1. O T T F F S S E __
What comes next?

2. It’s EASY if you know the PATTERN! (Just like Punnett Squares)9
NINE
O T T F F S S E __ I V E X
EVEN
IGHT N E W O H R E O U R

3. PROBABILITY & PUNNETT SQUARES 11-2

4. PROBABILITY
____________________ is the __________ that a particular _________________
likelihood
event will occur
It can be written as a:
Fraction ____
Percent ____
Ratio ____
1/4
25%
1:3

5. COIN FLIP 1/2 50% 1:1 There are 2 possible outcomes: HEADS TAILS
COIN FLIP
There are 2 possible outcomes:
HEADS TAILS
The chance the coin will land on either one is:
____ ____ ____
1/2
50%
1:1

6. Alleles segregate randomly just like a coin flip
Alleles segregate randomly just like a coin flip. . . So can use probability to predict outcomes of genetic crosses.

7. PROBABILITIES _____ outcomes ______ affect _________ones
_____________works ______ in ___________ a ________ number of events.
PAST
DON’T
FUTURE
If last coin flip was heads… there is still a 50/50 chance the next flip will be heads too.
Probability
predicting
best
large
The more flips. . . The closer results will be to
the expected 50:50 average.

8. DOMINANT/RECESSIVE T t capital Dominant Recessive lower-case
_____________ allele is represented by a ____________ letter. (usually the first letter of the trait)
____________ allele is represented by the SAME
_________________ letter.
EX: Tall = ______
Short =______
capital
Recessive
lower-case T t
NOT S for short

9. HOMOZYGOUS HETEROZYGOUS
When both alleles in the pair are the _______, the organism is _______________ or __________
EX: ____ or ___
When both alleles in the pair are _____________, the organism is
_________________ or _____________
Ex: ____
SAME
HOMOZYGOUS PURE
TT tt
DIFFERENT
HETEROZYGOUS HYBRID Tt

10. REMEMBER…. a dominant allele hides the presence of a recessive allele

11. PHENOTYPE/GENOTYPE The ________________ of an organism is
its _____________
The ____________of an organism is
genetic makeup
GENOTYPE
appearance
PHENOTYPE

12. MAKING A CROSS for only a __________ trait = ____________________
ONE GENE
MONOHYBRID CROSS
A Punnett square for a MONOHYBRID CROSS looks like this:

13. PUNNETT SQUARES
are used to show possible offspring from a cross between 2 parents
_______________ go at
top and on left side
Boxes show ____________ ___________________
Parent alleles
T T T t
possible offspring combinations

14. STEPS FOR MAKING CROSSES
Figure out parent alleles
Choose Punnett size
Put in parent gametes
Fill in offspring combinations
probabilities phenotypes genotypes
1. ___________ what _________________ are
2. ________correct__________ square __________
3. ______ possible_______________________
4. ______ boxes with _____________________
5. Determine ____________of_____________& ____________

15. T t TALL = ____ SHORT = ____ IN PEA PLANTS Tall is dominant over short
LET’S MAKE A CROSS!
PURE TALL PURE SHORT X

16. PURE TALL parent What are the parent alleles?
T T _________
HOMOZYGOUS  
What gametes
can it make? T T

17. PURE SHORT parent What are the parent alleles?
t t _________
HOMOZYGOUS  
What gametes
can it make? t t

18. T t T t T t T t T t Find the Pattern… ALL _____ of the offspring
____ %
___/4
will be t
T t
T t
100 4
T t
T t Tt
TALL
GENOTYPE _____ PHENOTYPE _______

19. HYBRID TALL parent What are the parent alleles?
T t _________
HETEROZYGOUS  
What gametes
can it make? T t

20. T t T t T T T t T t t t Find the Pattern… GENOTYPES ¼ = _____
½ = _____ T
T T
T t TT Tt t
T t
t t tt
3/4 75
TALL
PHENOTYPES ____ or ____% _________
____ or ____% _________
1/4 25
SHORT

21. PRACTICE MAKING GAMETES for a MONOHYBRID CROSS
Tall = ____ Round seeds = ___
Short = ____ Wrinkled seeds = ___ T t r

22. What are the possible gametes?
Homozygous Tall parent =
What gametes can it produce?
T T   T T

23. What are the possible gametes?
PURE wrinkled parent =
What gametes can it produce? rr   r r

24. What are the possible gametes?
Heterozygous Round parent =
What gametes can it produce?
R r   R r

25. What are the possible gametes?
Hybrid Tall parent =
What gametes can it produce? Tt   T t

26. SOUTH DAKOTA CORE SCIENCE STANDARDS
LIFE SCIENCE: Indicator 1: Understand the fundamental structures,
functions, classifications, and mechanisms found
in living things
9-12.L Students are able to relate cellular functions and processes to specialized structures within cells.
Storage and transfer of genetic information

27. SOUTH DAKOTA CORE SCIENCE STANDARDS
LIFE SCIENCE: Indicator 2: Analyze various patterns and products
of natural and induced biological change.
9-12.L.2.1. Students are able to predict inheritance
patterns using a single allele. (APPLICATION)

28. Core High School Life Science Performance Descriptors
High school students performing at the
ADVANCED level:
predict how traits are transmitted from parents to offspring
PROFICIENT level:
explain how traits are transmitted from parents to offspring;
BASIC level
identify that genetic traits can be transmitted from parents to offspring;