Chapter 7 Flashcards
Most genes come in alternative forms called
alleles
Albinism is caused by a recessive autosomal allele. A woman and man, both normally pigmented, have an albino child together. For this trait, what is the genotype of the albino child?
homozygous recessive
Which of the following pairings of blood type phenotypes CANNOT produce a child with type B blood?
AO x AO
The phenotype of an organism is:
its physical characteristics/consists of the observable properties of an individual
A diploid individual with two identical alleles for a particular gene is said to be:
homozygous for that gene
The same genetic condition that causes sickle-cell anemia can also protect against:
malaria
In certain plants, red flowers are dominant to white flowers. If a heterozygous plant is crossed with a homozygous red-flowered plant, what is the probability that the offspring will be white-flowered?
0%
In pea plants, purple flower color is dominant to white flower color. If two pea plants that are true-breeding for purple flowers are crossed, in the offspring:
all of the flowers will be purple
In snapdragons, there is an allele for flower color, CW, that produces no pigment. A plant with the genotype CWCW will produce _____________ flowers.
white
An allele: a) can be dominant or recessive, b) will assort independently from alleles on other chromosomes, c) can be identical to or different from its sister allele for any gene in a somatic cell, or d) can be one of several alternative forms of a gene
all of the above
A person with the genotype AB can receive blood of what type?
all types; it’s the universal recipient.
How can an individual carry a defective gene but not exhibit the defective phenotype?
individuals carry two copies of gene instructions, and one dominant allele could mask the presence of a recessive defective allele
Which of the following did Gregor Mendel never see?
a) a stamen b) the expression of an allele c) a hybrid d) an F2 generation e) a chromosome
a chromosome
Which about dominant traits is correct?
the dominant trait is the one which is expressed
The law of segregation states that:
each of two alleles for a given trait segregate into different gametes
Some genes, such as the human ABO blood groups, have more than two alleles. For these genes:
individuals can only possess two alleles
Vampire bats:
will sometimes regurgitate blood into the mouth of an unrelated individual that is close to starving
Evolution occurs:
only via natural selection, genetic drift, migration, or mutation
Sickle-cell anemia is a genetic disease caused by the presence of a faulty hemoglobin gene (HbS). The normal version of this gene is HbA. Which of the following is TRUE about HbS and HbA?
they’re both alleles for the same trait
Cystic fibrosis, which is usually lethal before reproductive ages, is a homozygous recessive disease. Why do cases continue to arise, even though people with the disease rarely live to reproduce?
The harmful allele can reside in heterozygous individuals with few to no negative effects.
In pea plants, purple flower color is dominant to white flower color. If two pea plants that are true-breeding for purple flowers are crossed, in the offspring:
all of the flowers will be purple
A plant with pink flowers is allowed to self-pollinate. Generation after generation, it produces pink flowers. This is an example of:
a true-breeding plant
The failure of a seedling to turn green if grown in the dark is an example of:
interaction between genotype and environment
Which of the following statements about a rare, X-linked dominant condition in humans is INCORRECT?
The son of a woman with this condition has a 100% chance of also having this condition
