[11] Mastering Biology Flashcards
In a particular plant, leaf color is controlled by gene locus D. Plants with at least one D allele have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-pollinate. The predicted outcome of the F2 is diagrammed in the Punnett square shown in the figure above, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. Which of the boxes marked 1−4 correspond(s) to plants with dark leaves?
1, 2, and 3
In a particular plant, leaf color is controlled by gene locus D. Plants with at least one D allele have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-pollinate. The predicted outcome of the F2 is diagrammed in the Punnett square shown in the figure above, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. Which of the boxes correspond(s) to plants with a heterozygous genotype?
2 and 3
In a particular plant, leaf color is controlled by gene locus D. Plants with at least one D allele have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-pollinate. The predicted outcome of the F2 is diagrammed in the Punnett square shown in the figure above, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. Which of the plants will be true-breeding?
1 and 4
What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?
Traits are inherited in discrete units and are not the results of the “blending” of traits.
Which of the following statements correctly describes a monohybrid cross?
a) A monohybrid cross involves organisms that are heterozygous for one character.
b) A monohybrid cross produces a single offspring.
c) A monohybrid cross involves a single parent.
d) A monohybrid cross is performed for one generation.
a) A monohybrid cross involves organisms that are heterozygous for one character.
How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?
8
Which of the following statements correctly describes one difference between the law of independent assortment and the law of segregation?
a) The law of segregation requires having two or more generations to describe.
b) The law of independent assortment explains the segregation of two or more genes relative to one another.
c) The law of segregation is accounted for by anaphase of mitosis.
d) The law of segregation explains the segregation of two or more genes relative to one another.
b) The law of independent assortment explains the segregation of two or more genes relative to one another.
Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. What does this suggest about the trait?
that the parents were both heterozygous for a single trait
A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?
HT
When crossing an organism that is homozygous recessive for a single trait with one that is heterozygous for the same trait, what is the chance of producing an offspring with the homozygous recessive phenotype?
50%
What was Mendel’s explanation for his observation that traits that had disappeared in the F1 generation reappeared in the F2 generation of the pea plants he used in his experiments?
Traits can be dominant or recessive, and the recessive traits were “hidden” by the dominant ones in the F1.
Why did the F1 offspring of Mendel’s classic pea cross always look like one of the two parental varieties?
One allele was dominant.
Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails?
1/2
In certain plants, the tall trait is dominant to the short trait. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short?
0
Two true-breeding stocks of pea plants are crossed. One parent has red axial flowers, and the other has white terminal flowers; all F1 individuals have red axial flowers. The genes for flower color and location assort independently. If 1,000 F2 offspring resulted from the cross, approximately how many of them would you expect to have red terminal flowers?
190
Two true-breeding stocks of pea plants are crossed. One parent has red axial flowers, and the other has white terminal flowers; all F1 individuals have red axial flowers. The genes for flower color and location assort independently. Among the F2 offspring, what is the probability of plants with white axial flowers?
3/16
What is the difference between heterozygous and homozygous individuals?
All of the gametes from a homozygote carry the same version of the gene while those of a heterozygote will differ.
When constructing a Punnett square, the symbols on the outside of the boxes represent _______, while those inside the boxes represent _______.
gametes, progeny
True or false? The same phenotype can be produced by more than one genotype.
True
True or false? In diploid organisms, a dominant phenotype will only be expressed if the individual is homozygous dominant for that trait.
False
If an organism with the genotype AaBb produces gametes, what proportion of the gametes would be Bb?
None
Two mice are heterozygous for albinism (Aa) . The dominant allele (A) codes for normal pigmentation, and the recessive allele (a) codes for no pigmentation. What percentage of their offspring would have an albino phenotype?
25%
A tall, purple-flowered pea plant (TtPp) is allowed to self-pollinate. (The recessive alleles code for short plants and white flowers.) The phenotypic ratio of the resulting offspring is 9:3:3:1. What is the genotype of the plant whose phenotype appeared once out of every 16 offspring (the “1” in the 9:3:3:1 ratio)?
ttpp
Which of the following statements apply to the variation in human skin color?
a) Variability in human skin color can be explained by the activity of a single gene.
b) The color of human skin and the skin of our closest primate relative exhibits a similar range in variability.
c) Human skin color variation likely evolved in response to differences in the intensity of sunlight around the world.
d) Human skin color variation is primarily determined by the type and amount of melanin pigment in the skin.
e) Human skin color variation evolved recently in hominid evolution, once some populations of our human ancestors migrated out of Africa.
c) Human skin color variation likely evolved in response to differences in the intensity of sunlight around the world.
d) Human skin color variation is primarily determined by the type and amount of melanin pigment in the skin.
e) Human skin color variation evolved recently in hominid evolution, once some populations of our human ancestors migrated out of Africa.