Question

why would it have been impossible for Mandel to create heterozygous pea plants with short stems , green seeds , or bumpy pods ?

Answer 1

Because those three traits are recessive in Mendel’s peas. A plant must have two copies of the recessive allele (homozygous recessive) to show the recessive phenotype. A heterozygote carries one recessive and one dominant allele, and the dominant allele masks the recessive one.

Examples:
- Short stems are recessive (tt). A heterozygote (Tt) is tall, not short.
- Green seeds are recessive (yy). A heterozygote (Yy) is yellow, not green.
- Constricted/bumpy pods are recessive. A heterozygote shows the dominant (smooth/inflated) pod.

So Mendel could produce heterozygous plants, but they would not look short, green, or bumpy — they’d show the dominant forms. To detect heterozygotes he had to do crosses (e.g., selfing or testcrosses) and examine the offspring ratios.