Module 04-06 Exam

All RNA except for __________ is made from DNA.

None of these.

When cultured normal human cells were infected with a virus that carried the genes that coded for a subunit of telomerase:

a. the cells underwent more cell divisions than normal.

In all organisms, the AUG codon codes for:

a. the initiation of translation.

Inducible genes are usually actively transcribed when:

a. the molecule degraded by the enzyme(s) is present in the cell.

An inducible operon is usually controlled by:

an active repressor that keeps it in the "off" state

Homologous chromosomes separate during what phase of meiosis?

anaphase I

In humans, the 22 pairs of chromosomes that don't include the sex chromosomes are called

autosomes.

During which stage of meiosis do the tetrads form (homologous chromosomes pair up)?

prophase I

Crossing over occurs during what phase?

prophase I of meiosis

The information carried by DNA is incorporated in a code specified by the:

specific nucleotide sequence of the DNA molecule

In peas, Mendel found that tall plants and yellow peas are dominant. The phenotype for a pea plant with the genotype TtYy would be:

tall with yellow peas

The separation of alleles of a gene takes place during:

telophase II of meiosis

The total number of different three-base combinations of the four nucleic acid bases is:

64

The codon is found in the:

a. mRNA.

The M phase of the cell cycle involves two main processes:

a. mitosis and cytokinesis.

Which of the following serves as an "adapter" in protein synthesis and bridges the gap between mRNA and proteins?

a. tRNA

Which of the following words is represented by word descriptions like black and tall?

phenotype

Two Martians fall in love and marry. One Martian is homozygous for red eyes and the other is heterozygous. The recessive eye color is purple. What is the probability that they will have a child with purple eyes?

0

A brown-eyed couple already has a child with blue eyes. What is the probability that their next child will have blue eyes, assuming that the brown eye allele is dominant and the blue eye allele is recessive?

1/4

An animal with a diploid number of 36 chromosomes will have __________ chromosomes in its gametes and __________ chromosomes in its somatic cells.

18;36

The phenotypic ratio of a monohybrid cross between two heterozygotes is:

1:2:1

The height of pea plants from a cross between parent plants heterozygous for height, in which tall is dominant, would be:s

3 tall : 1 short

Which of the following is a feature of plant cell division that distinguishes it from animal cell division?

A cell plate forms

Regulation of gene expression can be accomplished by controlling:

All of these

Why is color-blindness more common in males than in females?

All of these.

During which phase does crossing-over occur?

Prophase I

Which of the following crosses will yield four phenotypes in a ratio of 9:3:3:1?

RrYy x RrYy

Chromosomes are duplicated during __________ of the cell cycle.

S phase

DNA is replicated during what part of the cell cycle?

S phase

Which of the following is a characteristic of uracil?

The ability to bond with adenine.

Which of the following would be considered a true dihybrid genotype?

WwSs

A polyribosome is:

a complex of many ribosomes and an mRNA

The physical location of a particular gene on a chromosome is called:

a locus.

What is a testcross?

a mating between an individual of unknown genotype and an individual homozygous recessive for the trait of interest

During prophase I, each chiasma represents:

a site of crossing-over

Why does DNA synthesis only proceed in the 5' to 3' direction?

a. Because DNA polymerases can only add nucleotides to the 3' end of a polynucleotide strand.

Which of the following adds new nucleotides to a growing DNA chain?

a. DNA polymerase

A repressible operon is usually controlled by:

a. an inactive repressor that allows it to be in the "on" state.

During protein synthesis, ribosomes:

a. attach to the mRNA molecule and travel along its length.

Lactose induces the transcription of the lactose operon by:

a. binding to the allosteric site of the repressor after being converted to allolactose

In DNA replication, the lagging strand:

a. is synthesized as a series of Okazaki fragments.

Which of the following best describes semiconservative replication?

b. A DNA molecule consists of one parental strand and one new strand.

Why is only one strand of DNA transcribed into mRNA?

b. Because transcribing both DNA strands would produce different amino acid sequences.

Okazaki fragments are joined together by:

b. DNA ligase.

Which of the following is a difference between mitosis and meiosis?

b. In mitosis two daughter cells are produced, whereas in meiosis four daughter cells are produced.

A bacterial chromosome consists of:

b. a circular DNA molecule many times larger than the cell.

Mendel's principle of segregation states that:

b. alleles separate from each other before forming gametes.

Where is the amino-acid binding site located on the tRNA molecule?

b. at the end of the 3' end of the molecule

Eukaryotic transcription factors:

b. may be activators or repressors of transcription.

The focus of gene regulation in multicellular organisms is on:

b. the specificity of products in different tissues.

Repressible genes are usually actively transcribed when:

b. the supply of the end product formed by the enzymes encoded by these genes is low.

Which of the following are pyrimidines?

b. thymine and cytosine

Most prokaryotic organisms reproduce mainly by the process of

binary fission.

One of the mRNA codons specifying the amino acid leucine is 5' -CUA-3'. Its corresponding anticodon is:

c. 3'-GAU-5'.

__________ refers to multiple independent pairs of genes having similar and additive effects on the same characteristic.

c. Polygenic inheritance

Some eukaryotic DNA sequences act as introns in the cells of some tissues and exons in the cells of other tissues. This allows:

c. formation of different types of closely related proteins.

When certain medium height hybrid plants were crossed, they produced offspring that were dwarf, medium, and tall in a ratio of 1 : 2 : 1. This is an example of:

c. incomplete dominance.

The correct number of chromosomes is maintained during sexual reproduction by:

c. meiosis, which reduces the chromosome number by half.

The monomer units of DNA and RNA are

c. nucleotides.

The term "dominant" means that:

c. one allele can mask the expression of another in a hybrid.

Which of the following events does not occur during meiosis I?

c. separation of sister chromatids

A cell is in metaphase if:

c. the chromosomes are aligned at the midplane of the cell.

Translation consists of which of the following?

c. the conversion of genetic information from the language of nucleic acids to the language of proteins

The main reason scientists thought that proteins, rather than DNA, were the carriers of genetic material in the cell was:

c. the large number of possible amino acid combinations.

Translational controls of protein levels in bacteria are governed by:

c. the rate at which ribosomes attach to mRNA molecules

Using standard conventions for naming alleles, which of the following pairs is correct?

c. tt-homozygous.

Which of the following is an example of X-chromosome inactivation?

calico cats

During prophase, __________ is(are) compacted into visible chromosomes.

chromatin

Breeding a yellow dog with a brown dog produced puppies with both yellow and brown hairs intermixed. This is an example of:

codominance.

The gene that codes for the repressor protein of the E. coli lactose operon is:

constitutive

Chargaff determined that DNA from any source contains about the same amount of guanine as __________.

cytosine

____ are all of the body's cells with the exception of the sex cells.

d. Somatic cells

How is the chromosome of a bacterial cell replicated?

d. The circular DNA molecule is replicated from one origin of replication bidirectionally.

A pear plant with the genotype Aa can produce gametes containing:

d. either A or a.

DNA sequences called __________ increase the rate of RNA synthesis after initiation of transcription.

d. enhancers

A particular gene that controls seed coat color in peas also determines the susceptibility of these peas to a particular disease. This situation is referred to as:

d. pleiotropy.

In peas, Mendel found that tall plants and yellow peas are dominant. The phenotype for a pea plant with the genotype TTyy would be:

d. tall with green peas.

The ends of eukaryotic chromosomes can be lengthened by:

d. telomerase.

Thymine forms a complementary pair with __________ in RNA and __________ in DNA.

d. uracil; adenine

Most human somatic cells are:

diploid

Which of the following nucleotide sequences represents the complement to the DNA strand 5' - AGATCCG- 3'?

e. 3' - TCTAGGC- 5'

Eukaryotic enhancers are capable of which of the following?

e. All of these

How does the lactose repressor block transcription of the lactose operon?

e. by binding to the operator

The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called

e. cytokinesis.

Where do transcription and translation occur in prokaryotic cells?

e. in the cytoplasm

Retroviruses or RNA tumor viruses use __________ to make DNA.

e. reverse transcriptase

If a cell is dividing by binary fission then you know that:

e. the cell is prokaryotic.

RNA synthesis is also known as:

e. transcription

X-ray crystallography showed that DNA:

e. was a helix.

In peas, yellow is dominant over green in seed color. With which of the following is it best to cross a yellow-seeded pea plant to determine whether it is homozygous dominant or heterozygous?

homozygous green-seeded plant

Eukaryotic cells spend most of their cell cycle in which phase?

interphase

Genes that tend to be inherited together are said to be:

linked

Cells become haploid during which division of meiosis?

meiosis I

During which phase of mitosis do the chromosomes line up on a plane located equidistant from the two spindle poles?

metaphase

A new operon is discovered in a bacterium. The control of this operon is affected by a protein that is made by another gene, and is made in an active form that binds to the DNA near the operon to prevent transcription. This is an example of __________ control.

negative

Substitution of one base pair for another can result in a __________ mutation that results in the conversion of an amino acid specifying codon to a termination codon.

nonsense

Upstream promoter elements in eukaryotes are:

nucleotide sequences that regulate the efficiency of transcription initiation

Frameshift mutations result from:

the insertion or deletion of one or two base pairs.

The sex of a human is determined by:

the presence of a Y chromosome

Introns in pre-mRNA are known to:

undergo excision, whereby they are spliced out of the message