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Questions and Answers
If a spider has the genotype 'Dd' for leg length, where 'D' represents the dominant allele for long legs and 'd' represents the recessive allele for short legs, what is the spider's phenotype?
If a spider has the genotype 'Dd' for leg length, where 'D' represents the dominant allele for long legs and 'd' represents the recessive allele for short legs, what is the spider's phenotype?
- The phenotype cannot be determined from the genotype alone
- A mix of long and short legs
- Long legs (correct)
- Short legs
What is the purpose of using a Punnett square?
What is the purpose of using a Punnett square?
- To determine the sex of offspring
- To predict the possible genotypes and phenotypes of offspring in a genetic cross (correct)
- To determine the environmental factors that influence trait expression
- To identify the specific genes responsible for a trait
In a Punnett square, what do the letters on the sides of the square represent?
In a Punnett square, what do the letters on the sides of the square represent?
- The dominant and recessive alleles for a specific trait
- The sex chromosomes of the parents
- The possible genotypes of the offspring
- The gametes (sperm or egg) produced by each parent (correct)
If a mother spider has the genotype 'PP' for body color (P = purple, dominant) and a father spider has the genotype 'pp' (p = white, recessive), what is the probability of their offspring having a white body color?
If a mother spider has the genotype 'PP' for body color (P = purple, dominant) and a father spider has the genotype 'pp' (p = white, recessive), what is the probability of their offspring having a white body color?
Two spiders, both heterozygous for web-building pattern (W = complex, w = simple), are crossed. What is the ratio of offspring expected to have a complex web-building pattern?
Two spiders, both heterozygous for web-building pattern (W = complex, w = simple), are crossed. What is the ratio of offspring expected to have a complex web-building pattern?
If a Punnett square shows all possible combinations of alleles for two traits, what type of cross is being represented?
If a Punnett square shows all possible combinations of alleles for two traits, what type of cross is being represented?
How do Punnett squares help us understand inheritance patterns?
How do Punnett squares help us understand inheritance patterns?
What is the significance of the 'Ww' genotype in a Punnett square representing web-building pattern?
What is the significance of the 'Ww' genotype in a Punnett square representing web-building pattern?
Flashcards
Spider Traits
Spider Traits
Physical characteristics of spiders, like color and size.
Alleles
Alleles
Different forms of the same gene, can be dominant or recessive.
Dominant Allele
Dominant Allele
An allele that is expressed in the phenotype even with a recessive allele present.
Recessive Allele
Recessive Allele
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Genotype
Genotype
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Phenotype
Phenotype
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Punnett Square
Punnett Square
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Gametes
Gametes
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Study Notes
Spider Traits and Genotypes
- Spider traits are physical characteristics, such as color, size, leg length, and the presence or absence of specific markings.
- These traits are determined by the spider's genes, often expressed as alleles.
- Alleles are different forms of the same gene, and they can be dominant or recessive.
- A dominant allele will always be expressed in the phenotype even if there is also a recessive allele present.
- A recessive allele will only be expressed in the phenotype if there are two copies of the recessive allele.
- Genotype refers to the combination of alleles an organism possesses for a particular gene.
- Phenotype refers to the observable traits expressed by the genotype.
- Examples include genes for body color, leg structure, or web-building patterns.
- Specific spider traits can be visualized through the use of phenotype and genotype analysis.
Punnett Squares
- Punnett squares are a graphical method used to predict the possible genotypes and phenotypes of offspring in a genetic cross.
- They are diagrams that show the possible combinations of alleles from parents.
- They illustrate the probability of inheriting specific alleles.
- The parental alleles are represented by letters often 'P', 'p', 'D', 'd' which indicate dominant and recessive alleles.
- Punnett squares are helpful in determining the overall expected frequency/occurrence of each potential offspring's genotype.
- They are a visual representation that illustrates the likelihood of a specific phenotype or genotype in the next generation.
- In order to obtain the possible offspring genotypes from a Punnett square, the gametes of both parents are written on the sides of the square.
- Possible offspring genotypes are written within the square by combining alleles.
- For example, a Punnett square can be created to predict the outcome of a cross between two heterozygous parents (e.g., a cross between a parent with brown eyes (dominant) and a parent with blue eyes (recessive)).
- The square would arrange the different combinations of alleles each parent can donate (one allele from each parent).
- The completed square represents the possible genotypes and phenotypes, for example, the chances of a child having brown eyes versus blue eyes.
- Punnett squares, therefore, are a useful tool for understanding inheritance patterns.
- By visualizing the outcomes, they help scientists, breeders, and anyone interested in genetics.
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