1. Genetics Study Guide Answers

2. Phenotype: physical characteristics (tall, brown)
Genotype: genetic combination (Gg, GG, gg)
Genes: a segment of DNA, located on the chromosome, factors that control traits
Dominant Allele: an allele whose traits always show up if the allele is present (T)
Recessive Allele: an allele whose traits are masked by a dominant allele and only show up if two recessive alleles are present (t).

3. Heredity: the passing of traits from parents to offspring
Trait: a characteristic that a parent can pass to its offspring
Genetics: the study of heredity
Selective Breeding: selecting parents with traits that you want their offspring to have
Punnett Square: a chart that shows all of the possible combinations of alleles that can result from a genetic cross.
Probability: the likelihood a particular event will occur

4. Tall, brown eyes
Tt, TT, tt
Codominance is neither DOMINANT nor RECESSIVE. Therefore if you cross a dog with white fur and a dog with black fur the puppies will have WHITE and BLACK fur.
Purebred and HOMOZYGOUS both mean same (TT or tt).
Heterozygous and HYBRID both mean DIFFERENT (Tt).
GREGOR MENDEL is considered “the father of genetics” and studied PEA PLANTS.

5. Purebred tall and purebred short
Heterozygous tall
¾ tall, ¼ short
A Punnett Square shows all of the possible combinations of a genetic cross.
Mitosis creates new BODY cells for growth and repair. (ex. Skin, blood, muscle, bone, etc.)
Meiosis creates new SEX cells for reproduction.(sperm, egg)
How are Meiosis and Mitosis similar? They both produce new cells
After Mitosis occurs, the new cells will have the SAME number of chromosomes.
After Meiosis occurs, the new cells will have HALF the number of chromosomes.

6. What two people could have identical DNA? IDENTICAL TWINS
What is the point of mitosis? TO PRODUCE BODY CELLS
What is the product of meiosis? TO PRODUCE SEX CELLS
GENES are located on CHROMOSOMES which are found inside the nucleus of the cell.

7. Label the following as dominant or recessive
Aa DOMINANT
AA DOMINANT
aa RECESSIVE
Label the following as purebred recessive, purebred dominant, or hybrid dominant.
Aa Hybrid Dominant
AA Purebred Dominant
aa Purebred Recessive
Label the following as homozygous recessive, homozygous dominant, or heterozygous dominant.
Aa Heterozygous Dominant
AA Homozygous Dominant
aa Homozygous Recessive

8. 34. In humans, the allele for dimples (D) is dominant
34. In humans, the allele for dimples (D) is dominant. A woman with the genotype (dd) has children with a man with the genotype (Dd). If the couple has ten children, how many children would you logically expect to have a dimples? Dd (dimples) 50% dd (no dimples) 50% Half of their children will have dimples (5). d D Dd dd

9. 35. Linda has 10 children. She is heterozygous for her dimples and her husband has a homozygous dominant genotype. What is the probability that their 11th child will have dimples? DD 50%, Dd 50% Dimples 100% 4/4 All of her children will have dimples, so the 11th one will too. 4/4 D d DD Dd

10. 36. A cat with solid fur and one with purebred spotted fur had offspring, called the F1 generation. In time, two of the offspring from the F1 generation mated and produced offspring’s called the F2 generation. What percentage of F2 generation would be born with spotted fur? F1: F2: FF: 25% Spotted (75%) Ff: 50% Solid (25%) Ff: 25% F
Spotted f
Solid Fur F f Ff F f FF Ff ff

11. In humans, dimples (D) are dominant over no dimples (d)
In humans, dimples (D) are dominant over no dimples (d). A man with dimples marries a woman without dimples and they have three children, two of which have dimples and one that does not have dimples. If no dimples are recessive, what must the man’s genotype be?
Dd (all dimples) WRONG
Dd (dimples)
dd (no dimples)
Dad has to be Dd d D Dd d D Dd dd

12. 38. Cross a heterozygous tall pea plant with a homozygous short pea plant. Use “T” for tall and “t” for short.
What is the probability of the above offspring to be Tt? 2/4
What is the probability of the above offspring to be tt? 2/4
What is the probability of the above offspring to be TT? 0/4
What percentage of the offspring will be tall? 50%
What percentage of the offspring will be short? 50%
List all of the possible genotypes of the offspring. Tt (50%), tt (50%)
List all of the possible phenotypes of the offspring. Tall (50%), Short (50%) T t Tt tt