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Questions and Answers
What is the outcome of Gregor Mendel's study on the height of pea plants in the F2 generation?
What is the outcome of Gregor Mendel's study on the height of pea plants in the F2 generation?
What conclusion can be drawn from Mendel's observation that some alleles are dominant and others recessive?
What conclusion can be drawn from Mendel's observation that some alleles are dominant and others recessive?
According to Mendel's first law, what happens during gamete formation?
According to Mendel's first law, what happens during gamete formation?
What does Mendel's Second Law, the Law of Independent Assortment, describe?
What does Mendel's Second Law, the Law of Independent Assortment, describe?
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In Mendel's pea plant experiments, what was the genotype of the homozygous parent plant that contributed the tall trait?
In Mendel's pea plant experiments, what was the genotype of the homozygous parent plant that contributed the tall trait?
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What are homologous chromosomes characterized by?
What are homologous chromosomes characterized by?
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During self-pollination of Tt plants, what ratio is expected in F2 progeny based on Mendel's findings?
During self-pollination of Tt plants, what ratio is expected in F2 progeny based on Mendel's findings?
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If an organism has genotype Bb, what kind of gametes can it produce?
If an organism has genotype Bb, what kind of gametes can it produce?
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What is the probability that a mother who carries one gene for haemophilia will have a son with the disease?
What is the probability that a mother who carries one gene for haemophilia will have a son with the disease?
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Which statement about haemophilia inheritance is true?
Which statement about haemophilia inheritance is true?
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How is the phenotype of a bird best determined?
How is the phenotype of a bird best determined?
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What does the term 'genotype' refer to in genetics?
What does the term 'genotype' refer to in genetics?
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How many alleles for a single trait are typically found in an organism's genotype?
How many alleles for a single trait are typically found in an organism's genotype?
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Which of the following statements about alleles is incorrect?
Which of the following statements about alleles is incorrect?
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In a cross between Yy and Yy parents, what percentage of their offspring will have the same phenotype as both parents?
In a cross between Yy and Yy parents, what percentage of their offspring will have the same phenotype as both parents?
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What genotype do two purple-flowered plants have if some offspring are purple and some are red?
What genotype do two purple-flowered plants have if some offspring are purple and some are red?
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What is the dominant phenotype in the described pea plant generation?
What is the dominant phenotype in the described pea plant generation?
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Which cross demonstrates Mendel's Law of Segregation?
Which cross demonstrates Mendel's Law of Segregation?
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What does it mean when a phenotype is described as recessive?
What does it mean when a phenotype is described as recessive?
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Which choice represents a potential allelic pair?
Which choice represents a potential allelic pair?
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What is the expected phenotypic ratio when crossing two dihybrid organisms?
What is the expected phenotypic ratio when crossing two dihybrid organisms?
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How is the outward appearance of a trait determined in an organism?
How is the outward appearance of a trait determined in an organism?
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What constitutes a possible allelic pair?
What constitutes a possible allelic pair?
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What percentage of offspring from a homozygous dominant and a heterozygous trait would exhibit a recessive phenotype?
What percentage of offspring from a homozygous dominant and a heterozygous trait would exhibit a recessive phenotype?
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What is the expected phenotypic outcome when crossing a pure long-whiskered seal and a short-whiskered seal?
What is the expected phenotypic outcome when crossing a pure long-whiskered seal and a short-whiskered seal?
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Mendel's Law of Segregation was formulated after what type of study?
Mendel's Law of Segregation was formulated after what type of study?
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What phenotypic ratio results from a dihybrid cross involving independent assortment?
What phenotypic ratio results from a dihybrid cross involving independent assortment?
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Which of the following best describes Mendel's Law of Dominance?
Which of the following best describes Mendel's Law of Dominance?
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How many possible gamete combinations can be produced from the parent genotypes RrGg?
How many possible gamete combinations can be produced from the parent genotypes RrGg?
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What is the relationship between genotypes and phenotypes in a mono-hybrid cross?
What is the relationship between genotypes and phenotypes in a mono-hybrid cross?
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What is the expected offspring phenotype ratio for green pods and round seeds in a dihybrid cross of RrGg x RrGg?
What is the expected offspring phenotype ratio for green pods and round seeds in a dihybrid cross of RrGg x RrGg?
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Which statement correctly describes independent assortment?
Which statement correctly describes independent assortment?
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Which aspect does not contribute to the phenotypic ratio of a cross?
Which aspect does not contribute to the phenotypic ratio of a cross?
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Which statement is true about traits that are inherited independently according to Mendel's findings?
Which statement is true about traits that are inherited independently according to Mendel's findings?
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What would be the expected phenotype ratio for a cross between two heterozygous individuals (Tt x Tt) in a monohybrid cross?
What would be the expected phenotype ratio for a cross between two heterozygous individuals (Tt x Tt) in a monohybrid cross?
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What must a female have to express the recessive trait for a sex-linked gene?
What must a female have to express the recessive trait for a sex-linked gene?
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In what way do sex-linked traits typically manifest more often in one gender?
In what way do sex-linked traits typically manifest more often in one gender?
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In a dihybrid cross, what does the 9:3:3:1 ratio signify?
In a dihybrid cross, what does the 9:3:3:1 ratio signify?
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When crossing a pure round-seeded plant with a wrinkle-seeded plant, what is the phenotypic expectation?
When crossing a pure round-seeded plant with a wrinkle-seeded plant, what is the phenotypic expectation?
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What type of genetic linkage occurs when two traits are located on the same chromosome?
What type of genetic linkage occurs when two traits are located on the same chromosome?
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Which of the following is an example of a sex-linked trait in humans?
Which of the following is an example of a sex-linked trait in humans?
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What ratio would you expect for males and females in a cross involving a sex-linked recessive trait?
What ratio would you expect for males and females in a cross involving a sex-linked recessive trait?
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What is the relationship between genotype and phenotype in the context of independent assortment?
What is the relationship between genotype and phenotype in the context of independent assortment?
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Which trait is not likely to be influenced by sex-linked inheritance patterns?
Which trait is not likely to be influenced by sex-linked inheritance patterns?
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Which allele combination results in wrinkled seeds from the dihybrid cross RrGg?
Which allele combination results in wrinkled seeds from the dihybrid cross RrGg?
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What is a distinctive feature of sex-linked traits compared to autosomal traits?
What is a distinctive feature of sex-linked traits compared to autosomal traits?
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What genetic concept explains why results from a monohybrid cross show a 3:1 ratio in offspring?
What genetic concept explains why results from a monohybrid cross show a 3:1 ratio in offspring?
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Study Notes
Mendel's Laws of Inheritance
- Gregor Mendel studied seven characteristics of pea plants.
- His work led to the beginning of genetics.
- He discovered that organisms express only one trait from possible genotypes.
Law of Segregation
- Diploid organisms have matching chromosome pairs (homologous chromosomes).
- These have the same length, banding pattern, and genes at the same locations (loci).
- Organisms inherit two alternative forms of a gene (alleles) from each parent.
- During gamete formation, allele pairs separate (segregate).
- One allele per trait is passed to each gamete.
- When alleles differ, one is dominant, the other recessive.
- Example: TT (tall) x tt (short) → Tt (tall), F1 generation.
- F2 generation (Tt x Tt): 3 tall (Tt) : 1 short (tt).
Law of Independent Assortment
- This law deals with dihybrid crosses, examining two traits simultaneously.
- Alleles for different traits are distributed independently.
- Example: Seed texture (round/wrinkled), pod color (green/yellow); traits are inherited independently.
- Result of a dihybrid cross (RrGg x RrGg): 9:3:3:1 phenotypic ratio.
- 12 round/green, 4 round/yellow, 4 wrinkled/green, 1 wrinkled/yellow.
Gene Linkage
- Traits on the same chromosome tend to be inherited together (gene linkage).
- Mendel's pea plant traits were on separate chromosomes; hence, independent assortment.
- If genes are on the same chromosome, inheritance is linked; ratios deviate from 9:3:3:1.
Sex-Linked Traits
- Genes located on sex chromosomes (X or Y) determine sex-linked traits.
- X chromosome is larger, containing more genes than Y.
- Males have one X chromosome, females have two; recessive traits appear more often in males (due to one X).
- Example: Fruit fly eye color; affected by sex of offspring.
- X-linked recessive traits are passed on via females more often than males.
- Examples in humans: haemophilia & red-green colour blindness.
Determining Phenotype
- Phenotype is the observable physical expression of a trait (e.g., flower color, seed shape).
- To determine it, look at the characteristic.
Genotype vs. Phenotype
- Genotype is the genetic makeup (e.g., alleles) of a trait.
- Genotype determines phenotype.
- Phenotype is the visible trait.
Alleles
- Alleles are different forms of a gene. One inherits two alleles for each trait. Possible pairs examples are: "kk ", "Pp", "Tt", "Rr"
- A possible allele pair would be: "K" & "k"
Number of alleles per trait
- Normally, there are two alleles for one trait.
Specific Example Crosses:
- Various example crosses are provided to demonstrate the inheritance patterns and resulting phenotypic ratios.
Additional Questions (Multiple Choice)
- Several questions regarding these concepts are also included.
Punnett Square Examples
- Detailed Punnett square examples illustrate the predicted phenotypic ratios and genotypes for different crosses for the seven different traits studied by Mendel.
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Description
Explore the foundational principles of genetics through Mendel's experiments with pea plants. This quiz covers both the Law of Segregation and the Law of Independent Assortment, including key examples and definitions. Test your knowledge on how traits are inherited in organisms!
