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bio exam #2 (abbie)
Terms in this set (60)
Asexual and sexual reproduction differ in that sexual reproduction
can produce genetic variation among the offspring
Which event precedes cell division in both eukaryotes and prokaryotes?
duplication of DNA
In prokaryotes, binary fission includes which of the following?
copying the parental chromosome into daughter cells
In a hedgehog, what is a correct statement regarding the relationship between the base sequences of DNA in two sister chromatids?
The base sequences are identical.
How many chromosomes are present in a human cell that is in the process of dividing before the sister chromatids have separated?
46 duplicated chromosomes
At what point in the cell cycle is DNA synthesized in a eukaryotic cell that is NOT a nerve or a muscle cell?
in the S phase of interphase
Which choice lists the time periods of the phases of the cell cycle correctly from longest phase to shortest phase?
S, G2, mitosis
What would be the immediate effect on mitosis of destroying a cell's centrosomes?
The mitotic spindle would not form.
What causes the sister chromatids to move toward opposite poles of the cell in anaphase?
They are pulled by spindle microtubules attached at the kinetochore.
The phrase cleavage furrow is associated with all of the following except
cytokinesis in a plant cell
In a laboratory experiment, cancer cells that had been rapidly dividing began to slow their rate of division. What could account for this?
An inhibitor of vascular endothelial growth factor (VEGF) was added to the growth medium.
You applied two drugs, A and B, to two colonies of cancer cells in the laboratory. This type of cell normally takes about two days to double. When you examine your cultures two days later, you find that the number of cells treated with Drug B has indeed doubled, while the number of cells treated with Drug A has hardly changed. What might you conclude?
Drug A arrested cell growth in phase G1.
Growth factors signal the control system of a cell's cell cycle. What is the first event in the signaling process?
The growth factor binds to a receptor on the cell's plasma membrane.
Cells that do not divide are in phase __________ of the cell cycle. Which cell types live in this phase?
G0; mature neurons and muscle cells
Which of the following statements about cancer cells and the cell cycle is INCORRECT?
Cancer cells are fixed at the S stage.
A 2015 study of women with ductal carcinoma in situ (DCIS) told oncologists that the overall risk of death from breast cancer was about 3.3% in women who had been diagnosed with the condition. What else did the study show?
About 20% of women with DCIS were at much higher risk.
What are homologous chromosomes?
a matched pair of chromosomes that may have different genes at the same loci
Sex cells in humans contain the __________ number of chromosomes, which is _____
At the conclusion of meiosis I, the daughter cells are __________.
haploid and the sister chromatids are joined
Meiosis results in __________ gametes in __________ organisms. When gametes combine, the resulting zygote is __________
haploid; diploid; diploid
Which of the following occurs in Meiosis II?
Sister chromatids are separated.
Which of the following is a true statement for mitosis but NOT meiosis?
Daughter cells are used for tissue repair.
What is the meaning of random fertilization?
The probability that a given egg and a given sperm will fuse is random.
Crossing over occurs in stage __________ of meiosis. It involves the exchange of genetic information between two __________ chromatids of homologous chromosomes.
prophase I; nonsister
The chromosomes created by crossing over are called __________ chromosomes.
Nondisjunction during meiosis II results in which of the following?
Some gametes have an abnormal number of chromosomes.
How are cells obtained for constructing a karyotype?
White blood cells are cultured and stained.
Which of the following statements is NOT true of Down syndrome?
People with Down syndrome have an approximately normal lifespan.
Why do nondisjunctions of the sex chromosomes usually have a less dramatic impact on a person's life than nondisjunctions of somatic chromosomes?
The Y chromosome is small, and females have only one functional copy of an X chromosome
Women with Turner syndrome display which of the following sex chromosome abnormalities and characteristics?
a single X chromosome; short stature and infertility
Imagine a group of eight couples who meet each week to line-dance. Each couple consists of two people. Using the language of genetics, you could say that the haploid number of dancers is __________. The diploid number of dancers is __________. The tetraploid number of dancers is __________.
8; 16; 32
In a karyotype, how can you distinguish a trisomy from a chromosome duplication?
A trisomy is an extra chromosome; a duplication is an extra segment on one chromosome.
Which of the following are the most harmful types of alterations in chromosomal structure?
Imagine that an ancient Greek man had huge muscles from lifting heavy stone tablets. His wife was small and frail. What would Hippocrates have predicted regarding their son?
Pangenes passed from father to son would ensure that the son had huge muscles.
Mendel ensured that his pea plants could not self-fertilize by __________. The first generation of offspring after the plants had been bred was the __________ generation.
removing the stamens from the flowers to be fertilized; F1
In genetics, a heritable feature that varies among individuals is called a __________. Each variant of such a feature is called a __________.
In genetics, two varieties of the same species of plant that reproduce by cross-fertilization create __________ plant. The offspring of these organisms are the __________ generation of the original plants.
a hybrid; F2
An organism with two non-identical alleles for the same gene is said to be __________ for that gene (and trait). What is true of these alleles?
heterozygous; One is dominant and the other is recessive.
Imagine a particular character (such as flower color) that is determined by a single gene. If this gene is present in two forms, how can you tell which allele is dominant and which is recessive?
Perform a cross between two true-breeding individuals that differ for the trait and observe the traits expressed in the F1 individuals.
A typical monohybrid cross between two plants heterozygous for one character (Pp, purple flowers) yields which of the following genotypic ratios?
1PP; 2Pp; 1pp
A monohybrid cross is a cross between two individuals that are __________. A dihybrid cross is a cross between two individuals that are __________.
heterozygous for one character; heterozygous for two characters
Without knowing what characteristics these letters represent, you can tell that an insect with the genotype EeGGcc will have the same phenotype as an insect with the genotype __________.
In an individual of genotype Aa, where are the A and a alleles physically located?
One allele is on a chromosome from the individual's female parent, and the other is in the same position (locus) on the homologous chromosome from the male parent.
If you expressed Mendel's law of independent assortment using modern terminology, you would say that __________.
Each pair of alleles segregates independently of other pairs during gamete formation.
Assume that in cattle a spotted coat is dominant to a solid-colored coat, short horns are dominant to long horns, and the traits for coat color and horn length assort independently. In a cross between cattle that are heterozygous for both traits, what proportion of their offspring is expected to have long horns?
You have two dogs: a brown Labrador retriever and its sister, who is black. In these dogs, the B allele (black) is dominant over the b allele (brown). A bb dog is brown. Which of the following parent genotypes could NOT have resulted in the litter to which both of your dogs belong?
Mother BB × Father Bb
Imagine that long fins in zebrafish is a dominant trait. A breeder wants to set up a breeding program beginning with homozygous dominant long-finned fish. If she obtains several long- and short-finned fish, how can she tell which, if any, are homozygous for the trait that she wants?
Cross the long-finned fish with the short-finned fish; if the offspring are all long-finned, the long-finned parent is homozygous.
In Labrador retrievers, black coat is dominant to chocolate, normal vision is dominant to progressive retinal atrophy (PRA), and normal hip joint is dominant to hip dysplasia. The alleles for all of these traits assort independently. Two dogs that are heterozygous for alleles of all three genes are crossed. Using rules of probability (not a Punnett square), what is the chance that the first pup born to these dogs will be chocolate, have normal vision, and have normal hip joints?
Brittany marries a man with a rare single-gene blood disorder that is heritable and recessive. They have two children, each of whom develops this disorder. Neither Brittany nor her two siblings have this disorder. What were the genotypes of Brittany's parents for this disorder?
Either or both of her parents are heterozygous for the trait.
The dominant phenotype of a single-gene trait called Z results from the genotype __________. The recessive phenotype results from the genotype __________.
ZZ or Zz; zz
Most alleles that cause human genetic disorders are __________.
The most common lethal genetic disease in the United States is __________, a __________ disorder. Its characteristic symptom is __________.
cystic fibrosis; recessive; excess mucus production
Why are lethal dominant alleles much less common than lethal recessive alleles?
Lethal dominant alleles are harmful even when carried by heterozygotes, so there is strong selective pressure against these alleles.
Imagine you're counseling a couple who have undergone screening for Tay-Sachs disease. The man is a carrier of the Tay-Sachs allele and the woman is not. What information should you give them regarding any children they might have?
No child will have Tay-Sachs disease, but there is a 50% chance that a child will be a carrier of the Tay-Sachs allele.
Several methods are now available for diagnosing genetic disorders in fetuses. Which of the listed commonly available methods provides genetic information at the earliest point in pregnancy?
chorionic villus sampling (CVS)
Which of the following outcomes of a mating between a red flower (RR) and a white flower (rr) illustrates incomplete dominance?
How are prenatal diagnostic tests performed and how soon are results available?
What is the molecular basis for hypercholesterolemia in a person who is homozygous for the recessive allele h?
All members of the F1 generation have pink flowers.
To what do the letters "A," "B," "AB," and "O" refer when describing ABO blood group phenotypes?
between low and very high
Imagine that Gene X has 15 different alleles. What is the maximum number of different alleles of Gene X that can be present in an individual?
People who are hh have no cell-surface receptors for LDL cholesterol.
The blood group phenotypes of several siblings are Type A, 50%; Type AB, 25%; and Type B, 25%. What genotypes are the parents?
the presence of one of two carbohydrates (A or B) on the surface of red blood cells
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