In humans, free-ear lobes are dominant to attached. Two parented that are both heterozygous free are expecting a child. What are the chances that the child will
have free ear lobes of attached?
Key:
Parents & Gametes:

And can you show it in a Punnet square

See the answer below

Explanation:

First, let us assume that the allele for free ear lobes to be represented by A. Thus, the recessive attached earlobe would be a.

The genotype for the heterozygous parents would each be Aa.

          Aa    x    Aa

      AA   Aa   Aa   aa (see the attached image for the Punnet's square)

Offspring:

1/4 AA - free ear lobes

1/2 Aa - free ear lobes

1/4 aa - attached ear lobes

Hence

Probability of the child having free ear lobes = 3/4 or 75%

Probability of the child having attached ear lobes = 1/4 or 25%

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products