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Answer:
A) histone coding genes
Explanation:
Histones are the proteins involved in the packing of DNA in eukaryotes. They are positively charged proteins and are not found in bacteria. To analyze the evolutionary relationship in a gene between eukaryotes and bacteria, one must choose the gene present in both of them. The tRNA, rRNA and hexokinase encoding genes are common to both bacteria and eukaryotes. Therefore, one of these genes may be chosen for the study. However, histone encoding genes are not present in the genomes of bacteria. Therefore, the study of the histone encoding gene would not be useful for the mentioned purpose.
The answer is a half-filled circle.
In the pedigree charts, squares present males and circles present females. If a female is healthy, the circle is empty (white). If a female is affected with a trait, the circle is filled-in (usually black). However, if a female is a carrier of a disease, which means that one allele is dominant and one is recessive, then the circle is half-filled.