Why is American-style football often called the “gridiron sport?"

Which description best defines the nervous system and its two main branches? a: the message center of the body, split into the autonomic nervous system and the somatic nervous system b: the control panel of the body, split into the central nervous system and the exterior nervous system c: the message center of the body, split into the central nervous system and the peripheral nervous system d: the control panel of the body, split into the brain and the spinal cord

Which word can describe a person's gender identity? a) female b) intersexual c) asexual d) androgynous

Why do rna viruses appear to have higher rates of mutation? a) rna nucleotides are more unstable than dna nucleotides.b) replication of their genomes does not involve proofreading.c) rna viruses can incorporate a variety of nonstandard bases.d) rna viruses are more sensitive to mutagens.