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NAME: ________________________
GENETICS: HOW AND WHY?
(Intro to Genetics and Punnetts.doc)
1. Examine the drawings of the chromosomes below. Complete the table by filling in the information
about the chromosomes.
BODY CELL (diploid)
SEX CELL (gamete, haploid)
NUMBER OF
CHROMOSOMES PRESENT
CAN THE CHROMOSOMES
BE PUT INTO PAIRS?
2. A. Genes are often shown as lines on a chromosome. Examine the diagrams below of a pair of body
cell chromosomes and a sex cell chromosome.
BODY CELL
CHROMOSOMES
SEX CELL
CHROMOSOME
Wing length gene
Body color gene
Leg number gene
Eye size gene
C. How many genes for wing length are present in the body cell? ______________________
D. Would a cell with this number of chromosomes be 2N or N? ________________
E. How many genes for wing length are present in the sex cell? ________________________
F. Would a cell with this number of chromosomes be 2N or N? ____________________
G. Would the body cell be considered haploid or diploid? ______________________
3. Below each of the following words are choices. Circle the choices that are examples of each of
those words.
a. DOMINANT GENE
D
e
k
L
N
o
R
S
b. RECESSIVE GENE
M
n
d
F
G
I
k
P
c. HOMOZYGOUS DOMINANT
AA
Gg
KK
ll
pp
Rr
TT
Ff
d. HOMOZYGOUS RECESSIVE
ee
Ff
HH
Oo
qq
Uu
ww
ii
e. OFFSPRING COMBINATIONS IN WHICH THE DOMINANT GENE MUST SHOW
AA
Dd
EE
ff
Jj
RR
Ss
Qq
f. OFFSPRING COMBINATIONS IN WHICH THE RECESSIVE GENE MUST SHOW
aa
Gg
Ff
KK
Oo
PP
ss
tt
4. Now on to Mendel. In dogs, the black fur gene (B) is dominant to the recessive brown fur gene (b).
Circle the correct combination of genes and write down the color of the dog if it is:
homozygous dominant ( BB Bb bb ) _______________________
homozygous recessive ( BB Bb bb ) __________________
heterozygous ( BB Bb bb ) _________________________
5. Fill in the blanks below using these choices: dominant, genes, genetics, heterozygous, homozygous,
recessive, chromosomes, Punnett Square.
a. Chromosomes have chunks of nucleotides that determine traits. These parts are
________________.
b. A person having two genes that are alike is said to be _________________________.
c. A gene that prevents others from showing is said to be ________________________.
d. A gene that may not show up even though it is there is said to be _______________.
e. Long rod shaped bodies inside a cell’s nucleus are called _______________________.
f. One who studies how traits are passed on is studying _________________________.
g. A person with one dominant and one recessive gene for a trait is ________________.
h. A way to show which genes can combine when an egg and a sperm join are a