Deck 2: Genetics

Question 1

Which of the following statements is true of homologous chromosomes?

A) They come in pairs.
B) They move together into the gametes during meiosis.
C) They are found only in mammals.
D) They have three codons.

Answer 1

A

Question 2

Which of the following occurs during mitosis?

A) A haploid cell divides into two diploid cells.
B) A diploid cell divides into two haploid cells.
C) A haploid cell divides into two haploid cells.
D) A diploid cell divides into two diploid cells.

Answer 2

D

Question 3

What does Mendel's second principle (of independent assortment) state?

A) Eggs and sperm are formed independently of one another.
B) Transmission includes both blending and particulate inheritance.
C) The inheritance of one trait does not affect the inheritance of another trait.
D) Particles inherited from the mother are more likely to be transmitted to female offspring, and particles inherited from the father are more likely to be transmitted to male offspring.

Answer 3

C

Question 4

When Mendel crossed true-breeding pea plants bearing yellow seeds, the offspring bore

A) all yellow seeds.
B) one-half yellow and one-half green seeds.
C) three yellow seeds and one green seed.
D) all green seeds.

Question 5

Mendel's crossbreeding of offspring of true-bred green and yellow peas led to ________ in the second generation.

A) only green individuals surviving the first days of life
B) a 3:1 ratio of yellow to green offspring
C) yellowish-green individuals
D) half the offspring being green and the other half yellow

Question 6

If you have two parents with the genotype Aa, what is the chance that they will have an offspring with the genotype AA?

A) one-eighth
B) one-half
C) one-fourth
D) one-sixteenth

Question 7

The DNA sequence ATATATATATATATATATATATATAT is

A) a common regulatory sequence first discovered in fruit flies.
B) the most common sequence making up introns.
C) the most common sequence making up exons.
D) a simple repeat pattern usually found in specific sites in a given eukaryote.

Question 8

Which of the following statements describes gametes?

A) They contain both homologous chromosomes.
B) They are responsible for normal body growth of organisms.
C) They can be eggs or sperm.
D) They are diploid.

Question 9

One of Mendel's pea plants with only green seeds is

A) homozygous recessive.
B) always tall.
C) an example of blending inheritance.
D) heterozygous.

Question 10

Where are chromosomes contained?

A) in the gametes of prokaryotes
B) in the nuclei of eukaryotes
C) in the ribosomes
D) in the mitochondria

Question 11

Which of the following is the result of mitosis?

A) half the number of chromosomes in the daughter cells
B) either sperm or an egg
C) a daughter cell that has the exact copy of the chromosomes of its parent
D) an egg only

Question 12

Which of the following statements is true of chromosomes?

A) They are composed of ribonucleic acid.
B) They are replicated during cell division.
C) They are attached to organelles.
D) They are made of proteins.

Question 13

Why is it important to understand the overall relationship between genes, proteins, and chemical reactions in cells?

A) Many changes in the morphology or behavior of organisms can be linked to variations in the proteins and genes that build them.
B) Genetic effects on the biology of organisms account for as much as 10% of the variation we see from species to species.
C) Although most evolutionary change is extracellular, it is sometimes influenced by genetic systems.
D) Only by controlling these relationships can we treat most disease symptoms.

Question 14

Which of the following is true of diploid organisms?

A) Chromosomes occur in homologous pairs.
B) Chromosomes occur in homologous triplets.
C) Meiosis produces diploid gametes.
D) Mitosis produces haploid cells.

Question 15

Which of the following statements is true of gametes?

A) They are not involved in the transmission of genes.
B) They are the sex cells, or eggs and sperm.
C) They do not differ between male and female animals.
D) They were discovered by Darwin.

Question 16

To what does the genotype of an individual refer?

A) the alleles it carries
B) its visible characteristics
C) the number of chromosomes in its sex cells
D) the number of chromosomes in its body cells

Question 17

Mendel observes a pea plant with yellow seeds, where A and a are the alleles for color, but he knows nothing else about the plant. Which of the following must he infer is the possible genotype(s) of this plant?

A) AA only
B) AA or aa
C) Aa only
D) AA or Aa

Question 18

Reduction of chromosome number occurs during

A) recombination.
B) meiosis.
C) somatic cell formation.
D) gene linking.

Question 19

What does Mendel's first principle (of segregation) imply?

A) Characteristics from the parents blend together to produce intermediate offspring.
B) Characteristics from the parents do not blend together in offspring.
C) Only paternally derived characteristics segregate into gametes during meiosis.
D) Only maternally derived characteristics segregate into gametes during meiosis.

Question 20

Which of the following occurs during meiosis?

A) Haploid cells are produced from a single diploid cell.
B) Haploid cells are produced from two diploid cells.
C) Diploid cells are produced from a single diploid cell.
D) Diploid cells are produced from two haploid cells.

Question 21

Why is the understanding of molecular genetics an important set of scientific discoveries?

A) The discovery of the structure and other properties of DNA requires us to throw out Mendel's observations.
B) Without understanding molecular genetics it would be impossible to discover the dominant or recessive properties of common genes.
C) We can now describe the processes underlying Mendel's observations in ways that explain evolution more fully, and understand disease and physiology much more precisely.
D) We now understand the origin, or genesis, of molecules.

Question 22

What is an individual with two identical alleles at a locus?

A) an independent phenotype
B) a homozygote
C) a heterozygote
D) dominant

Question 23

Mendel claimed that transmission from parent to offspring of alleles of a given gene is independent for each gene and its alleles. What does this mean?

A) If a parent has the genotype Aa for one gene and aB for another gene, the a allele is more likely to be passed on because it corresponds to a dominant allele on another gene.
B) Dominant alleles in different loci are organized to enhance their likelihood of being passed on, a process called codominance.
C) Dominant alleles act independently of recessive alleles.
D) With the exception of genes on the same chromosome, the probability of transmission of a gene is unrelated to the transmission of other alleles on different genes.

Question 24

Mendel crossed true-breeding plants bearing yellow seeds with true-breeding plants bearing green seeds. He then crossed the offspring from that mating with each other (F₁ generation). What was the genotypic ratio among the offspring of the F₁ generation?

A) all Aa or aA
B) 25% aa, 50% Aa/aA, and 25% AA
C) all AA or aa
D) 33.3% aa, 33.3% Aa/aA, and 33.3% AA

Question 25

Under which circumstance does Mendel's principle of independent assortment hold?

A) only when traits are tightly linked (close together) on the same chromosome
B) only when traits are on different chromosomes
C) only when there is crossing over
D) only when the traits are not influenced by selection

Question 26

All cells in a multicelled organism have the same DNA. What does this mean?

A) Every cell produces the same range of proteins.
B) Each cell ultimately produces the same range of proteins but in a different order as the cell ages.
C) RNA polymerase affected by activator or inhibitor sequences is one way in which genes in most cells can be selectively turned on or off.
D) External chemical inputs must be used to determine which genes are expressed in which cells.

Question 27

Which of the following is true of chromosomes?

A) Hereditary material is contained in the chromosomes.
B) Chromosomes come in sets of three.
C) Two chromosomes from each homologous pair are normally passed on to daughter cells during meiosis.
D) One chromosome from each homologous pair is passed on to daughter cells during mitosis.

Question 28

Recombination and crossing over are very important in the genetic process because they produce

A) variation.
B) a new somatic cell.
C) DNA.
D) linked chromosomes.

Question 29

Imagine two loci on one homologous pair of chromosomes. At one locus the genotype is Aa, and at the other locus the genotype is Bb. After meiosis, what are all the possible genotypes of the gametes?

A) AB and ab gametes
B) AB, ab, Ab, and aB gametes
C) all AB gametes
D) Ab and aB gametes

Question 30

When Mendel crossed true-breeding plants bearing yellow seeds with true-breeding plants bearing green seeds, what was the genotypic ratio among the offspring?

A) 100% aa individuals
B) 100% Aa individuals
C) 100% AA individuals
D) 3:1 yellow to green individuals

Question 31

Mendel crossed AABB with aabb individuals, where B = smooth, b = wrinkled, A = yellow, and a = green. What was the genotypic ratio of the F₁ generation?

A) all AAbb
B) one-half AAbb and one-half aaBB
C) all AaBb
D) all AABB

Question 32

Consider a cross between tall and short plants in which all of the offspring are tall. What does this suggest?

A) The allele for tall is recessive.
B) The allele for tall is dominant.
C) The alleles for tall and short are codominant.
D) The allele for short is dominant.

Question 33

When a true-breeding plant bearing yellow seeds produces gametes, what alleles are represented among those gametes?

A) only A alleles
B) only a alleles
C) both a and A alleles, in equal frequencies
D) both a and A alleles, but mostly A alleles

Question 34

Mendel crossed true-breeding plants bearing yellow seeds with true-breeding plants bearing green seeds. He then crossed the offspring from that mating with each other (F₁ generation). What was the phenotypic ratio among the offspring?

A) all yellow
B) three-fourths yellow and one-fourth green
C) one-half green and one-half yellow
D) three-fourths green and one-fourth yellow

Question 35

What is the probability that an Aa individual will produce a gamete with an A allele?

A) 100%
B) 75%
C) 50%
D) 25%

Question 36

Imagine a cross between AA and Aa individuals. What is the genotypic ratio among the offspring?

A) one-half AA and one-half aa
B) one-half Aa and one-half aa
C) one-half AA and one-half Aa
D) all AA

Question 37

A heterozygote is an individual with

A) the same paternal and maternal allele at a particular locus.
B) a different paternal and maternal allele at a particular locus.
C) a recessive allele.
D) a dominant allele.

Question 38

When Mendel crossed true-breeding plants bearing yellow seeds with true-breeding plants bearing green seeds, what was the phenotypic ratio among the offspring?

A) all aa individuals
B) all AA individuals
C) half yellow and half green individuals
D) all yellow individuals

Question 39

For Mendel's peas, what genotype do true-breeding plants bearing yellow seeds have?

A) aa
B) aA
C) Aa
D) AA

Question 40

To what does the phenotype of an individual refer?

A) its visible characteristics
B) the number of homologous pairs of chromosomes
C) the number of chromosomes in its body cells
D) the number of chromosomes in its sex cells

Question 41

Which of the following makes a prokaryote different from a eukaryote?

A) A prokaryote does not have DNA.
B) A prokaryote has many chromosomes.
C) A prokaryote has many introns and exons.
D) A prokaryote does not have a nucleus.

Question 42

What are the organelles that splice the mRNA in eukaryotes after the introns have been snipped out called?

A) splitosomes
B) ribosomes
C) spliceosomes
D) Golgi bodies

Question 43

Which of the following is true of sickle-cell anemia?

A) It is on the decline.
B) It is caused by the change in two amino acids that make up the hemoglobin molecule.
C) It results when hemoglobin molecules do not fold correctly, reducing their ability to bind to oxygen.
D) It increases an individual's susceptibility to malaria.

Question 44

________ binds to complementary mRNA molecules and regulates the translation of mRNA into proteins.

A) Transfer RNA
B) Noncoding DNA
C) MicroRNA
D) Mitochondrial RNA

Question 45

The effect of both repressors and activators on a regulatory sequence allows for ________ of gene expression.

A) translation
B) combinatorial control
C) a biochemical pathway
D) primary structure

Question 46

If the DNA codon for an amino acid is ACC, what are the mRNA and its tRNA anticodon, respectively?

A) TGG; UCC
B) GTG; CAC
C) GGT; CCA
D) UGG; ACC

Question 47

As DNA codes for proteins, it can be interrupted by noncoding sequences called

A) organelles.
B) proteins.
C) introns.
D) synthetases.

Question 48

Which of the following occurs when DNA is replicated?

A) The two strands of the parent DNA are separated and then recombined before being passed on to the daughter cell.
B) The two strands of the parent DNA are separated, and two daughter DNA strands are formed.
C) Each of the two strands of parent DNA is reordered through the process of linkage, adding significant variation to the daughter cells.
D) One strand of the parent DNA is preserved; the other is destroyed.

Question 49

At least ________ of the genome is expressed as noncoding DNA.

A) 50%
B) 25%
C) 75%
D) 5%

Question 50

Which of the following is true of the structure of DNA?

A) It is a series of intertwining chromosomes.
B) It is a double-stranded molecule, consisting of sequences of two distinct bases.
C) It is a series of bases: adenine, guanine, thymine, and cytosine.
D) It is a sequence of genetic data made up of numerous chromosomes.

Question 51

What does analysis of DNA sequences tell us?

A) Humans and chimpanzees share a more recent common ancestor than either shares with gorillas.
B) The last common ancestor of chimpanzees and humans were gorillas.
C) Humans left Asia about 1 million years ago.
D) Humans left Asia and went to Africa.

Question 52

Which of the following is true of molecular genetics?

A) It links biology to geophysics.
B) It has explained the way the solar system works.
C) It has demonstrated that humans descended from chimpanzees.
D) It provides data for reconstructing the evolutionary history of species.

Question 53

Which of the following is true when two loci are very close together on a chromosome?

A) They may exhibit a high degree of linkage.
B) They are not subject to crossing over.
C) Only one of them will be expressed.
D) The alleles at those loci are more likely to swap positions.

Question 54

Which of the following does alternative splicing allow?

A) the same DNA sequence to code for more than one protein
B) prokaryote exons to be included in the genome of eukaryotes
C) only certain sections of DNA to be copied
D) a maximum of four exons to be attached to mRNA

Question 55

Some biologists hypothesize that introns are maintained in eukaryotes because their population sizes are much smaller than in prokaryotes. ________ is the random, nonadaptive evolutionary process that explains this phenomenon.

A) Genetic drift
B) Protein synthesis
C) Natural selection
D) Transcription

Question 56

Which of the following statements is true?

A) DNA has a nonrepeating four-base structure.
B) DNA is contained in chromosomes.
C) DNA stands for "determining nuclear acid."
D) DNA does not tell us why heredity leads to the patterns Mendel described in pea plants.

Question 57

Which of the following sequences is accurate for transcription and translation?

A) DNA tRNA mRNA protein
B) DNA mRNA protein
C) protein tRNA DNA
D) protein tRNA DNA

Question 58

Which of the following is true of DNA transcription/translation?

A) Each codon corresponds to a different amino acid.
B) A DNA sequence codes for a protein.
C) A protein consists of a series of codons.
D) DNA is translated in mitosis, but transcribed in mitosis.

Question 59

Because there are 64 possible codons and only 20 amino acids

A) many mutations have no effect on phenotype.
B) every mutation has some effect on phenotype.
C) each tRNA molecule contains two extra amino acids.
D) each tRNA molecule contains two extra codons.

Question 60

Which of the following is true of crossing over?

A) It can occur between loci on nonhomologous chromosomes.
B) It can occur between alleles for a given gene on the same chromosome.
C) It increases genetic variation.
D) It decreases genetic variation.

Question 61

How does a sequence of DNA produce a protein through transcription and translation?

Question 62

The following terms would appear in any summary of the key steps in the process of genes coding for proteins, and the basic function of those proteins, in living organisms:
catalyzing
chromosomes
DNA molecule
enzyme
gene
mRNA
protein
protein structure
structure
transcription
variation in DNA sequence
Write such a description in 200 words or less.

Question 63

Explain the life cycle of diploid organisms in terms of meiosis and mitosis.

Question 64

The products of a gene's transcription and translation determine aspects of the physiology, behavior, and morphology of living organisms. How does variation in genes relate to variation in the characteristics of the organisms?

Question 65

Consider a homologous pair of chromosomes with the genotype Aa at one locus and the genotype Bb at another locus. After undergoing meiosis, what are all the possible genotypes of the gametes produced?

Question 66

What is the role of regulatory genes? What is meant by the combinational control of gene expression? Illustrate your answer with an example.

Question 67

How do enzymes control the chemical composition of cells?

A) by determining which genes are passed on to each cell during mitosis
B) by catalyzing some chemical reactions but not others within a cell
C) by catalyzing all of the chemical reactions in a cell so that the cell grows larger and can divide
D) by determining which amino acids survive within a cell and, thus, which proteins can be produced

Question 68

How do the results of Mendel's experiments affect our understanding of how variation is preserved?

Question 69

Compare and contrast mitosis and meiosis. Include in your discussion for each process (a) the number of daughter cells produced and (b) the number of chromosomes each new cell contains. What are recombination and crossing over, and why are they important in the study of evolution?

Question 70

Imagine a cross between two AaBb individuals, where A = yellow, a = green, B = smooth, and b = wrinkled. What is the genotypic and phenotypic ratio among the offspring?

Question 71

How does alternative splicing allow the same DNA sequence to code for more than one protein? Why is alternative splicing important in eukaryotes?