Consider the following statements about enzymes: 1. They are biological catalysts. 2. They are consumed in the reaction. 3. They lower the activation energy of reactions. Which of the above is/are correct? MCQ with Answer and Explanation

Explanation:
The sarcoplasmic reticulum is a specialized smooth endoplasmic reticulum in muscle cells that stores and releases calcium ions, which trigger muscle contraction. Mitochondria produce ATP, Golgi processes proteins, nucleus controls gene expression.

Explanation:
Cholecystokinin (CCK) is a peptide hormone released by the I cells of the duodenum when acidic chyme containing fats (lipids) and partially digested proteins enters from the stomach. CCK has two major digestive actions: 1) It stimulates the gall bladder to contract, releasing stored bile into the duodenum to emulsify fats. 2) It stimulates the pancreatic acinar cells to secrete a juice rich in digestive enzymes (lipases, proteases, amylase). It also slows down gastric emptying, allowing more time for digestion in the small intestine.

Explanation:
Photorespiration is a wasteful pathway that occurs when RuBisCO fixes O2 instead of CO2, producing phosphoglycolate. This 2-carbon compound is metabolized through a complex pathway involving three organelles: it is processed in the peroxisome, then the mitochondria, and finally returns to the chloroplast. This process consumes ATP and releases CO2 without producing any sugar.