Lipoprotein lipase is responsible for degrading triglycerides into two fatty acids and a monoacylglycerol molecule. It is attached to the endothelial lumen of the blood vessel. It removes triglycerides from very-low density lipoproteins and chylomicrons in the blood. HMG-CoA reductase and synthase are important enzymes in de novo cholesterol synthesis, but do not cause hypertriglyceridemia (high levels of triglycerides in the blood). Acetyl-CoA carboxylase and fatty acid synthase are part of lipid anabolism, form fatty acids and do not cause hypertriglyceridemia.

Cholesterol and lipids are carried in the blood by lipoproteins. HDL are lipoproteins that remove cholesterol accumulated in blood vessels and take it to the liver for excretion in the bile or further processing by steroidogenic tissues. HDL delivers cholesterol to liver cells through the scavenger receptor SR-B1. HDL can also transfer cholesterol to intermediate-density lipoproteins (IDL) using the cholesterol transfer protein. Incorporation of LDL (low-density lipoproteins), not HDL by macrophages leads to formation of fatty streaks in atherosclerotic plaques. This does not remove cholesterol from periphery, but rather contributes to it. 

When oxaloacetate is low in the body as a result of starvation, acetyl-CoA can no longer combine with it to continue through the Krebs cycle. Oxaloacetate can go through gluconeogenesis to form more glucose, however acetyl-CoA does not. Instead, the acetyl-CoA molecules go through a series of steps (acetoacetyl-CoA and 3-hydroxy-3-methyl-glutaryl-CoA are intermediate molecules in these steps) to form ketone bodies.

Apoliporoteins carry lipids in the blood as lipids are insoluble. ApoB100 is a protein found on different types of lipoproteins circulating in the body. ApoB 48 is another apolipoprotein that is present on chylomicrons. Both ApoB 100 and ApoB 48 are encoded by the ApoB gene, but ApoB 48 is shorter than ApoB 100 and is produced in the intestine.

In photosynthesis, light is absorbed in order to move electrons from water molecules to NADPH.  The reduction of  to NADPH is accompanied by the movement of protons across a membrane which sets up a gradient similar to that of oxidative phosphorylation.  The protons eventually run through ATP synthase and ATP is formed.

During photosynthesis, the light phase is responsible for creating  which the dark phase then consumes as a part of its process. In addition to  is used in the dark phase as a high energy substrate to work properly.

Absorbing four photons by photosystem II creates one oxygen molecule, so absorbing 12 would produce 3 molecules of .

During photosynthesis, the dark phase follows the light phase. The light phase produces  which, along with , is fed into the dark phase where it is consumed (becomes  and ). If the light phase continues working, but the dark phase does not, the  and  created during the light phase will not be consumed. Thus, there will be a decrease in the level of  and  (the correct answer). The relative proportion of  will actually increase.

Carbohydrate production is a result of the dark phase working properly, so their levels would decrease in this instance. The sensitivity of the chloroplast to light would not change.

All of the answer choices are steps in the Calvin cycle, but the only one that describes the first stage - fixation - is  and ribulose 1,5-bisphosphate reacting to form 3-phosphoglycerate.

The stages of the Calvin cycle in the order that they occur are fixation, reduction, and then regeneration.  While carboxylation does occur as a part of the first stage, it is not what defines that stage.