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Final Exam
The distinguishing feature that defines “male” and “female” is the size of their gametes. What type of selection gave rise to males and females?
Disruptive selection
Given the substantial costs, why did sex evolve (increase variation)?
Because sex leads to variation and helps organisms better deal with environmental change
The evolution of sex is actually fairly difficult to understand from a theoretical perspective. There are at least four different costs associated with sex. What has NOT been proposed to be a cost of sex?
The cost of making females sometimes known as the cost of mitosis
What is polyandry
One female forming a pairbond with several males simultaneously
Why do males typically compete for mates while mate choice is primarily exercised by females?
Sperm outnumber eggs
Eggs are more costly to produce than sperm
Females usually provide more parental care than males do'
Males usually produce offspring at a faster rate than females do
A female selects for a particular male trait in order to gain indirect benefits. What would she NOT be selecting for?
High quality territories that will speed up young development rates
Why do female widow birds prefer males with long tails?
Males with long tails provide better resources, parental care, better nests and allow for the males to court females more vigorously
Which type of selection is most likely to result in speciation
Disruptive selection
Speciation is usually defined as:
Evolution of reproductive isolation between polulations
Why is there usually no ideal or normal genotype that is most fit in a population?
Fitness varies in space and time due to environmental heterogeneity
Why are melanistic (dark-winged) peppered moths favoured in regions of industrial pollution caused by burning coal?
Dark moths are less visable then light moths to bird predators of soot-blackened tree trunks
Phylogenetic analysis differs from classical evolutionary biology in that phylogenetics…
Takes into account both morphological and genetic information
In the construction of a cladogram for the five vertebrates - lizard, horse, seal, lion and house cats - what would be a plesiomorphic character?
Lungs
Homologous structures:
Can not be shared by organisms placed in two different phyla
Convergent evolution is the result of
Multiple introduction of the same species to islands
Systematists strive to create phylogenetic groups, that are _____. These groups have a ______ trait that groups them together from the outgroup.
Monophyletic; derived
What is informative on the order of evolutionary branching?
Synapomorphies
If we examine a pair of homologous structures, we always find that:
They serve similar functions
The molecular “tree of life” was built by comparing ribosomal RNA from various bacteria, archaea and eukaryotes. What could have also been used to build the tree?
The sequence of ATP synthase, which builds ATP and the sequence of hexokinase, an enzyme in glycolysis
Did we evolve from chimps?
No, we did not evolve from chimpanzees but we do have a common ancestor
The great apes group from which we descended does not include:
New world monkeys
What is the major impact of the five mass extinction events that have occured on earth?
Shifted from the dominant life forms on the planet
What reason was given for why human evolution may be continuing?
We are more spread out geographically weakening the effect of genetic drift
What would be an abiotic factor?
Soil moisture
Antibiotic resistant bacteria are an example of _________ in the evolutionary approach
an arms race
Mitosis results in two _______ cells, while meiosis results in ______ haploid cells.
Diploid; four
The diploid number pf chromosomes is 46. The haploid number is
23
In dividing animal cells, a drug that blocks the action of microfilaments would likely result in cells that could not complete:
The S phase
Honeybee eggs that are not fertilized develop into fertile, haploid, males called ‘drones’. Fertilized eggs can develop into diploid females, one of which might become ‘Queen’. If the queen has 32 chromosomes in her body cells, how many chromatids would be present in a G2 drone cell?
32
A cell that contains 24 sister chromatids at prophase would contain how many chromosomes at telophase?
12
A cell that has 10 pairs of chromatids in prophase will have how many chromosomes at telophase?
10
At anaphase…
Kinesins promote movement of chromosomes along microtubules
Chromatids become chromosomes
What doesn’t occur during mitosis?
The synthesis of DNA
A centromere is a small body that joins a pair of
Chromatids
The stage of the cell cycle during which the cell actually divides to form two cells is called
Cytokinesis
You look into your microscope and see 16 centromeres. How many chromosomes does the organism have?
16
Interphase is
The combination of G1, S and G2
In a diploid cell in the metaphase of mitosis there are 100 chromatids. The haploid number of chromosomes for this organism would be
25
What is the number of chromosomes at the end of meiosis II in a diploid organism in which n=8?
8
Variations within a species are more likely the result of
Mutations and sexual reproduction
During synapsis, chromatids in homologous pairs of chromosomes often twist around each other, break, exchange segments and rejoin. This process usually contributes to
Increased variability in offspring
There is a greater possibility for the evolution of a new species in organisms which reproduce by
Fertilization
How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis?
They have half the number of chromosomes and on-fourth the amount of DNA
Concerning DNA replication in prokaryotes…
DNA polymerase III moves towards the 5’ end of the template strand
Concerning DNA replication as a whole…
Telomerase attempts to solve the end replication problem
DNA polymerase can:
Only add nucleotides to the 3’OH
Polymerizes both the lagging and leading strand
Okazaki fragments are used to elongate
The lagging strand away from the replication fork
With few exceptions, all nuclei of eukaryotes contain
All the information needed for growing the whole organism
DNA replication is called semiconservative because _______ of the original appears in the duplex formed in replication
Hardly any
During your summer job at virotech, you isolate a previously unknown virus. Analysis of its genome reveals that it is composed of a double stranded DNA molecule containing 14% Thymine. Based on this information, what would you predict the % of Cytosine to be?
36%
Although the sequences of mobile genetic elements of various kinds are found throughout the human genome, they are rarely found inserted into exons. This is likely due to the fact that insertions into exons would:
Result in null mutations that would tend to be detrimental and therefore selected out of the genome
Mutations are HARMFUL or BENEFICIAL because
They result in more or less efficient movement
The role of tautomerism in causing mutations relates to the fact that the process ultimately affects the
Hydrogen bonding affinities of the nitrogenous base
The ames test assays whether or not a compound causes
Gene mutations
What is the maximum number of alleles an SNP can have?
2
A couple who are both carriers of the gene for cystic fibrosis have two children who have cystic fibrosis. What is the probability that their next child will have cystic fibrosis?
25%
A couple who are both carriers of the gene for cystic fibrosis have two children who have cystic fibrosis. What is the probability that their next child will be phenotypically normal?
25%
The F1 offspring of Mendel’s classic pea pod cross always looked like one of the two parental varieties because
One allele was completely dominant over another
Natural selection…
operates on both breeding potential and offspring success
Gene frequencies in a gene pool may shift randomly and by chance. This is called
Genetic drift
Natural selection DOES NOT
Favour individuals that are better adapted to future environmental conditions
What evolutionary process DOES NOT change allele frequencies in a population?
Mating between relatives
Gene flow is important as an evolutionary process because it
leads to speciation
Dominant alleles
Inhibit the total expression of recessive alleles
Inbreeding depression is caused by
Homozygosity for deleterious and lethal genes
Genetic drift…
Occurs when populations are small
Results in the loss of rare alleles from populations
The fact that the average weight of newborn humans has been maintained at 3-4kg over many generations is evidence for
Stabilizing selection
Inbreeding has several genetic consequences. The most important for the Darwinian fitness of individuals is that
Deleterious and lethal recessive genes are exposed to selection
Note
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