Zusammenfassung der Ressource
Frage 1
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Individuals heterozygous for a reciprocal translocation often have, at metaphase 1 of meiosis:
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Both a chromosome bridge and a fragment
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A loop in a bivalent
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Large number of unpaired chromosomes
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None of the other answers
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A quadrivalent
Frage 2
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The maximum value of r, the recombination percentage, is 50% because:
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Chromosomes have 2 chromatids
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Crossing over is between 2 of the 4 chromatids present in a bivalent
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In females, only one of the 4 products of meiosis develops into an egg, but in males all products form sperm
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None of the other answers
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At anaphase II, the bivalents split into the 2 chromosomes
Frage 3
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The coding sequence of a gene is called
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An exon
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A partitioning sequence
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A promoter
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An intron
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An operon
Frage 4
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Non-coding DNA can best be described as:
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DNA that codes for factors that regulate gene expression
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Including stretches of DNA that may have an as yet undefined function for the organism
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DNA that is composed of repetitive sequences of bases
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DNA that is the promoter region for genes
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“junk” DNA that is of little or no value to the organism
Frage 5
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A “jumping gene” is more often called a:
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Non-coding DNA element
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Transcription sequence
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Transposable element
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Partitioning sequence
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Repetition sequence
Frage 6
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Given that different organisms can have sections of DNA that are almost identical, which of the following statements is CORRECT?
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These organisms are always very closely related, as with chimpanzees and humans
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Identical sections of DNA will always perform the same function, regardless of the organisms in which they are found
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This DNA is usually non-functional
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This is only true for repetitive DNA
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This constitutes evidence of evolution of these organisms from a common ancestor
Frage 7
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Phenotypic variation between individuals of a species:
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Is the basis upon which natural selection acts
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Is solely a result of genetic differences
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Is greater than variation between members of different species
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Has its primary source in environmental effects
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Is a result of the deletion of specific genes
Frage 8
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Which of the following statements about DNA is CORRECT?
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Transposable Elements repair DNA damage
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DNA synthesis is self-perpetuating and does not require enzyme mediation
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Introns are segments of genes that are inserted at replication forks
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Mitochondrial DNA is replicated in the nucleus
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Only 2 per cent of mammalian DNA codes for proteins
Frage 9
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Genes are being discovered using cDNA. cDNA is:
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Created from mRNA transcripts, and therefore does not include introns
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None of the answers are correct
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A direct copy of the DNA at a particular gene locus
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The complementary double-stranded DNA of a specific gene
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Only useful if the gene product is an enzyme
Frage 10
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Genomes are measured as:
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The number of base pairs of DNA in a somatic cell
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The total number of base pairs of DNA in a haploid set of different chromosomes of an organism
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None of the answers are correct
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The number of chromosomes in a somatic cell of an organism
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The number of genes found in the nuclear DNA of an organism