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Biology & Life Science
Q:
Assume that an organism has a diploid chromosome number of six. Two chromosomal pairs are telocentric, and the other pair is metacentric. Assume that the sex chromosomes are morphologically identical. Draw chromosomes as you would expect them to appear at the following stages:
Primary oocyte (metaphase)
Secondary spermatocyte (metaphase)
First polar body (metaphase)
Q:
Down syndrome, or trisomy 21, in humans is caused by an extra copy of the relatively small, acrocentric chromosome #21. Including only chromosome #21, the X chromosome (medium in size and somewhat metacentric), and the Y chromosome (small and acrocentric), draw one possible array of chromosomes in the four sperm cells produced by the complete meiosis of one primary spermatocyte. For the purposes of this question, assume that males with Down syndrome produce normal ratios of sperm cells. (More than one answer is possible.)
Q:
Drosophila melanogaster, the fruit fly, has a 2n chromosome number of 8. Assume that you are microscopically examining the mitotic and meiotic cells of this organism. You note that in the female, two chromosomal pairs are metacentric and that two pairs are acrocentric.
a) Draw the chromosomal configurations as you would expect to see them at the stages listed:
Mitotic metaphase First polar body (metaphase)
Primary oocyte (metaphase) Ootid (G1)
Secondary oocyte (metaphase)
b) Given that the above-mentioned cells are from individuals heterozygous for two independently segregating, autosomal loci, plum eyes and curled wings, place appropriate symbols (of your designation) on chromosomes in the drawings you made in part (A) above. Assume no crossing over, and there may be more than one correct answer in some cases.
c) Assuming that a somatic G2 nucleus from one of the individuals in this scenario contains about 8.0 picograms of DNA, how much nuclear DNA would you expect in each of the cells mentioned above?
Q:
Normal diploid somatic (body) cells of the mosquito Culex pipiens contain six chromosomes. Assign the symbols AmAp, BmBp, and CmCp to the three homologous chromosomal pairs. The "m" superscript indicates that the homolog is maternally derived; the "p" indicates a paternally derived homolog. Assume that in the genus Culex, the sex chromosomes are morphologically identical.
a) For each of the cell types given below, draw and label (with reference to the symbols defined above) an expected chromosomal configuration.
Mitotic metaphase
Metaphase of meiosis I
Metaphase of meiosis II
b) The stage at which "sister chromatids go to opposite poles" immediately follows which of the stages listed in (a)?
c) Assuming that all nuclear DNA is restricted to chromosomes and that the amount of nuclear DNA essentially doubles during the S phase of interphase, how much nuclear DNA would be present in each cell listed above? Note: Assume that the G1 nucleus of a mosquito cell contains 3.0 x 10-12 grams of DNA.
d) Given that the sex of Culex is determined by alleles of one gene, males heterozygous, Mm, and females homozygous, mm, illustrate a labeled chromosomal configuration (involving the symbols AmAp, BmBp, and CmCp and the M locus) in a primary spermatocyte at metaphase. Assume that the M locus is on the AmAp chromosome and that crossing over has not occurred between the M locus and the centromere.
Q:
Two terms, reductional and equational, generally refer to which stages of meiosis (I or II)?
Q:
List in order of occurrence the phases of (a) mitosis and (b) prophase I of meiosis.
Q:
After which meiotic stage (meiosis I or II) would one expect monads to be formed?
Q:
What is meant by the term chiasma?
Q:
Name two evolutionarily significant benefits of meiosis that are not present in mitosis.
Q:
The horse (Equus caballus) has 32 pairs of chromosomes, whereas the donkey (Equus asinus) has 31 pairs of chromosomes. How many chromosomes would be expected in the somatic tissue of a mule?
Q:
The accompanying sketch depicts a cell from an organism in which 2n = 2 and each chromosome is metacentric.
a) Circle the correct stage for the cell in this sketch:
anaphase of mitosis
anaphase of meiosis I
anaphase of meiosis II
telophase of mitosis
b) Given that each G1 nucleus from this organism contains 16 picograms of DNA, how many picograms of chromosomal DNA would you expect in the cell shown below?
Q:
Trisomy 21, or Down syndrome, occurs when there is a normal diploid chromosomal complement of 46 chromosomes plus one (extra) chromosome #21. Such individuals therefore have 47 chromosomes. Assume that a mating occurs between a female with Down syndrome and a normal 46-chromosome male. What proportion of the offspring would be expected to have Down syndrome? Justify your answer.
Q:
Assume that the somatic cells of a male contain one pair of homologous chromosomes (e.g., AaAb), and an additional chromosome without a homolog (e.g., W). What chromosomal combinations would be expected in the meiotic products (spermatids) of a single primary spermatocyte? (There may be more than one answer.)
Q:
Regarding the mitotic cell cycle, what is meant by a checkpoint?
Q:
You may have heard through various media of an animal alleged to be the hybrid of a rabbit and a cat. Given that the cat (Felis domesticus) has a diploid chromosome number of 38 and a rabbit (Oryctolagus cuniculus) has a diploid chromosome number of 44, what would be the expected chromosome number in the somatic tissues of this alleged hybrid?
Q:
How many haploid sets of chromosomes are present in an individual cell that is tetraploid (4n)?
Q:
How many haploid sets of chromosomes are present in a diploid individual cell with a chromosome number of 46? 32?
Q:
The house fly, Musca domestica, has a haploid chromosome number of 6. How many chromatids should be present in a diploid, somatic, metaphase cell?
Q:
When cells withdraw from the continuous cell cycle and enter a "quiescent" phase, they are said to be in what stage?
Q:
In which stage of the cell cycle is G0 located?
Q:
Homologous chromosomes are those that can be matched by virtue of their similar structure and function within a nucleus. Which chromosomes making up a genome do not follow the same characteristics of homology?
Q:
List four terms used to describe the normal morphologies, with respect to arm ratio, of eukaryotic chromosomes.
Q:
The nucleolus organizer (NOR) is responsible for production of what type of cell structure?
Q:
Name two cellular organelles, each containing genetic material, which are involved in either photosynthesis or respiration.
Q:
Electron microscopy of metaphase chromosomes demonstrated various degrees of coiling. What was the name of the model that depicted this process?
A) folded-fiber
B) double-stranded
C) chromatid folding
D) packing
E) condensation
Q:
In a healthy male, how many sperm cells would be expected to be formed from (a) 400 primary spermatocytes? (b) 400 secondary spermatocytes?
A) (a) 800; (b) 800
B) (a) 1600; (b) 1600
C) (a) 1600; (b) 800
D) (a) 400; (b) 400
E) (a) 100; (b) 800
Q:
In a healthy female, how many secondary oocytes would be expected to form from 100 primary oocytes? How many first polar bodies would be expected from 100 primary oocytes?
A) 200; 50
B) 100; 50
C) 200; 300
D) 100; 100
E) 50; 50
Q:
What is the outcome of synapsis, a significant event in meiosis?
A) side-by-side alignment of nonhomologous chromosomes
B) dyad formation
C) monad movement to opposite poles
D) side-by-side alignment of homologous chromosomes
E) chiasma segregation
Q:
Myrmecia pilosula actually consists of several virtually identical, closely related species, with females having chromosome numbers of 18, 20, 32, 48, 60, 62, and 64. Assume one crossed a female of species (A) with 32 chromosomes and a male of species (B) with 9 chromosomes (males are haploid, and each gamete contains the n complement). How many chromosomes would one expect in the body (somatic) cells of the female offspring?
A) 4.5
B) 9
C) 25
D) 32
E) 41
Q:
For the purposes of this question, assume that a G1 somatic cell nucleus in a female Myrmecia pilosula contains 2 picograms of DNA. How much DNA would be expected in a metaphase I cell of a female?
A) 16 picograms
B) 32 picograms
C) 8 picograms
D) 4 picograms
E) Not enough information is provided to answer the question.
Q:
The ant, Myrmecia pilosula, is found in Australia and is named bulldog because of its aggressive behavior. It is particularly interesting because it carries all its genetic information in a single pair of chromosomes. In other words, 2n = 2. (Males are haploid and have just one chromosome.) Which of the following figures would most likely represent a correct configuration of chromosomes in a metaphase I cell of a female?
A) B) C) D) E)
Q:
In an organism with 52 chromosomes, how many bivalents would be expected to form during meiosis?
A) 13
B) 26
C) 52
D) 104
E) 208
Q:
If a typical somatic cell has 64 chromosomes, how many chromosomes are expected in each gamete of that organism?
A) 8
B) 16
C) 32
D) 64
E) 128
Q:
During interphase of the cell cycle, ________.
A) DNA recombines
B) sister chromatids move to opposite poles
C) the nuclear membrane disappears
D) RNA replicates
E) DNA content essentially doubles
Q:
What significant genetic function occurs in the S phase of the cell cycle?
A) cytokinesis
B) karyokinesis
C) DNA synthesis
D) chromosome condensation
E) centromere division
Q:
The diploid chromosome number of an organism is usually represented as 2n. Humans have a diploid chromosome number of 46. What would be the expected haploid chromosome number in a human?
A) 92
B) 16
C) 12
D) 24
E) 23
Q:
What hypothesis concerns the evolutionary origin of eukaryotic organelles?
A) endosymbiont hypothesis
B) homologous hypothesis
C) analogous hypothesis
D) evolutionary hypothesis
E) Darwinian hypothesis
Q:
What is the name of the membranous structure that compartmentalizes the cytoplasm of eukaryotic organisms?
A) ribosome
B) mitochondria
C) cytosol
D) endoplasmic reticulum
E) nucleoid
Q:
Living organisms are categorized into two major groups based on the presence or absence of a nucleus. What group is defined by the presence of a nucleus?
A) eukaryotic organism
B) virus
C) bacterium
D) prokaryotic organism
E) mitochondrial organism
Q:
Bioinformatics is a discipline involved in the development of both hardware and software for processing, storing, and retrieving nucleotide and protein data.
Q:
Complementarity in a genetic sense refers to the polymerization of nucleotides in DNA.
Q:
Genetics is the study of heredity and variation.
Q:
Arabidopsis is a model organism for the study of ________.
Q:
Organisms that are well understood from a scientific standpoint and are often used in basic biological research are often called ________.
Q:
A number of genomes have been sequenced in recent years: Escherichia coli, Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster, and Mus musculus. What are the common names for these organisms?
Q:
The human genome sequence was reported in 2003 by two groups, the publicly funded ________ and ________.
Q:
What term is applied to a variety of projects whereby genome sequences are deposited in databases for research purposes?
Q:
In 1996, a cloning experiment produced the sheep named Dolly. Contrary to the more traditional method of cloning by embryo splitting, Dolly was produced by which procedure?
Q:
What is a transgenic organism?
Q:
What represents an organism's genome?
Q:
Recombinant DNA technology is dependent on a particular class of enzymes, known as ________ that cuts DNA at specific nucleotide sequences.
Q:
Research dealing with which human blood disorder was instrumental in linking the genotype to a specific phenotype, and what conclusion was reached?
Q:
What is another term for a biological catalyst?
Q:
Given that DNA is the genetic material in prokaryotes and eukaryotes, what other general structures (macromolecules) and substances made by the cell are associated with the expression of that genetic material?
Q:
Reference is often made to adapter molecules when describing protein synthesis in that they allow amino acids to associate with nucleic acids. To what class of molecules does this term refer?
Q:
What is meant by complementarity in terms of the structure of DNA?
Q:
What is the composition of the genetic material?
Q:
List the two relatively complex processes in which genetic information is converted into functional products.
Q:
What is meant by the term genetic code?
Q:
Name the bases in DNA and their pairing specificities.
Q:
Distinguish the functions of DNA and RNA in a eukaryote.
Q:
A fundamental property of DNA's nitrogenous bases that is necessary for the double-stranded nature of its structure is ________.
Q:
In nonviral systems, what is the nature of the hereditary substance?
Q:
Name the substance that serves as the hereditary material in eukaryotes and prokaryotes.
Q:
The various characteristics of organisms that result from their genetic makeup are collectively referred to as an organism's ________.
Q:
Alternative forms of a gene are called ________.
Q:
What term refers to the similarity between parents and offspring and what term refers to the lack of similarity between parents and offspring?
Q:
What term is used to describe the fact that different genes in an organism often provide differences in observable features?
Q:
Name two individuals who provided the conceptual basis for our present understanding that genes are on chromosomes.
Q:
What does the term genetics mean?
Q:
Name the individual who, while working with the garden pea in the mid-1850s, demonstrated quantitative patterns of heredity and developed a theory involving the behavior of hereditary factors.
Q:
Until the mid-1940s, many scientists considered proteins to be the likely candidates for the genetic material. Why?
Q:
What is a simple definition of an allele?
Q:
What is a mutation?
Q:
Early in the twentieth century, Walter Sutton and Theodor Boveri noted that the behavior of chromosomes during meiosis is identical to the behavior of genes during gamete formation. They proposed that genes are carried on chromosomes, which led to the basis of the ________.
Q:
Name one of the botanists who, in 1900, rediscovered the work of Gregor Mendel.
Q:
Genetics is the study of ________.
A) inheritance and variation
B) mutation and recession
C) transcription and translation
D) diploid and haploid
E) replication and recombination
Q:
In many species, there are two representatives of each chromosome. In such species, the characteristic number of chromosomes is called the ________ number. It is usually symbolized as ________.
A) haploid; n
B) haploid; 2n
C) diploid; 2n
D) diploid; n
E) None of the answers listed are correct.
Q:
Who was the Augustinian monk that conducted a decade of experiments on the garden pea, eventually showing that traits are passed from parents to offspring in predictable ways?
A) Francis Crick
B) Alfred Wallace
C) Hippocrates
D) Aristotle
E) Gregor Mendel
Q:
Who, along with Alfred Wallace, formulated the theory of natural selection?
A) Gregor Mendel
B) William Harvey
C) Louis Pasteur
D) Charles Darwin
E) James Watson