Mendel & his experiments
Who is considered the father of genetics and studied inheritance patterns using pea plants?
Gregor Mendel
What is Mendel’s first law called?
Law of Segregation
What is the difference between genotype and phenotype?
What is a Punnett square used for?
Predicting possible genetic outcomes of offspring.
What is a pedigree?
A chart showing inheritance patterns of a genetic trait within a family.
What organism did Mendel use for his experiments?
Garden pea plants (Pisum sativum)
What does the Law of Segregation state?
Each individual has two alleles for each trait, but these alleles separate during gamete formation so each gamete receives only one allele.
What does homozygous mean?
Having two identical alleles for a trait.
Example: AA or aa
What is a monohybrid cross?
A genetic cross involving one trait.
In pedigrees, what shape represents males?
Square
Why were pea plants a good choice for Mendel’s experiments? Give two reasons.
During what process do homologous chromosomes separate, explaining Mendel’s Law of Segregation?
Meiosis
What does heterozygous mean?
Having two different alleles for a trait.
Example: Aa
What phenotype ratio did Mendel observe in his F₂ generation during a monohybrid cross?
3:1 dominant to recessive
In pedigrees, what shape represents females?
Circle
What does it mean when a plant is “true-breeding”?
The plant consistently produces offspring with the same trait as the parent when self-pollinated.
What is Mendel’s second law called?
Law of Independent Assortment
In genetics, what does a dominant allele do?
It masks the expression of a recessive allele.
A cross between two heterozygous individuals (Aa × Aa) produces what possible genotypes?
25% AA
50% Aa
25% aa
What is an autosomal recessive disorder?
A disorder requiring two recessive alleles to be expressed.
Example: aa
Why did Mendel study thousands of pea plants instead of only a few?
To make his results statistically significant and reduce the chance that his results happened randomly.
Explain the Law of Independent Assortment.
Alleles for different traits separate independently during gamete formation, allowing different combinations of traits in offspring.
What is the difference between a homozygous dominant and heterozygous individual?
What is a testcross used for?
To determine whether an individual showing a dominant phenotype is homozygous dominant or heterozygous.
What is an autosomal dominant disorder?
A disorder where only one dominant allele is needed to express the condition.
Example: Aa or AA