What describes the man's trait and the alleles in his sperm cells if he inherited the dominant allele from his mother and recessive allele from his father?

As long as you aren't talking about a trait or gene that behaves co-dominately or some other exception, the man would have the dominant trait show up and his alleles would be dominant and recessive (or Dd if you are using letter symbols for the alleles- upper case being the dominant allele from the mom's egg and lower case for the recessive allele from the dad's sperm). So for example if we are talking about the gene for earlobes we can use the letter E to represent the two alleles or genetic variations: E for un-attached earlobes and e for attached earlobes. A sex cell (sperm or egg) has one allele each so that when they unite to make an embryo the new person has 2 alleles- one from each parent. So if the man inherited a dominant allele E from his mom and a recessive allele e from his father then he would have Ee as his "genotype"(what alleles he has). His "phenotype" is what trait he shows, which would be what ever is dominant-- in this case E equals un-attached earlobes.