Name:_________________________Assessment Date: Thurs., 1/8 or Fri., 1/9
Study Guide Heredity Assessment
 heredity: the passing of traits from parents to offspring (young of parent)
 genes: small segments of chromosomes with a set of instructions donated by parents to
to the offspring. Genes are found on chromosomes.
 alleles: different forms of the same gene (represented by letters such as TT, Tt, or tt)
These may be dominant or recessive.
Alleles make up your genotype.
 genotype: the inherited combination of alleles (BB, Tt)
 phenotype: an organism’s inherited physical appearance
o Examples of inherited traits: brown hair, attached earlobes, curly hair, blue eyes
 purebred, homozygous: an organism with two same alleles for a trait
(BB- pure dominant, bb- pure recessive)
 hybrid, heterozygous: an organism with two different alleles for a trait (Bb)
 dominant trait: a trait observed when at least one dominant allele (represented by a
capital letter) for a characteristic is inherited (for example Rr or RR)
o A dominant trait will cover up or hide a recessive trait
 recessive trait: a trait that is apparent only when two recessive alleles ( represented by
small letters) for the same characteristic are inherited (for example rr or bb)
o This trait fades into the background and only shows when paired with another
recessive allele.
 sex chromosomes: The X and Y Chromosomes that is responsible for determining an
organism’s gender. XX= female XY= male
o Any parent has a 50% chance of having a baby girl or boy.
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
**Practice making Punnett Squares and figuring out percentages of each genotype
and phenotype.**
A= Red apples
a= green apples
Statistics:
Genotype Ratio
Phenotype Ratio
1 : 2 : 1
AA
Aa
aa
3
:
Red apples
Phenotype Percentage
75% or
25% or
1
Green apple
¾
¼
red apples
green apples