Question

Pea shape is controlled by a gene that specifies an enzyme known as Sbe1 (for Starch-branching enzyme 1). A recessive allele of Sbe1 likely encodes;

- an Sbe1 enzyme with reduced function.
- an Sbe1 enzyme with enhanced catalytic activity.
- an Sbe1 enzyme with a new function.
- a different type of enzyme.

Answer 1

A recessive allele of the gene Sbe1 in pea plants likely encodes a nonfunctional or less effective version of the enzyme, not a different type of enzyme, leading to wrinkled pea seeds as opposed to the smooth seeds produced by the dominant allele.

Step-by-step explanation:

In pea plants, if there is a recessive allele of the gene Sbe1, which encodes the Starch-branching enzyme 1, it would likely encode a nonfunctional or less effective version of the enzyme rather than a completely different type of enzyme.

The dominant allele of Sbe1 is responsible for producing an active enzyme that results in the smooth shape of pea seeds. When a pea plant inherits two copies of the recessive allele, the resulting enzyme is either nonfunctional or less effective, leading to the accumulation of starch and giving the pea seeds a wrinkled appearance.

This is an example of a single gene influencing a phenotype, but in many cases such as eye color in humans, multiple genes can contribute to a single characteristic.