AP Bio 5.2 Mendelian Genetics
36 flashcards covering AP Bio 5.2 Mendelian Genetics for the AP-BIOLOGY Unit 5 section.
Mendelian genetics is a fundamental concept in AP Biology, as outlined by the College Board in their AP Biology Curriculum Framework. This topic covers the principles of inheritance established by Gregor Mendel, including concepts such as dominant and recessive traits, homozygous and heterozygous genotypes, and the use of Punnett squares to predict genetic outcomes. Understanding these principles is crucial for grasping more complex genetic concepts later in the course.
On practice exams and competency assessments, questions about Mendelian genetics often involve problem-solving scenarios where students must analyze genetic crosses or interpret phenotypic ratios. Common traps include misinterpreting the terms dominant and recessive or failing to recognize the significance of allele combinations. Students may also overlook the importance of conducting multiple trials in genetic experiments, which can lead to inaccurate conclusions about inheritance patterns. A practical tip is to always double-check your Punnett squares for accuracy before finalizing your answers.
Terms (36)
- 01
What is the principle of segregation in Mendelian genetics?
The principle of segregation states that during the formation of gametes, the two alleles for a trait separate from each other so that each gamete carries only one allele for each gene. This principle is fundamental to Mendelian inheritance (College Board AP CED).
- 02
How does a dihybrid cross demonstrate independent assortment?
A dihybrid cross shows that the alleles for two different traits segregate independently of one another during gamete formation, leading to a 9:3:3:1 phenotypic ratio in the F2 generation when both traits are heterozygous (College Board AP CED).
- 03
What is the expected phenotypic ratio for a monohybrid cross?
The expected phenotypic ratio for a monohybrid cross between two heterozygous parents is 3:1, where three offspring exhibit the dominant trait and one exhibits the recessive trait (College Board AP CED).
- 04
Define homozygous and heterozygous genotypes.
Homozygous genotypes have two identical alleles for a specific gene, while heterozygous genotypes have two different alleles for that gene (College Board AP CED).
- 05
What is the significance of a test cross?
A test cross is used to determine the genotype of an individual exhibiting a dominant phenotype by crossing it with a homozygous recessive individual, revealing the presence of recessive alleles if any offspring display the recessive phenotype (College Board AP CED).
- 06
How often must genetic traits be analyzed in a population for Mendelian studies?
Genetic traits must be analyzed across multiple generations to observe inheritance patterns and validate Mendelian ratios, typically requiring at least two generations for accurate assessment (College Board AP CED).
- 07
What is the role of Punnett squares in genetics?
Punnett squares are tools used to predict the genotypic and phenotypic outcomes of genetic crosses by illustrating the possible combinations of alleles from parental gametes (College Board AP CED).
- 08
What does it mean for a trait to be dominant?
A dominant trait is one that is expressed in the phenotype even when only one copy of the allele is present, overshadowing the effect of a recessive allele (College Board AP CED).
- 09
In a monohybrid cross, what is the ratio of homozygous dominant to homozygous recessive offspring?
In a monohybrid cross between two heterozygous parents, the ratio of homozygous dominant to homozygous recessive offspring is 1:1 (College Board AP CED).
- 10
What is the expected genotypic ratio from a dihybrid cross?
The expected genotypic ratio from a dihybrid cross between two heterozygous parents is 1:2:1:2:4:2:1:2:1 for the combinations of the two traits (College Board AP CED).
- 11
How does incomplete dominance differ from complete dominance?
Incomplete dominance occurs when the phenotype of heterozygotes is intermediate between the phenotypes of the two homozygotes, unlike complete dominance where one allele completely masks the other (College Board AP CED).
- 12
What is the significance of the F1 and F2 generations in Mendelian genetics?
The F1 generation is the first filial generation resulting from a cross, while the F2 generation is produced by crossing F1 individuals; studying these generations helps in understanding inheritance patterns (College Board AP CED).
- 13
What is the expected phenotypic ratio for a dihybrid cross?
The expected phenotypic ratio for a dihybrid cross between two heterozygous parents is 9:3:3:1, representing the four possible combinations of traits (College Board AP CED).
- 14
What is meant by the term 'allele'?
An allele is a variant form of a gene that can result in different traits; individuals inherit one allele from each parent for each gene (College Board AP CED).
- 15
How can a pedigree chart be used in genetics?
A pedigree chart is used to track the inheritance of traits through generations in a family, helping to identify carriers of genetic disorders and patterns of inheritance (College Board AP CED).
- 16
What is the difference between autosomal and sex-linked traits?
Autosomal traits are located on non-sex chromosomes and affect both sexes equally, while sex-linked traits are found on sex chromosomes and often exhibit different patterns of inheritance in males and females (College Board AP CED).
- 17
Define codominance in terms of allele expression.
Codominance occurs when both alleles in a heterozygote are fully expressed, resulting in a phenotype that displays both traits simultaneously, such as AB blood type (College Board AP CED).
- 18
What is the role of environmental factors in gene expression?
Environmental factors can influence gene expression by affecting how genes are turned on or off, leading to variations in phenotype that are not solely based on genotype (College Board AP CED).
- 19
How does the concept of linkage affect inheritance patterns?
Linkage refers to genes located close together on the same chromosome, which tend to be inherited together more often than not, deviating from Mendelian ratios due to recombination (College Board AP CED).
- 20
What is a monohybrid cross?
A monohybrid cross is a genetic cross between parents that differ in a single trait, used to study inheritance patterns of that trait (College Board AP CED).
- 21
How can the law of independent assortment be demonstrated?
The law of independent assortment can be demonstrated through dihybrid crosses, showing that the segregation of alleles for one trait does not affect the segregation of alleles for another trait (College Board AP CED).
- 22
What is the expected genotypic ratio from a monohybrid cross?
The expected genotypic ratio from a monohybrid cross between two heterozygous parents is 1:2:1, representing the homozygous dominant, heterozygous, and homozygous recessive genotypes (College Board AP CED).
- 23
Define phenotype in the context of genetics.
Phenotype refers to the observable physical or biochemical characteristics of an organism, determined by both genetic makeup and environmental influences (College Board AP CED).
- 24
What is the significance of a back cross in genetics?
A back cross involves crossing a hybrid organism with one of its parents or an individual with a similar genotype, used to determine the genotype of the hybrid and to produce offspring with specific traits (College Board AP CED).
- 25
How do mutations affect genetic traits?
Mutations are changes in the DNA sequence that can alter gene function and potentially lead to new traits or variations within a population (College Board AP CED).
- 26
What is the expected phenotypic ratio for a test cross?
The expected phenotypic ratio for a test cross will depend on the genotype of the tested individual; if it is homozygous dominant, all offspring will show the dominant trait, while if heterozygous, a 1:1 ratio may occur (College Board AP CED).
- 27
How do dominant and recessive traits interact in offspring?
In offspring, dominant traits will mask the expression of recessive traits when present, leading to the dominant phenotype being expressed (College Board AP CED).
- 28
What is the purpose of using a Punnett square in genetic predictions?
A Punnett square is used to visualize and calculate the probabilities of different genotypes and phenotypes resulting from a genetic cross (College Board AP CED).
- 29
Define the term 'genotype'.
Genotype refers to the genetic constitution of an individual, specifically the alleles present for a particular gene (College Board AP CED).
- 30
What is the role of the environment in the expression of traits?
The environment can influence the expression of traits by affecting gene activity and resulting in phenotypic variations that are not solely determined by genotype (College Board AP CED).
- 31
How does a dihybrid cross illustrate the law of independent assortment?
A dihybrid cross illustrates the law of independent assortment by showing that the inheritance of one trait does not influence the inheritance of another trait, as seen in the resulting phenotypic ratios (College Board AP CED).
- 32
What is a genetic carrier?
A genetic carrier is an individual who possesses one copy of a recessive allele for a genetic trait but does not express the trait phenotypically (College Board AP CED).
- 33
How can Mendelian genetics explain variations in traits?
Mendelian genetics explains variations in traits through the inheritance of different alleles, leading to diverse phenotypes based on dominant and recessive interactions (College Board AP CED).
- 34
What is the expected genotypic ratio for a test cross involving a heterozygous individual?
The expected genotypic ratio for a test cross involving a heterozygous individual crossed with a homozygous recessive is 1:1 for dominant to recessive genotypes (College Board AP CED).
- 35
How do multiple alleles affect inheritance patterns?
Multiple alleles increase the genetic diversity of a trait, allowing for more than two possible alleles in the population, which can lead to a wider variety of phenotypes (College Board AP CED).
- 36
What is the importance of studying Mendelian genetics in modern biology?
Studying Mendelian genetics is crucial for understanding inheritance patterns, genetic disorders, and the principles of heredity, which are foundational to fields like genetics and biotechnology (College Board AP CED).