Domain: Healthcare — Nutrition and Food Hygiene
Target concept: Cyanogenic Glycosides Detection

Video generation prompt: A test tube containing 10 mL of bitter almond extract containing cyanogenic glycosides was treated with picric acid-sodium carbonate solution and heated in a water bath for 10 minutes.

Evaluation guide:
(i) Target concept: Visual confirmation of cyanogenic glycoside presence via color development in the Guignard (alkaline sodium-picrate) test.
Minimum mechanism: Alkaline hydrolysis of the cyanogenic glycoside (e.g., amygdalin) releases HCN; under alkaline conditions the cyanide ion undergoes nucleophilic addition to the electron-poor picrate ring, converting sodium picrate into the red-orange sodium salt of isopurpuric acid; this requires both reagent addition AND thermal activation to proceed, and does not involve diazotization or azo-dye chemistry (which would require a primary aromatic amine and nitrous acid).
(ii)Storyline: [Frame 0–2] Test tube held upright with pale-yellow bitter almond extract visible; [Frame 3–4] Yellow-orange picric acid-sodium carbonate solution added and mixed → uniform orange-yellow liquid; [Frame 5–6] Tube lowered into active water bath (visible steam/ripples); [Frame 7–9] Liquid gradually transitions from orange-yellow to homogeneous red-orange hue, fully developed by final frame; perspective is fixed frontal close-up, tube centered, full liquid column visible throughout, no occlusion.

Manual:
Experimental Procedure
1. Place 10 mL bitter almond extract into a clean test tube.
2. Add picric acid-sodium carbonate solution to the tube.
3. Mix gently, then immerse tube in boiling water bath.
4. Heat for 10 minutes.
Observation of Experimental Phenomena
The solution changes from pale-yellow to orange-yellow upon mixing, then develops a stable red-orange color after heating.
Summary of Experimental Principles
Cyanogenic glycosides (e.g., amygdalin) in bitter almond extract hydrolyze under alkaline heat to release HCN, which reacts with alkaline sodium picrate via nucleophilic addition to form the red-orange sodium salt of isopurpuric acid (the Guignard/alkaline sodium-picrate test), confirming presence.

Prompt Grounding rubric:
level_1: No test tube is shown; no bitter almond extract is visible; no picric acid-sodium carbonate solution is shown being added; no water bath appears; no heating action occurs; none of these elements (tube, extract, reagent, bath) appear.
level_2: At least one element appears (e.g., a test tube), but not all four are present; or the wrong containers/liquids are used (e.g., a beaker instead of a test tube, or a colorless solvent instead of the yellow-orange picrate reagent); or the tube's liquid volume clearly contradicts 10 mL (e.g., barely a film at the bottom, or completely full to the rim); or no water bath or heating action is shown at all.
level_3: All four elements are present and correctly typed: a cylindrical test tube, a pale-yellow liquid identified as the bitter almond extract, a yellow-orange picric acid-sodium carbonate solution, and a water bath with visibly heated water or steam; the extract and reagent are combined inside the tube; the tube is placed into the active water bath.
level_4: All conditions of the 3-point level hold, and in addition the tube holds only the two combined liquids, with no third liquid, solid debris, or precipitate visible before heating begins; the tube stays upright and still while immersed in the bath; the bath remains visibly active (steam or surface movement) for the whole heating segment; no unrelated tool or hand movement interrupts the sequence.
level_5: All conditions of the 4-point level hold, and in addition the tube is shown entering the bath near the start of the clip and stays fully submerged without being lifted, tilted, or repositioned again; the liquid volume inside the tube looks unchanged throughout (no visible boiling over, bubbling out, or shrinking level); the camera framing stays fixed, with the tube centered and the bath visible in the lower part of the frame the whole time.

Scientific and Causal Correctness rubric:
level_1: No color change happens at all; or the liquid turns an implausible color for this reaction (e.g., bright green, purple, or black); or the color changes before the reagent is added or before heating starts; or the final color looks identical to either the plain extract or the plain reagent alone.
level_2: A color change does happen, but not the expected progression: for instance the liquid jumps straight to a brown or red color without first passing through an orange-yellow mixed stage, or the color changes without any heating shown, or the shift happens instantly rather than developing gradually as the tube warms.
level_3: The color develops in the expected order: the pale-yellow extract and yellow-orange reagent combine into an orange-yellow mixture, which then shifts to a distinct red-orange (brick-red) color once heating is underway; the shift begins only after heating starts and the red-orange color persists to the end of the clip without reverting.
level_4: All conditions of the 3-point level hold, and in addition the red-orange color is even across the whole liquid column, with no streaks, layers, or isolated patches, and is clearly different from both the pre-heating orange-yellow stage and from the reagent's own color; no cloudiness or solid particles accompany the color change.
level_5: All conditions of the 4-point level hold, and in addition the red-orange color starts appearing within roughly the first half of the heating segment shown (not only in the last instant), reaches a fully even, saturated red-orange with no fading or patchiness by the end, and matches the red-orange shade expected of a positive Guignard (alkaline sodium-picrate) reaction rather than a duller brown or washed-out orange.

Spatiotemporal Consistency rubric:
level_1: The test tube jumps between two different positions between shots with no motion carrying it there; the liquid inside disappears and reappears; the water bath's steam or bubbling switches on and off abruptly between frames; a shadow disappears entirely and then reappears with no lighting change to explain it; the tube appears to crack or reform without cause; or the tube suddenly rotates by more than about 45 degrees between frames with no corresponding motion.
level_2: The reagent is shown pouring into the tube while the tube is outside the bath, and then the tube is suddenly inside the bath with no travel shown in between; the liquid's level changes abruptly between two consecutive frames with no pouring or evaporation shown; steam is visible above the water before the water's surface itself is shown; a hand places the tube into the bath but is never shown letting go of it.
level_3: The test tube's position relative to the water bath doesn't change from one frame to the next; the liquid's meniscus stays level and doesn't flicker or jump; nothing about the tube or bath appears to clip through another object or flip in perspective; the tube's placement into the bath and the rise of steam both happen as continuous, gradual motions rather than sudden jumps.
level_4: All conditions of the 3-point level hold, and in addition the events happen in the right order: the reagent is added before the tube goes into the bath, the color starts changing only after the tube is submerged and heating has begun, and the red-orange color is shown developing gradually through the orange-yellow stage rather than snapping directly from pale-yellow to fully red-orange.
level_5: All conditions of the 4-point level hold, and in addition the tube's descent into the bath happens at a steady, unhurried speed with no sudden jerks; the steam rises continuously from the water's surface without flickering on and off; the liquid surface shows only the gentle, natural movement expected from being warmed, with no violent shaking; the whole sequence plays out smoothly with no visible skips or repeated frames.