Which of the following statements about genes is incorrect?
One gene only is used in a specific cell type.
Asexual reproduction and sexual reproduction differ in all but which of the following ways?
Asexual reproduction is utilized only by fungi and protists, whereas sexual reproduction is utilized only by plants and animals.
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.
Asexual reproduction results in identical offspring unless which of the following occurs?
The human genome is minimally contained in which of the following?
Every human cell
A geneʹs location along a chromosome is known as which of the following?
What is a karyotype?
A display of every pair of homologous chromosomes within a cell, organized according to size and shape
At which stage of mitosis are chromosomes usually photographed in the preparation of a karyotype?
The human X and Y chromosomes
include genes that determine an individualʹs sex.
Which of the following is true of a species that has a chromosome number of 2n = 16?
Each cell has 8 homologous pairs.
Eukaryotic sexual life cycles show tremendous variation. Of the following elements, which do all sexual life cycles have in common? I. Alternation of generations II. Meiosis III. Fertilization IV. Gametes V. Spores
II, III, and IV
Which of these statements is false?
At sexual maturity, ovaries and testes produce diploid gametes by meiosis.
In animals, meiosis results in gametes, and fertilization results in
Referring to a plant 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
A karyotype results from which of the following?
The ordering of human chromosome images
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.
When does the synaptonemal complex disappear?
Late prophase of meiosis I
Tetrads of chromosomes are aligned at the equator of the spindle; alignment determines independent assortment.
Synapsis of homologous pairs occurs; crossing over may occur.
Centromeres of sister chromatids disjoin and chromatids separate.
Which of the following happens at the conclusion of meiosis I?
Homologous chromosomes are separated.
A cell divides to produce two daughter cells that are genetically different
The statement is true for meiosis I only.
Homologous chromosomes synapse and crossing over occurs.
The statement is true for meiosis I only
Chromatids are separated from each other.
The statement is true for mitosis and meiosis II.
Independent assortment of chromosomes occurs.
The statement is true for meiosis I only.
You have in your possession a microscope slide with meiotic cells on it and a light microscope. What would you look for if you wanted to identify metaphase I cells on the slide?
Tetrads lined up at the center of the cell
Which of the following occurs in meiosis but not in mitosis?
Synapsis of chromosomes
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 cohesions. Such molecules must have which of the following properties?
They must be removed before anaphase can occur.
Experiments with cohesions have found that
cohesions 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
A certain femaleʹs chromosomes 12 both have the blue gene and chromosomes 19 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, she will produce which of the following egg types?
1/2 blue and 1/2 orange gene eggs
A female with a paternal set of one orange and one long gene chromosomes 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 1/4 chance of having blue long, blue short, orange long, or orange short combinations
Chiasmata are what we see under a microscope that let us know which of the following is occurring?
How does the sexual life cycle increase the genetic variation in a species?
By allowing independent assortment of chromosomes
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.
When pairs of homologous chromosomes separate during anaphase I,
the sister chromatids remain attached to one another.
Natural selection and recombination due to crossing over during meiosis I are related in which of the following ways?
Recombinants may have combinations of traits that are favored by natural selection.
A human cell containing 22 autosomes and a Y chromosome is
Which life cycle stage is found in plants but not animals?
Homologous chromosomes move toward opposite poles of a dividing cell during
Meiosis II is similar to mitosis in that
sister chromatids separate during anaphase.
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
How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8 (2n = 8)?