In his breeding experiments, Mendel first crossed true-breeding plants to produce a second generation, which were then allowed to self-pollinate to generate the offspring. How do we name these three generations?
P ... F1 ... F2
Which of the following is true about a plant with the genotype AABbcc?
It is triploid.
It has recessive alleles at three loci.
It is homozygous at two loci.
It is heterozygous at two loci.
It will not express the recessive c allele.
It is homozygous at two loci.
What is an allele?
alternative form of a gene
Consider pea plants with the genotypes GgTt and ggtt . These plants can each produce how many type(s) of gametes?
Two organisms with genotype AaBbCcDdEE mate. These loci are all independent. What fraction of the offspring will have the same genotype as the parents?
You cross a true-breeding red-flowered snapdragon with a true-breeding white-flowered one. All of the F1 are pink. What does this say about the parental traits?
red shows incomplete dominance over white
Height in humans generally shows a normal (bell-shaped) distribution. What type of inheritance most likely determines height?
a combination of polygenic inheritance and environmental factors
Folk singer Woody Guthrie died of Huntington's disease, an autosomal dominant disorder. Which statement below must be true?
1. His daughters will die of Huntington's disease but not his sons.
2. It is very likely that at least one of Woody Guthrie's parents also have had the allele for Huntington's disease.
3. His sons will develop Huntington's disease but not his daughters.
4. All of his children will develop Huntington's disease.
5. There is not enough information to answer the question.
Various procedures can be used to detect genetic disorders before birth. Among the tests discussed in this chapter, which is the least invasive (list first), and which two allow the chromosomes of the fetus to be examined?
ultrasound imaging ... chorionic villus sampling ... amniocentesis
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?
What process is responsible for the independent assortment of alleles?
How do cells acquire homologous chromosome pairs that carry the alleles that are independently assorted?
fusion of gametes
Which of the following statements most accurately describes the process of independent assortment?
1. Genes located on the same chromosome assort as an independent unit.
2. Alleles of different genes segregate from one another in a random manner.
3. Alleles found on separate chromosomes segregate based upon their origin.
4. Dominant alleles segregate with recessive alleles.
True or false? The principle of independent assortment is best illustrated by events that take place during metaphase II, during which sister chromatids segregate independently of each other.
How many genetically unique types of gametes could be produced by an individual with the genotype RrYY?
Which of the following parental genotypes would yield a 1:1:1:1 phenotypic ratio in the offspring?
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 _______.
True or false? The same phenotype can be produced by more than one genotype.
True or false? In diploid organisms, a dominant phenotype will only be expressed if the individual is homozygous dominant for that trait.
Mendel worked _____.
in a monestary
Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be either all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies. what is this called?