The cross bridge cycle is a series of molecular events that occur after excitation of the sarcolemma. what is a cross bridge?

The cross-bridge cycle is part of the process of muscle fiber contraction analysis of a set of steps:

1) Excitation of skeletal muscle fiber - involving the unleash the potential for action and its spread throughout the Sarcolemma.

2) Excitation/contraction coupling, which includes the processes of excitation transduction in contractile vegetation.

3) Cross bridges cycle, responsible for cyclic formation and rupture complexes of action and the generation of force and mechanical work.

4) Muscle Relaxation - A contraction of muscle fiber in response to a single action potential.

In the Cross Bridges Cycle, actin and myosin myofilaments do not change in length during contraction of the skeletal muscle. Instead, the myofilaments actin and myosin glide along with each other in a way that takes shortening of the sarcomere. During contraction, bridges are formed between the actin molecules and the heads of the myosin molecules. As bridges form, move, break free and reform in a way similar to paddling a boat. The voluntary movement of the bridges makes actin myofilaments at each end of the sarcomere slide to beyond myosin myofilaments towards the H-zone. Bands I and zones H become narrower, but bands A keep a constant length. Zone H may disappear when Actin myofilaments overlap in the center of the sarcomere. When actin myofilaments slide over the myosin myofilaments, the lines Z approach and the sarcomere shortens.

d. in sexual reproduction, offspring have more chromosomes than

either parent.

asexual reproduction results in offspring which are genetically the same as the parent organism (not counting a rare mutation). sexual reproduction produces a random mixture of the genetics derived from both parents

explanation:

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.