11.23.10 Molecular Genetics I (13 & 14)
What is the expected phenotypic ratio of a cross between two orange-eyed MendAliens?
0 black-eyed:1 orange-eyed
In a cross AaBbCc * AaBbCc, what is the probability of producing the genotype AABBCC?
1/64
In snapdragons, heterozygotes have pink flowers, whereas the two homozygotes have red flowers or white flowers. When plants with red flowers are crossed with plants with white flowers, what proportion of the offspring will have pink flowers?
100%
If the liver cells of an animal have 24 chromosomes, its sperm cells would have how many chromosomes?
12
What is the expected phenotypic ratio of the following cross: AaBb * AaBb? In this example A is dominant to a and B is dominant to b.
9:3:3:1.
Which of these statements is false?
At sexual maturity, ovaries and testes produce diploid gametes by meiosis
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
Below are three major discoveries that led to our understanding of genetics.
I. An understanding of mitosis and meiosis II. An understanding of DNA structure and function III. Mendel's realization of the particulate nature of heredity
Which of the following is a correct historical progression of these three events, from first to last?
III, I, II
What was the most significant result Gregor Mendel drew from his experiments with pea plants?
Traits are inherited in discrete units, and are not the results of "blending".
What is a karyotype?
a display of homologous chromosomes of a cell organized in relation to their number, size and type
Which of the following is the term for a human cell that contains 22 pairs of autosomes and two chromosomes?
a female somatic cell
A human cell containing 22 autosomes and a Y chromosome is
a sperm cell
For a species with a haploid number 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes?
about 8 million
Which of the following is missing from the life cycle listed below?
fertilization Zygote-sporophyte-spore-gametophyte-gametes-zygote
What is the end result of meiosis?
four haploid cells
Syngamy occurs between
gametes
The X and the Y chromosomes are called sex chromosomes because
genes located on these chromosomes play a role in determining the sex of the individual
After telophase I of meiosis, what is the chromosomal makeup of each daughter cell?
haploid, and the chromosomes are composed of two chromatids
All of the offspring of a cross between a red-flowered plant and a white-flowered plant have pink flowers. This means that the allele for red flowers is to the allele for white flowers.
incompletely dominant
Both mitosis and meiosis are preceded by
interphase
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Eukaryotic sexual life cycles show tremendous variation. Of the following elements, which do all sexual life cycles have in common?
meiosis, fertilization, and gametes
The F1 offspring of Mendel's classic pea cross always looked like one of the two parental varieties because
one allele was completely dominant over another
Multicellular haploid organisms
produce gametes by mitosis
The phases of meiosis that produce the most genetic variation from crossing-over and independent assortment are
prophase I and anaphase I
What are the sources of genetic variation in sexual life cycles of animals?
random fertilization, crossing over during meiosis, and independent assortment of chromosomes during meiosis
The fact that all seven of the garden pea traits studied by Mendel obeyed the principle of independent assortment means that the
seven pairs of alleles determining these traits behave as if they are on different chromosomes
Which of the following is an example of polygenic inheritance?
skin pigmentation in humans
The immediate product of meiosis in a plant is a
spore
Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. This indicates
that the parents were both heterozygous
What is a genome?
the complete complement of an organism's genes
A plant with purple flowers is allowed to self-pollinate. Generation after generation, it produces purple flowers. This is an example of
true-breeding
The couple (both normally pigmented) decides to have a second child. What is the probability that this child will be albino?
¼
