Unit 2 Post Class Assignment questions Flashcards
In a given population, a few individuals may, by random chance, leave behind more descendants than other individuals. Thus, the genes of the next generation will have a higher proportion of the alleles of the “lucky” individuals. Which concept does this example represent?
genetic drift
Natural selection can only act on traits that:
are heritable.
If evolution has occurred:
the allele frequencies in a population have changed.
Which statement is the best description of evolution as currently understood by modern biologists?
Evolution is influenced by the differential survival and reproduction of phenotypes.
A population is:
a group of individuals of the same species that live in the same general location and have the potential to interbreed.
Which statement describes an important difference between natural selection and genetic drift?
Natural selection involves differential reproductive success in the struggle for existence in an environment, whereas genetic drift does not.
Gene flow means most nearly the same as:
migration.
Which statement about mutations is false?
Mutations are always passed on to offspring.
___________ can result from many processes, including ___________ and __________.
Evolution; mutation; immigration
The migration of reproductive individuals between populations results in a movement of alleles called:
gene flow.
What wavelengths of light are absorbed by melanin?
ultraviolet
What gene in humans is involved in melanin production?
MC1R
What essential nutrient is broken down by UV light?
folate
What evolutionary mechanism is most responsible for the variation in human skin color?
natural selection
What essential nutrient is produced in our skin from UVB light?
vitamin D
What is melanin?
a pigment in human skin
Which of these is least likely to be an adaptation of an organism to its environment?
Cave fish have evolved degenerated eyes because they have no use for vision in dark, underwater caves.
While traveling around the world on the HMS Beagle, Charles Darwin made which of the following observations?
Island species of finch closely resembled mainland finches.
Darwin’s observations while traveling on the Beagle helped him develop which theory?
Species might change over time.
Which statement best describes the difference between natural and artificial selection?
Natural selection can act without the input of humans; artificial selection requires some human input.
“Scientists can never observe evolution in action.” This statement is:
false. Multiple replicated, controlled laboratory experiments and long-term studies of natural populations have enabled scientists to observe and measure evolution as it occurs.
Natural selection means most nearly the same as:
differential reproductive success.
According to Darwin’s theories and observations on “the struggle for existence,” organisms better suited to an environment have a greater probability of surviving and will also:
leave more offspring.
The best measure of an organism’s fitness is:
the number of fertile offspring it produces.
What is the difference between artificial selection and natural selection?
Artificial selection requires human intervention, whereas natural selection does not require human intervention.
Which statement about Charles Darwin is false?
He influenced Malthus’s ideas about the limits of population growth.
How did bats coevolve/adapt in response to moths gaining the ability to hear/jam their ultrasonic clicks?
They moved the frequency and intensity of their echolocation cries away from the peak sensitivity of moth ears.
What benefit do corals gain from their mutualism with zooxanthellae?
Energy from the photosynthetic Zooxanthellae.
What is an example of Mullerian mimicry?
Monarch and Viceroy butterflies
What is different about coevolutionary interactions and adaptations compared to other types of evolution?
They are reciprocal, when one organism adapts the other adapts in response.
Which organismal interaction is NOT coevolutionary?
Commensalism
What type of mimicry involves a non-harmful/toxic organism mimicking a harmful/toxic organism?
Batesian
If DNA replication occurs by unwinding and rebuilding, then:
the two resulting DNA molecules each contain one original strand and one new strand.
Errors sometimes occur when DNA duplicates itself. Why might that be a good thing?
New alleles are produced, making it possible for the population to evolve.
All of the following are cells that undergo mitosis, except:
sperm cells.
A human brain cell contains 46 chromosomes. It divides by mitosis. How many chromosomes will be in each daughter cell?
46
What is the purpose of mitosis?
to make genetically identical cells for growth and replacement of dead cells
Which of the following places the events of mitosis into the correct order?
Chromosomes condense, chromosomes line up in the middle of the cell, sister chromatids separate, and the cell divides into two.
Sister chromatids are held together:
at the centromere.
The function of the spindle is to:
move chromosomes
Which of the following is the direct product of DNA replication?
two sister chromatids
In humans, somatic cells have 46 chromosomes. Sperm and egg cells have:
23 chromosomes.
Whether it is eggs or sperm being produced through meiosis, under normal circumstances, each gamete ends up with:
exactly one copy of each chromosome.
Crossing over means the same as:
the process by which pieces of homologous chromosomes are exchanged.
Chromosomes on which crossing over (recombination) takes place:
have a mixture of maternal and paternal chromosomes.
Which statement about homologous chromosomes is false?
One of the two homologous chromosomes is produced by the cell during the DNA replication.
Which process is necessary to prevent the doubling of genome size during sexual reproduction?
meiosis
What type of chromosomal abnormality leads to the phenotype known as Down syndrome?
trisomy 21
An abnormal number of chromosomes can occur due to one particular erroneous meiotic event called:
nondisjunction (chromosomes don’t separate).
During metaphase II in meiosis, a cell contains ________ of the DNA it did at the beginning of metaphase I.
1/2
Sexual reproduction leads to offspring that are all genetically different from one another and from either parent. What are the three aspects of sexual reproduction that lead to this variation?
crossing over during the production of gametes; shuffling and reassortment of homologues during meiosis; and combination of alleles from two parents at fertilization
Unicellular organisms
Are all comprised of a single cell
Complex multicellularity evolved
Several times independently
Which of the following may have led to the evolution of simple multicellularity?
Predation and gene co-option
Which of the following is not a feature of simple multicellular organisms?
Few cells are capable of reproduction
Which of the following is not a feature of complex multicellularity?
Most cells are capable of reproduction
Prokaryotes and eukaryotes are similar in that they both
have DNA and ribosomes
What global environmental factor may have promoted the evolution of complex multicellularity?
Increased oxygen concentrations in the atmosphere and oceans
How do cells of complex multicellular organisms communicate with each other?
Through direct cell connections
Through genetic signal transduction pathways
