What is the fuction of the spindle fibers

Which of the following is most likely the result of an organism having lipids in its body a) water cannot be absorbed through the surface of a leaf b)human eats fruits to get a quick source of energy c) a sheep sleeps for more hours in the winter d) a warm river is filled with fish and algae

In general, characteristics that an organism survive and reproduce become more common in a population over time. what mechanism of evolution cause this change?

Where does the esophagus lead to in a frog?