Chapter 10 Practice Test
Crossing over occurs during _____.
Prophase 1
In a diploid set of chromosomes, one member of each pair of homologs is paternal and the other is maternal. If 2n=6, what is the probability of obtaining a gamete with all paternal chromosomes?
1/8; one out of the eight combinations (2^3) will have only paternal chromosomes
Ignoring crossing over, how many kinds of gametes can be produced by an organism with a diploid number of 8?
16; 2^n n=4 so 2^4=16
How many pairs of autosomes do humans have?
22
In humans, the haploid number of chromosomes is 23. Independent assortment has the possibility of producing ______ different types of gametes.
2^23
The egg of a rabbit contains 22 chromosomes. How many are in the somatic cell of a rabbit?
44 chromosomes
In a diploid cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing _____ chromosomes.
5
Synapsis occurs during _____.
Prophase 1
Fertilization produces ______.
a diploid zygote
Unless the chromosomes were stained to show band patterns, a karyotype would be least likely to show which of the following?
a part of a chromosome turned around
A karyotype is _____.
a photograph of all an individual's chromosomes
What is a locus?
a precise location of a gene on a chromosome
Which, if any, of the following statements are true?
all are true; diploid cells can divide by mitosis diploid cells can divide by meiosis haploid cells can divide by mitosis haploid cells cannot divide by meiosis
Which statement reflects an advantage of sexual reproduction?
although sexual reproduction is energetically more costly than asexual reproduction, sexual reproduction leads to different combinations of alleles that can provide adaptability.
Sister chromatids ______.
are identical copies of each other formed during DNA synthesis
A clone if the product of _____.
asexual reproduction mitosis
Nearly all life cycles have both haploid and diploid phases. Usually, the transition from haploid to diploid takes place ______.
at fertilization when gametes fuse
Regions of chromosomes where the non-sister chromatids cross over are called ______.
chiasmata
Which function makes meiosis lengthier and more complex than mitosis?
decreasing the chromosome number to haploid introducing genetic variation among the daughter cells ensuring each daughter cell gets a single, complete set of chromosomes undergoing two rounds of cytokinesis
Regarding the role of cohesin protein in maintaining cohesion between sister chromatids, which statement is false?
during meiosis 2, cohesion holds sister chromatids along their lengths as the second meiotic spindle forms
In a male mammal, every cell that undergoes meiosis gives rise to _____ sperm.
four
What is the result when a diploid cell undergoes meiosis?
four haploid cells
Spores and gametes are different in that ______.
gametes fuse to form a zygote, but spores can develop into independent organisms without first forming a zygote
Which of the following occurs during anaphase 1?
homologs separate and migrate towards opposite poles
Humans have 46 chromosomes. This number of chromosomes will be found in ______.
liver cells
Which of the following results in cells that contain half the parental number?
meiosis
In sexually reproducing species, the chromosome number remains stable over time because ______ and _______ always alternate.
meiosis ... fertilization
The sexual life cycle of the multicellular algal genus Fucus involves ______.
mitosis, meiosis, and fertilization
Which of the following is part of the life cycle called alternation of generations?
multicellular haploid stage (gameophyte) multicellular diploid stage (sporophyte) zygote spores
Which of the following is a function of mitosis in humans?
multiplication of body cells
The synaptonemal complex ______.
physically connected homologous chromosomes during prophase 1
Which of the following contributes to genetic variation in sexually reproducing species?
random fertilization, independent assortment, crossing over
Although ______ is nearly universal among animals, bdelloid rotifers ______.
sexual reproduction ... asexually reproduce but can increase genetic variation present in the population by means of the uptake of DNA from other rotifers.
Which of the following occurs during anaphase 2?
sister chromatids separate and migrate towards opposite poles
Which event occurs only during prophase 1 of the first meiotic division?
synapsis of the homologous pairs
How many genes are present in the human genome?
tens of thousands
The major contribution of sex to evolution is ______.
that is provides a method to increase genetic variation
When we say that an organism is haploid, we mean _______.
that its cells have a single set of chromosomes
Which of the following is not involved in or is an outcome of crossing over?
the random alignment of homologous pairs during metaphase 1
The diploid number of chromosomes in an animal is 8 (2n=8). How do the four pairs of homologs align and separate during meiosis?
they align and assort independently to form any of 16 combinations
Sexual and asexual reproduction are alike in that _____.
they can both occur in multicellular organisms
What is the function of meiosis?
to make cells with a haploid number of chromosomes
Somatic cells in humans contain _____ sets of chromosomes and are therefore termed ______.
two .... diploid
At the end of telophase 1 if meiosis and the first cytokinesis there are ______.
two haploid cells