(Pierce, 2020), Chapter 1-26 | 9781319216801 All Chapters
with Answers and Rationals
What are the classification of organisms? - ANSWER: Organisms are classified as prokaryotes or
eukaryotes, and
prokaryotes consist of archaea and eubacteria. A prokaryote is a
unicellular organism that lacks a nucleus, its DNA is not complexed
to histone proteins, and its genome is usually a single chromosome.
Eukaryotes are either unicellular or multicellular, their
cells possess a nucleus, their DNA is complexed to histone proteins,
and their genomes consist of multiple chromosomes
List several characteristics that eubacteria and archaea have in
common and that distinguish them from eukaryotes. - ANSWER: Eubacteria and archaea are
prokaryotes. They differ from
eukaryotes in possessing no nucleus, a genome that usually
consists of a single, circular chromosome, and a small
amount of DNA.
How do cells reproduce? - ANSWER: Cells reproduce by copying and separating their genetic
information
and then dividing. Because eukaryotes possess multiple chromosomes,
mechanisms exist to ensure that each new cell receives
one copy of each chromosome. Most eukaryotic cells are diploid,
and their two chromosome sets can be arranged in homologous
pairs. Haploid cells contain a single set of chromosomes.
Diploid cells have
a. two chromosomes.
b. two sets of chromosomes.
c. one set of chromosomes.
d. two pairs of homologous chromosomes. - ANSWER: b. two sets of chromosomes.
What are sister chromatids? - ANSWER: Sister chromatids are copies of a chromosome held together
at
the centromere. Functional chromosomes contain centromeres,
telomeres, and origins of replication. The kinetochore is the point
of attachment for the spindle microtubules; telomeres are the stabilizing
ends of a chromosome; origins of replication are sites
where DNA synthesis begins
What are three essential elements required for a chromosome to
function? - ANSWER: A centromere, a pair of telomeres, and an origin of
replication
What are the active cell-cycle phases? - ANSWER: The active cell-cycle phases are interphase and the
M phase.
Interphase consists of G1, S, and G2. In G1, the cell grows and prepares
for cell division; in the S phase, DNA synthesis takes place;
in G2, other biochemical events necessary for cell division take
place. Some cells enter a quiescent phase called G0. The M phase
includes mitosis and cytokinesis and is divided into prophase,
prometaphase, metaphase, anaphase, and telophase.
, Which is the correct order of stages in the cell cycle?
a. G1, S, prophase, metaphase, anaphase
b. S, G1, prophase, metaphase, anaphase
c. Prophase, S, G1, metaphase, anaphase
d. S, G1, anaphase, prophase, metaphase - ANSWER: a. G1, S, prophase, metaphase, anaphase
What processes does meiosis consist? - ANSWER: Meiosis consists of two distinct processes: meiosis I
and meiosis II.
Meiosis (usually) produces four haploid cells that are genetically
variable.The two mechanisms responsible for genetic variation are
crossing over and the random distribution of maternal and paternal
chromosomes.
Which of the following events takes place in meiosis II but not
meiosis I?
a. Crossing over
b. Contraction of chromosomes
c. Separation of homologous chromosomes
d. Separation of chromatids - ANSWER: d. Separation of chromatids
What undergoes meiosis in the testes? - ANSWER: In the testes, a diploid spermatogonium undergoes
meiosis, producing
a total of four haploid sperm cells. In the ovary, a diploid
oogonium undergoes meiosis to produce a single large ovum and
smaller polar bodies that normally disintegrate.
A secondary spermatocyte has 12 chromosomes. How many
chromosomes will be found in the primary spermatocyte that gave
rise to it?
a. 6
b. 12
c. 18
d. 24 - ANSWER: d. 24
How are haploid cells produced? - ANSWER: In the stamen of a flowering plant, meiosis produces
haploid
microspores that divide mitotically to produce haploid sperm in a
pollen grain. Within the ovary, meiosis produces four haploid
megaspores, only one of which divides mitotically three times to
produce eight haploid nuclei.After pollination, one sperm fertilizes
the egg cell, producing a diploid zygote; the other fuses with two
nuclei to form the endosperm.
Which structure is diploid?
a. Microspore c. Megaspore
b. Egg d. Microsporocyte - ANSWER: d. Microsporocyte
Prokaryotic cells and eukaryotic cells - ANSWER: A prokaryotic cell possesses a simple structure, with
no
nuclear envelope and usually a single, circular chromosome.
A eukaryotic cell possesses a more complex structure, with a
nucleus and multiple linear chromosomes consisting of DNA
complexed to histone proteins.
What does cell reproduction require? - ANSWER: Cell reproduction requires the copying of the genetic
material,
separation of the copies, and cell division.