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?
Clone the plant asexually to produce an identical one
In the human species, all somatic cells have 46 chromosomes. Which of the following can also be true?
A plant species (privet shrubs) has 46 chromosomes per cell
Which of the following is a true statement about sexual vs. asexual reproduction?
In sexual reproduction, individuals transmit 50% of their genes to each of their offspring
At which stage of mitosis are chromosomes usually photographed in the preparation of a karyotype?
Which of the following is true of a species that has a chromosome number of 2n = 16?
Each cell has eight homologous pairs
Eukaryotic sexual life cycles show tremendous variation. Of the following elements, which do all sexual life cycles have in common?
II, III, and IV
Which of these statements is false?
At sexual maturity, ovaries and testes produce diploid gametes by meiosis
Referring to a plant's sexual life cycle, which of the following terms describes the process that leads directly to the formation of gametes?
Which of the following is an example of alternation of generations?
A diploid plant (sporophyte) produces, by meiosis, a spore that gives rise to a multicellular, haploid pollen grain (gametophyte)
The karyotype of one species of primate has 48 chromosomes. In a particular female, cell division goes awry and she produces one of her eggs with an extra chromosome (25). The most probable source of this error would be a mistake in which of the following?
either anaphase I or II
A given organism has 46 chromosomes in its karyotype. We can therefore conclude which of the following?
Its gametes must have 23 chromosomes
A triploid cell contains three sets of chromosomes. If a cell of a usually diploid species with 42 chromosomes per cell is triploid, this cell would be expected to have which of the following?
63 chromosomes in 21 sets of 3
Which of the following best describes a karyotype?
a display of each of the chromosomes of a single cell
If a cell has completed the first meiotic division and is just beginning meiosis II, which of the following is an appropriate description of its contents?
It has half the amount of DNA as the cell that began meiosis
Which of the following can utilize both mitosis and meiosis in the correct circumstances?
a plantlike protist
Which of the following might result in a human zygote with 45 chromosomes?
an error in either egg or sperm meiotic anaphase
The somatic cells of a privet shrub each contain 46 chromosomes. To be as different as they are from human cells, which have the same number of chromosomes, which of the following must be true?
Genes of privet chromosomes are significantly different than those in humans
In a human karyotype, chromosomes are arranged in 23 pairs. If we choose one of these pairs, such as pair 14, which of the following do the two chromosomes of the pair have in common?
Length, centromere position, staining pattern, and traits coded for by their genes
After telophase I of meiosis, the chromosomal makeup of each daughter cell is
haploid, and the chromosomes are each composed of two chromatids
How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis?
They have half the number of chromosomes and one-fourth the amount of DNA
A cell divides to produce two daughter cells that are genetically different
The statement is true for meiosis I only
If an organism is diploid and a certain gene found in the organism has 18 known alleles (variants), then any given organism of that species can/must have which of the following
at most, 2 alleles for that gene
Whether during mitosis or meiosis, sister chromatids are held together by proteins referred to as cohesins. Such molecules must have which of the following properties?
They must be removed before anaphase can occur
Experiments with cohesins have found that
cohesins are protected from cleavage at the centromere during meiosis I
) A tetrad includes which of the following sets of DNA strands?
two sets of sister chromatids that have synapsed
When we see chiasmata under a microscope, that lets us know which of the following has occurred?
To view and analyze human chromosomes in a dividing cell, which of the following is/are required?
DNA stain and a light microscope
To visualize and identify meiotic cells at metaphase with a microscope, what would you look for?
tetrads all aligned at the cell's center
Tetrads of chromosomes are aligned at the equator of the spindle; alignment determines independent assortment.
How does the sexual life cycle increase the genetic variation in a species?
by allowing crossing over
For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes?
about 8 million
Independent assortment of chromosomes is a result of
the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I
Which of the following best describes the frequency of crossing over in mammals?
at least 1-2 per chromosome pair
When homologous chromosomes crossover, what occurs?
Specific proteins break the two strands and re-join them with their homologs
In part III of Figure 13.1, the progression of events corresponds to which of the following series?
sporophyte, meiosis, spore, mitosis, gametophyte, mitosis, gametes, fertilization
In a life cycle such as that shown in part III of Figure 13.1, if the zygote's chromosome number is 10, which of the following will be true?
The sporophyte's chromosome number per cell is 10 and the gametophyte's is 5
A certain female's number 12 chromosomes both have the blue gene and number 19 chromosomes both have the long gene. As cells in her ovaries undergo meiosis, her resulting eggs (ova) may have which of the following?
one chromosome 12 with one blue gene and one chromosome 19 with one long gene
If a female of this species has one chromosome 12 with a blue gene and another chromosome 12 with an orange gene, and has both number 19 chromosomes with short genes, she will produce which of the following egg types?
one-half blue short and one-half orange short gene eggs
A female with a paternal set of one orange and one long gene chromosome and a maternal set comprised of one blue and one short gene chromosome is expected to produce which of the following types of eggs after meiosis?
Each egg has a one-fourth chance of having either blue long, blue short, orange long, or orange short combinations
Assuming that the eggs are diploid, tetraploid, or partially tetraploid, what mechanism may still occur without fertilization?
crossing over of homologs
In these asexual rotifers, how does variation occur without meiosis and fertilization?
Variation is caused by mutation and maintained by selection
How is natural selection related to sexual reproduction as opposed to asexual reproduction?
Sexual reproduction results in many new gene combinations, some of which will lead to differential reproduction
If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be
If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of a single cell at metaphase of meiosis II would be