Study Guide for the LS

Study Guide for the Heredity Quiz
Date of quiz: _________
 heredity: the passing of traits from parents to offspring
 offspring- the young (or baby) of two parents
 probability: the mathematical chance that an event will occur
 phenotype: an organism’s inherited physical appearance (blue eyes, tall, curly hair)
 genotype: the inherited combination of alleles (BB, Tt)
 alleles: two forms of the same gene (represented by letters such as TT, Tt, or tt) These
may be dominant or recessive.
 dominant trait: a trait observed when at least one dominant allele (capital letter) for a
characteristic is inherited (for example Rr or RR)/ A dominant trait will cover up a
recessive trait and ALWAYS appears in first generation offspring.
 recessive trait: a trait that is apparent only when two recessive alleles (small letters) for
the same characteristic are inherited (for example rr or bb) This trait recedes
into the background in first generation offspring.
 generation: all of the people born at about the same time (example brothers and sisters)
Important People:
Punnett developed a square that is used to visualize all the possible combinations of alleles
in offspring resulting from a genetic cross.
- Gregor Mendel is considered the father (first to discover) of genetics. He used plants to
study the way traits are passed from one generation to the next.
Back 
Know how to read and draw a Punnett Square.
B- dominant for black hair
b- recessive for brown hair
(homozygous dominant for black)
(homozygous recessive for brown)
Offspring phenotype= 100% Black hair
A= Red apples
a= green apples
Genotype Ratio
Phenotype Ratio
1 : 2 : 1
Red apples
Phenotype Percentage
green apple
75% red apples
25% green apples