Scientific researchers discovered agents that behaved like bacteria causing diseases such as rabies and hoof-and-mouth, but were much smaller. at this time it became the general view that viruses were biologically "alive." this changed in 1935 when the tobacco mosaic virus was crystallized and scientists demonstrated that the particles lacked any mechanisms necessary for metabolic function. it was determined that viruses consisted of a nucleic acid, dna or rna, surrounded by a protein shell and the scientific view changed: viruses are complex biochemical mechanisms but not alive. when not in contact with a host, the virus remains dormant. during this time there are no biological activities occurring and the virus is nothing more than a static organic particle. in this state viruses can remain for extended periods of time, waiting to come into contact with the appropriate host. when in contact with a host, it becomes active, reacts to its environment and/or host and directs its efforts toward self-replication. the viral goal now is to produce more viruses to attack host cells.
according to the passage above, all but one is a reason to classify viruses as living. that is they
a) are capable of protein synthesis.
b) contain a nucleic acid, dna or rna.
c) response to changes in the environment.
d) lack mechanisms for metabolic function.

In a hypothetical breed of dogs, coat color is controlled by two genes. there are six different coat colors in this breed: black, brown, cream, gray, silver, and tan. consider the following crosses. cross 1: black females from a lineage of all black dogs are crossed with brown males from a lineage of all brown dogs. f1 males and females are all black. when f1 are intercrossed, f2 males and females are black or brown. cross 2: black females from a lineage of all black dogs are crossed with tan males from a lineage where all males are tan and all females are cream. f1 males are black, f1 females are gray. when f1 are intercrossed, f2 males and females are black, brown, gray, or tan. cross 3: silver females from a lineage where all females are silver and all males are gray are crossed with brown males from a lineage of all brown dogs. f1 males and females are all gray. when f1 are intercrossed, f2 males are black, brown, gray, or tan, f2 females are cream, gray, silver, or tan. select the correct statements regarding the mode of inheritance of the coat color genes. a) both genes are x-linked. b) both genes are autosomal. c) one of the genes modifies the expression of the other gene. d) each gene has an additive effect on the intensity of coat color. e) each gene independently specifies three colors. f) one of the genes is autosomal, and the other is x-linked.

The terrestrial planets are characterized by having a a.) silicate core b.) iron-rich silicate core c.) iron-rich metallic core d.) none of these

All organisms contribute some water to the water cycle by conducting