Question

1. Continuous trait can be defined as: a. Having a wide range of possible phenotypes b. Having only a few distinct phenotypes c. Traits that are not influenced by environment d. Traits heavily influenced by environment 2. Quantitative geneticists seek to answer general questions such as: a. To what degree do alleles differ at different loci interact with each other? b. How many genes affect the phenotype? c. What are the relative contributions to the phenotype by the genes? d. All of the above are general questions quantitative geneticists seek to answer 3. The key aspect of Johannsen's work with bean seed weight was: a. He ran a series of selection experiments b. He threw out seeds that did not fit his weight ranges c. He moved seeds from the ends his class ranges into the next weight class d. He was able to compare seeds with only small weight differences 4. We only looked at this type of distribution when studying continuous traits: a. Pie-shaped b. Normal c. Sigmoidal d. Random 5. Quantitative trait loci (QTL) are: a. The loci that contributes all of the variation in a continuous trait b. The loci that contributes all of the genetic variation in a continuous trait c. The loci that contributes the broad-sense heritability in a continuous trait d. The loci that contributes the narrow-sense heritability in a continuous trait 6. We looked at a study where Drosophila flies where selected for phototaxis (either attracted to or repelled by light). This experiment measures how much genetic variation existed in the original population and is known as a__study. a. Response to selection b. Selection c. Selection differential d. Screening 7. You run a test cross involving two loci three times and think the results indicate the two loci are linked. The best way to verify this is to: a. Repeat the experiment many more times b. Analyze the date with the chi square test c. Cross the loci with other loci on the chromosome d. All of the above are correct 8. Meiotic recombination takes place due to a protein complex called a: a. Chiasma b. Recombinase c. Cross-over d. Allelase 9. When running a two point (two loci) mapping cross: a. The most common progeny classes are called parentals b. The least common progeny are called recombinants c. There should be two parental and two recombinant classes d. All the above are true 10. A "hot spot” for genetic recombination is where: a. The physical distance between loci matches the recombination frequency b. The loci appear to be further apart as more than expected recombination is occurring c. The loci appear to be closer together as less than expected recombination is occurring d. Loci that are far apart on a chromosome may have 50% recombination between them 11. You suspect that genes a and b are linked but find that they assort independently; you should: a. Try crosses with each with loci that may be between them on the same linkage group b. Realize that you were wrong and list them as being unlinked c. Repeat the experiment until you get data that fits your expectations d. One of the above are correct 12. The recombination frequency between two genes located far apart on the same chromosome cannot exceed? a. 10% b. 25% c. 50% d. 100%

Answer 1

1) a). It displays a range of expression like weight, height, etc rather than an all-or-none appearance (such as white or red).these are usually under polygenic control and subject to substantial environmental influence in expression.

2) d ) Quantitative genetics deals with the genetics of continuously varying characters. Rather than considering changes in the frequencies of specific alleles of genotypes, quantitative genetics seeks to "quantify" changes in the frequency distributions of traits that cannot easily be placed in discrete phenotypic classes. The reason for the continuous variation is usually that the traits are polygenic (controlled by many genes) and there are environmental effects that alter the phenotypic state of each individual .

5) b)

A quantitative trait locus (QTL) is a region of DNA which is associated with a particular phenotypic trait, which varies in degree and which can be attributed to polygenic effects, i.e., the product of two or more genes, and their environment.These QTLs are often found on different chromosomes. The number of QTLs which explain variation in the phenotypic trait indicates the genetic architecture of a trait. It may indicate that plant height is controlled by many genes of small effect, or by a few genes of large effect.

Basically QTLs underlie continuous traits,those traits which vary continuously, e.g. height  as opposed to discrete traits .

6) a)...phototaxis is an iconic example for innate preferences. Such preferences probably reflect evolutionary adaptations to predictable situations .

We conclude that flies monitor their ability to fly, and that flying ability exerts a fundamental effect on action selection in Drosophila.