Which of the following components of the electron transport chain passes electrons to O2 and causing it to be reduced to H20? A. Cytochrome c oxidase
B. Succinate -Q reductase
C. NADH
D. NADH-Q oxidoreductase

The correct answer is option A, that is, cytochrome c oxidase.

Explanation:

A sequence of complexes, which conduct electrons from electron donors to electron acceptors through redox reactions, that is, both oxidation and reduction reactions taking place simultaneously is termed as the electron transport chain. This conduction of electrons is further combined with the mediation of protons across a membrane.  

Four membrane-bound complexes are present within the mitochondria, of these in complex IV or cytochrome c oxidase, the withdrawal of 4 electrons takes place from 4 molecules of cytochrome c, and is mediated towards the molecular oxygen, which further gives rise to 2 molecules of water. During the process, 8 H+ are withdrawn from the mitochondrial matrix, which contributes to the proton gradient.  

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:

answer; /// i believe that the correct answer is (50%);