exam 4 flashcards
Traits that are controlled by genes located on the X chromosome are said to be __________.
sex linked
In Mendel’s experiments on seed color in pea plants, when a dominant yellow seed-bearing plant was crossed with a recessive green seed-bearing plant, what was the approximate phenotypic ratio among the F2 generation?
3 yellow: 1 green
Structures that have no apparent function but had a function in ancestral species are
vestigial structures
Select which blood type could be safely given to anyone
O
ABO blood group determination is an example of
multiple alleles
Which offspring inherit all their mitochondrial DNA from their mother and none from their father?
Both sons and daughters
The observation that different geographical areas sometimes exhibit plant and animal communities of similar appearance, even though the individual plants and animals are not closely related, is called
convergent evolution
Alternate forms of the same gene are called
alleles
The allelic make up of a cell or individual is referred to as its
genotype
When viewing a human pedigree for a particular genetic condition, you observe that affected individuals appear in some generations, but not in others. This suggests the condition is ___________.
recessive
Let R = red pigment and r = no pigment (white). In carnations, RR offspring make a lot of red pigment, rr offspring make no pigment and Rr offspring make a small amount of red pigment, thus appearing pink. Pink carnations are therefore an example of
incomplete dominance
If an individual allele has more than one effect on the phenotype, this is called
pleiotropy
An allele for a particular trait that is only expressed in the presence of a second copy of the same allele is called
recessive
Let P = purple flowers and p = white, and T = tall plants and t = short. What are the genotypes of the gametes that are produced by a plant that is heterozygous for both traits?
PT, Pt, pT, and pt
Which observations illustrate shared ancestry by anatomical comparison studies? (check 3)
a. Structures are found to be homologous
b. Different structures evolve in similar ways when subjected to the same selective pressures
c. The same structure has evolved to carry out different functions’
d. A structure becomes vestigial
a, c, d
Eukaryotic cells acquired mitochondria and chloroplasts by
endosymbiosis
The first detailed and quantitative studies on inheritance were carried out by an Austrian monk named __________.
Mendel
Small RNAs can regulate gene expression. One type, called micro RNA (miRNA), acts by binding directly to
mRNA to prevent translation
The shape of the beaks of Darwin’s finches and industrial melanism are often cited as examples of the process of _______ _______ leading to evolutionary change.
natural selection
The group that probably gave rise to chloroplasts is the
cyanobacteria
A Punnett square is generally used to
predict the genotypic ratio among the offspring
True multicellularity is a major characteristic of
_____________ only
eukaryotes only
A defining characteristic of eukaryotic organisms
transcription occurs in the ________. translation occurs in the _______.
transcription occurs in the nucleus and translation in the cytoplasm
Which statement describes artificial selection, but not natural selection?
_____________ variation is mostly selected by ________.
Phenotypic variation is mostly selected by humans
The observable expression of the genes present in an organism is called
phenotype
Darker-colored individuals predominating due to selection in a polluted environmentIndustrial melanism is reffered to as
Industrial Melanism
Indicate which factors support the industrial melanism hypothesis (2)
a) pollutants darken bark surfaces
b) dark moths have greater camouflage on trees in polluted woodlands.
c) pollution inhibits the growth dark colored lichen
d) light moths have greater camouflage on trees in highly polluted woodlands
a, b
Choose the scientific evidence that supports evolutionary theory
a) the molecular record
b) the fossil record
c) pollution inhibits the growth of a dark colored lichen
d) light moths have a greater camouflage on trees in highly polluted woodlands
a, b, c, d
In Drosophila, the sex of an individual is determined by the number of…..
X chromosomes
Of the 23 pairs of human chromosomes, 22 pairs are homologous and are found in both males and females. These are called _____________.
autosomes
Natural selection has favored the dark form of the peppered moth in areas subject to severe air pollution, perhaps because on darkened trees, moth-eating birds see them less easily. As pollution abated, the light forms increased in the population because
a) light moths were more genetically variable than dark moths
b) light moths had lower fitness than dark moths
c) light moths survived and produced more offspring than dark moth
d) bird ate more light moths
c
Life apparently originated on Earth about
3.5 billion years ago
Mendel used the ___________ to determine whether an individual with the dominant phenotype was homozygous or heterozygous for that trait.
testcross
The oldest microfossils are of
prokaryotes
Sometimes, one gene pair will interfere with the expression of a second gene pair in an interaction called
epistasis
If you were able to look very closely at a portion of DNA and find methylated histones, you would be looking at
a region of __________ ____________
a region of inactive chromatin
Homologous structures
look different, but evolved from the same body part in a common ancestor
The age of the Earth according to modern estimates is about
4.6 billion years
Which feature is visible on the Archaeopteryx fossil and shared with modern birds?
a) claws on forelimbs
b) bony tails
c) feathers
d) homeothermy
e) teeth
c) feathers
A diploid individual carrying two identical alleles at a given gene locus is called
homozygous
A protein that regulates transcription by binding to the operator is known as the
repressor
In 2006, scientists discovered a fossil that scales and gills, a flat head with eyes on top like a crocodile, and fin and neck bones that would allow it to prop itself out of the water. The best explanation for this fossil is that it is
a ____________ fossil between fish and ______________
a transitional fossil between fish and amphibians
A cross test where we follow the inheritance of two pairs of alleles is called
dihybrid
The early Earth’s reducing atmosphere probably contained all of the following except
a) carbon dioxide
b) oxygen
c) methane
d) water
e) hydrogen sulfide
oxygen
Histones that are tightly wound by DNA and are the basic unit of chromatin are called
nucleosomes
The Principle of ____________ states that the 2 alleles present at each gene locus separate from one another during gamete formation and remain distinct
Segregation
When Mendel crossed purple-flowered pea plants with white-flowered pea plants, he never got offspring with flowers that had an intermediate color. This was counter to the theory of
blending inheritance
Any genetic differences between individuals in a population are called
polymorphisms
The maintenance of a constant environment in a cell is called _________.
a) homeostasis
An extensive study was conducted on identical twins who were separated at birth. Among other things, the study showed that the individual from each pair who received better nutrition during childhood tended to score higher on standardized intelligence tests. This can best be described as an example of how
environment alters phenotype
