BIOD 102 Module 1 (2026/2027 Update) | Essential Biology II with Lab | Verified Questions & Answers | 100% Correct Solutions | Grade A+ | Portage Learning

BIOD 102 Module 1 (2026/2027 Update) | Essential Biology II with Lab | Verified Questions & Answers | 100% Correct Solutions | Grade A+ | Portage Learning Q: At what levels does regulation of gene expression occur? Answer At the DNA, RNA, and post transcriptional levels. Q: In what ways does regulation of gene expression at the DNA level occur? Answer Acetylation - induces transcription and Methylation - inhibits transcription Q: In what ways does regulation of gene expression at the RNA level occur? Answer Activator proteins - proteins that increase transcription by binding to other regulatory regions and Repressor proteins - proteins that decrease transcription by binding to control element regions or blocking activator proteins from binding Q: In what ways does regulation of gene expression occur at the post- transcription level? Answer Alternative splicing - splicing and rejoining of different regions from one primary transcript - influences the amount of function proteins produced Q: In what ways does regulation of gene expression occur after RNA processing? Answer Activation or inactivation of proteins that are needed to start transcription Q: In what ways does regulation of gene expression occur at the post-translational level? Answer Selective degradation - specific proteins are targeted and degraded, acting as a regulation process Q: What are the three phases of translation? Answer 1. Initiation 2. Elongation 3. Termination Q: What happens during the initiation phase of translation? Answer The translation initiation complex is created. It is composed of the large ribosomal subunit, mRNA, tRNA, and the small ribosomal subunit. Q: What happens during the elongation phase of translation? Answer Amino acids are added from the N-terminus with the help of elongation factors which help length the polypeptide chain Q: What happens during the termination phase of translation? Answer Releasing factors bind to the A site when a stop codon is reached. Then, hydrolysis at the P site occurs which causes removal of the polypeptide chain. Lastly, the translation initiation complex is disassembled. Q: What are mutations and what are their effects? Answer Mutations are changes in DNA that can be beneficial by resulting in new genes, detrimental by resulting in abnormal phenotypes, or neutral by resulting in no changes. Q: What are the different types of mutation? Answer Point mutations - single nucleotide is changed within a gene Silent substitutions - no change in phenotype despite change in genetic code Missense mutations - one amino acid is replaced with another Nonsense mutations - the intended codon becomes a stop codon, causing translation to end early Insertion/deletion mutations - gain or loss of nucleotides within a gene Frame shift mutation - insertions/deletions in numbers not in multiples of three Q: What are the three phases of transcription? Answer 1. Initiation 2. Elongation 3. Termination Q: What occurs during the initiation phase of transcription? Answer RNA polymerase binds to the promoter region. TFs bind to the TATA box of the promoter region. RNA polymerase II binds and unwinds and separates the two DNA strands. Q: What occurs during the elongation phase of transcription? Answer RNA polymerase creates the complementary RNA strand from the DNA strand as it unwinds. Note: Uracil in place of Thymine Q: What occurs during the termination phase of transcription? Answer Termination occurs when the polyadenylation sequence is encountered by RNA polymerase in the template DNA. The pre-mRNA strand is then released when nuclear proteins bind and leave the RNA transcript. Later, it undergoes modification to become a functional, mature mRNA strand. Q: What modifications does pre-mRNA need to undergo to become a functional, mature mRNA? Answer 1. 5' cap - modified guanine nucleotide 2. poly-A-tail - 50 to 250 nucleotides added to the 3' end that protects the mRNA and helps w/ its export 3. RNA splicing - removal of introns (non coding regions) and rejoining of the exons (encoding regions) of the RNA strand Q: What 4 nucleotide bases encode for the 20 amino acids? Answer Adenine, Thymine, Guanine, and Cytosine Q: What is the central dogma? Answer DNA - RNA - protein Q: What is mismatch repair? Answer Mismatch repair is nucleotides are mismatched and are replaced with the correct one. Q: Describe nucleotide excision repair. Answer Occurs when there are long stretches of DNA that need to be replaced. It is facilitated by nucleases which cut erroneous DNA on the new strand and then DNA polymerase adds the correct nucleotides back. DNA ligase then binds sand seals the new base pairs to the parent strand. Q: Why is the daughter DNA strand shorter than the parent, template strand? Answer Because with each round of replication, ends of the DNA molecule are shortened. This is due to the initial RNA primer being removed and new DNA not being able to be added. Q: What is the function of telomeres? Answer They are short nucleotide sequences that do not have any relevant genetic information and serve as the protective end of the strand to slow degradation of the 5' ends. Q: Describe the difference between germ cells and somatic cells when it comes telomeres. Answer Germ have an enzyme called telomerase that facilities lengthening of telomeres while somatic cells don't. Somatic cells cannot infinitely divide. Q: Homologous structures such as mammalian forelimbs and bird wings share same anatomy and ancestry but perform different functions. This is a result of ________ evolution Answer divergent Q: Scientists who discover and study fossils are called Answer paleontologists Q: The evolution of two anatomically similar species that are not related via a recent common ancestor happens as a result of? Answer Convergent Evolution The odds of ____ are much higher in a bacteria due to their ____ generation time. Answer mutation, small Evolution explains life's unity and _____. Answer diversity Which one of the following piece of evidence most strongly supports the common origin of all life on earth Answer all organisms use the same genetic code Descent with modification refers to a process of change that has ____ life on earth. Answer transformed A certain selection and breeding of plants or animals for desired traits is an example of? Answer artificial selection Mark all those that act upon the Genetic Variation of a population & alter it, in order for evolution to take place? Answer natural selection, genetic drift, gene flow Drosophila Melanogaster has about 13,700 genes in its genome and on average it is _____ for about 1,920 of its genes. Answer heterozygous The Nucleotide variability in Drosophila Melanogaster has been found to be? Answer 1% Crossing over, independent assortment and random fertilization are the reasons behind ______ of alleles. shuffling The transfer of alleles between individuals of a population is known as? gene flow Over a period of time, sexual selection can lead to? Sexual Dimorphism The selection that favors individuals at both extremes of a Phenotypic range is called? Disruptive selection A certain kind of immunity (cells shape) that populations have against the malarial parasite in places where malaria is rampant, is studied as? heterozygote advantage Which of the following is a Postzygotic reproductive barrier? reduced hybrid viability The production of sterile mules by interbreeding between female horses (mares) and male donkeys (jacks) is an example of? reduced hybrid fertility Speciation that occurs suddenly over a short period of time is called ______ Equilibrium punctuated T/F: In some instances, speciation may occur in 4,000 years while in other in other instances may take up to 40,000,000 years True T/F: Reproductive isolation can result in the origin of new species. True When one species splits into two or more species, the process is referred as_____. speciation A group of organisms with the potential to interbreed and produce viable fertile offsprings is called ? A species What is adaptation? Behavioral adaptations, structural adaptations, Biochemical adaptations, physiological adaptations. Natural Selection is a process in which organisms with certain inherited characteristics are more likely to survive and reproduce than are individuals with other characteristics. Population a group of individuals of the same species living in the same place at the same time Evolution the genetic composition of a population changes over time. Natural selection leads to A population changing over generations, and evolutionary adaptation. The Origin of Species challenged.. The notion that earth was relatively young and populated by unrelated species The Greek philosopher Aristotle held the belief.. that species are fixed and do not evolve. Two points from the Origin of Species Organisms inhabiting Earth today descended from ancestral species; Natural selection was the mechanism for descent with modification Fossils Imprints or remains of organisms that lived in the past, often found in sedimentary rocks Fossil record Is the ordered sequence of fossils as they appear in rock layers; reveals the appearance of organisms in a historical sequence; fits the molecular and cellular evidence that prokaryotes are the ancestors of all life Paleontologists Are scientists that study fossils Biogeography the study of the geographic distribution of species that first suggested to Darwin that today's organisms evolved from ancestral forms. Comparitive Anatomy Is the comparison of body structure between different species; confirms that evolution is a remodeling process Homology The similarity in structures due to common ancestry Illustrated by the remodeling of the pattern of bones forming the forelimbs of mammals Vestigial Structures Are remnants of features that served important functions in an organism's ancestors; now have only marginal, if any, importance DNA, and DNA encoded proteins The hereditary background of an organism is documented in Darwins two observations All species tend to produce excessive numbers of offspring; Organisms vary, and much of this variation is heritable Modern synthesis the fusion of genetics with evolutionary biology. Gene pool The total collection of alleles in a population at any one time Microevolution evolution is occurring on its smallest scale Polygenic traits tend to produce phenotypes that vary more or less continuously. Single gene traits tend to produce only a few distinct phenotypes. Genetic variation results from Mutations, changes in the DNA of an organism, sexual recombination, the shuffling of alleles during meiosis Gene pool a reservoir from which the next generation draws its genes. Alleles can be symbolized by p for the relative frequency of the dominant allele in the population; and q for the frequency of the recessive allele in the population The Hardy-Weinberg formula can be used to calculate the frequencies of genotypes in a gene pool from the frequencies of alleles. PKU Is a recessive allele that prevents the breakdown of the amino acid phenylalanine; occurs in about one out of every 10,000 babies born in the United States genetic equilibrium in which the population gene pool remains constant over time Genetic drift A change in the gene pool of a small population; due to chance The bottleneck effect Is an example of genetic drift; results from a drastic reduction in population size Founder effect the genetic drift resulting from the establishment of a small new population whose gene pool differs from that of the regular parent population Gene flow Is genetic exchange with another population; tends to reduce genetic differences between populations fitness the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals. Directional selection Shifts the phenotypic "curve" of a population; Selects in favor of some extreme phenotype Disruptive selection can lead to a balance between two or more contrasting phenotypic forms in a population. Stabilizing selection Favors intermediate phenotypes; is the most common Sexual dimorphism A distinction in appearance between males and females; not directly associated with reproduction or survival Sexual selection a form of natural selection in which inherited characteristics determine mating preferences. Mass extinctions Pave the way for the evolution of new and diverse forms, but take millions of years for Earth to recover Specitation the formation of a new species, occurs when one species evolves into two or more species nonbranching evolution A population transforms but does not create a new species Species Latin word meaning "Kind" or "Appearance." Biological species concept A group of populations whose members have the potential to interbreed and produce fertile offspring Prezygotic barriers prevent mating or fertilization between species. Postzygotic barriers Interspecies mating occurs and hybrid zygotes form Allopatric specitation occurs when a population forms a new species after being geographically isolated from its parent population Sympatric specitation occurs when a part of a population becomes a new species while in the midst of it's parent population Gradual model big changes (speciations) occur by the steady accumulation of many small changes punctuated equilibria model Long periods of little change, equilibrium, punctuated by abrupt episodes of speciation Evolutionary developmental biology the study of the evolution of developmental processes in multicellular organisms. Paedomorphosis Is the retention into adulthood of features that were solely juvenile in ancestral species Homeotic genes control When/how/where structures develop geologic time scale reflecting a consistent sequence of geologic periods; cenozoic, mesozoic, paleozoic, and precambrian Relative age revealing the sequence in which groups of species evolved absolute age requiring other methods such as radiometric dating Radiometric dating Is the most common method for dating fossils; is based on the decay of radioactive isotopes; helped establish the geologic time scale Permian Mass Extinction Occurred at about the time the merging continents formed Pangaea (250 million years ago); claimed about 96% of marine species Cretaceous extinction Occurred at the end of the Cretaceous period, about 65 million years ago; included the extinction of all the dinosaurs except birds; permitted the rise of mammals Systematics Classifying organisms; determining their evolutionary relationships Taxonomy Identification of species; naming of species; classification of species Carolus Linnaeus proposed the current taxonomic system Binomail two part name taxonomic hierarchy Family, Order, Class, Phylum, Kingdom, Domain Phylogenetic trees Depict hypotheses about the evolutionary history of species; reflect the hierarchical classification of groups nested within more inclusive groups Convergent Evolution Involves superficially similar structures in unrelated organisms; is based on natural selection Analogy similarity due to convergence Molecular systematics Compares DNA and amino acid sequences between organisms; can reveal evolutionary relationships Clade Consists of an ancestral species and all its descendants; forms a distinct branch in the tree of life Cladistics Scientific search for clades Linnaeus Divided all known forms of life between the plant and animal kingdoms; prevailed with his two kingdom system for over 200 years Five kingdom system Placed all prokaryotes in one kingdom; divided the eukaryotes among four other kingdoms Three Domain System Two domains of prokaryotes (Bacteria and Archaea); one domain of eukaryotes (Eukarya) Prokaryotes Evolved by 3.5 billion years ago; began oxygen production about 2.7 billion years ago; lived alone for almost 2 billion years; continue in great abundance today Single celled eukaryotes developed about 2.1 billion years ago; multiple celled 1.2 billion years ago Biogenesis All life today arises by the reproduction of preexisting life spontaneous generation life regularly arises from nonliving matter ribozymes short strands of RNA that replicated themselves without the assistance of proteins, perhaps using RNAs that can act as enzymes endospheres thick-coated, protective cells that are produced within the cells when they are exposed to unfavorable conditions exotoxins poisonous proteins secreted by bacterial cells. Endotoxins chemical components of the outer membrane of certain bacteria. Bioremediation the use of organisms to remove pollutants from water, air and soil Protists Are eukaryotic; evolved from prokaryotic ancestors; are ancestral to all other eukaryotes, which are plants, fungi and animals Endosymbiosis one species living inside another host species, in which free-living bacteria came to reside inside a host cell, producing mitochondria and chloroplasts 4 types of Protists Protozoans, Slime molds, Unicellular algae, Seaweeds Protozoans Protists that live primarily by ingesting food are called Flagellates Protozoans with flagella Pseudopodia temporary extensions of the cell Ameobas Great flexibility in their body shape; the absence of permanent organelles for locomotion apicomplexans Named for a structure at their apex (tip) that is specialized for penetrating host cells and tissues Ciliates Are mostly free-living (nonparasitic), such as the freshwater ciliate Paramecium; Use structures called cilia to move and feed Algae Photosynthetic protists Plankton the communities of mostly microscopic organisms that drift or swim weakly in aquatic environments Diatoms which have glassy cell walls containing silica Dinoflagellates with two beating flagella and external plates made of cellulose Green algae Unicellular, sometimes flagellated, such as Chlamydomonas; colonial, sometimes forming a hollow ball of flagellated cells, as seen in V olvox