What is often a problem when calibrating a molecular clock? A. There are frequently not enough negative mutations to accurately calibrate the clocks.
B. There are many different clocks, each of which "ticks" at a different rate.
C. The clocks use mutations that are difficult to identify and track.
D. The frequency of crossing over is used to calibrate the clocks.​

What is the difference between self-pollination and cross-pollination? question 2 options: self-pollination leads to the creation of a fruit. cross-pollination does not. during cross-pollination, ovules are carried from one plant to another plant.. during self-pollination the ovules stay on the same plant. during cross-pollination, ovules are carried from one plant to another plant.. during self-pollination the ovules stay on the same plant. during cross-pollination the pollen grains are carried from one plant to another plant. during self-pollination the pollen and ovules are from the same plant. during cross-pollination, the pollen grains travel from the stigma to the anthers. during self-pollination, the pollen grains travel from the anthers to the stigma.

Explain why phospholipid molecules form a bilayer. (3 marks)

The fascicles of the deltoid are ; the fascicles of the pectoralis parallel; bipennate fusiform; unipennate multipennate; triangular bipennate; fusiform