Terms of Inheritance Match the terms on the left-hand side with the correct definitions on the right. Use a ruler to join the terms and definitions. Term Definition Allele Involves sex chromosomes, decides whether an organism is male or female. Gamete Basic unit of inheritance. Many make up a chromosome and control an inherited characteristic. Gene The set of genes, combination of alleles. Genotype Sex cell that carries genes from one generation to the next; contains a single set of chromosomes in its nucleus. Phenotype Threadlike structure found in the nucleus of a cell. Sex Determinism Alternative forms of a gene. Chromosome Physical appearance of an organism.