end of week 3 Bi 211 homework
Drag the terms on the left to correctly complete these sentences. Not all the terms will be used.
. DNA replication produces two identical DNA molecules, called sister chromatid(s), which separate during mitosis. After chromosomes condense, the centromere(s) is the region where the identical DNA molecules are most tightly attached to each other. During mitosis, microtubules attach to chromosomes at the kinetochore(s). In dividing cells, most of the cell's growth occurs during interphase. The mitotic spindle(s) is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division. During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called chromatin. In most eukaryotes, division of the nucleus is followed by cytokinesis, when the rest of the cell divides. The centrosome(s) are the organizing centers for microtubules involved in separating chromosomes during mitosis.
Ignoring crossover, how many kinds of gametes can be produced by an organism with a diploid number of 8?
16
The egg (ovum) of a rabbit contains 22 chromosomes. How many chromosomes are in the somatic (body) cells of a rabbit?
44
__________ are a group of genetically identical individuals produced by a process called __________.
Clones; asexual reproduction
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.
What is the result when a diploid cell undergoes meiosis?
Four haploid cells
Which of the following occurs in meiosis, but not mitosis?
Homologous chromosomes separate.
Which of the following is the correct sequence of events in the origin of life? I. Formation of protocells II. Synthesis of organic monomers III. Synthesis of organic polymers IV. Formation of DNA-based genetic systems
II, III, I, IV
Which life cycle stage is found in plants but not animals?
Multicellular haploid
Which of the following is a function of mitosis in humans?
Multiplication of body cells
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.
Based on this tree, which statement is correct? Tree divides in two; one Branch is Salamander, on divides again into Lizard and another branch, which divides into Goat and Human.
Salamanders are a sister group to the group containing lizards, goats, and humans.
As the chromosomes of a parent cell are duplicated and distributed to the two daughter cells during cell division, the structure of the chromosomes changes.
Sister chromatids form when DNA replicates in the S phase. The sister chromatids become individual chromosomes once they separate in early anaphase. Similarly, the cellular DNA content doubles in the S phase when the DNA replicates. However, the cell's DNA content does not return to its normal (undoubled) levels until after cytokinesis is complete and two daughter cells have formed. The condensation state of the DNA is not related to the presence or absence of sister chromatids. The DNA condenses in prophase and remains condensed until after the sister chromatids separate and the new daughter cells begin to form. In late telophase/cytokinesis, the emphasis shifts to cell growth and DNA replication for the next cell cycle. For these processes to occur, the DNA needs to be de-condensed so it is accessible to the cellular machinery involved in transcription.
How many genes are present in the human genome?
Tens of thousands
What is a locus?
The precise location of a gene on a chromosome.
Which of the following statements about homologous chromosomes is correct?
They have genes for the same traits at the same loci.
The life cycle called __________ in plants has two multicellular stages: the __________ and the __________.
alternation of generations; haploid gametophyte; diploid sporophyte
If a bacterium regenerates from an endospore that did not possess any of the plasmids that were contained in its original parent cell, the regenerated bacterium will probably also lack ________
antibiotic-resistant genes
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
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
A clone is the product of __________.
asexual reproduction and mitosis
Somatic cells in humans differs from gametes in that human somatic cells __________.
contain two sets of each of the 23 chromosome types
Regardless of whether an organism is an animal, a plant, a fungus, or an algal cell, all zygotes are __________ and are formed during the __________ of two __________ gametes.
diploid; fertilization; haploid
Darwin realized the importance of heritable variation to evolution __________.
even though he never read any of Gregor Mendel's work
Darwin used the phrase "descent with modification" to explain ________.
evolution of the unity and diversity of life
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
Which of the following showed their greatest diversity during the Mesozoic era, but were a small, less diverse group during the Paleozoic era?
gymnosperms
A pair of genetic structures carrying genes that control the same inherited characters are called __________.
homologous chromosomes
What are adaptations?
inherited characteristics of organisms that enhance their survival
Characteristic of the bdelloid rotifer is that it __________.
is an example of an animal that has not reproduced sexually in 40 million years
The major contribution of sex to evolution is that __________.
it provides a method to increase genetic variation
The process called __________ reduces the chromosome number by __________.
meiosis; two consecutive cell divisions
Use the following figure to answer the question. A phylogenetic tree begins with A and divides. One of the two labeled arms is labeled Bacteria; the other divides into two branches labeled Archaea and Eukarya. The phylogenetic tree ________.
ncludes every single life form on this earth
In meiosis, __________ of __________ cross over and form __________.
nonsister chromatids; homologous pairs; chiasmata
The zipper-like complex that forms in meiosis occurs during __________ and is called the __________.
prophase I; synaptonemal complex
Genetic diversity requires __________.
sexual reproduction, independent assortment, crossing over between nonsister chromatids of homologous chromosomes, and random fertilization
Compared to eukaryotes, prokaryotes are ________.
simpler morphologically, but not more evolutionarily primitive
The various taxonomic levels (for example, phyla, genera, classes) of the hierarchical classification system differ from each other on the basis of _____.
their inclusiveness
Somatic cells in humans contain __________ set(s) of chromosomes and are therefore termed __________.
two; diploid
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
