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Chapter 14
Review Questions
29
Biology
Undergraduate 2
07/24/2014

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Term
For Gregor Mendel's studies of inheritance, why was the pea plant a good model organism for his experiments?
Definition
Individual pea plants differed in easily recognizable traits, and he could control which parents were involved in mating
Term
Explain how the pea plant can be controlled so that the researcher can allow the plant to self-pollinate or force it to undergo cross-pollination
Definition
Mendel could prevent self-fertilization by removing the male reproductive organs from a flower before any pollen formed. Later he could transfer pollen from another pea plant to the target flower's female reproductive organ with a brush
Term
Allele
Definition
a particular form of a gene; the two alleles in a diploid may be the same or different
Term
Pure line
Definition
individuals of the same phenotype that, when crossed, always produce offspring with the same phenotype; these individuals are homozygous for the gene in question
Term
Dominant allele
Definition
an allele that produces its phenotype only in homozygous form; phenotype "recedes" or disappears in heterozygous individuals; symbolized by a lower case letter
Term
Homozygous dominant genotype
Definition
having two of the same dominant alleles; symbolized by two capital letters
Term
Heterozygous genotype
Definition
having two different alleles; symbolized by a capital letter and a lowercase letter
Term
Homozygous recessive genotype
Definition
having two of the same recessive alleles; symbolized by two lowercase letters
Term
P generation
Definition
parent generation
Term
F1 generation
Definition
first generation (kids)
Term
F2 generation
Definition
second generation (kids' kids)
Term
Principle of Segregation
Definition
-pairs of alleles are separated during meiosis in the formation of gametes
-explained by meiosis by the two members of a parent's gene pair segregate into different gametes because homologous chromosomes separate during meiosis I
Term
Principle of Independent Assortment
Definition
-the genes for seed shape and seed color assort independently, because they are located on different chromosomes
-explained by meiosis by the genes for different traits assort independently because non-homologous chromosomes assort independently during meiosis
Term
A man and a woman have three children: two girls and one boy. The couple decides to have a fourth child. What is the probability that their fourth child will be a girl?
Definition
50%
Term
A couple doesn't have any children; however, they plan to have three children someday. What is the probability that all three of their future children will be boys?
Definition
12.5%
Term
Autosomal Recessive Inheritance Examples
Definition
-sickle cell disease
-phenylketonuria (PKU)
-maple syrup urine disease
Term
Autosomal Dominant Inheritance Examples
Definition
-Huntington's disease
-Marfan syndrome
Term
X-linked Recessive Inheritance Examples
Definition
-Red-green color blindness
-Hemophilia
-Severe combined immunodeficiency (SCID)
Term
Incomplete dominance
Definition
heterozygotes have intermediate phenotypes
Term
Co-dominance
Definition
heterozygotes have phenotype of both alleles
Term
Polygenic inheritance
Definition
having two or more genes combine to determine a single phenotype
-ex: fruit color in bell peppers; coat color in labs
Term
Epistasis
Definition
when one gene masks the expression of the other
Term
Pleiotropy
Definition
when one gene controls many traits
ex: Marfan syndrome
Term
T/F: An individual's phenotype is often much a product of the environment as it is a product of the genotype
Definition
True
Term
T/F: Core temperature of the body DOES NOT determine if the pigment is made in cat coat color
Definition
False
Term
Why is the allele for wrinkled seed shape in garden peas considered recessive?
Definition
The trait associated with the allele is not expressed in heterozygotes
Term
The alleles found in haploid organisms cannot be dominant or recessive. Why?
Definition
Dominance and recessiveness describe in which allele is expressed in phenotype when different alleles occur in the same individual
Term
Why can you infer that individuals that are "pure line" are homozygous for the gene in question?
Definition
Because no other phenotype is ever observed in a pure-line population, this implies that only one allele is present
Term
The artificial sweetner NutraSweet consists of a phenylalanine molecule linked to aspartic acid. The labels of diet sodas that contain NutraSweet include a warning to people with PKU? Why?
Definition
People with PKU have to avoid phenylalanine in their diet
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