Download Genetics and Heredity - Formative Assessment – Answer Key Name

Genetics and Heredity - Formative Assessment – Answer Key
Name: _________________________ Per: ___
1. What did Gregor Mendel do to study different characteristics in his genetics experiments? - He crossed pollinated plants
2. In Mendel’s experiments, what proportion of the plants in the F2 generation had a trait that had been absent in the F1
generation? - One fourth or ¼
3. Define “genes” - Factors that control traits
4. Define hybrid. - An organism that has two different alleles for a trait.
5. What does the notation TT meant to geneticists? - Two dominant alleles
6. What does the notation Tt mean to geneticists? - One dominant and one recessive allele
7. What is probability? - A number that describes how likely it is that an event will occur
8. What is the probability of producing a tall pea plant from a genetic cross between two hybrid tall pea plants?- 3/ 4 or 75%
9. What does a Punnett square show? - All the possible outcomes of a genetic cross
10. If a homozygous black guinea pig (BB) is crossed with a homozygous white guinea pig (bb), what is the probability that
an offspring will have black fur? - 100 percent or 4/4
11. Define phenotype. - an organisms physical appearance
12. A purebred chicken with white feathers is crossed with a purebred chicken that has black feather. Each of their
offspring has both black and white feathers. Why does this happen?
- the alleles for feather color are neither dominant or recessive. So codominance is present.
13. What term refers to physical characteristics that are studied in genetics? - Traits
14. Define alleles. - The different forms of a gene
15. Define genotype. - an organisms genetic makeup. What two alleles were inherited.
16. An organism that has two dominant alleles for a trait is called ________________. - homozygous
17. Define heterozygous. - Two different alleles for a trait.
18. In pea plants, green pod color is controlled by a dominant allele. Yellow is controlled by a recessive allele. Explain why
a plant with yellow pods can never be a hybrid. - Recessive traits only show when the offspring collects 2 recessive
traits from parents. A hybrid has one dominant and one recessive trait from the parents. Yellow is always yy.
19. Explain why Mendel’s cross of purebred tall and short pea plants resulted in only tall plants.
- A purebred tall can only pass a dominant (tall) allele. Therefore, all offspring will be tall, even if they are heterozygous.
20. In pea plants, the allele for smooth pods (S) is dominant over the allele for pinched pods (s). Construct a Punnett
square that shoes a cross between an SS plant and an Ss plant. Predict what percent of the offspring are likely to have
smooth pods. - 100 percent will be smooth
S
s
S
SS
Ss
S
SS
Ss
21. Which trait—white flowers or purple flowers—is controlled by a dominant allele? Which is controlled by a recessive
allele? How do you know?
- White flowers are dominant because it is represented by a capital letter.
- Purple flowers are recessive because they are represented by a lower case letter
22. In which generation are the parents purebred? In which generation are they hybrids?
- F1 Generation is purebread and F2 is Hybrid.
23. In the F1 generation, what is the genotype of the offspring? What is their phenotype?
- 100 percent of the offspring will be Ww which will yield white flowers
24. In the F2 generation, what percent of the offspring have purple flowers? What is the genotype of the purple-flowered
offspring?
- 25 % will be purple with the genotype ww
25. In the F2 generation, what percent of the offspring have white flowers? What are the genotypes of the white-flowered
offspring?
- 75% the genotypes will be Ww and WW