Question

in roses, red flowers and long stems are dominant traits. a rose plant that is homozygous for long stems is crossed with a rose plant that is heterozygous for red flowers and homozygous for percentage of the offspring will exhibit red, long - stemmed flowers? 25 percent 50 percent 75 percent 100 percent

Explanation:

Step1: Determine the genotypes

Let \( R \) represent the allele for red flowers (dominant) and \( r \) for non - red flowers. Let \( L \) represent the allele for long stems (dominant) and \( l \) for short stems.
The homozygous plant for red flowers and long stems has the genotype \( RRLL \).
The heterozygous plant for red flowers and homozygous for short stems has the genotype \( Rrll \).

Step2: Analyze the gametes

The \( RRLL \) plant can only produce \( RL \) gametes.
The \( Rrll \) plant can produce \( Rl \) and \( rl \) gametes in a \( 1:1 \) ratio.

Step3: Perform the cross

Using the Punnett square method (or the multiplication of probabilities for independent traits):
For the flower color ( \( R\times Rr \) ):
The probability of getting a red - flowered offspring (\( R - \)):
When \( R\times Rr \), using the rule of monohybrid cross \( (AA\times Aa) \), the probability of \( A - \) (in this case \( R - \)) is \( 1\) (since \( R\times Rr \) gives \( RR:Rr = 1:1 \), both \( RR \) and \( Rr \) show the dominant red phenotype).
For the stem length ( \( LL\times ll \) ):
When \( LL\times ll \), all offspring will have the genotype \( Ll \) (showing the dominant long - stemmed phenotype).
Since the two traits (flower color and stem length) are independent (assuming they assort independently), we use the multiplication rule for independent events.
The probability of red flowers (\( P(R -)=1 \)) and long stems (\( P(L -)=1 \)).
The probability of red and long - stemmed flowers \( P = 1\times1=1\) (or \( 100\%\)).

Answer:

100 percent