Biology - 9.2 Genetic Crosses TestVersion en ligne BIOOOOOOOOOO par John Lawrence 1 What's complete dominance? a Heterozygous and dominant homozygous individuals have the same phenotype b Neither allele is completely dominant over the other and both influence the phenotype 2 What's incomplete dominance? a Heterozygous and dominant homozygous individuals have the same phenotype b Neither allele is completely dominant over the other and both influence the phenotype 3 What's codominance? a Neither allele is completely dominant over the other and both influence the phenotype b Neither allele is dominant or recessive; both are expressed in heterozygotes 4 The appearance of an organism is its... a Genotype b Phenotype c Phenotypic ratio 5 A genetic cross performed many times produces 798 long-stemmed plants and 266 short-stemmed plants. The probability of obtaining a short-stemmed plant in a similar cross is... a 266/1,064 b 266/798 c 798/1,064 6 A monohybrid cross of two individuals that are heterozygous for a trait exhibiting complete dominance would probably result in a phenotypic ratio of... a 4 dominant: O recessive b 3 dominant: 1 recessive c 1 dominant: 3 recessive 7 To determine the genotype of an individual that shows the dominant phenotype, you would cross that individual with one that is... a Homozygous recessive b Homozygous dominant c Heterozygous recessive d Heterozygous dominant 8 In a dihybrid cross between an individual with the genotype RRYY and an individual with the genotype rryy, all if the offspring will have the genotype... a RrYy b RRYY c rryy 9 What's the difference between a homozygous individual and a heterozygous individual? a In a homozygous individual, both alleles of a pair are the same; in a heterozygous individual, the two alleles of a pair are different b In a homozygous individual, both alleles of a pair are different; in a heterozygous individual, the two alleles of a pair are the same c In a homozygous individual, both alleles of a pair are twisted tightly; in a heterozygous individual, the two alleles of a pair are loose 10 If the probability that a specific trait will appear in the F₂ generation is 0.25, how many individuals would be expected to show that trait in an F₂ generation consisting of 80 individuals? a 0.25 x 50 = 12 individuals b 0.25 x 80 = 20 individuals c 80 x 0.3 = 24 individuals 11 A homozygous dominant individual (AA) is crossed with an individual that is heterozygous for the same trait (Aa). What are the possible genotypes of the offspring, and what percentage of the offspring is likely to show the dominant phenotype? a Aa and aa will result. 10% will have the dominant phenotype. b AA and Aa will result. 100% will have the dominant phenotype. c AA and aa will result. 50% will have the dominant phenotype. 12 Some animals, such as cows, normally produce only one offspring from each mating. If a cow showed a dominant phenotype, why would a typical testcross be a difficult way to determine the genotype of that animal? a The dominant phenotype would appear in all of the offspring if the cow were homozygous recessive but in only about 50% of the offspring if the cow were heterozygous. Would take a long time, until a calf with the recessive genotype was born. b The dominant phenotype would appear in all of the offspring if the cow were heterozygous dominant but in only about 50% of the offspring if the cow were homozygous. Would take a long time, until a calf with the recessive phenotype was born. c The dominant phenotype would appear in all of the offspring if the cow were homozygous dominant but in only about 50% of the offspring if the cow were heterozygous. Would take a long time, until a calf with the recessive phenotype was born. 13 What proportion of the offspring will be dominant for both traits? a 9/16 b 1/4 c 5/16 14 What proportion of the offspring will have the same genotype as their parents? a 1/16 b 1/4 c 9/16 15 What proportion of the offspring will be homozygous dominant for both traits? a 1/16 b 4/16 c 8/16 16 What proportion of the offspring will be homozygous recessive for both traits? a 3/16 b 4/16 c 1/16 17 What is the difference between a dominant trait and a recessive trait? a The dominant trait slows down a factor for a specific trait, but recessive traits makes the process faster for dominant traits b The dominant trait masks/dominates a factor for a specific trait, but recessive traits are masked by dominant traits c The dominant trait dominates a factor for a niche trait, but recessive traits are masked by itself 18 Differentiate genotype from phenotype. a Genotype: The non-genetic parts of an organism. Phenotype: The appearance of an organism as a result of its genotype b Genotype: The genetic makeup of an organism. Phenotype: The appearance of an organism as a result of its genotype c Genotype: The appearance of an organism as a result of its phenotype. Phenotype:The genetic makeup of an organism 19 What is the difference between homozygous and heterozygous? a Homozygous: When both alleles are alike (homo = same). Heterozygous: When two alleles in the pair are different (hetero = different) b Homozygous: When both alleles are different (homo = different). Heterozygous: When two alleles in the pair are alike (hetero = same) c Homozygous: When both alleles are intertwined. Heterozygous: When two alleles in the pair are disconnected 20 A procedure in which an individual of an unknown genotype is crossed with a homozygous recessive individual to determine the genotype of the unknown individual is called a... a testcross b dihybrid cross c monohybrid cross 21 What's a gene? a A particle similar to an atom b The nucleus c A segment of DNA 22 An example of a genotype of a heterozygous individual is... a Zz b ZZ c zz 23 Segregation of alleles occurs during... a Meiosis b Mitosis c Cell division 24 Phenotypes can appear to be altered by... a chromosomes, gametes, or autosomes b behavior, hair dye, plastic surgery, or contact lenses c knee surgery, tears, toes, fire 25 What do punnett squares do? a Predict the probability that certain traits will be inherited by offspring b Predicts the number of times an event is expected to happen/number of opportunities for an event to happen c Predicts the cross between individuals that involves one pair of contrasting traits 26 What's probability? a The amount of times a scientist/biologist says probably b The likelihood that an event will occur c raw raw raw or whatever lady gaga said 27 Probability equals... a Tropical rainforests b length x width x height c Number of times an event is expected to happen/number of opportunities for an event to happen 28 What's a monohybrid cross? a a cross between individuals that involves one pair of contrasting traits b a cross between individuals that involves two pairs of contrasting traits. more possible combos of alleles to work out. c When both alleles of a pair are the same; can be dominant or recessive (PP or pp) 29 What's a dihybrid cross? a a cross between individuals that involves one pair of contrasting traits b a cross between individuals that involves two pairs of contrasting traits. more possible combos of alleles to work out c when both alleles of a pair are the same; can be dominant or recessive (PP or pp) 30 When the two allele pairs are the same... they're a Homozygous b Heterozygous c Gay d Straight 31 When the two allele pairs are different... they're a Homozygous b Heterzygous c Gay d Straight 32 What's genotypic ratio? a The ratio of genotypes that appear in an offspring b The ratio of the offspring’s phenotypes c Heterozygous and dominant individuals have the same phenotype 33 What's phenotypic ratio? a The ratio of genotypes that appear in an offspring b The ratio of the offspring’s phenotypes c Heterozygous and dominant individuals have the same phenotype 34 This cross is an example of... a homo/homo b homo/hetero c hetero/hetero d monohybrid cross 35 This cross is an example of... a homo/homo b homo/hetero c hetero/hetero d monohybrid cross 36 This cross is an example of... a homo/homo b homo/hetero c hetero/hetero d monohybrid cross 37 This cross is an example of... a homo/homo b homo/hetero c hetero/hetero d monohybrid cross
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