The correct sequence for aerobic metabolic breakdown of glucose is
a. glycolysis—preparatory reaction--cirtric acid cycle--electron transport system
b. preparatory reaction-- transport--citric acid cycle
c. electron transport system--citric acid reaction--glycolysis
d. none of the choices are correct.

a. glycolysis—preparatory reaction--cirtric acid cycle--electron transport system

Explanation:

Glycolysis is the first stage of cellular respiration that occurs in the cytoplasm of the cell. During glycolysis one 6 carbon glucose is converted into two molecules of 3 carbon pyruvic acid or pyruvate. In the preparatory reaction, the pyruvate converted into a two-carbon molecule called acetyl CoA. In this reaction, a carbon dioxide molecule is released and a molecule of NADH is released. The citric acid cycle begins with the reaction of the acetyl CoA with a four-carbon molecule in the mitochondrisl matrix. It goes through a cycle of reactions regenerating the four-carbon starting molecule. ATP, NADH and FADH₂ are produced. The electron transport system is the terminal step of aerobic respiration that operates on the inner membrane of the mitochondria. Reduced coenzymes NADH and FADH₂ move along electron transport system release high-energy electrons and produce ATP.

An autotrophic protist - they can perform photosynthesis and mainly consist of unicellular algae. they can be divided into number of systematic group according to the shape of their cell and the type of photosynthetic pigments they use.