If Tp sperm are observed by future researchers, how many chromosomes should be found in a Tp sperm nucleus?
6
Which of the following is a true statement about sexual vs. asexual reproduction?
In sexual reproduction, individuals transmit half of their nuclear genes to each of their offspring.
A triploid cell contains sets of three homologous 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
If a cell has completed meiosis I 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.
The somatic cells of a privet shrub each contain 46 chromosomes. How do privet chromosomes differ from the chromosomes of humans ,who also have 46?
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 are in prophase of meiosis I? 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
Which of the following happens at the conclusion of meiosis I?
Homologous chromosomes of a pair are separated from each other.
Sister chromatids separate from each other during _____.
mitosis and meiosis II
Independent assortment of chromosomes occurs during _____.
meiosis I only
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 eighteen known alleles (variants), then any given organism of that species can/must have which of the following?
AT MOST, two alleles for that gene
Whether during mitosis or meiosis, sister chromatids are held together by proteins referred to as cohesins. Such molecules must _____.
be REMOVED before SISTER chromatids can separate
What is the ploidy of organisms that have two sets of chromosomes?
2n
What information can not be obtained from an individual's karyotype?
The SEQUENCE of bases of a particular gene
True or false? A haploid organism has one pair of homologous chromosomes.
F
If a cell has 24 chromosomes, how many chromosomes would each of its four daughter cells have after meiosis?
12
Which of the following statements about meiosis and mitosis is true?
MEIOSIS II is similar to mitosis in that sister chromatids of each chromosome separate.
Which structure is directly correlated with the production of genetic variability in the daughter cells produced during meiosis?
CHIASMA
What is the composition of a tetrad at the beginning of prophase I?
ONE pair of homologous chromosomes
What makes sexually reproduced offspring genetically different from their parents?
genetic recombination during MEIOSIS
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 WAY each pair of HOMOLOGOUS chromosomes lines up at the metaphase plate during meiosis I
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.
If crossing over did not occur, which of the following statements about meiosis would be true? Select all that apply.
There would be less genetic variation among gametes.
Human gametes are produced by _____.
MEIOSIS
Normal human gametes carry _____ chromosomes.
23
Which of these cells is (are) haploid?
C AND D
A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.
16
Which of these individuals is a homozygous genotype?
AA
All the genes in a population are that population's _____.
GENE POOL
Genetic drift is a process based on _____.
THE ROLE OF CHANCE
A mutation occurs when _____.
there is a change in the DNA sequence of a gene
Every few years a giant axe chops off the head of every person who is over 6 feet tall. How will this affect the human population?
Alleles that promote "tallness" will decrease in frequency.
Modern travel along with migration reduces the probability of _____ having an effect on the evolution of humans.
GENETIC DRIFT
The ease with which humans travel across the globe is likely to increase _____.
GENE FLOW
Homologous pairs of chromosomes are lined up independently of other such pairs during _____.
metaphase I
Crossing over, resulting in an increase in genetic variation, occurs between _____.
NONsister chromatids of HOMOlogous chromosomes
In human gamete production there is an average of _____ crossover events per chromosome pair.
2-3
Which of these gametes contains one or more recombinant chromosomes?
b and c
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
Which of the following is an example of monosomy?
turners syndrome
A triploid individual _____.
is UNABLE to undergo NORMAL MEIOSIS
What is the most common source of the extra chromosome 21 in an individual with Down syndrome?
nondisjunction in the MOTHER
Plants produce more seeds when they reproduce asexually than sexually. Yet most plants reproduce sexually in nature. What is the probable explanation for the prevalence of sexual reproduction? Sexual reproduction _____.
MIXES up alleles contributing to variation in a species
Genetic mutations in asexually reproducing organisms lead to more evolutionary change than do genetic mutations in sexually reproducing ones because _____.
ASEXUALLY reproducing organisms, BUT not sexually reproducing organisms, pass all mutations on to their offspring
What is a nondisjunction?
AN ERROR IN CELL DIVISION that causes homologous chromosomes or sister chromatids to move to the same side of the dividing cell
When can nondisjunction occur? Choose the best answer.
All three answers are correct.
Which syndrome is characterized by the XO chromosome abnormality?
turner
What kind of cell results when a diploid and a haploid gamete fuse during fertilization?
a triploid cell
Of the following chromosomal abnormalities, which type is most likely to be viable in humans?
trisomy
If a diploid cell undergoes meiosis and produces two gametes that are normal, and one with n ? 1 chromosomes, and one with n + 1 chromosomes, what type of error occurred?
A nondisjunction error occurred in MEIOSIS II, in which both sister chromatids of a chromosome migrated to the same pole of the cell.
If a diploid cell undergoes meiosis and produces two gametes with n + 1 chromosomes and two gametes with n? 1 chromosomes, what type of error occurred?
A NONDISJUNCTION error occurred in meiosis I, in which both members of A homologous pair migrated to the same pole of the cell.