The centromere is a region in which

A) Chromatids remain attached to one another until anaphase

B) Metaphase chromosomes become aligned at the metaphase plate

C) Chromosomes are grouped during telophase

D) The nucleus is located prior to mitosis

A

Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?

A) 4

B) 16

C) 8

D) 32

D

If there are 20 chromatids in a cell, how many centromeres are there?

A) 10

B) 20

C) 30

D) 40

A

For a newly evolving protist, what would be the advantage of using eukaryote-like cell division rather than binary fission?

A) Binary fission would not allow for the formation of new organisms.

B) Cell division would allow for the orderly and efficient segregation of multiple linear chromosomes.

C) Cell division would be faster than binary fission.

D) Cell division allows for lower raters of error per chromosome replication.

B

Suppose a biologist can separate one of a dozen pieces of chromatin from a eukaryotic (animal) nucleus. It might consist of which of the following?

A) one-twelfth the genes of the organism

B) two chromosomes, each with six chromatids

C) a single circular piece of DNA

D) Two long strands of DNA plus proteins

D

In which group of eukaryotic organisms does nuclear envelop remain intact during mitosis?

A) seedless plants

B) dinoflagellates

C) diatoms

D) dinoflagellates and diatoms only

D

If a horticulturist breeding gardenias succeeds in having a single plant with a particularly desirable set of traits, which of the following would be her most probable and efficient route to establishing a line of such plants?

A) Backtrack through her previous experiments to obtain another plant with the same traits

B) Breed this plant with another plant with much weaker traits

C) Clone the plant asexually to produce an identical one

D) Force the plant to self-pollinate to obtain an identical one

C

The human genome is minimally contained in which of the following?

A) every human cell

B) each human chromosome

C) the entire DNA of a single human

D) the entire human population

A

In the human species, all somatic cells have 46 chromosomes. Which of the following can also be true?

A) A plant species has 46 chromosomes per cell.

B) some adult humans have 69 chromosomes per cell

C) Some adult humans have 23 chromosomes per cell.

D) A certain fungal species has only one chromosme per cell.

A

Which of the following is a true statement about sexual vs. asexual reproduction?

A) Asexual reproduction, but not sexual reproduction, is characteristic of plants and fungi

B) In sexual reproduction, individuals transmit 50% of their genes to each of their offspring

C) In asexual reproduction, offspring are produced by fertilization without meiosis.

D) Sexual reproduction requires that parents be diploid.

B

Which of the following defines a genome?

A) representation of a complete set of a cell's polypeptides

B) the complete set of an organism's polypeptides

C) the complete set of a species' polypeptides

D) the complete set of an organism's genes

D

At which stage of mitosis are chromosomes usually photographed in the preparation of a karyotype?

A) prophase

B) metaphase

C) anaphase

D) telophase

B

The human X and Y chromosomes

A) are both present in every somatic cell of males and females alike

B) are of approximately equal size and number of genes

C) are almost entirely homologous, despite their different names

D) include genes that determine an individual's sex

D

Which of the following is true of a species that has a chromosome number of 2n=16?

A) The species is diploid with 32 chromosomes per cell

B) The species has 16 sets of chromosomes per cell

C) Each cell has eight homologous pairs

D) During the S phase of the cell cycle there will be 32 separate chromosomes

C

Eukaryotic sexual life cycles show tremendous variation. Of the following elements, which do all sexual life cycles have in common?

I. Alternation of generations

II. Meiosis

III. Fertilization

IV. Gametes

V. Spores

A) I, IV, and V

B) I, II, and IV

C) II, III, and IV

D) I, II, III, IV, and V

C

Which of these statements is false?

A) In humans, each of the 22 maternal autosomes has a homologous paternal chromosome.

B) In humans, the 23rd pair, the sex chromosomes, determines whether the person is female (XX) or male (XY).

C) Single, haploid (n) sets of chromosomes in ovum and sperm unite during fertilization, forming a diploid (2n), single-celled zygote.

D) At sexual maturity, ovaries and testes produce diploid gametes by meiosis.

D

Referring to a plant's sexual life cycle, which of the following terms describes the process that leads directly to the formation of gametes?
A) sporophyte meiosis
B) gametophyte mitosis
C) gametophyte meiosis
D) sporophyte mitosis
E) alternation of generations

B

Which of the following is an example of alternation of generations?
A) A grandparent and grandchild each have dark hair, but the parent has blond hair.
B) A diploid plant (sporophyte) produces, by meiosis, a spore that gives rise to a multicellular, haploid pollen grain (gametophyte).
C) A diploid animal produces gametes by meiosis, and the gametes undergo fertilization to produce a diploid zygote.
D) A haploid mushroom produces gametes by mitosis, and the gametes undergo fertilization, which is immediately followed by meiosis.
E) A diploid cell divides by mitosis to produce two diploid daughter cells, which then fuse to produce a tetraploid cell.

B

A karyotype results from which of the following?
A) a natural cellular arrangement of chromosomes in the nucleus
B) an inherited ability of chromosomes to arrange themselves
C) the ordering of human chromosome images
D) the cutting and pasting of parts of chromosomes to form the standard array
E) the separation of homologous chromosomes at metaphase I of meiosis

C

Which of the following can utilize both mitosis and meiosis in the correct circumstances?
A) a haploid animal cell
B) a diploid cell from a plant stem
C) any diploid animal cell
D) a plantlike protist
E) an archaebacterium

D

When Thomas Hunt Morgan crossed his red-eyed F₁ generation flies to each other, the F₂ generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result?

A) The gene involved is on the Y chromosome.
B) The gene involved is on the X chromosome.
C) The gene involved is on an autosome, but only in males.
D) Other male-specific factors influence eye color in flies.
E) Other female-specific factors influence eye color in flies.

B

Sturtevant provided genetic evidence for the existence of four pairs of chromosomes in Drosophila in which of these ways?

A) There are four major functional classes of genes in Drosophila.
B) Drosophila genes cluster into four distinct groups of linked genes.
C) The overall number of genes in Drosophila is a multiple of four.
D) The entire Drosophila genome has approximately 400 map units.
E) Drosophila genes have, on average, four different alleles.

B

Which of the following is the meaning of the chromosome theory of inheritance as expressed in the early 20th century?

A) Individuals inherit particular chromosomes attached to genes.
B) Mendelian genes are at specific loci on the chromosome and in turn segregate during meiosis.
C) Homologous chromosomes give rise to some genes and crossover chromosomes to other genes.
D) No more than a single pair of chromosomes can be found in a healthy normal cell.
E) Natural selection acts on certain chromosome arrays rather than on genes.

B

Thomas Hunt Morgan's choice of Drosophila melanogaster has been proven to be useful even today. Which of the following has/have continued to make it a most useful species?

I. its four pairs of chromosomes
II. a very large number of visible as well as biochemically mutant phenotypes
III. easy and inexpensive maintenance
IV. short generation time and large number of offspring

A) I and IV only
B) II and III only
C) I, II, and III only
D) II, III, and IV only
E) I, II, III, IV, and V

E

A woman is found to have 47 chromosomes, including three X chromosomes. Which of the following describes her expected phenotype?

A) masculine characteristics such as facial hair
B) enlarged genital structures
C) excessive emotional instability
D) normal female
E) sterile female

D

Males are more often affected by sex-linked traits than females because

A) male hormones such as testosterone often alter the effects of mutations on the X chromosome.
B) female hormones such as estrogen often compensate for the effects of mutations on the X chromosome.
C) X chromosomes in males generally have more mutations than X chromosomes in females.
D) males are hemizygous for the X chromosome.
E) mutations on the Y chromosome often worsen the effects of X-linked mutations.

D

SRY is best described in which of the following ways?

A) a gene present on the X chromosome that triggers female development
B) an autosomal gene that is required for the expression of genes on the Y chromosome
C) a gene region present on the Y chromosome that triggers male development
D) an autosomal gene that is required for the expression of genes on the X chromosome
E) a gene required for development, and males or females lacking the gene do not survive past early childhood

C

In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male?
A) tortoiseshell females; tortoiseshell males
B) black females; orange males
C) orange females; orange males
D) tortoiseshell females; black males
E) orange females; black males

D

Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents?
A) XcXc and XcY
B) XcXc and XCY
C) XCXC and XcY
D) XCXC and XCY
E) XCXc and XCY

E

Calico cats are female because
A) the males die during embryonic development.
B) a male inherits only one of the two X-linked genes controlling hair color.
C) the Y chromosome has a gene blocking orange coloration.
D) only females can have Barr bodies.
E) multiple crossovers on the Y chromosome prevent orange pigment production.

B

Duchenne muscular dystrophy (DMD) is caused by a gene on the human X chromosome. The patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein. They rarely live past their 20s. How likely is it for a woman to have this condition?

A) Women can never have this condition.
B) One-half of the daughters of an affected man could have this condition.
C) One-fourth of the children of an affected father and a carrier mother could have this condition.
D) Very rarely would a woman have this condition; the condition would be due to a chromosome error.
E) Only if a woman is XXX could she have this condition.

D

Which of the following statements is true of linkage?
A) The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.
B) The observed frequency of recombination of two genes that are far apart from each other has a maximum value of 100%.
C) All of the traits that Mendel studied–seed color, pod shape, flower color, and others–are due to genes linked on the same chromosome.
D) Linked genes are found on different chromosomes.
E) Crossing over occurs during prophase II of meiosis.

A

What is the reason that linked genes are inherited together?
A) They are located close together on the same chromosome.
B) The number of genes in a cell is greater than the number of chromosomes.
C) Chromosomes are unbreakable.
D) Alleles are paired together during meiosis.
E) Genes align that way during metaphase I of meiosis.

A

One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called?
A) deletion
B) transversion
C) inversion
D) translocation
E) duplication

D

A nonreciprocal crossover causes which of the following products?
A) deletion only
B) duplication only
C) nondisjunction
D) deletion and duplication
E) duplication and nondisjunction

D

Which of the following variations on translation would be most disadvantageous for a cell?
A) translating polypeptides directly from DNA
B) using fewer kinds of tRNA
C) having only one stop codon
D) lengthening the half-life of mRNA
E) having a second codon (besides AUG) as a start codon

A

the nitrogenous base adenine is found in all members of which group?
A) proteins, triglycerides, and testosterone
B) proteins, ATP, and DNA
C) ATP, RNA, and DNA
D) α glucose, ATP, and DNA
E) proteins, carbohydrates, and ATP

c

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is
A) 3' UCA 5'.
B) 3' UGA 5'.
C) 5' TCA 3'.
D) 3' ACU 5'.
E) either UCA or TCA, depending on wobble in the first base.

A

The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?
A) A gene from an organism can theoretically be expressed by any other organism.
B) All organisms have experienced convergent evolution.
C) DNA was the first genetic material.
D) The same codons in different organisms translate into the different amino acids.
E) Different organisms have different numbers of different types of amino acids.

A

Which of the following provides some evidence that RNA probably evolved before DNA?
A) RNA polymerase uses DNA as a template.
B) RNA polymerase makes a single-stranded molecule.
C) RNA polymerase does not require localized unwinding of the DNA.
D) DNA polymerase uses primer, usually made of RNA.
E) DNA polymerase has proofreading function.

D

Which of the following statements best describes the termination of transcription in prokaryotes?
A) RNA polymerase transcribes through the polyadenylation signal, causing proteins to associate with the transcript and cut it free from the polymerase.
B) RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.
C) RNA polymerase transcribes through an intron, and the snRNPs cause the polymerase to let go of the transcript.
D) Once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome.
E) RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA.

B

Which of the following does not occur in prokaryotic eukaryotic gene expression, but does in eukaryotic gene expression?
A) mRNA, tRNA, and rRNA are transcribed.
B) RNA polymerase binds to the promoter.
C) A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end.
D) Transcription can begin as soon as translation has begun even a little.
E) RNA polymerase requires a primer to elongate the molecule.

C

In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein?
A) ligase
B) RNA polymerase I
C) RNA polymerase II
D) RNA polymerase III
E) primase

c

A part of the promoter, called the TATA box, is said to be highly conserved in evolution. Which of the following might this illustrate?
A) The sequence evolves very rapidly.
B) The sequence does not mutate.
C) Any mutation in the sequence is selected against.
D) The sequence is found in many but not all promoters.
E) The sequence is transcribed at the start of every gene.

C

During splicing, which molecular component of the spliceosome catalyzes the excision reaction?
A) protein
B) DNA
C) RNA
D) lipid
E) sugar

c

Alternative RNA splicing
A) is a mechanism for increasing the rate of transcription.
B) can allow the production of proteins of different sizes from a single mRNA.
C) can allow the production of similar proteins from different RNAs.
D) increases the rate of transcription.
E) is due to the presence or absence of particular snRNPs.

B