The illustration shows 'Segregation and Probability' in Mendel's crossing experiment as:

1. F1: Both F1 plants have the same set of alleles (Tt) and are tall.
2. Gametes: The probability of each gamete acquiring the tall (T) allele is one-half. Similarly, the probability of acquiring the short (t) allele is also one-half.
3. F2: When the alleles pair up in the F2 generation, the probability of a tall offspring (TT or Tt) is one-fourth plus one-fourth plus one-fourth or three-fourths. The probability that the offspring will be short (tt) is one-fourth.

The following are also marked on the illustration:

• Tall
• Tt
• Short
• homozygous
• heterozygous
• homozygous