The Z disc is the: Group of answer choices separation between sarcomeres. electrical voltage at which a muscle cell fires an action potential. area of a sarcomere where only thick myofilaments are found. point where the axon and the sarcolemma meet. place where two cardiac muscle cells meet.

Separation between sarcomeres.

Explanation:

The structure of the muscle fibre is composed of many functional units called sarcomere which is interrupted by the discs called Z-discs.

These Z-discs are made of the alpha-actin homodimers which allow the actin filament allows to bind to it along with other proteins.  The Z-discs since present at regular intervals in a muscle appears to separate the sarcomere and defines the boundaries of the sarcomere.

Thus, the selected option is correct.

1) gene flow

- it is described as the transfer of genes from one population to another population so that frequency of gene is increased.

-a zebra migrates to join a different herd of zebras.

2) natural selection

- a mechanism of evolutionary change in which individuals with advantageous traits survive and reproduce whereas the others ( those that can not adapt) eliminate from the population.

-competition for sunlight leads to taller trees.

3) mutation

- permanent change in the nucleotide sequence of dna ( genetic material) that could have harmful or useful consequences.

-the dna of a snake changes to make its venom stronger.

4) genetic drift - it is a random phenomenon ( that occurs by chance such as fire) that results in change in the gene frequency in a small population.    

-a grassfire randomly sweeps through a population of buffalo and kills most of the animals.

explanation: