Basic Genetics Check-Up
R = red flower B = brown eyes G = grey fur T = tall plants L = long tail
r = white flower b = non-brown eyes g = white fur t = short plants l = short tail
Use the above combinations of letters to write the correct combinations of genes for the following traits: 1. hybrid tall plant 2. Homozygous long tailed 3. white flowers 4. White fur
Tell which is the dominant feature in the above traits.
5. eye color 6. Plant height 7. Tail length
Tell which is the recessive feature in the above traits.
8. flower color 9. Fur color
Identify the phenotype using the above traits.
10. Rr 11. GG 12. Ll
13. Circle the ones that are homozygous:
RR Rr BB bb Bb Gg Tt Ll ll
Using the chart above:
14. Is it possible to have a heterozygous short tail? 15. Is it possible to have a pure white flower?
Probability
16. What is the possibility of flipping a heads, then a tails, and then another heads? 17. What is the chance of a parent who is Bb of providing a b gamete?
Monohybrid Cross
B = brown eyes b = blue eyes
Cross a female who has brown eyes (whose mother had blue eyes) with a male who has blue eyes.
Parental Cross = x
Genotypic Ratio =
What is the chance of having a blue eyed child?
Complete a F1 cross.
Genotypic Ratio =
Monohybrid
If the ability to roll your tongue is a recessive trait (t) and the inability to roll your tongue is a dominant trait (T). Cross a woman who can roll her tongue with a man who cannot roll his tongue (but whose father could):
Key: Inability to roll tongue Ability to roll tongue P Cross: __ X
Genotypic Ratio: Phenotypic Ratio:
In pea plants tall (T) is dominant to short (t). Cross two heterozygous tall pea plants. Key: Tall pea plant
Short pea plant
P Cross: __ X
Incomplete Dominance
S = straight hair S’ = curly hair SS’ = wavy hair
Cross a female with curly hair and a male with straight hair. Parental Cross = x
Genotypic Ratio = Phenotypic Ratio =
Cross a female with wavy hair and a male with curly hair.
Parental Cross = x
This couple has four children. How many of them would you expect to have: Straight hair
Incomplete Dominance
In mice black hair (B) is incompletely dominant over white hair (B’). Cross two grey mice. Key: = black hair
= grey hair = white hair
Parental Cross = x
Genotypic Ratio = Phenotypic Ratio =
If these mice had 120 babies identify how many they would have of each color: = black hair
Dihybrid Cross
R = ringed r = solid T = heavy coat t = thin coat
Cross a female raccoon that is heterozygous for ringed tail and a thin coat with a male that has a solid tail and is heterozygous for a heavy coat.
Parental Cross = x
only use the squares you need
If these raccoons had 8 offspring how many would you expect to be ringed tailed and heavy coated?
If you crossed two raccoons heterozygous for each trait what is the phenotypic ratio?
Dihybrid:
In grasshoppers the body color of brown is dominant (B) and green is recessive (b). Strong legs (L) is dominant and weak legs (l) is recessive.
A brown female grasshopper who is homozygous recessive for leg strength who has a green mother mates with another brown strong legged grasshopper (who’s mother was also green and father had weak leg strength). Key: brown green
strong legs weak legs
Parental Cross = x
only use the squares you need
If this couple had 32 offspring how many would expect to be: Brown & strong legs
Dihybrid
Cross a blue-eyed (b) mom with straight hair (H) (whose mother had curly (h) hair) with a brown eyed (B) curly haired dad (whose dad had blue eyes).
Key: brown eyes blue eyes Straight hair Curly hair
Parental Cross = x
only use the squares you need
Could they have a blue-eyed curly haired child?
If they had four children, how many would have brown eyes and straight hair? How many would look like their mom? Their dad?
Sex Linked
N = normal vision n = color blind
Cross a female with normal vision whose mother is color blind with a male who has normal vision but whose father is colorblind.
Parental Cross = x
What are the chances that of their offspring they will have a colorblind child?
If they had 4 boys, how many of them would you expect to be color blind?
Sex-linked
Hemophilia is a sex-linked trait. Normal blood clotting is regarded as dominant (H) & hemophilia is recessive (h). Cross a normal female who’s father was a hemophiliac with a hemophiliac male.
Parental Cross = x
What is the probability they could have an offspring who has hemophilia?
What is the probability they could have an offspring who was a female AND has hemophilia?
If they had four boys how many would you expect to have hemophilia?
Of their children how many have the potential to have children with hemophilia?
