Normally tree rings will disappear, damage, or go missing when the tree doesn't have enough nutrients, another factor that contributes to that is drought.
Answer:
B
Explanation:
B is the most likely consequence because of the following facts we are told:
- After apple trees were introduced, some apple maggots began feeding from and laying their eggs on apple trees
- Adult apple maggots will only mate on the type of tree on which they were born.
This provides a geographical isolation (because they are feeding and laying eggs on separate trees) and reproductive isolation (because they will only mate on the type of tree on which they are born).
These two factors increase the chances that apple maggots feeding on apple trees will only encounter those who have mated on the same tree, and continue to mate this way. Over time, the populations (i.e. apple tree vs hawthorn tree) will intermix less and less. This will mean the genetic pool will become distinct, and natural selection will be acting differently (different habitats and different genes), encouraging speciation.
The right answer is A patient who is Rh– can receive only Rh– blood.
The blood group is not the only thing that matters, it adds a category: rhesus. Rhesus refers to a red blood cell antigen that is on their wall. There are two blood group systems: Rh positive (Rh +) and Rh negative (Rh-).
Rhesus is positive in people who have this antigen. It concerns the majority of the population. Negative rhesus refers to people without the antigen. This rhesus factor is especially useful to know if a blood transfusion is feasible between two people.
The blood transfusions can be "iso-rhesus", that is to say between Rh + and Rh- but only in one sense: Rh- can give to Rh + but Rh + can not give to Rh-. Again because of the presence of antibodies directed against the antigen in Rh- people.
Using the gas pedal analogy, the proto-oncogene would be an accelerator since they promote cell division and
deregulate apoptosis, while tumor suppressor would
be the brakes since they constrain the progress of the cell
cycle and induce cell apoptosis. An
oncogene is, therefore, when the accelerator
is stuck in down position and the brakes are not working.