Chapter 13 Meiosis and sexual life cycles Flashcards
In meiosis, __________ of __________ cross over and form __________.
nonsister chromatids; homologous pairs; chiasmata
Which of the following is a function of mitosis in humans?
Multiplication of body cells
Which of the following statements about homologous chromosomes is correct?
They have genes for the same traits at the same loci.
The process called __________ reduces the chromosome number by __________.
meiosis; two consecutive cell divisions
Which life cycle stage is found in plants but not animals?
Multicellular haploid
A pair of genetic structures carrying genes that control the same inherited characters are called __________.
homologous chromosomes
A life cycle in which the only multicellular form is haploid is most typical of __________.
fungi
Allelic variation is an important source of __________ in a population.
genetic diversity
What is the result when a diploid cell undergoes meiosis?
Four haploid cells
Genetic diversity requires __________.
sexual reproduction, independent assortment, crossing over between nonsister chromatids of homologous chromosomes, and random fertilization
Ignoring crossover, how many kinds of gametes can be produced by an organism with a diploid number of 8?
16
Characteristic of the bdelloid rotifer is that it __________.
is an example of an animal that has not reproduced sexually in 40 million years
Which of the following occurs in meiosis, but not mitosis?
Homologous chromosomes separate.
What is a locus?
The precise location of a gene on a chromosome.
Somatic cells in humans differs from gametes in that human somatic cells __________.
contain two sets of each of the 23 chromosome types
Regarding the role of cohesin protein in maintaining cohesion between sister chromatids, which of the following statements is false?
During meiosis II, cohesion holds sister chromatids together along their lengths as the second meiotic spindle forms.
The life cycle called __________ in plants has two multicellular stages: the __________ and the __________.
alternation of generations; haploid gametophyte; diploid sporophyte
At the end of mitosis, __________ daughter cells that are genetically __________ are formed, while at the end of meiosis, __________ daughter cells that are genetically __________ are formed.
two; identical; four; distinct
How many genes are present in the human genome?
Tens of thousands
Sister chromatids differ from nonsister chromatids in that sister chromatids __________.
are products of the S phase of the cell cycle and are two copies of one chromosome
The major contribution of sex to evolution is that __________.
it provides a method to increase genetic variation
__________ are a group of genetically identical individuals produced by a process called __________.
Clones; asexual reproduction
Unless the chromosomes were stained to show band patterns, a karyotype would be least likely to show which of the following?
Part of a chromosome turned around.
A clone is the product of __________.
asexual reproduction and mitosis
Darwin realized the importance of heritable variation to evolution __________.
even though he never read any of Gregor Mendel’s work
Somatic cells in humans contain __________ set(s) of chromosomes and are therefore termed __________.
two; diploid
The zipper-like complex that forms in meiosis occurs during __________ and is called the __________.
prophase I; synaptonemal complex
The egg (ovum) of a rabbit contains 22 chromosomes. How many chromosomes are in the somatic (body) cells of a rabbit?
44
Somatic cells in animals differ from gametes in that somatic cells __________.
are all of the cells of the body except for the gametes and their precursors
What must happen to a chromosome before a cell starts mitosis?
The single DNA molecule in the chromosome must be replicated.
Which of the following phases make up the stages of mitosis?
Prophase, prometaphase, metaphase, anaphase, and telophase
Which of the following events characterizes metaphase of mitosis?
alignment of the chromosomes at the equator
Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms (pg) per nucleus. During the entirety of which stage of the cell cycle did the nucleus contain 6 pg of DNA?
G2
Asexual reproduction __________.
produces offspring genetically identical to the parent
What number and types of chromosomes are found in a human somatic cell?
44 autosomes and 2 sex chromosomes