- Red eye is a dominant trait in fruit flies
- Sepia eye is a recessive trait in fruit flies
- A red eye fruit fly crossed with sepia eye fruit fly produces offspring with sepia eye
- Hence, a dominant red eye male fruit fly crossed with a recessive sepia eye female fruit fly produces offspring with recessive sepia eye

- A dominant red eye male fruit fly crossed with a recessive sepia eye female fruit fly produces offspring with recessive sepia eye
- Parents produces offspring
- If an offspring has a recessive trait , then each parent has at least one recessive gene
- Therefore, each parent fruit fly will have at least one recessive gene

- Each parent fruit fly will have at least one recessive gene
- The dominant red eye male fruit fly is one of the parents
- So, the male fruit fly has at least one recessive gene

- The male fruit fly has at least one recessive gene
- The male fruit fly has dominant red eyes
- A fruit fly is a kind of organism
- If an organism has dominant trait and one recessive gene for that trait, then the organism contains both dominant and recessive genes
- Therefore, the male fruit fly has both dominant and recessive genes

- The male fruit fly has both dominant and recessive genes
- A heterozygous organism contains both dominant and recessive genes
- A fruit fly is a kind of organism
- Therefore, the male fruit fly is heterozygous dominant for the trait

- The female fruit fly has recessive sepia eyes
- If a recessive trait is expressed, then the organism only contains recessive genes for that trait
- A fruit fly is a kind of organism
- Hence, the female fruit fly only has recessive genes for sepia eyes

- The female fruit fly only has recessive genes for sepia eyes
- A homozygous recessive organism contains only recessive genes
- A fruit fly is a kind of organism
- So, the female fruit fly is homozygous recessive for the trait

- The male fruit fly is heterozygous dominant for the trait
- The female fruit fly is homozygous recessive for the trait
- Therefore, the male fruit fly is heterozygous dominant and the female fruit fly is homozygous recessive

So, the male fruit fly is heterozygous dominant and the female fruit fly is homozygous recessive
Question: In fruit flies, red eyes are dominant over sepia eyes. A male with red eyes is crossed with a female with sepia eyes producing first generation offspring that all had sepia eyes. What does this indicate about the flies that were crossed?
Context: - Red eye is a dominant trait in fruit flies 
- Sepia eye is a recessive trait in fruit flies 
- If a recessive trait is expressed, then the organism only contains recessive genes for that trait 
- If an offspring has a recessive trait , then each parent has at least one recessive gene 
- The male fruit fly has dominant red eyes 
- A fruit fly is a kind of organism 
- The dominant red eye male fruit fly is one of the parents 
- If an organism has dominant trait and one recessive gene for that trait, then the organism contains both dominant and recessive genes 
- A red eye fruit fly crossed with sepia eye fruit fly produces offspring with sepia eye 
- Parents produces offspring 
- A heterozygous organism contains both dominant and recessive genes 
- A homozygous recessive organism contains only recessive genes 
- The female fruit fly has recessive sepia eyes