Unit 7 Study Guide Flashcards
Mendel based his principles on his observations of what plant?
Pea plant
What is probability?
The number of possible desired outcomes divided by the possible total outcomes.
What are Mendel’s principles?
Principle of Dominance and Recessiveness
Principle of Independent Assortment
Principle of Segregation
A test cross is a cross between an individual of unknown genotype and an individual whose genotype is _____?
Homozygous recessive
What does a dihybred cross involve?
Two traits
What is a Punnett square?
A tool to determine probability
Do individuals have to exhibit a trait in order for it to appear in their offspring?
No. It could be recessive.
A cross of two individuals for a single contrasting trait is called what?
Monohybrid
What fraction of the offspring resulting from a heterozygous X heterozygous dihybrid cross are homozygous recessive for both traits?
1/16
What is the expected genotype ratio resulting from a heterozygous X heterozygous monohybrid cross?
1:2:1
What is the modern term for one of Mendel’s factors?
Gene
What is an inversion mutation?
When the DNA of a chromosome is reversed.
What is a frame shift mutation?
When a base pair is added or removed from DNA shifting the rest of the bases to the left or right.
What is a carcinogen?
Something that causes cancer.
A stable change in the DNA of an organism is called a(n)
A mutation
Who was the “father” of genetics?
Gregor Mendel
What is the form of dominance where neither trait is dominant over the other?
Codominance
The first generation after the parental generation is called what?
F1
A type of cross that predicts the probability of one trait is called what?
Monohybrid
What is the substance that can cause a genetic mutation called?
Mutagen
A white mouse whose parents are both white produces only brown offspring when mated with a brown mouse. The white mouse is most probably ____.
Homozygous recessive
In chickens, rose comb (R) is dominant to single comb (r). A homozygous rose-combed rooster is mated with a single-combed hen. All of the chicks in the F1 generation were kept together as a group for several years. They were allowed to mate only within their own group. What is the expected phenotype of the F2 chicks?
75% rose comb and 25% single comb
In mink, brown fur color is dominant to silver-blue fur color. If a homozygous brown mink is mated with a silver-blue mink and 8 offspring are produced, how many would be expected to be silver-blue?
Zero
You should be able to answer #29 in the study guide.
Can you?
The answer is heterogenous. Ii
A pure-breeding tall pea plant is crossed with a pure-breeding short pea plant, and all the offspring are tall. What is the most likely genotype of the offspring?
Tt
In mice, black is dominant to white color and color is determined by a single gene. Two black mice are crossed. They produce 3 black offspring and one white offspring. If the white offspring is crossed with one of its parents, what percent of the offspring are expected to be white?
50%
Mendel crossed a pure-breeding plant that produced green seeds with a pure-breeding plant that produced yellow seeds to produce an F1 generation. The entire F1 generation produced yellow seeds. Then he crossed the F1 offspring with each other to produce the F2 generation. From the F2 generation, he counted 6022 yellow seeds. Which of these is the most likely estimate of the number of green seeds he collected from the F2 generation?
2000
A heterozygous organism is best described as?
An organism that is a hybrid or has both the dominant and recessive genes.
If two heterozygous individuals are crossed, what percent of their offspring are also expected to be heterozygous?
50%
You should understand pedigrees and be able to answer questions 36-39 in the study guide.
Can you?
36) 50%
37) Sex linked
38) Carriers
39) Grandparents/Grandchild
If a female fruit fly heterozygous for red eyes (XRXr) crossed with a white-eyed male (XrY), what percent of their offspring would have white eyes?
25%
A cross between a white rooster and a black hen results in 100% blue Andalusian offspring (Andalusian is in between white and black). When two of these blue offspring are mated, the probable phenotypic ratio seen in their offspring would be ____.
25% black
50% blue
25% white
A phenotype that results from a dominant allele must have at least _____ dominant allele(s) present in the parent(s).
One
You should be able to answer #43 in the study guide.
Can you?
43) Many answers could be possible.
A man heterozygous for blood type A marries a woman heterozygous for blood type B. The chance that their first child will have type O blood is ____.
25%
You should be able to answer #45 and 46 in the study guide.
Can you?
45) 0 - It’s sex linked.
46) Type B blood
A pea plant homozygous for the trait of smooth seeds is crossed with a pea plant that is homozygous for the trait of wrinkled seeds. The first generation produces seeds that are all smooth. What percent of the second-generation plants will have smooth seeds when the F1 generation is self-fertilized?
75%
A man with a certain syndrome marries a woman who is normal for that trait. They have 6 children, three girls and three boys. All of the girls have the same syndrome as the father whereas none of the boys is affected. Which type of heredity is not possible here?
X linked recessive
Mendel’s work on garden pea plants resulted in the discovery that
Traits are passed on from parents to offspring.
An individual has two alleles for each trait.
Alleles separate during gamete formation.
Inheritance of genes located on different chromosomes is independent from one another.
In humans, the ability to roll one’s tongue is a dominant trait. If a heterozygous tongue roller had a baby with someone who could not roll their tongue, what would be the chance that their child would be a tongue roller?
50%
If a woman has an X-linked dominant genetic disorder (remember that homozygous dominant indivuals do not survive pregnancy) and her husband does not, what percent of her children will be expected to have the disorder?
50%
What is the percent chance that parents of normal height will have children with achondroplasia?
0%
If a woman with blood type AB has a child with a man who is blood type O, what are all the possibilities for their child’s blood type?
A and B only
In humans, there are three alleles that code for blood type - A, B and O. This is an example of which complex inheritance pattern?
Multiple alleles
Some genes are found on the sex chromosomes. These traits make it so that the traits shows up more commonly in one gender than the other. For example, boys are far more likely to be colorblind than girls are. This is an example of which complex inheritance pattern?
Sex linked
Most genetic disorders in humans are caused by:
Recessive alleles
Eye color in humans is a result of the interaction between 6 seperate genes. This is an example of:
Multiple alleles
A child has a rare genetic disease that neither parent has. How might the child have inherited it?
The disorder is recessive and was carried by both parents.
Mendel’s law of segregation states that during meiosis, the alleles that control each trait separate, and only _____ from each pair is/are passed to the offspring.
one allele
