TEAS 7 - Science (Mendel's Laws of Inheritance) Flashcards
___ is the process by which genetic information is passed down from parents to their offspring through DNA.
Inheritance
When fertilization occurs, the offspring receives ___ allele from each parent, thus restoring the pair.
1
Mendel observed that each individual has ___ copies of each gene, which we now call alleles.
2
During the formation of gametes (sperm and egg cells), these alleles ___, with each gamete receiving only one copy of each gene.
separate
What is Mendel’s Second Law, the Law of Independent Assortment?
this law states that the inheritance of one gene does not influence the inheritance of another gene
Which law states that the inheritance of one gene does not influence the inheritance of another gene
Mendel’s Law of Independent Assortment
Mendel found that different traits, such as flower color and seed shape, were inherited ___ from each other.
independently
This is why offspring typically have a ___ of characteristics from their parents –– each trait is passed along ___ and trait dominance is what determines which traits are expressed in the offspring.
combination
independently
Are the genes for eye and hair color inherited together?
No
*If one of your parents has brown hair and green eyes, it does not mean that if you inherit their gene for brown hair, you will also inherit their gene for green eyes.
The alleles for different genes ___ and assort into gametes ___ during meiosis. This means that the inheritance of one trait does ___ affect the inheritance of another trait, and that they are passed down randomly.
segregate
independently
not
If one of your parents has brown hair and green eyes, does it mean that if you inherit their gene for brown hair, you will also inherit their gene for green eyes?
No
*The inheritance of one trait does not affect the inheritance of another trait, and they are passed down randomly. For instance, eye and hair color are not inherited together.
So, how can we predict which inherited traits will “show up” in an offspring?
trait dominance
A ___ is an organism’s genetic makeup. It is the combination of alleles an individual has inherited for a specific trait.
genotype
We represent an individual’s genotype by ___ which represent the two alleles for one gene
letters
For example, the two alleles for the flower color of Mendel’s pea plants can be represented by P and p. The capital P represents the ___ allele and the lowercase p represents the ___ allele.
dominant
recessive
Can we “see” an organism’s genotype?
no
*the traits that we can observe in an individual are known as the phenotype.
The traits that we can observe in an individual are known as the ___.
phenotype
A phenotype refers to the ___ physical characteristics of an individual. It represents the actual ___ of genes and is influenced by the genotype.
observable
expression
How do genotypes influence an organism’s phenotype?
through dominance
The ___ allele is the trait that will be expressed if this allele is present in a genotype.
dominant allele
The ___ allele is the trait that will not be expressed if this allele is present in a genotype with a dominant allele.
recessive allele
___ refers to a genotype in which an individual has two identical alleles for a specific trait. These alleles can be either dominant or recessive.
Homozygous
___ ___ is represented by two capital letters. In this case, both alleles are dominant.
Homozygous Dominant
What are the 2 types of homozygous genotypes?
- homozygous dominant
- homozygous recessive
___ ___ is represented by two lowercase letters. In this case, both alleles are recessive
Homozygous Recessive
For example, a genotype of pp would be ___ ___, where both alleles are for white flowers.
homozygous recessive
For example, if we consider the gene for flower color in pea plants, a genotype of PP would be ___ ___, where both alleles are for purple flowers.
homozygous dominant
___ refers to a genotype in which an individual has two different alleles for a specific trait. In other words, the alleles are not identical. The genotype contains both a dominant allele and a recessive allele.
Heterozygous
Heterozygous genotypes are represented by one ___ letter and one ___ letter.
capital
lowercase
For example: a genotype of Pp would be ___. In this case, the dominant allele (P) is paired with the recessive allele (p), resulting in a purple flower phenotype since the ___ allele masks the ___ allele.
heterozygous
dominant
recessive
Since the ___ allele will always be the one that is expressed, the recessive alleles will only be expressed when paired together.
dominant
When will recessive alleles be expressed?
when paired together
If an individual’s genotype is a combination that includes a B for brown eyes, what genotype must they have to inherit brown eyes?
BB and Bb
If an individual’s genotype is a combination that includes a B for brown eyes and b for blue eyes, what genotype must they have to inherit blue eyes?
an individual would only have blue eyes if their genotype is bb
*blue eyes are recessive, so the offspring with blue eyes will have to inherit a recessive allele from each parent
What tool makes it easier to understand inheritance?
a Punnett Square
Remember that each parent has ___ alleles for a particular gene, which could be represented by letters.
2
Each square in the Punnett square represents a possible ___ of the offspring.
By looking at the combinations of letters in the square, we can determine the genotypes and ___ (physical appearance) of the offspring.
genotype
phenotype
Let’s say that a Punnett Square has the genotypes BB, Bb, Bb, and bb. What genotypes represent the phenotype for Brown eyes?
BB, Bb, Bb
Let’s say that a Punnett Square has the genotypes BB, Bb, Bb, and bb. What genotypes represent the phenotype for blue eyes?
bb
Let’s say that a Punnett Square has the genotypes BB, Bb, Bb, and bb. What is the probability that the offspring having brown eyes?
3 out of 4 (75%)
Let’s say that a Punnett Square has the genotypes BB, Bb, Bb, and bb. What is the probability that the offspring having blue eyes?
1 out of 4 (25%)
Which of the following statements correctly describes the inheritance of traits in humans?
Both parents produce different haploid gametes via meiosis that fertilize to form a diploid zygote.
The presence of genes contributes to the entire cell’s functioning and unique character traits. How are these genes inherited?
The two alleles in a particular gene pair are inherited, one from the mother and one from the father, during fertilization.
What are alleles?
Alleles are an alternate form of a gene.
Which of the following correctly defines genotype?
Genotype is a specific combination of alleles found in an individual.
The presence of two varying alleles of a gene is called a ____________ individual.
Heterozygous
Which of these statements describes a dominant allele?
A dominant allele always expresses itself phenotypically even in the presence of other alleles.
Which of the following is a correct definition of recessive allele?
Recessive alleles are the ones that express phenotypically only when two identical copies of alleles are present.
Which of these is seen in the human blood group system?
Multiple allelism
Multiple allelism is seen when more than two alleles are present. The blood group system in humans has three alleles, that are A, B and O.
When the phenotype of two alleles is expressed partially, its called:
Incomplete dominance
*Incomplete dominance is when the phenotype is expressed partially by two different alleles. It presents as a “blend” of the two characteristics, such as parents with red and white flowers producing offspring with pink flowers.
Which of the following correctly describes the law of segregation?
It states that allele pairs segregate during gametogenesis and reunite randomly during the fertilization process.
Which of the following best describes the law of independent assortment?
It states that the different traits or pairs of traits segregate independently of another pair during gametogenesis.
WW and ww are the allelic combinations that are responsible for red and white flowers, respectively. What do WW, ww, and the flower colors represent?
WW and ww are the genotypes; red and white flowers are the phenotypes.
When HH crosses with Hh, what is the probability of getting offspring with hh?
0%
In a particular species of plant, orange flower petals are dominant over recessive white flower petals. What will be the genotype of the F1 generation if a homozygous dominant parent crosses with a homozygous recessive parent?
(Note that P = dominant allele, and p = recessive allele)
All F1 generations will be heterozygous dominant.
While studying a family tree, an observation made stated that all the male members of the family show the symptoms of hemophilia. If a hemophilic man (XhY) and a carrier female (XhX) sexually reproduce, what is the probability of the mother giving birth to a carrier-daughter and a non-carrier child?
(Xh = mutant X-chromosome)
25% carrier-daughters and 25% non-carrier children
One of the most common X-linked recessive disorders is color-blindness. A boy with color-blindness is born to a couple with normal vision. If NN and Nc represent the normal vision and color-blindness respectively, what would be the possible genotypes of the parents?
Father: NN; Mother: Nc
