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Any type of cell in a multicellular organism except eggs, sperm, and their precursor cells. Also


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A haploid reproductive cell produced by meiosis that can fuse with another haploid cell to form a
zygote. Most multicellular eukaryotes have two
zygote. Most multicellular eukaryotes have two
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BIO 148 Exam 3
| Question | Answer |
|---|---|
| Any type of cell in a multicellular organism except eggs, sperm, and their precursor cells. Also  | Somatic cells |
| A haploid reproductive cell produced by meiosis that can fuse with another haploid cell to form a zygote. Most multicellular eukaryotes have two | Gamete |
| The formation of male gametes (sperm) | Spermatogenesis |
| The formation of female gametes (eggs) | Oogenesis |
| The number of distinct (different) chromosome sets in a cell. Symbolized as n. | Haploid number |
| The number of chromosomes in a cell that has two of each type. Symbolized as 2n. | Diploid number |
| Chromosomes which are similar in size, shape, and gene content. A diploid organisms has two homologous chromosomes of each ty | Homologous chromosomes |
| Created by replication of a chromosome. The identical daughter strands of DNA remain paired and connected at their centromeres until t | Sister Chromatids |
| Chromatids on homologous chromosomes. Crossing over occurs between non-sister chromatids during meiosis I. | Nonsister Chromatids |
| In sexually reproducing organisms, a special two-stage type of cell division in which one diploid (2n) parent cell produces four haploid (n) reproductive cells (gametes); results in halving of the chromosome number. | Meiosis |
| the first cell division of meiosis, in which synapsis and crossing over occur, and homologouschromosomes are separated from each other, producing daughter cells with half as many chromosomes (each composed of two sister chromatids) as the parent cell. | Meiosis I |
| The second cell division of meiosis, in which sister chromatids are separated from each other. | Meiosis II |
| The structure formed by synapsed homologous chromosomes during prophase of meiosis I. | Tetrad |
| the physical sites of crossing over between non-sister chromatids | Chiasmata |
| the fusion of and egg and a sperm cell to form a diploid zygote | Fertilization |
| The diploid cell formed by the union of two haploid gametes; fertilized egg | Zygote |
| An error that can occur during meiosis or mitosis in which one daughter cell receives two copies of a particular chromosome, and the other daughter cell receives none. | Nondisjunction |
| The state of having an abnormal number of copies of a certain chromosome. | Aneuploidy |
| Having only one copy of a particular type of chromosome. | Monosomy |
| The state of having three copies of one particular type of chromosome. | Trisomy |
| medical procedure to predict chromosomal abnormalities in which a small amount of amniotic fluid (containing fetal cells) is removed for analysis | Amniocentesis |
| The distinctive appearance of all of the chromosomes in an individual, including the number of chromosomes and their length and banding patterns (after staining | Karyotype |
| An organism selected for intensive scientific study based on features that make it easy to work with (e.g., body size, life span), in the hope that findings will apply to other species. Example: Mendel’s pea plants). | Model organism |
| The alleles of two different genes segregate independently from each other, such that a dihybrid will produce four types of gametes, each in equal proportions (A RrYy plant produces gametes that are 1⁄4 RY, 1⁄4 ry, 1⁄4 Ry and 1⁄4 rY). | Independent Assortment, pattern component |
| A method for predicting the genotypes that should appear in offspring of a cross or mating. | Punnett Square |
| a section of DNA that encodes a protein (or a functional RNA) and its associated regulatory sequences | Gene |
| A gene's physical location on a chromosome. The location of a gene. | Locus |
| a particular version of a gene. Alleles of a gene differ in nucleotide sequence. | Allele |
| Having two identical alleles of a certain gene. | Homozygous |
| Having two different alleles of a certain gene. | Heterozygous |
| Did not distinguish between genotype and phenotype. hypothesis proposed that the phenotypes of parents blend in offspring and formed new traits that were intermediate between parents&that the offspring will pass on the modified version of the traits | Blending inheritance |
| Distinguishes between genotype and phenotype. This hypothesis proposed that discrete units of heredity (genes) are inherited by offspring and remain unchanged in the offspring. Those genes are passed on by the progeny and subsequent generations unchanged. | Particular inheritance |
| The process by which individuals with certain heritable traits tend to produce more surviving offspring than do individuals without those traits, often leading to a change in the genetic makeup of the population. | Natural Selection |
| Any heritable trait that increases the fitness of an individual with that trait, compared with individuals without that trait, in a particular environment | Adaptation |
| Similarity among organisms of different species due to their inheritance from a common ancestor. Features that exhibit such similarity (e.g., DNA sequences, proteins, body parts) are said to be homologous | Homology |
| Similarities in DNA sequences or amino acid sequences that are due to inheritance from a common ancestor. | Genetic homology |
| A similarity in embryonic form, or in the fate of embryonic tissues, that is due to inheritance from a common ancestor | Developmental homology |
| Similarities in organismal structures (e.g., limbs, shells, flowers) that are due to inheritance from a common ancestor | Structural homology |
| any trace of an organism that existed in the past. Includes tracks, burrows, fossilized bones, casts, etc. | Fossil |
| The evolutionary history of a group of organisms. | Phylogeny (phylogenetic tree) |
| All of the alleles of all of the genes in a certain population | Gene pool |
| Any permanent change in the hereditary material of an organism | Mutation |
| In genetics, referring to any mutation or allele that reduces an individual's fitness | Deleterious |
| In genetics, referring to any mutation, allele, or trait that increases an individual's fitness. | Beneficial |
| a trait produced by the interaction and additive effects of numerous genes (each of which contribute a small amount to phenotype) | Quantitative Traits |
| The number and relative frequency of alleles present in a particular population. | Genetic variation |
| A pattern of natural selection that favors one extreme phenotype with the result that the average phenotype of a population changes in one direction. Generally reduces overall genetic variation in a population. | Directional Selection |
| A pattern of natural selection that favors phenotypes near the middle of the range of phenotypic variation. Reduce | Stabilizing Selection |
| A pattern of natural selection that favors extreme phenotypes at both ends of the range of phenotypic variation. | Disruptive Selection |
| Any change in allele frequencies due to random events. Causes allele frequencies to drift up and  | Genetic Drift |
| A reduction in allelic diversity resulting from a sudden reduction in the size of a large population (population bottleneck) due to a random event. | Genetic bottleneck |
| A change in allele frequencies that often occurs when a new population is established from a small group of individuals (founder event) due to sampling error (i.e., the small group is not a representative sample of the source population). | Founder Effect |
| The movement of alleles between populations; occurs when individuals leave one population, join  | Gene Flow |
| A pattern of natural selection that favors individuals with traits that increase their ability to obtain mates. Acts more strongly on males than females. | Sexual Selection |
| Any trait that differs between males and females. | Sexual dimorphism |
| A pattern of natural selection that favors extreme phenotypes at both ends of the range of phenotypic variation. | Disruptive Selection |
| The definition of a species as a population/group of populations that are reproductively isolated from other groups. Members of a species have the potential to interbreed to produce viable/fertile offspring but cannot with members of other species. | Biological Species concept |
| The definition of a species as a population or group of populations that have measurably different anatomical features from other groups | Morphospecies concept |
| The definition of a species as the smallest monophyletic group in a phylogenetic tree. | Phylogenic Species Concept |
| An evolutionary unit that includes an ancestral population and all of its descendants but no others. Also called a clade or lineage. | Monophyletic group |
| A population that has distinctive traits and some genetic differences relative to other populations of the same species but that is not distinct enough to be classified as a separate species. | Subspecies |
| any mechanism preventing gene flow between different populations by preventing the individuals from mating with each other | Prezygotic isolation |
| any mechanism preventing gene flow between different populations by preventing the hybrid progeny from surviving or reproducing | Postzygotic isolation |
| The divergence of populations into different species by physical isolation of populations in different geographic areas. | Allopatric speciation |
| emigration of individuals from one population establish a new population in a geographically isolated location. | Allopatric Speciation by dispersal |
| a population becomes fragmented into subpopulations that are unable to  | Allopatric Speciation by vicariance |
| The divergence of populations living within the same geographic area into different species as the result of their genetic (not physical) isolation. Can occur by disruptive selection or polyploidization. | Sympatric Speciation |
| both extremes of a quantitative trait are adaptive, which genetically splits a population into two, genetically distinct, subpopulations. | Sympatric Speciation by disruptive selection |
| autopolyploids or allopolyploids form, creating new species that cannot interbreed with the original diploid population(s). | Sympatric Speciation by polyploidization |
| The natural selection for traits that prevent interbreeding between recently diverged, sympatric species. | Reinforcement |
| A geographic area where interbreeding between related, sympatric species occurs and where hybrid individuals are common. | Hybrid Zones |
| Can create new species if the hybrids between related, sympatric species are fertile and have adaptive traits. | Hybridization |
| What is the ploidy of organisms that have two sets of chromosomes? | 2n |
| What information can not be obtained from an individual's karyotype? | The sequence of bases of a particular gene |
| True or false? A haploid organism has one pair of homologous chromosomes. | False |
| If a cell has 24 chromosomes, how many chromosomes would each of its four daughter cells have after meiosis? | 12 |
| Which of the following statements about meiosis and mitosis is true? | Meiosis II is similar to mitosis in that sister chromatids of each chromosome separate. |
| Human gametes are produced by _____. | meiosis |
| Normal human gametes carry _____ chromosomes. | 23 |
| A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes. | 16 |
| In peas, the allele for round seeds (R) is dominant to the allele for wrinkled seeds (r). What would be the genotype and phenotype ratios of offspring from a cross between Rr and rr individuals? | Genotype: 1/2 Rr: 1/2 rr; Phenotype: 1/2 Round: 1/2 Wrinkled |
| Which theory was disproved when Mendel observed that the F1 generation of a monohybrid cross resembled one of the parents? | blending inheritance |
| Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. This ratio suggests that _____. | the parents were both heterozygous for the particular trait |
| A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism? | HT |
| When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype? | 50% |
| What is the difference between heterozygous and homozygous individuals? | All of the gametes from a homozygote carry the same version of the gene while those of a heterozygote will differ. |
| When constructing a Punnett square, the symbols on the outside of the boxes represent _______, while those inside the boxes represent _______. | gametes, progeny |
| True or false? The same phenotype can be produced by more than one genotype. | True |
| True or false? In diploid organisms, a dominant phenotype will only be expressed if the individual is homozygous dominant for that trait. | False |
| If an organism with the genotype AaBb produces gametes, what proportion of the gametes would be Bb? | None |
| Two mice are heterozygous for albinism (Aa) . The dominant allele (A) codes for normal pigmentation, and the recessive allele (a) codes for no pigmentation. What percentage of their offspring would have an albino phenotype? | 25 |
| A triploid cell contains sets of three homologous chromosomes. If a cell of a usually diploid species with 42 chromosomes per cell is triploid, this cell would be expected to have which of the following? | 63 chromosomes in 21 sets of 3 |
| After telophase I of meiosis, the chromosomal makeup of each daughter cell is _____. | haploid, and the chromosomes are each composed of two chromatids |
| What is a nondisjunction? | An error in cell division that causes homologous chromosomes or sister chromatids to move to the same side of the dividing cell |
| When can nondisjunction occur? | All three answers are correct. |
| Which syndrome is characterized by the XO chromosome abnormality? | Turner syndrome |
| What kind of cell results when a diploid and a haploid gamete fuse during fertilization? | A triploid cell |
| Of the following chromosomal abnormalities, which type is most likely to be viable in humans? | Trisomy |
| If a diploid cell undergoes meiosis and produces two gametes that are normal, and one with n − 1 chromosomes, and one with n + 1 chromosomes, what type of error occurred? | A nondisjunction error occurred in meiosis II, in which both sister chromatids of a chromosome migrated to the same pole of the cell. |
| If a diploid cell undergoes meiosis and produces two gametes with n + 1 chromosomes and two gametes with n− 1 chromosomes, what type of error occurred? | A nondisjunction error occurred in meiosis I, in which both members of a homologous pair migrated to the same pole of the cell. |
| The wing of a bat is homologous to the _____ of a whale. | flipper |
| What is plausible evidence supporting the hypothesis that birds evolved from dinosaurs? | Fossilized transitional forms are discovered that possess features of birds and dinosaurs yet are difficult to classify into either group. |
| Why are human and chimpanzee DNA 96 percent similar? | The two species descended from a recent common ancestor. |
| Which of the following statements is correct? | Fossils form in sedimentary rocks. |
| The fossil record resembles the living species in the same geographic area. How does this pattern support the theory of evolution by natural selection? | It is evidence that species can change over time. |
| Which statement about vestigial traits is correct? | Vestigial traits are similar to functional traits in closely related species. |
| Why do related species share homologous traits? | Related species inherited homologous traits from a common ancestor. |
| Which is an example of a structural homology? | Vertebrate forelimbs have the same number and arrangement of bones. |
| Which of the following evidence most strongly supports the common origin of all life on Earth? All organisms _____. | use essentially the same genetic code |
| In biology, fitness is defined as _____. | the ability of an individual to produce surviving offspring |
| Which of the following is the best modern definition of evolution? | descent with modification |
| Which statement shows population thinking? | Variation among individuals in a species is real and important. |
| Which of the following is the best modern definition of evolution? | descent with modification |
| Of the following anatomical structures, which is homologous to the bones in the wing of a bird? | bones in the flipper of a whale |
| The Irish "elk" described by Georges Cuvier suggests that _____. | organisms could go extinct |
| Similar gill pouches in embryos of a chick, human, and cat are an example of _____. | developmental homology |
| The same basic internal organs (kidneys, stomach, heart, lungs) are found in frogs, birds, snakes, and rodents. This is primarily an example of _____. | structural homology |
| What is biological fitness? | Biological fitness measures the reproductive success of an individual relative to others in the population. |
| Why is the continual use of the antibacterial triclosan in soaps a potential health risk? | Bacteria could evolve a resistance to commonly used antibiotics. |
| A farmer uses triazine herbicide to control pigweed in his field. For the first few years, the triazine works well and almost all the pigweed dies; but after several years, the farmer sees more and more pigweed. Which of these explains what happened? | Triazine-resistant weeds were more likely to survive and reproduce. |
| In biology, an adaptation is defined as _____. | a heritable trait that increases the fitness of an individual in a particular environment |
| Do individuals change when natural selection occurs? Why or why not? | No. Individuals do not change, but the population does. |
| Which statement is correct? | Populations can evolve, but individuals cannot. |
| Which of the following are basic components of the Hardy–Weinberg model? | Frequencies of two alleles in a gene pool before and after many random matings |
| Which of the following statements is not a part of the Hardy–Weinberg principle? | The genotype frequencies in the offspring generation must add up to two. |
| True or false? The Hardy–Weinberg model makes the following assumptions: no selection at the gene in question; no genetic drift; no gene flow; no mutation; random mating. | True |
| What is the frequency of the A1A2 genotype in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals? | 0.4 |
| What is the frequency of the A1 allele in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals? | The frequency of the A1 allele is 0.3 |
| Which of the following evolutionary forces results in adaptive changes in allele frequencies? | Selection |
| What genotype frequencies are expected under Hardy–Weinberg equilibrium for a population with allele frequencies of p = 0.8 and q = 0.2 for a particular gene? | The expected genotype frequencies are 0.64, 0.32, and 0.04 for A1A1, A1A2, and A2A2, respectively. |
| Which of the following evolutionary forces could create new genetic information in a population? | Mutation |
| Which assumption must be correct for a population in Hardy-Weinberg equilibrium for a specific gene? | No genetic drift can affect allele frequencies for the gene |
| How does inbreeding alter genotype and allele frequencies? | Homozygotes increase in frequency in the population over generations. |
| Which type of selection tends to increase genetic variation? | Disruptive selection |
| In a bell-shaped curve, the x-axis (horizontal direction) of the graph represents which of the following? | The value of a particular characteristic; characteristics of an organism can include such traits as size and color. |
| True or false? Heterozygote advantage refers to the tendency for heterozygous individuals to have better fitness than homozygous individuals. This higher fitness results in less genetic variation in the population. | False |
| Long necks make it easier for giraffes to reach leaves high on trees, while also making them better fighters in "neck wrestling" contests. In both cases, which kind of selection appears to have made giraffes the long-necked creatures they are today? | Directional selection |
| Women often have complications during labor while giving birth to very large babies, whereas very small babies tend to be underdeveloped. Which kind of selection is most likely at work regarding the birth weight of babies? | Stabilizing selection |
| Black-bellied seedcrackers have either small beaks (better for eating soft seeds) or large beaks (better for hard seeds). There are no seeds of intermediate hardness; therefore, which kind of selection acts on beak size in seedcrackers? | Disruptive selection |
| Small Aristelliger lizards have difficulty defending territories, but large lizards are more likely to be preyed upon by owls. Which kind of selection acts on the adult body size of these lizards? | Stabilizing selection |
| Generation-to-generation change in the allele frequencies in a population is _____. | microevolution |
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