Biology Practice Test Exam 3, Ch. 5 & 6 – Flashcards

Which of the following is NOT true about DNA? a. Humans lack DNA in their brain cells. b. Plants have DNA in three places: the nucleus, chloroplasts, and mitochondria. c. It can be found in human saliva, hair, and blood. d. It is found in nearly all cells of all living things. e. It can be used to identify an individual person. .

Which of the following is NOT true about mutations? a. When one nucleotide base pair is replaced by another, this constitutes a point mutation. b. Sunlight can cause mutation. c. Mutations are very rare. d. One general type of mutation is a change to the overall organization of chromosomal genes. e. A mutation in DNA always leads to changes in the structure and function of the protein produced

The bacterium, E. coli prefer to consume glucose. If, however, there is no glucose present, they will utilize lactose as an energy source. Which of the following is the regulatory mechanism occurring when there is no glucose, but there is lactose? a. activators initiate gene expression b. RNA cannot bind to the promoter c. no lactose metabolism genes are transcribed d. RNA polymerase is blocked e. the repressor protein binds to the operator region

Which of the following is TRUE about selective breeding and genetically modified organisms? a. Farmers have been able to produced new varieties of crops by selective breeding alone. b. Vitamin A genes have been introduced into rice to make these crops resistant to herbicides. c. Desired traits engineered into crops must come from DNA of the same species (e.g. rice genes must always be used to genetically engineer rice). d. Vitamin A genes have been introduced into rice to make these crops resistant to pests. e. GMOs are always superior to selectively bred organisms.

Which of the following statements about the process of forensic DNA profiling is INCORRECT? a. After a profile has been done, a complete DNA sequence is often used to verify the results. b. The technique takes advantage of the fact that portions of the human genome vary greatly throughout the population. c. Since the tests are often run on very small biological samples, like drops of blood, PCR reactions are used to amplify the DNA before the profiling begins. d. The results are always given in terms of the probability that two individual's DNA could give the exact same genetic profile. e. All of the above are correct.

Which of the following molecules is NOT DIRECTLY involved in translation? a. mRNA b. DNA c. ribosomes d. tRNA e. All of the above molecules are directly involved in translation.

Which of the following about DNA is FALSE? a. Alleles are different versions of a gene for a certain characteristic or trait. b. The number of chromosomes increases with the complexity of the organism. c. Eukaryotes hold their DNA as long, linear strands while prokaryotes have circular loops. d. A DNA gene serves as the coded instructions for making a particular molecule of protein. e. All the DNA found in an adult elephant cell is known collectively as the elephant genome.

To start the transcription process, a large molecule, __________________, recognizes a _______________________. a. DNA polymerase; promoter site b. RNA polymerase; promoter site c. DNA polymerase; promoter site d. RNA polymerase; messenger RNA e. DNA polymerase; termination site

Since its discovery in 1953, the double helix structure of DNA is now one of the most recognizable molecules in biology. What was so groundbreaking about the "double" part of the double helix molecule? a. It suggested that information could be contained in both strands of the helix and that this information was related by base pairs. b. It suggested that two helices are required for transcription. c. The symmetry of the molecule made it perfect for X-ray crystallography. d. It suggested that information could be contained in both strands of the helix independently. e. It suggested how genetic information could be copied and inherited.

Which of the following is TRUE about human DNA? a. A newt, onion, and amoeba all have smaller genomes than we humans have. b. Human genes do not have non-coding regions of DNA within them. c. The genome size of an organism is a good measure of the complexity of that organism. d. More than 95% of our DNA is non-coding DNA. e. Bacteria have far more non-coding regions in their DNA than humans.

Which of the following is a reason why DNA sequencing alone is not sufficient in identifying sequences that encode proteins? a. The presence of pseudo genes. b. Degeneracy in the genetic code. c. The presence of introns in the coding regions. d. Methylation of certain regions of the DNA sequence. e. The abundance of start and stop codons in the DNA sequence

Which of the following is NOT a reasonable fear of genetically modified foods? a. Organisms that we don't want to kill, like the monarch butterfly, may be killed inadvertently. b. Eating genetically modified foods could be dangerous. c. The loss of genetic diversity among crop plants is risky. d. Organisms that we want to kill may become invincible. e. All of the above are reasonable fears of genetically modified foods.

What are the three functions of the tRNA molecule? a. The tRNA molecule transcribes, translates, and replicates the DNA. b. The tRNA molecule carries an amino acid, associates with mRNA molecules, and replicates DNA. c. The tRNA molecule carries an amino acid, associates with mRNA molecules, and binds to one of three sites on the large subunit of a ribosome. d. The tRNA molecule carries an amino acid, associates with rRNA molecules, and binds to one of three sites on the large subunit of an mRNA molecule. e. The tRNA molecule transcribes DNA, associates with rRNA molecules, and synthesizes activating enzymes.

A particular virus is known to attack the immune system of humans and continues to infect people no matter how many vaccines are developed against it. What can you predict about the genome of this virus? a. This viral genome is composed of RNA. b. This viral genome is very small compared to other viruses. c. This viral genome mutates at a rapid rate. d. All of the above. e. Nothing can be predicted about this viral genome with the given information.

What is the most common reason that DNA analyses overturn incorrect criminal convictions? a. Most juries have an irrational bias in favor of DNA evidence. b. In more than three-quarters of the cases overturned by DNA analysis, inaccurate eyewitness testimony played an important role in the original guilty verdict. c. Two-thirds of incorrect criminal convictions are the result of defense attorney incompetence, and DNA evidence cannot be used improperly by defense attorneys. d. Two-thirds of incorrect criminal convictions are the result of prosecutorial misconduct, and DNA evidence cannot be used improperly by prosecutors. e. DNA analytical technology has improved markedly over the last decade, so cases in which earlier DNA analysis had been used to convict a defendant, more modern DNA analysis has overturned that conviction.

The genes that code for proteins and the genes for RNA products such as rRNA and tRNA constitute a surprisingly small portion of the genomes of most multicellular eukaryotes. The majority of most eukaryotic genomes consist of non-coding regions, sometimes described as "junk DNA." However, recent evidence shows that even this so-called "junk DNA" can play important roles. Which of the following is NOT a type of non-coding DNA? a. exons b. introns c. regulatory sequences d. repetitive DNA e. transposable elements

When a triplet of bases in the coding sequence of DNA is GCA, the corresponding codon for the mRNA that is transcribed from it is: a. UGC. b. GCA. c. TGC. d. CGU. e. CGT.

Each codon on a DNA strand codes for: a. a single amino acid. b. a single gene. c. multiple genes. d. multiple amino acids. e. a protein.

During translation, chain elongation continues until: a. the ribosome falls off the end of the mRNA. b. all the tRNAs are enzymatically broken down. c. all the amino acids in the cell are used up. d. all the tRNAs are converted to mRNAs. e. a stop codon is encountered.

Sexual reproduction leads to offspring that are all genetically different from one another and from either parent. What are the three aspects of sexual reproduction that lead to this variation? a. crossing over during the production of gametes; shuffling and reassortment of homologues during mitosis; and combination of alleles from two parents during binary fission. b. crossing over during the production of gametes; shuffling and reassortment of homologues during mitosis; and combination of alleles from two parents at fertilization. c. crossing over during the production of gametes; shuffling and reassortment of homologues during meiosis; and combination of alleles from two parents at fertilization. d. crossing over during the production of zygotes; shuffling and reassortment of homologues during mitosis; and combination of alleles from two parents at fertilization. e. shuffling and reassortment of homologues during mitosis; shuffling and reassortment of homologues during meiosis; and combination of alleles from two parents at fertilization.

The rate at which mitosis occurs varies dramatically for different types of cells. The most rapid cell division occurs: a. in the gametes. b. on the skin. c. in the blood and the heart. d. in the blood and the cells lining the various tissues of organs. e. in the liver and the brain.

9. I. two daughter nuclei are formed (telophase) II. centromeres separate (early anaphase) III. cytoplasm is divided (cytokinesis) IV. chromosomes move toward opposite poles (anaphase) V. chromosomes line up in single file (metaphase) Which of the following represents the correct order of events in the mitotic cell cycle listed above? a. III, V, I, IV, II b. V, II, IV, I, III c. V, IV, I, III, II d. IV, I, II, V, III e. V, II, I, IV, III

6. Seventy to ninety percent of the genetic material in a gamete made in your body could be inherited from your mother. How could this be? a. You receive many mitochondria, which have their own genome, from your mother, but not from your father. b. The maternal genes contain more dominant genes so they are expressed at least seventy percent of the time. c. Your maternal genes kill off your paternal genes at a greater rate than your paternal genes kill of your maternal genes. d. The X chromosome is substantially larger than the Y chromosome. e. The above statement is incorrect. Fifty percent of the genetic material in your gametes comes from your father.

Radiation therapy for cancer works because a cell's DNA is exposed during mitosis and most vulnerable to damage from radiation. Because cancer cells are uncontrollably undergoing mitosis, they die when exposed to the treatment. The common side effects of radiation treatment are hair loss and vomiting. What does this imply? a. Radiation treatment will be ineffective in treating stomach cancer. b. Both skin and stomach cancer will be made worse if treated with radiation. c. Radiation therapy is an ineffective way to treat cancer. d. Both stomach and skin cells are constantly being replaced. e. Radiation treatment will be most effective for the treatment of skin and stomach cancers.

In DNA replication, when the DNA molecule separates into two strands: a. it is possible to reconstruct perfectly all the information on the missing strand because one strand carries all the information needed to construct its complementary strand. b. the rebuilding process begins, in which an enzyme connects the appropriate complementary base to the exposed base. c. the cell is ready for prophase. d. All of the above are correct. e. Only the first and second choices are correct.

Which of the following is NOT a disadvantage of sexual reproduction? a. It takes time and energy to find a mating partner. b. Variability among offspring enables parents to produce a range of offspring, any one of which may be suitable to changes in the environment. c. Organisms can expose themselves to danger during the mating process. d. Sexual reproduction breaks down genotypes that are well adapted for a stable environment. e. The transfer of genetic information from generation to generation is not as efficient as it is dur

When a male donkey is bred with a female horse, the offspring produced is a mule, which is healthy but sterile. Karyotyping experiments have revealed that horses and donkeys have different numbers of chromosomes, 64 for horses and 62 for donkeys. The mule therefore has 63 chromosomes. Knowing this, what is the best explanation for the inability of mules to produce offspring? a. Proper pairing of homologues is impossible during meiosis I. b. Gametes formed in meiosis II do not contain sex-determining chromosomes. c. Crossing over is not possible between unmatched chromosomes during meiosis II. d. Spindle fibers cannot properly bind to the odd number of chromosomes during meiosis I. e. Chromosomes cannot align on the metaphase plate during meiosis II

Bacteria divide by a type of ______________________ called ____________________. a. sexual reproduction; binary fission b. asexual reproduction; binary fission c. asexual reproduction; elongation d. sexual reproduction; replication e. asexual reproduction; replication

Eukaryotic cells can divide by: a. replication only. b. mitosis only. c. meiosis only. d. segregation only. e. mitosis and meiosis.

What is the difference between embryonic development and differentiation? a. Development and differentiation are really two words for the same thing. b. Development involves the formation of three germ layers; differentiation includes the formation of a blastula. c. Development involves meiosis; differentiation involves the creation of the three germ layers. d. Development involves mitosis and embryonic growth; differentiation involves specialization of tissues. e. Development involves the events just before birth; differentiation specifically refers to neurulation.

For crossing over to increase genetic variation, it must involve the exchange of material between: a. gametes from the two different sexes. b. non-homologous chromosomes. c. sister chromatids of a single chromosome. d. non-sister chromatids of a homologous pair of chromosomes. e. Crossing over can increase genetic variation in any of the ways mentioned above.

Side effects of undergoing chemotherapy for cancer treatment include: a. reduction of the rate at which red blood cells are produced, causing fatigue and shortness of breath. b. reduction of the rate at which white blood cells are produced, causing increased susceptibility to infection. c. reduction of the rate at which hair follicle cells divide, causing loss of hair. d. All of the above are correct. e. The first and third choices are correct.

The ability for cancer cells to divide indefinitely is made possible because: a. cancer cells rebuild their telomeres after every cell division. b. cancer cells rebuild their centromeres after every cell division. c. cancer cells break down their centromeres after every cell division. d. cancer cells break down their telomeres after every cell division. e. cancer cells avoid interphase during cell division.

In many species of birds, males are XX and females are XZ. With birds like this, who is most likely to display a sex-linked recessive trait? a. males b. females c. Males and females are equally likely to display a sex-linked recessive trait. d. The gender that's incubated at a higher temperature. e. The traits will show up equally in males and females.

All of the following are cells that undergo mitosis, EXCEPT: a. yeast. b. skin cells. c. sperm cells. d. muscle cells. e. stomach cells.

During DNA replication, errors occasionally occur when DNA strands are copied. However, there are many cellular mechanisms that help to remove many of these errors. Suppose an organism evolved such that DNA replication was seemingly perfect every time. What consequences might this hold for the organism? a. It would be robust and out-compete other organisms. b. It would be less robust and more susceptible to predation. c. It would evolve slowly and would therefore be more likely to become extinct. d. It would not be prone to dominant genetic disorders. e. It would be more susceptible to recessive genetic disorders.