The alternate forms of a gene are known as:
a. collinear transcripts
b. alleles
c. pseudogenes
d. polypeptides
e. unit factors

Alleles

Explanation:

The genetic traits exhibit variations. The forms of a particular gene that govern the variations of a specific genetic trait are called alleles.

Alleles occupy corresponding loci on the homologous chromosomes. A gene may have two or more than two alleles. For a diploid organism, two alleles for a gene may be present in the genome irrespective of the multiple alleles for the trait present in the gene pool of the population.  

For example, "T" and "t" are the alleles for the plant height gene wherein the allele "T" imparts the "tall" phenotype and the allele "t" imparts the "dwarf" phenotype to the plants.

a- all cells come from pre-existing cells

the correct answer in apex is tissue development, i know because i just had this question