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Genetics
Question | Answer |
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Define traits. | Differences in an organism’s characteristics. Ex: Eye color such as blue or brown |
What plant did Gregor Mendel use to investigate how organisms inherit traits from their parents? | Pea plants. Specifically, white and purple flower colored pea plants. |
What is considered true-breeding plants? | Parent plants that, after many generations of self-pollination, a colored flower plant produces only that color. |
What was Mendel's scientific method? | He crossed two contrasting, true breeding plants for two different traits for a particular characteristic. |
What is an F1 generation? | This is the first filial generation. The "F" stands for filial. The number indicates the generation. |
What was Mendel's conclusion? | Mendel concluded that differences in inherited traits result from alternative versions of genes (which Mendel called “factors”). These are referred to as alleles. Each organism receives 2 copies. |
If an organism inherited two different alleles for a given character, which would be expressed? | The dominant allele would be expressed while the recessive allele would lie dormant. |
Where can recessive alleles be seen? | Recessive alleles only show in the phenotype when there is no dominant allele. |
How are alleles represented? | They're represented by single italicized letters. Dominant alleles are represented by capital letters. The recessive versions of the alleles are represented by the lowercase version of the same letter. |
How many alleles do organisms inherit for each character? | Two alleles, one from each parent. |
What does heterozygous mean? | An organism that contains two different alleles for a given character. |
What does homozygous mean? | When an organism contains two identical alleles. An organism can be homozygous recessive (if both alleles are recessive) or homozygous dominant (if both alleles are dominant). |
What is a phenotype? | An observable trait. |
What is a genotype? | It describes precisely which alleles are present, no matter which is showing. |
Explain the law of segregation. | Two alleles for a given character must separate when gametes are produced. Each allele ends up in one gamete (egg or sperm). In this way, when gametes combine during fertilization, an offspring will inherit one allele from each parent. |
When does the law of segregation apply? | During meiosis. Two partner chromosomes in each pair separate. Each gamete receives one chromosome and thus one allele for each gene. |
What is the law of independent assortment? | States each pair of alleles segregates independently of one another during the formation of gametes |
When does the law of independent assortment not apply? | When the alleles for 2 different characters are located on the same chromosome. |
What needs to be known in order to draw a Punnett square? | The genotype for a given trait for two breeding individuals. This is a prediction for the offspring. |
If you knew someone's genotype for eyes was brown and blue (Bb), and another's genotype was brown and blue (Bb), what is the probability their offspring will express blue eyes using a monohybrid cross? | 25% chance. |
Explain co-dominant alleles. | They will equally affect the phenotype of the organism. |
Explain incomplete dominance. | Two alleles for a given character are only somewhat, or partially, expressed. Neither allele is dominant over the other, and so a blend of the two results. |
What determines the sex of a baby? | The 23rd pair of chromosomes that comes from males. |
What is one "problem" that Mendel had with his work? | When Mendel selected traits to study in his pea plants, he chose ones that were controlled by single genes. It doesn't give a complete picture as to how most phenotypes are determined. |
True or False: Most phenotypes are controlled by more than one gene. | True. Because of this they are referred to as being controlled by multiple genes or polygenic. They do not follow Mendel's inheritance rules. |
By observing more than one type of trait simultaneously over multiple generations, which law did Mendel discover? | The law of independent assortment. |
The blue flowers that a plant inherits from its parents are an example of a _________________. | Trait |
Joseph expresses a recessive phenotype for red hair. What is the best prediction regarding his genotype? | He has a homozygous genotype for hair color. |
True or False: An organism can have more than two alleles in its genome for a particular gene. | False. |
What are the chances that two heterozygous (Bb) parents will have a dominant expressing child? | 75% |
A newborn puppy has 2 alleles for floppy ears. During which part of the reproductive process did the alleles separate as the puppy was developing? | Meiosis |
If a cow contains two co-dominant alleles—one for white hide color and one for red hide color—what would the cow's hide probably look like? | Patches of white and patches of red. |
True or False: If the attached-earlobe allele is recessive to the free-earlobe allele, a person with one of these alleles will have free earlobes. | True |
If a person has a dominant allele for brown eyes and a recessive allele for blue eyes, what is their eye color? | Brown eyes. |
True or False: If a "widow's peak" of hair is a dominant trait, someone with a widow's peak may not be heterozygous for the trait. | False. Someone with a widow's peak may be heterozygous or homozygous for the trait |
An individual who expresses a recessive trait is ______ for that trait. | Homozygous. |
Under normal circumstances, an organism receives _________ chromosomes. | Equal numbers of |
Two parents have webbed toes and are homozygous for the trait. What can be concluded based ONLY on this information? | Their offspring will all have webbed toes. |