Mendel’s Laws
What is the Law of Segregation state?
Alleles separate during gamete formation.
What inheritance shows both traits equally (e.g., AB blood)?
Codominance
What chromosome is red-green colorblindness found on?
X chromosome
What are chromosomes 1–22 called?
Autosomes
What’s the chance of Aa x Aa producing aa?
25%
What is the result of a dihybrid cross between heterozygotes?
9:3:3:1 ratio in F2.
What is it called when heterozygotes show a blended phenotype?
Incomplete dominance
Can a father pass an X-linked trait to his son?
No, sons get Y from father
What is nondisjunction?
Failure of chromosomes to separate
What rule is used for “and” events?
Rule of multiplication
What genotypic ratio results from an Aa x Aa cross?
1:2:1
What is polygenic inheritance?
Traits influenced by multiple genes (e.g., skin color)
What makes a woman a carrier for hemophilia?
She has one affected X allele (XHXh)
What chromosomal change causes Down syndrome?
Trisomy 21
What type of cross reveals an unknown genotype?
Test cross
What law explains how genes on different chromosomes separate independently?
Law of Independent assortment.
What is epistasis?
One gene masks the expression of another
Why are males more likely to have X-linked disorders?
Only one X chromosome (hemizygous)
What are parental vs. recombinant offspring
Parental = same as parents, recombinant = new combos from crossing over
What’s the probability of producing AaBbCc offspring from AaBbCc × AABbCc?
1/8
Which phase of homologous chromosomes separating?
Anaphase 1
What’s it called when one X chromosome becomes inactive in females?
X-inactivation (Barr body)
Why do traits sometimes skip generations in a pedigree?
Recessive alleles carried by heterozygotes
What does a recombination frequency of 1% represent?
1 map unit / 1 centimorgan
In a trihybrid cross, what rule do you use to calculate complex outcomes?
Multiplication rule across each gene pair.