Chapter 9 Review Questions – Flashcards

The scientific study of heredity is called ________. A. breeding B. genetics C. true-breeding D. heredity

Which of the following statements is correct? A. Offspring of two different true-breeding varieties are called hybrids. B. A genetic cross produces the P generation. C. True-breeding plants are able to produce a variety of flower colors when self-fertilized. D. Mendel's pea plants could cross-fertilize but not self-fertilized.

The physical traits of an organism are called its _________. A. allele B. genotype C. gene D. phenotype

A plant with the genotype AABbcc is _____________. A. triploid B. recessive for three different genes C. homozygous for two different genes D. heterozygous for two different genes

GgTt pea plants can produce __________ type(s) of gamete(s), but a ggtt plant can produce __________ type(s) of gamete(s). A. four ... one B. two ... one C. one ... two D. four ... two

Which of the following is a true statement? A. A cross between Bb and bb genotypes would lead to offspring with a 1:4 phenotypic ratio. B. An example of a homozygous individual is Bb. C. You may associate pedigrees with purebred animals, such as purebred dogs, but pedigrees cannot represent human matings. D. A testcross is a mating between an individual with a dominant phenotype (but unknown genotype) and a homozygous recessive individual.

In a dihybrid cross ratio, what is the probability of getting the genotype aa when you cross genotypes Aa and aa? A. 1/1 B. 1/8 C. 1/4 D. 1/2

The most common phenotype in a natural population is referred to as the _______. A. autosome B. wild type C. mutant phenotype D. genotype

The most common lethal genetic disease in the United States is __________. A. sickle-cell disease B. hemophilia C. cystic fibrosis D. Huntington's disease

An important technique that helps provide insight into interesting genetic questions at the molecular level, such as reasons for hairless dogs, is called __________. A. DNA sequencing B. genetic testing C. inbreeding D. a testcross

You cross a true-breeding red-flowered snapdragon with a true-breeding white-flowered snapdragon. All of the F1 are pink. What can you say about the alleles for the parental traits? A. Red and white show incomplete dominance. B. Pink is dominant, whereas red and white are recessive. C. Both red ad white are recessive. D. Red is dominant.

Incomplete dominance is a condition in plants and people where __________. A. offspring have an appearance in between the phenotypes of the two parents B. most heritable diseases arise C. a single gene impacts more than one characteristic D. multiple alleles are responsible for an inheritance pattern

The ABO blood group in humans is an example of __________ producing four phenotypes. A. polygenic inheritance B. multiple alleles C. people with genetic disorders D. pleiotropy

This genetic disorder causes red blood cells to assume an unusual shape and produce abnormal hemoglobin proteins. A. Tay-Sachs disease B. Huntington's disease C. achondroplasia D. sickle-cell disease

Which of the following is used to define a phenotypic characteristic resulting from the expression of two or more genes? A. linked genes B. incomplete dominance C. pleiotropy D. polygenic inheritance

Surprising new evidence has shown that, in some cases, environment factors can modify chromosomes in such a way that changes the expression of genes without changing themselves or any part of the DNA sequence. These modifications are called epigenetic effects. Epigenetic effects can sometimes even be passed from generation to generation. In what way would this kind of "inheritance" be an exception to Mendel's laws? A. According to Mendel's laws, the effects of our environment are not passed on to the next generation. B. Since they are scientific laws, Mendel's laws can't be violated even if there is new evidence to the contrary. C. These effects must be caused by mutations. D. Mendel's laws apply only to pea plants, not all sexually reproducing organisms.

Linked genes are genes that _______. A. reside on the sex chromosomes B. have the same alleles residing on them C. are on the same chromosomes D. govern traits (such as hair texture and hair color) that are functionally related

Assume you were studying two characteristics of peas, and when you crossed heterozygous F1 individuals you did not see the 9:3:3:1 ratio predicted for a dihybrid cross. You later found that these two characteristics were on the same chromosome. With this information, how would you explain the results? A. The results can be explained as polygenic inheritance. B. There must have been a mutation. C. The genes must be on the sex chromosomes. D. The genes are linked and are inherited together.

The percentage of recombinant phenotypes resulting from fertilization involving recombinant gametes is called ___________. A. recombination frequency B. a linkage map C. mitosis D. genetic recombination

In general, the frequency with which crossing over occurs between two linked genes depends on _________. A. the phase of meiosis in which the crossing over occurs B. whether the genes are on the X chromosomes or not C. how far apart they are on the chromosomes D. whether the genes are dominant or recessive

Using recombination data, it is possible to determine the location of genes on a chromosome. The result is _________. A. a pedigree B. a carrier C. linked genes D. a linkage map

The sex chromosome in humans that make an individual a male are __________. A. a and b B. X and X C. A and B D. X and Y

In humans, the _________ determines the sex of the offspring because __________. A. male ... the sperm can fertilize either a female egg or a male egg B. female ... only the female has two functional sex chromosome C. male ... the male can contribute either an X or a Y chromosome D. chromosome contribution from both parents ... the offspring uses all the parents' chromosomes

A gene that is located on a sex chromosome (X or Y chromosome) is _______. A. the cause of albinism and cystic fibrosis B. a sex-linked gene C. a linked gene D. usually a sex-determining factor

Why are human males much more likely than human females to inherit the recessive condition hemophilia (a failure of the blood to clot properly)? A. the gene for hemophilia is carried on the Y chromosome B. the hemophilia gene is carried on an autosome C. the gene for hemophilia is sex-linked D. hemophilia is the wild type

Modern advances in _________ have provided important insights into the evolutionary history of life on Earth. A. research on human subjects B. technology C. dog breeding D. constructing evolutionary trees