Consider statements about human digestion: 1. Saliva contains the enzyme ptyalin. 2. The stomach secretes hydrochloric acid. 3. Bile is produced by the gall bladder. Which are correct? MCQ with Answer and Explanation

Explanation:
Anthocyanins are water-soluble vacuolar pigments that appear red, purple, or blue depending on pH. They are flavonoids. Chlorophyll is green, carotenoids yellow/orange, lycopene red.

Explanation:
Restriction endonucleases are molecular scissors that recognize and cut DNA at specific, highly specific palindromic nucleotide sequences, creating fragments with sticky or blunt ends. DNA ligase is an enzyme that catalyzes the formation of phosphodiester bonds between adjacent DNA fragments, effectively joining or 'pasting' them together, crucial in recombinant DNA technology. PCR (Polymerase Chain Reaction) is used to exponentially amplify specific DNA segments, not to sequence them; DNA sequencing is a separate technique. Thus, statements 1 and 2 are correct.

Explanation:
Electron microscopes use beams of electrons to achieve much higher resolution than light microscopes, enabling visualization of organelles and macromolecular complexes. Types include TEM (internal) and SEM (surface). Light microscopes use visible light, spectrophotometry measures absorbance, chromatography separates.