Part 2
In an organism with a haploid number of 9, a skin cell has ______ chromosomes, a developing sperm cell at prophase II of meiosis has ______ chromosomes, and a newly formed zygote has ______ chromosomes.
18; 9; 18
In a diploid species, an individual can carry a maximum of ______ different allele(s) of a given gene.
2
In mice, 2n = 40. A mouse cell that is the product of meiosis I contains:
20 replicated chromosomes
In mice, 2n = 40. Each mouse cell that is the product of meiosis II will contain
20 unreplicated chromosomes
How many chromosomes are in a human sperm cell?
23
How many pairs of chromosomes are there in the human genome?
23
A human sperm cell contains ______ chromosomes and ______ copies of the HBB gene (the gene that encodes the beta-globin protein).
23; 1
In humans, 2n = 46. A human gamete contains ______ chromosomes, and a human zygote contains ______ chromosomes.
23; 46
A bivalent (also called a tetrad) consists ______ chromosomes and a total of ______ chromatids.
2; 4
When DNA polymerase corrects an incorrect base pair by proofreading, it removes and replaces the nucleotide located at the
3' end of the daughter DNA strand
When a human somatic cell divides by mitosis, how many chromosomes are in each of the daughter cells?
46
In humans, the diploid chromosome number is 46 (2n = 46). A human germ cell that has just replicated its DNA in preparation for meiosis contains ______ chromosomes and ______ copies of the HBB gene (the gene that encodes the beta-globin protein).
46; 4
Horses have a diploid number of 64 chromosomes (2n = 64). In a horse cell that is in metaphase I, how many chromosomes, chromatids, and bivalents (tetrads) would be present?
64 chromosomes, 128 chromatids, and 32 bivalents
Approximately how long after fertilization does implantation occur, in humans?
8 days
The mouse diploid genome (2n) contains 40 chromosomes. A mouse cell at the end of prophase I contains:
80 chromatids, 40 chromosomes, and 20 tetrads
How many base pairs are represented in the DNA sequence below? 5'-CCGATCAAG-3' 3'-GGCTAGTTC-5'
9 base pairs
The inner cell mass of the blastula develops into:
An embryo with three cell layers: ectoderm, endoderm, and mesoderm
Homologous chromosomes separate from each other during
Anaphase I of meiosis
During meiosis, the sister chromatids separate during
Anaphase II
How does binary fission differ from mitosis?
Binary fission does not require microtubules.
After replication, sister chromatids are held together by a protein called
Cohesin
The protein that holds together sister chromatids is called
Cohesin
What is the genome of an organism made of?
DNA
HbA and HbS are two alleles of the human β-globin gene. If a person carries both the HbA and HbS alleles of the β-globin gene, when could the chromosomes pictured below be observed?
During meiosis I
What are the three germ layers found in a vertebrate gastrula?
Ectoderm Endoderm Mesoderm
What are the germ layers found in an animal with diploblastic development?
Endoderm Ectoderm
What are the germ layers found in an animal with triploblastic development?
Endoderm Ectoderm Mesoderm
T/F Organisms that are large and complex always have larger genomes than small, simple organisms.
False
What process results in formation of a zygote?
Fertilization
Meiosis results in the production of
Four haploid daughter cells
During cleavage, the cell cycle is modified so that cell division occurs rapidly and without cell growth. Which phase(s) of the cell cycle is likely to be eliminated or extremely shortened during these cell divisions?
G1
Which of the following types of cells are haploid?
Gamete
The products of meiosis are called
Gametes
Which of these terms best describe the entire set of genetic information found within a cell?
Genome
The cell that enters meiosis is called a
Germ Cell
A cell that has completed meiosis I but has not yet entered meiosis II contains ________ as a germ cell in G2 (right before meiosis).
Half as much DNA Half as many chromosomes
At the end of meiosis I, the daughter cells that are produced are ______ and contain ______ chromosomes.
Haploid; Replicated
All animals with bilateral symmetry
Have triploblastic development
A frameshift mutation could result from:
Insertion of two bases in the coding sequence. Insertion of a single base in the coding sequence. Deletion of a single base in the coding sequence.
The separation of sister chromatids in a eukaryotic cell:
Is called mitosis.
External fertilization:
Is found in some fish and amphibians. Involves releasing gametes directly into a wet environment.
A point mutation may have no effect on an organism if:
It occurs in a non-coding region of DNA. It results in a different codon for the same amino acid.
During cell division, spindle fibers attach to
Kinetochore proteins
In eukaryotes, the process that is used to produce gametes is called _________.
Meiosis
Homologous chromosomes separate from each other during
Meiosis I only.
Point mutations that cause amino acid replacements are called _____.
Missense mutations
DNA replication occurs before
Mitosis and Meiosis I
The compact cluster of cells that results from cleavage is called a
Morula
Which of the following cellular functions depend on microtubules?
Movement of chromosomes during cell division Intracellular transport Cell movement using cilia and flagella
Replication of a eukaryotic chromosome begins at
Multiple origins of replication
What happens during crossing over?
Non-sister chromatids from the same homologous pair exchange DNA.
How many copies of the beta-globin gene are present in a mouse cell that is the product of meiosis II?
One
A somatic cell of a human male contains:
One Y chromosome and one X chromosome.
A newly formed gamete (a cell that has completed both meiotic divisions) contains ________ as a germ cell in G2 (right before meiosis).
One quarter of the amount of DNA Half as many chromosomes
An animal that has internal fertilization but completes development in an egg laid outside the mother's body is
Oviparous
Homologous chromosomes can be defined as:
Pairs of chromosomes that have the same size and appearance.
Crossing over (the exchange of genetic material between chromatids on homologous chromosomes) occurs during
Prophase I.
Which of the following structures are derived from the embryonic mesoderm?
Red blood cells Kidney tubule cells Muscle
A point mutation may be introduced into a gene during the process of:
Replication
Which of the following events occur during interphase of the eukaryotic cell cycle?
Replication of the genome Cell growth
During the eukaryotic cell cycle, DNA is replicated during:
S phase
Which of the following events occur during M phase of the eukaryotic cell cycle?
Separation of chromosomes Division of the cytoplasm
A point mutation that does not result in a change in the amino acid sequence of a protein is called a _____.
Silent mutation
Which of the following cell types are gametes?
Sperm Egg
How does the nucleus of a cell in G2 differ from the nucleus of the same cell in G1?
The G2 nucleus has twice the amount of DNA as the G1 nucleus.
In animals that are protostomes, the blastopore develops into
The Mouth
Select all statements that are correct about the two chromosomes that are circled in this diagram.
These two chromosomes are called homologous chromosomes. These two chromosomes contain the same genes in the same order.
Which of the following statements about sister chromatids are correct?
They are attached to each other at a region called the centromere. They are formed when a chromosome undergoes replication. They have identical DNA sequences.
Chronic myelogenous leukemia (CML) is caused when a segment of chromosome 9 and a segment of chromosome 22 both break off and switch places. How is this mutation classified?
Translocation
How many copies of the beta-globin gene are present in a mouse cell that is the product of meiosis I?
Two
Which structure supports fetal development in mammals?
Uterus
Nearly all mammals, including humans, are
Viviparous
The layer of glycoproteins that surrounds a human egg cell is called the
Zona Pellucida
Which of the following sequences lists the stages of animal development in the correct order, from first to last?
zygote, morula, blastocyst, gastrula, fetus