LAB: Fruit Fly Single Cross Trait (Part 1)

Students will use descriptions of individual genotypes and phenotypes to construct a key and Punnett squares to make correct predictions about probabilities for offspring genotypes and phenotypes including single trait crosses.

Fruit Fly Lab

Part 1

This section practices the basics of Punnett Square theory for application later in the activity.

Drosophila melanogaster is the scientific name for the small fly found near fruit and commonly referred to as a fruit fly. 

Fruit flies are used in genetic research as a model organism because they have a short life cycle, are small and easy to work with and produce a large number of offspring.

To start this activity we will explore a wing phenotype.

 

Here you can see two different phenotypes in wings:

Part 1: Punnett Square Practice - Fruit Fly Wings

​Normal Wings in fruit flies results from a dominant allele, we will assign this trait the letter "R". 

A dominant phenotype appears in the presence of at least one dominant allele.

There are two possible genotypes that confer this normal wing phenotype:

• homozygous: RR

• heterozygous: Rr

Both RR and Rr genotypes result in the dominant phenotype, normal wings.

Vestigial wings in fruit flies are a recessive trait. As a recessive trait this phenotype will appear only in the absence of the dominant allele.

There is one possible genotypes that confer this vestigial wing phenotype:

• homozygous: rr

In this section you will use Punnett squares to predict the theoretical results of various crosses. 

Multiple Choice

Use this Punnett Square to answer the following questions.

1. Which of the following describes the phenotypes of the parents?

• Both parents have normal wings.

• One has normal wings and one has vestigial wings.

• Both parents have vestigial wings.

Multiple Choice

Use this Punnett Square to answer the following questions.

2.Which of the following are possible genotypes that result from Cross #1?

• rr

• RR

• Rr

Multiple Choice

Use this Punnett Square to answer the following questions.

3.What is the predicted genotype ratios or percentages that result from Cross #1?

• 75% RR & 25% rr

• 100% RR

• 50% RR & 50% Rr

• 100% rr

• 50% Rr & 50% rr

Multiple Choice

Use this Punnett Square to answer the following questions.

4.Which of the following are predicted phenotypes that result from Cross #1?

Hint: Phenotype means the physical expression of the trait or what you would see.

• Vestigial winged flies

• Normal winged flies

Multiple Choice

Use this Punnett Square to answer the following questions.

5.What would be the predicted phenotype ratios that result from Cross #1?

• 0% Normal wings and 100% Vestigial wings

• 75% Normal wings and 25% Vestigial wings

• 100% Normal wings and 0% Vestigial wings

• 50% Normal wings and 50% Vestigial wings

We will be using this Punnett square for the next few questions.

​

Now, let's look at a parent cross #2.

Multiple Choice

Use this Punnett Square to answer the following questions.

6.Which of the following describes the phenotypes of the parents in Cross #2?

• Both parents have vestigial wings.

• One has normal wings and one has vestigial wings.

• Both parents have normal wings.

Multiple Select

Use this Punnett Square to answer the following questions.

7.Which of the following are possible genotypes that result from Cross #2? Select all that apply.

• RR

• Rr

• rr

Multiple Choice

Use this Punnett Square to answer the following questions.

8.What are the predicted genotype ratios or percentages that result from Cross #2?

Hint: Remember each Punnett square represents 25%.

• 100% RR

• 50% RR & 50% Rr

• 50% Rr & 50% rr

• 75% Rr & 25% rr

• 25% RR & 75% Rr

Multiple Choice

Use this Punnett Square to answer the following questions.

9.Which of the following are predicted phenotypes that result from Cross #2?

Hint: Phenotype means the physical expression of the trait or what you would see.

• Vestigial winged flies

• Normal winged flies

Multiple Choice

Use this Punnett Square to answer the following questions.

10.What are the predicted phenotype ratios that would result from Cross #2?

Hint: Remember each Punnett square represents 25%.

• 0% Normal wings and 100% Vestigial wings

• 75% Normal wings and 25% Vestigial wings

• 25% Normal wings and 75% Vestigial wings

• 50% Normal wings and 50% Vestigial wings

• 100% Normal wings and 0% Vestigial wings

Now, let's look at the 4th parent combination.

We will be using this Punnett square to answer the next few questions

Let's do 2 more!

Multiple Choice

Use this Punnett Square to answer the following questions.

11.Which of the following describes the phenotypes of the parents in Cross #4?

• Both parents have vestigial wings.

• Three have normal wings and one has vestigial wings.

• Both parents have normal wings.

Multiple Select

Use this Punnett Square to answer the following questions.

12.Which of the following are possible genotypes that result from Cross #4? Select all that apply.

• RR

• Rr

• rr

Multiple Choice

Use this Punnett Square to answer the following questions.

13.What are the predicted genotype ratios or percentages that result from Cross #4?

Hint: Remember each Punnett square represents 25%.

• 100% RR

• 50% RR & 50% Rr

• 50% Rr & 50% rr

• 75% Rr & 25% rr

• 25% RR, 50% Rr, & 25% rr

Multiple Select

Use this Punnett Square to answer the following questions.

14.Which of the following are predicted phenotypes that result from Cross #4?

Hint: Phenotype means the physical expression of the trait or what you would see.

• Vestigial winged flies

• Normal winged flies

Multiple Choice

Use this Punnett Square to answer the following questions.

15.What are the predicted phenotype ratios that would result from Cross #4?

Hint: Remember each Punnett square represents 25%.

• 0% Normal wings and 100% Vestigial wings

• 75% Normal wings and 25% Vestigial wings

• 25% Normal wings and 75% Vestigial wings

• 50% Normal wings and 50% Vestigial wings

• 100% Normal wings and 0% Vestigial wings

Now, let's look at the 6th parent combination.

We will be using this Punnett square to answer the next few questions

Last One!

Multiple Choice

Use this Punnett Square to answer the following questions.

16.Which of the following describes the phenotypes of the parents in Cross #6?

• Both parents have vestigial wings.

• One has normal wings and one has vestigial wings.

• Both parents have normal wings.

Multiple Choice

Use this Punnett Square to answer the following questions.

17.Which of the following are possible genotypes that result from Cross #6?

• RR

• Rr

• rr

Multiple Choice

Use this Punnett Square to answer the following questions.

18.What are the predicted genotype ratios or percentages that result from Cross #6?

Hint: Remember each Punnett square represents 25%.

• 100% RR

• 50% RR & 50% Rr

• 50% Rr & 50% rr

• 100% rr

• 25% RR, 50% Rr, & 25% rr

Multiple Choice

Use this Punnett Square to answer the following questions.

19.Which of the following are predicted phenotypes that result from Cross #6?

Hint: Phenotype means the physical expression of the trait or what you would see.

• Vestigial winged flies

• Normal winged flies

Multiple Choice

Use this Punnett Square to answer the following questions.

20.What are the predicted phenotype ratios that would result from Cross #6?

Hint: Remember each Punnett square represents 25%.

• 0% Normal wings and 100% Vestigial wings

• 75% Normal wings and 25% Vestigial wings

• 25% Normal wings and 75% Vestigial wings

• 50% Normal wings and 50% Vestigial wings

• 100% Normal wings and 0% Vestigial wings

Multiple Choice

Which wing trait is the dominant trait and which is the recessive?

• Normal wing length is the dominant trait. Vestigial wing length is the recessive trait.

• Vestigial wing length is the dominant trait. Normal wing length is the recessive trait

Multiple Choice

Select the key that correctly describes the genotypes and phenotypes for the wing form trait.

• RR is normal wing length

  Rr is normal wing length

  rr is vestigial wing length

• RR is vestigial wing length

  Rr is vestigial wing length

  rr is normal wing length