They protect bacterial cells from white blood cells.
Yes, it is possible.
In this case both of the parental plants were heterozygotes and they manifested dominant allele in their phenotype, which is round seed.
P: Aa x Aa
F5: AA, Aa, aA, aa - possible genotypes in fifth generations.
A- dominant allele (round seeds); a- recessive allele (wrinkled seeds)
Wrinkled phenotype is manifested only if there are two recessive alleles present.