_________/ 30 points
Your Name: __________________
Team # __________________
Date: _______________
What are the chances . . .?
BACKGROUND: Genes are passed on to offspring from their parents. Genes determines many of
the traits of offspring. In many cases, the trait that an organism has depends on which genes it
happens to get from its parents. Some other parents may be homozygous (having the same genes) for a
given trait, while others may be heterozygous (having different genes) for that trait. The gene that any
particular offspring receives from its parents depends on chance.
PURPOSE: To make a gene model for the fur color of rabbits. In most rabbits the allele for black fur
is dominant over the allele for brown fur. You will use the models to explore the chances of rabbit
offspring having black or brown fur.
MATERIALS: 4 index cards, 2 paper bags, this investigation report, and pencil
PROCEDURE:
 First, place one gene pair in the Father bag and the other gene pair in Mother
 Working with your team, take one card out of each bag without looking at them
 Put the two cards together on your lab table to represent the allele
combination of the offspring
 Record the results in your table by placing a tally mark in the row for the gene
combination you pulled from the bag
 Place those two cards back in the correct bags
 Repeat 20 times
Table 1: Inherited Fur Color with PARENTS GENOTYPES: BB x bb
Offspring inherited
Fur Color
Tallies
Black
Or
Brown
Homozygous
or
Heterozygous
BB
Bb
bb
(1) What percentage of offspring had black fur? _____________
(2) What percentage of offspring had brown fur? ____________
TOTAL
Table 2: Inherited Fur Color with PARENT GENOTYPES: Bb x Bb
Offspring inherited
Fur Color
Tallies
Black
Or
Brown
Homozygous
or
Heterozygous
TOTAL
BB
Bb
bb
(1) What percentage of offspring had black fur? _____________
(2) What percentage of offspring had brown fur? ____________
ANALYSIS:
1. What are the chances of two parents, both of who are homozygous for brown fur,
having offspring with brown fur? Use examples from data.
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2.
Can a male parent with the genes BB and a female parent with the genes Bb have
any offspring with brown fur? Use examples from data.
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