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