This statement is true. Plaque is considered dangerous because it can break off and create a clot in the arteries. one of the most common results of this is heart attack.
D. Chloroplast is only found in plant cells not in animal cells
Glucose can diffuse from the digestive tract into the human blood system without first being digested.
Bones are made up of Calcium Phosphate given by the chemical formula,
. When bones are kept in Hydrochloric acid, given by the chemical formula, HCl, they become soft because the calcium compound present in the bones changes its form. The following double displacement reaction takes place when the bones are kept in HCl,
---> 
Calcium chloride is water soluble, and gets washed away. This makes the bone thin and soft.