Question

1. the sex chromosomes x and y in humans are considered:

a. fully homologous with identical sizes and genes
b. autosomes that determine traits like eye color
c. non - homologous, differing in size and composition but with short homologous regions
d. circular structures found only in prokaryotes

1. the slight differences in dna sequences between homologous chromosomes account for:

a. allelic differences, such as in eye color genes
b. identical alleles in all genes
c. complete chrompsomal duplication
d. absence of gene loci

Explanation:

1. Human X and Y chromosomes are not fully homologous. X is larger. They have short homologous regions (pseudoautosomal regions) but differ in size and gene content. So C is correct. A is wrong as they aren't fully homologous. B is wrong as they are sex chromosomes, not autosomes. D is wrong as human chromosomes are linear.
2. Homologous chromosomes have same gene loci but can have different alleles (versions of a gene). Slight DNA sequence differences lead to allelic differences (e.g., eye color alleles). B is wrong as alleles aren't identical. C is wrong as it's about duplication, not sequence differences. D is wrong as gene loci are present.

Answer:

1. C. Non - homologous, differing in size and composition but with short homologous regions
2. A. Allelic differences, such as in eye color genes