Stabilizing selection | Favors the survival of individuals with intermediate phenotypes and selects against those with extreme phenotypes. |
| Example of stabilizing selection | Clutch size, too many eggs can lead to offspring dying due to lack of care and food, too few eggs cannot contribute enough to the next generation. |
| Diversifying (Disruptive) selection | Favors the survival of two or more different genotypes that produce different phenotypes. |
| Example of Diversifying selection | Grass on contaminated soil, both metal-sensitive and metal-resistant can grow. |
| Balancing selection | Maintains genetic diversity in a population. |
| Example of Balancing selection | Over many generations, it results in balanced polymorphism, where 2 or more alleles are kept in balance and maintained in a population. |
| What is involved in Balancing selection? | Heterozygote advantage and Negative frequency-dependent selection. |
| Heterozygote advantage | When heterozygotes have the highest fitness. |
| Negative frequency-dependent selection | Common individuals have a lower fitness and rare individuals have a higher fitness. |
| Who studied natural selection in finches on the Galapagos islands? | Rosemary Grant and Peter Grant. |
| What did the Grants study? | The finches beaks grew larger to eat larger seeds that were produced after the drought. |
| Sexual selection | Form of natural selection by which individuals with certain traits are more likely than others to engage in successful mating. |
| Intrasexual selection | Members of one sex, usually males, directly compete with each other for the opportunity to mate with individuals of the opposite sex. |
| Intersexual selection | Members of one sex, usually females, choose their mates on the basis of certain desirable characteristics. |
| Genetic drift | Changes in allele frequencies due to random chance. |
| Genetic drift favors | Either the elimination or the fixation of an allele. |
| Bottleneck effect | Refers to the change in allele frequencies of the resulting population due to genetic drift. |
| Example of Bottleneck effect | Green, brown, and yellow frogs wiped out by a hurricane, only brown and yellow are left. |
| Founder effect | Occurs when a small group of individuals separates from a larger population and establishes a new colony in a new location. |
| Neutral Theory of Evolution, proposed by Japanese evolutionary biologist Motoo Kimura. | Genetic drift promotes the accumulation of neutral genetic changes that do not affect reproductive success. |
| Gene flow | Transfer of alleles into or out of a population; it occurs whenever individuals move between populations having different allele frequencies. |
| Migration and Gene flow tend to? | Enhance the genetic diversity within a population. |
| Nonrandom mating forms: | Assortative, Disassortative, Inbreeding. |
| Assortative mating | Occurs when individuals with similar phenotypes are more likely to mate, decreases heterozygotes. |
| Disassortative mating | Occurs when individuals with dissimilar phenotypes are more likely to mate, increases heterozygotes. |
| Inbreeding | Occurs when individuals choose a mate that is part of the same genetic lineage, increases proportion of homozygotes and decreases proportion of heterozygotes. |
| Viruses are | Nonliving particles with nucleic acid genomes that must be taken up by living cells to replicate. |
| Viruses infect... | All types of organisms. |
| A virus is a | Small infectious particle that consists of nucleic acid enclosed in a protein coat. |
| Host range | Number of species and cells a virus can infect. |
| All viruses have a protein coat called | Capsid, which varies in shape and complexity. |
| Viral Envelope | Lipid bilayer derived from the host cell. |
| Viral Genome | Composed of DNA or RNA, may be single-or double stranded, and may be linear or circular. |
| Bacteriophages | Have complex protein coats. |
| Viral reproductive cycle | Results in production of new viruses and generally follows 5 to 6 steps. |
| Attachment | Attaches to the surface of the host cell. |
| Entry | Viral Genome into host cell. |
| Integration | Host's chromosomal DNA; occurs for some viruses that carry a gene that encodes integrase. |
| Synthesis of viral components | Occurs as the host cell machinery synthesizes new copies of the viral genome and viral proteins. |
| Viral Assembly | Occurs as synthesized components are assembled into new viruses. |
| Release | New viruses into the environment; phages lyse their host cell and enveloped viruses bud from the host cell. |
| What cycles do some bacteriophages follow? | Lytic cycle or Lysogenic cycle. |
| Lytic cycle | New phages are made and the bacterial cell is lysed. |
| Lysogenic cycle | Integrated phage DNA, called prophage, is replicated along with the DNA of the host cell. |
| During the lysogenic cycle | Viruses integrate their genomes into a host chromosome; the resulting prophage/provirus can be latent for a long time. |
| Emerging viruses | Arise via mutations in pre-existing viruses. |
| Antiviral drugs inhibit | Viral proliferation, although they cannot eliminate the virus from the body. |
| Bacteria typically have | Circular chromosomes that carry a few thousand genes tightly packed within a nucleoid region. |
| Compaction involves | Formation of loops and DNA supercoiling. |
| Loop Domains are | Formed through interaction with DNA-binding proteins. |
| Topoisomerases | Twist the DNA and control the degree of supercoiling. |
| Bacterial cells commonly contain | Plasmids that exist separately from the bacterial chromosome. |
| Resistance plasmids (R factors) | Contain genes that confer resistance against antibiotics and other toxins. |
| Degradative plasmids | Enable digestion and utilization of an unusual substance. |
| Col-plasmids | Encode colicins. |
| Colicins | Proteins that kill other bacteria. |
| Virulence plasmids | Turn a bacterium into a pathogenic strain. |
| Fertility plasmids (F factors) | Allow bacteria to transfer genes to each other. |
| Binary Fission | How most bacteria can rapidly produce new cells. |
| Bacterial colony | Group of genetically identical cells. |
| Binary Fission is what type of reproduction? | Asexual cell division. |
| What happens during Binary Fussion? | DNA replication produces 2 identical copies of the chromosome, the plasma membrane is drawn inward and new cell wall is formed, separating the 2 daughter cells. |
| Unless a mutation occurs, | Daughter cells are genetically identical to the mother cell. |
| Are plasmids also replicated in Binary Fussion? | No, they are replicated independently and are distributed into daughter cells during Binary Fussion. |
| Although bacteria reproduce asexually, what do they exhibit? | Genetic diversity through mutations and gene transfer. |
| What are the three different ways bacteria can transfer genes? | Conjugation, transformation, and transduction. |
| Conjugation | Requires direct contact between a donor cell and recipient cell. Donor cell transfers a strand of DNA to the recipient. |
| Transformation | A fragment of DNA from a donor cell is released into the environment. May happen when a bacteria cell dies, DNA fragment is taken up by a recipient cell which incorporates the DNA into its chromosome. |
| Transduction | When a bacteriophage infects a donor cell, it causes the bacterial chromosome of the donor cell to break up into fragments. A fragment of the bacterial chromosomal DNA is incorporated into a newly made bacteriophage. Transfers fragment to recipient. |
| Strains | Linages of same species that have genetic differences. |
| Which F cell has the fertility plasmid? | F+ cells have the fertility plasmid and F- cells do not. |
| Sex pili are made by? | F+ cells and specifically bind to F- cells. |
| What cells are capable of transformation? | Only competent cells with competence factors. Factors that facilitate binding, uptake, and incorporation of DNA. |
| Horizontal gene transfer | Refers to any process in which an organism incorporates genetic material from another organism without being the offspring of that organism. |
| Examples of horizontal gene transfer | Conjugation, transformation, and transduction. |
| Inheritance | Acquisition of traits by their transmission from parent to offspring. |
| Particulate inheritance | Idea that determinants of hereditary traits are transmitted in discrete units from one generation to the next. |
| What are the advantageous properties of pea plants? | Pea plants have many different characters each found in discrete forms called variants. |
| Trait | Identifiable characteristic of an organism, refers to a variant for a character. |
| True-breeding line | Line of plants that continues to exhibit the same trait after several generations of self-fertilization. |
| Hybridization | Two individuals of the same species with different characteristics are bred or crossed. |
| P (parental) generation | True-breeding and their offspring are the F1 (first filial) generation. |
| F1 offspring are | Single-character hybrids or monohybrids, they self-fertilize to generate the F2 generation. |
| F2 generation typically has a ratio of what? | 3:1, all tall with one dwarf. |
| Dominant trait | Trait that is usually shown in the generation. |
| Recessive trait | Trait that is masked in the first generation then reappears in the second generation. |
| Alleles | Variant forms of a gene. |
| Mendel's Law of Segregation | Two alleles of a gene separate from each other during the process that gives rise to gametes so that every gamete receives only one allele. |
| Genotype | Genetic composition of an individual, often represented with letters. |
| Phenotype | Physical or behavioral characteristics that are the result of gene expression. |
| Genotype and Phenotype ratios | Genotype 1:2:1 TT:Tt:tt Phenotype 3:1 Tall:Dwarf Phenotype ratio for dihybrid (AaBb x AaBb) 9:3:3:1 |
| Mendel's Law of Independent Assortment | Alleles of different genes assort independently of each other during the process that gives rise to gametes. |
| The nucleus of a diploid cell contains | 2 sets of chromosomes, which are found in homologous pairs. Maternal and Paternal sets of homologous chromosomes each carries a full complement of genes. |
| Locus | A gene's physical location on a chromosome. |
| What explains the patterns in Mendel's Law of Segregation? | Pairing and segregation of homologous chromosomes during meiosis. |
| Pedigree analysis | Allows us to determine whether a mutant allele is dominant or recessive and to predict the likelihood of an individual being affected. |
| Wild-type allele | Common, usually encodes a protein that is made in the proper amount and functions normally. |
| Mutant allele | Rare |
| Can two unaffected individuals produce an affected offspring? | Yes, they are presumed heterozygotes. |
| Every affected individual has an affected parent. | True. |
| Can an affected parent produce an unaffected offspring? | Yes, if the other parent does not carry the disease. |
| In simple Mendelian inheritance, | The alleles are dominant or recessive. |
| Loss-of-function alleles | Mutations that produce recessive alleles. |
| How can a heterozygote increase the expression of a functional allele? | By using gene regulation. |
| Pleiotropy | Occurs when a mutation in a single gene can have multiple effects on an individual's phenotype. |
| Incomplete dominance | Occurs when the heterozygote shows an intermediate phenotype. |
| Example of incomplete dominance | Red and white flowers breed to make pink. |
| Incomplete dominance ratio is | 1:2:1 for F2 generation. |
| Norm of reaction | Phenotype range that individuals with a particular genotype exhibit under differing environmental conditions. |
| Sex chromosomes | Different between males and females and determine the sex of individuals. |
| Several mechanisms for sex determination | X-Y system in mammals X-O system in many insects Z-W system in some birds and fish. |
| In bees, male is _______ and the female is _______ | Haploid, Diploid. |
| Sex-linked genes | Found on one sex chromosome but not the other. |
| X-linked genes | Found on the X chromosome. |
| Hemizygous | Only one copy of genes on the X chromosome. |
| X-linked recessive diseases occur more frequently in | Males than females. |
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