ch 9-11 bio – Flashcards
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When a gland releases a hormone into the bloodstream, what form of cellular signaling would this be?
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endocrine signaling
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Which statements correctly describe intracellular receptors? Select all that apply.
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Typically contain a DNA-binding domain Interact with signaling molecules that are hydrophobic
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Ion channel-linked receptor
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Permits substances to cross the membrane following a conformational change
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G-protein-linked receptor
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contains 7 transmembrane domain
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Tyrosine Kinase receptor
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Has phosphorylation activity when it is dimerizes
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When ligands specifically interact with intracellular receptors, the end result is most often
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a change in gene expression.
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What type of receptor alters the distribution of ions across a membrane upon binding a signaling molecule?
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Ligand-gated ion channel
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Many ligands are hydrophobic. How do these signaling molecules usually enter the cell?
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They enter the cell passively through the phospholipid bilayers.
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Cell signaling in order
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1. synethesis of the signaling molecule 2. Release of the signaling molecole 3. Transport of the signaling molecule to the target cell 4. Detection of the signal by the receptor. 5. Target cell responds to the signal
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What is the function of the external domain of a cell-surface receptor?
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Bind the signaling molecule.
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In order for a target cell to respond to a signal, the steps/stages that must occur in order are:
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signal reception, signal transduction, and cellular response.
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What amino acids are often phosphorylated during cell signaling?
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serine, threonine, and tyrosine
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Which statement best describes an effect that an inhibitor might have?
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The inhibitor may cause a decrease in enzyme activity or function.
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Which statement accurately describes a diploid cell?
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Contains two copies of each chromosome.
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Which statements describe the DNA of eukaryotic cells? Select all that apply.
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Chromosomes contain molecules of DNA and protein. Correct! Nuclear chromosomes are linear molecules.
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Suppose that a certain animal has 23 unique or different chromosomes. How many chromosomes would be found in a diploid cell from this organism? Enter only a numeral/number in the provided box.
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46
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Diploid cells
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skin cell, liver cell. somatic cell, hair cell
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haploid
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egg cell, gamete, sperm cell
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If N=10 for a certain species, how many chromosomes would be found in a hexaploid (6N) cell? Enter only the numeral/number in the provided box.
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60
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Which statement(s) about chromatin structure is correct? Select all that apply.
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The DNA packaging amount/level/degree is adjustable depending on the cell's needs. Nucleosomes are composed of proteins called histones.
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What process leads to the creation of "sister chromatids"?
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DNA replication
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Which statement best describes the overall function/purpose of interphase?
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To duplicate all of the cellular contents.
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G2
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Replenish cell's energy stores
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G1
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increase in overall cell size
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S phase
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DNA is duplicated to produce identical sister
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M Phase
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Sister chromatids are pulled apart
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In eukaryotic organisms, cell division is used for growth and development as well as the production of replacement cells. There are times when new cells are not needed. If a cell is not actively dividing or getting ready to divide, what phase/stage would it be in?
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G0
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Suppose that a cell in G1 contains 7 picograms (pg) of DNA. How many picograms would you expect to find in this same cell during G2? Note that a picogram (pg) is a measured quantity/mass. Think about how the amount of DNA changes as the cell progresses from G1 to G2.
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14
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Suppose that a single somatic cell undergoes mitosis and cytokinesis. If you compared the original parent cell in G1 with the daughter cells that are produced, which of the following statements would be true?
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The daughter cells have the same number of chromosomes and the same amount of DNA.
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Select all of the following phases where "duplicated" chromosomes would be present:
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prophase prometaphase G2 metaphase
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Suppose that rats have a diploid chromosome number of 42 (2n=42] ). How many chromatids will be present in a cell that is in the middle of mitosis metaphase?
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84
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Select all of the following statements that apply to prophase and prometaphase:
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The chromosomes become tightly coiled with condensin proteins. Centrosomes separate and migrate towards opposite sides of the cell. The microtubules become attached to the kinetochores. Chromosomes become visible.
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Which of the following correctly describes the order of mitosis events?
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The mitotic spindle becomes attached to the kinetochore. Sister chromatids line up at the metaphase plate. Cohesin proteins degrade and the sister chromatids separate.The nucleus reforms and the cell divides.
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Select all of the following statements that typically occur during anaphase:
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The kinetochore microtubules shorten. Cohesin proteins are degraded.
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Cytokinesis of animal cells is characterized by the appearance of a cleavage furrow. When does the cleavage furrow first start to appear?
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Anaphase
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What is one major difference between cytokinesis in plant cells and animal cells?
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The first visual sign of cytokinesis in plant cells is a cell plate, whereas in animal cells it is a cleavage furrow.
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Genes that are involved in causing uncontrolled cell division are known as
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oncogenes.
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cyclin
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positive regulator involved in activating CDKs
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CDK
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positive regulator w/ phosphory activity
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retinoblastoma protein (Rb)
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negative regulator that monitors cell size
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p53
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negative regulator that monitors DNA damage
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Which statement does NOT correctly describe the bacterial chromosome?
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The DNA is organized with associated histone proteins.
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Knowing that embryos have a very high rate of cell division, a biologist counted 1500 cells from an embryo to analyze this process. The following data was collected: Stage Number of Cells Observed Prophase 75 Metaphase 30 Anaphase 30 Telophase 15 Interphase 1350 Total 1500 Assuming that these cells were dividing randomly, which of the following statements would be a reasonable conclusion?
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Interphase is the longest stage of the cell cycle.
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Which statement best describes the characteristic difference between haploid cells and diploid cells?
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Haploid cells have one full set of chromosomes while diploid cells have two.
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Suppose you were looking at a replicated/duplicated pair of homologous chromosomes. Answer the following questions by entering only a number/numeral in each provided box.
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How many chromatids would you expect to see? 4 How many arms would you expect to see? 8 How many centromeres would you expect to see? 2 How many telomeres would you expect to see? 8
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Diploid cells contain homologous chromosomes. While homologous chromosomes are very similar and contain the same loci, they are not identical. Which statement correctly explains why homologous chromosomes are not identical?
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The two members of a homologous pair originated from different parents/different individuals.
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Select all of the following statements that are true concerning the daughter cells of meiosis:
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Each daughter cell has half as many chromosomes as the original parent cell. Each daughter cell only contains one member/chromosome of each homologous pair.
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How is meiosis anaphase I distinctly different from mitosis anaphase? Select all that apply.
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During meiosis anaphase I the chromosome number does not change, while during mitosis anaphase the chromosome number doubles. Correct! During meiosis anaphase I the homologous chromosomes will separate, while during mitosis anaphase the sister chromatids will separate.
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What is the product of crossing over?
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recombinant chromosomes
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How does crossing over contribute to genetic variation?
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It creates new DNA sequence combinations.
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Select all of the events that are unique to meiosis. In other words, which events only occur in meiosis?
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Producing recombinant chromosomes. Crossing over. Separating of tetrads. Synapsis of homologous chromosomes.
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Assuming that meiosis occurred in a mammal, which statement best describes the cells that resulted?
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They are genetically different from the parent cell.
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If an egg cell from a certain animal contains "x" amount of DNA, how much DNA would you expect to find in a typical somatic cell from that same animal?
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2x
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Match the following statements/functions with the appropriate type of cell division:
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Meiosis: Gamete production Reduction of ploidy from diploid to haploid generation of genetic variation potential survival of the species in a changing environnment Sexual reproduction Mitosis: Production of clones organism growth and development tissue renewal asexual reproduction
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What property enables the residues of the amino acids serine, threonine, and tyrosine to be phosphorylated?
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They contain a hydroxyl group.
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Quorum sensing is triggered to begin when ___________.
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a sufficient number of bacteria are present
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What is the effect of an inhibitor binding an enzyme?
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The enzyme is inactivated.
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A transcription factor is a receptor with three domains: a ligand-binding domain, a DNA-binding domain, and a transactivation domain. What kind of receptor is a transcription factor?
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intracellular receptor
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Which type of molecule acts as a signaling molecule in yeasts?
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mating factor
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What property prevents the ligands of cell-surface receptors from entering the cell?
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The molecules are hydrophilic and cannot penetrate the hydrophobic interior of the plasma membrane.
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Endocrine signals are transmitted more slowly than paracrine signals because ___________.
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the ligands are transported through the bloodstream and travel greater distances
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Apoptosis can occur in a cell when the cell is ________________.
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damaged no longer needed infected by a virus
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The autocrine/paracrine signaling system has a ____________signaling distance and ___________duration of response.
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short; short
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When a chemical messenger (or ligand) reaches a target cell, it binds to a receptor. A hydrophobic ligand binds to a(n)________, whereas a hydrophilic ligand binds to a(n) ___________.
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intracellular receptor; cell surface receptor
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The first level of DNA organization in a eukaryotic cell is maintained by which molecule?
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histone
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Which eukaryotic cell cycle event is missing in binary fission?
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karyokinesis
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Which protein is a positive regulator that phosphorylates other proteins when activated?
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cyclin-dependent kinase (Cdk)
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The genes that malfunction in cancer normally
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regulate cell division.
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The mitotic spindles arise from which cell structure?
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centrosome
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A duplicated chromosome typically has how many molecules of DNA?
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2
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Attachment of the mitotic spindle fibers to the kinetochores is a characteristic of which stage of mitosis?
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prometaphase
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Unpacking of chromosomes and the formation of a new nuclear envelope is a characteristic of which stage of mitosis?
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telophase
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One of the major differences in the cell division of prokaryotic cells compared to eukaryotic cells is that
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the chromosomes do not separate along a mitotic spindle in prokaryotic cells.
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The fusing of Golgi vesicles at the metaphase plate of dividing plant cells forms what structure?
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cell plate
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Which of the following statements about the relationship between DNA molecules and chromatids is correct?
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Each chromatid contains a single linear DNA molecule.
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A cell in G2 before meiosis compared with one of the four cells produced by that meiotic division has
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four times as much DNA and twice as many chromosomes.
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Pairs of homologous chromosomes
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have genes for the same traits at the same loci.
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Meiosis II is similar to mitosis because
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sister chromatids separate.
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How many chromosomes and how many chromatids are present in a haploid cell during metaphase if a diploid cell from the organism has 48 chromosomes during G1?
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24 and 48
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Which of the following describes why or how recombinant chromosomes add to genetic variability?
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Genetic material from two parents is combined on the same chromosome.
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During which stage of meiosis do chromatids separate completely?
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Anaphase II
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The restoration of the diploid chromosome number after halving in meiosis is due to
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fertilization
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Asexual reproduction of a diploid organism would
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produce identical offspring.
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Which of the following is not true of homologous chromosomes?
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They synapse during the S phase of meiosis.
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What is a karyotype?
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a pictorial display of an individual's chromo¬somes
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How does prophase I differ from prophase II?
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During prophase I there is one diploid cell; during prophase II there are two haploid cells.
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Which of the following would not be considered a haploid cell?
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cell in prophase I
