Ch 23 HW dew Flashcards
What do we mean when we use the terms monohybrid cross and dihybrid cross?
A dihybrid cross involves organisms that are heterozygous for two characters that are being studied, and a monohybrid cross involves organisms that are heterozygous for only one character being studied
How does diploidy help to preserve genetic variation?
It allows recessive alleles that may not be favored in the current environment to be preserved in the gene pool by propagation in heterozygotes.
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.
What is the frequency of the A1A2 genotype in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals?
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?
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?
If, on average, 46% of the loci in a species' gene pool are heterozygous, then the average homozygosity of the species should be _____.
In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.3. What is the frequency of individuals that are homozygous for this allele?
In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.2. What is the frequency of individuals that are heterozygous for this allele?
You sample a population of butterflies and find that 56% are heterozygous at a particular locus. What should be the frequency of the recessive allele in this population?
Allele frequency cannot be determined from this information.
In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?
The evolutionary effects of genetic drift are greatest when _____.
the population size is small
An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The surviving population happens to have broader stripes, on average, than the initial population. If broadness of stripes is genetically determined, what effect has the ground-squirrel population experienced during the earthquake?
a genetic bottleneck
You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, you notice that the viability of the flies has decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to _____.
cross your flies with flies from another lab
In evolutionary terms, an organism's fitness is measured by its _____.
contribution to the gene pool of the next generation
What is the only evolutionary mechanism that consistently leads to adaptive evolution?
Natural selection changes allele frequencies because some _______ survive and reproduce more successfully than others.
No two people are genetically identical, except for identical twins. The main source of genetic variation among human individuals is
the reshuffling of alleles in sexual reproduction.
Blue poppies native to China were grown at a plant-breeding center in California. The plants with the thickest leaves were most likely to survive and reproduce in the drier climate. After several generations, the percentage of thick-leaved plants had increased by 42%. This adaptation of the poppies to their new environment is due to _____.