Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are fertile. This kind of isolation is most similar to which of the following reproductive isolating mechanisms?

#Question id: 11628

#Unit 8. Inheritance Biology

Two  varieties of maize averaging of 180 cm and  20cm, inches in height respectively, are crossed. The F1 progeny is quite uniform averaging  100cm in height. How many different  Phenotype express in f2 generation?

#Question id: 12985

#Unit 10. Ecological Principles

#Question id: 7284

#Unit 5. Developmental Biology

Choose the correct match.

#Question id: 1167

#Unit 4. Cell Communication and Cell Signaling

After a meal, when blood glucose rises, circulating insulin binds to insulin receptors on various cell types and reduces blood glucose levels by:

a. fusion of intracellular vesicles containing GLUT4 glucose transporters with the plasma membrane.

b. stimulation of the conversion of glucose to glycogen.

c. inhibition of glucose synthesis from smaller molecules.

Which of the following combination is correct?

#Question id: 12961

#Unit 10. Ecological Principles

Refer to the following experiment, which is designed to test the co evolutionary relationships among an unpalatable butterfly (the  monarch),  a  palatable  butterfly  (the  viceroy),  and  a  butterfly  predator  (the  jay).  Monarch butterflies are reared on three diets: milkweed (their natural food), cabbage, and cabbage treated with an extract from milkweed leaves. Viceroy butterflies, mimics of monarchs, also are reared on three diets: willows (their natural food), cabbage, and cabbage treated with an extract from milkweed leaves. In trial 1 of the first experiment, adult butterflies reared on a particular diet are presented one at a  time  at  1-hour  intervals  to  jays  and  the  jays  are  allowed  to  feed.  Each jay is  fed  until  it refuses to eat the butterfly presented, but no more than 12 butterflies are presented to a jay during a particular test. Five birds are used for each test; therefore, up to 60 butterflies can be consumed for each diet test. The observer records the actual number of butterflies  eaten. In trial 2, the experiment is repeated 2 weeks later. In the second experiment, the butterflies are reared on the same diets as in experiment 1. However, when they are offered to jays, some jays receive a monarch  reared  on  milkweed  before  being  offered  the  butterflies  reared  on  the  experimental  diets;  the  other  group  of jays is  first given a viceroy reared on willow before being  offered the butterflies reared on the experimental diets. The initial butterfly offered is included in the total number eaten, but no more than 12 butterflies are presented to each jay.

The data in the table indicate which of the following?