99 points me 1.) species y and z have very different genes. species a and b have only a few different genes. what is most likely true about these species? a.) species y and z are more closely related to each other than species a and b are to each other. b.) species a and b are more closely related to each other than species y and z are to each other. c.) species y is the ancestor of species a and species z is the ancestor of species b. d.) all four of these species are probably equally related to each other 2.) what is a molecular clock? a.) a tool scientists use to dat fossils b.) a tool scientist use to determine how many mutations a species accumulates over time c.) a tool scientists use to determine how long two species have been evolving independently d.) a tool scientists use to determine how long it takes to sequence a strand of dna 3.) what type of mutations do scientists look for in a molecular clock? a.) mutations that increase fitness b.) mutations that decrease fitness c.) mutations that have no effect on fitness d.) mutations that natural selection can work on 4.) how do scientists calibrate a molecular clock? a.) they determine the number of mutations accumulated in a gene of species of known age b.) they compare the ticking of the molecular clock with that of the atomic clock c.) they use the clock that ticks at the appropriate rate for the divergence rate that they are trying ot calculate d.) they compare the number of positive mutations that have occurred in a particular species with the number of negative mutations that have occurred 5.) a scientist wants to determine hen lions and house cats last shared a common ancestor. she should use a molecular clock that a.) "ticks" faster than a molecular clock used to determine when mammals and amphibians last shared an ancestor b.) "ticks" slower than a molecular clock used to determine when mammals and amphibians last shared an ancestor c.) "ticks" at the same rate as all other molecular clocks d.) consists of a gene that accumulates mutations

1.) Species Y and Z have very different genes. Species A and B have only a few different genes. What is most likely true about these species?

A.) Species Y and Z are more closely related to each other than species A and B are to each other.

B.) Species A and B are more closely related to each other than species Y and Z are to each other.

C.) Species Y is the ancestor of species A and species Z is the ancestor of species B.

D.) All four of these species are probably equally related to each other

2.) What is a molecular clock?

A.) a tool scientists use to dat fossils

B.) a tool scientist use to determine how many mutations a species accumulates over time

C.) a tool scientists use to determine how long two species have been evolving independently

D.) a tool scientists use to determine how long it takes to sequence a strand of DNA

3.) What type of mutations do scientists look for in a molecular clock?

A.) mutations that increase fitness

B.) mutations that decrease fitness

C.) mutations that have no effect on fitness

D.) mutations that natural selection can work on

4.) How do scientists calibrate a molecular clock?

A.) they determine the number of mutations accumulated in a gene of species of known age

B.) they compare the ticking of the molecular clock with that of the atomic clock

C.) they use the clock that ticks at the appropriate rate for the divergence rate that they are trying ot calculate

D.) they compare the number of positive mutations that have occurred in a particular species with the number of negative mutations that have occurred

5.) A scientist wants to determine hen lions and house cats last shared a common ancestor. She should use a molecular clock that

A.) "ticks" faster than a molecular clock used to determine when mammals and amphibians last shared an ancestor

B.) "ticks" slower than a molecular clock used to determine when mammals and amphibians last shared an ancestor

C.) "ticks" at the same rate as all other molecular clocks

D.) consists of a gene that accumulates mutations

c: warm water flows from the western tropical pacific toward south america. that should be the right answer! hope it .

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.