Domain: Natural Science — Chemistry
Target concept: Fluorescein diacetate hydrolyzed by esterase produces visible fluorescence.

Video generation prompt: Two transparent vials containing fluorescein diacetate in buffer were placed on the lab bench. Esterase was added to the vial on the left, while the vial on the right contained only buffer. Both vials were then illuminated with a handheld ultraviolet lamp.

Evaluation guide:
(i) Target concept: Enzyme-dependent fluorogenic activation via hydrolysis.
Minimum mechanism: Esterase must be present to cleave acetate groups from fluorescein diacetate, yielding fluorescein, which absorbs UV and emits visible yellow-green light; absence of esterase leaves substrate intact and non-fluorescent under UV.
(ii)Storyline: Frame 0–2: Two identical transparent vials, filled with clear buffer solution, placed side-by-side on bench; no fluorescence. Frame 3–4: Esterase solution is dispensed into left vial only; liquid enters and mixes; right vial untouched. Frame 5–10: Handheld UV lamp approaches and illuminates both vials simultaneously; left vial begins emitting sustained yellow-green fluorescence exclusively within its liquid volume; right vial remains visually inert (no glow, no color change, same transparency). Perspective: Fixed frontal view, centered on vial pair; full vials and lamp hand visible; no occlusion; lighting reveals vial content clarity and emission localization.

Manual:
Experimental Procedure
1. Place two identical transparent vials side-by-side on a lab bench.
2. Add fluorescein diacetate in buffer to both vials.
3. Add esterase solution to the left vial only.
4. Illuminate both vials simultaneously with a handheld ultraviolet lamp.
Observation of Experimental Phenomena
The left vial emits visible yellow-green fluorescence; the right vial remains non-fluorescent (no emission).
Summary of Experimental Principles
Fluorescein diacetate is non-fluorescent until hydrolyzed by esterase into fluorescent fluorescein — a reaction requiring enzymatic catalysis and UV excitation to visualize.

Prompt Grounding rubric:
level_1: Neither vial appears; there's no handheld UV lamp; no left/right arrangement is shown; no addition of esterase to either vial is depicted.
level_2: Two vials are shown, but which one is on the left versus right is unclear, or the UV lamp appears without ever illuminating the vials, or the esterase-addition step is skipped, shown twice, or applied to the wrong vial (or to both, or to neither).
level_3: Two transparent vials sit side by side; a handheld UV lamp is held near both of them and switched on; esterase is added only to the left vial while the right vial holds only buffer, matching the setup described.
level_4: In addition to the above, both vials stay in place while the lamp illuminates them, the lamp stays pointed toward both vials rather than angled away, the esterase is added before the lamp is switched on, and no unrelated object (gloves, extra pipettes, etc.) blocks the view of either vial.
level_5: In addition to the above, the left and right vials stay unmistakably distinguishable by their position in frame throughout, the lamp isn't switched on until after the esterase addition is complete, and nothing crops or blocks the view of either vial or its contents at any point.

Scientific and Causal Correctness rubric:
level_1: Neither vial fluoresces under the UV lamp; the two vials look identical throughout; there's no visible difference between the esterase-treated vial and the buffer-only one.
level_2: Fluorescence appears in only one vial, but it's the buffer-only (right) vial; or both vials fluoresce; or fluorescence appears before the esterase is added; or the glow is the wrong color (white or blue instead of yellow-green); or a glow appears and then disappears immediately rather than persisting.
level_3: Only the esterase-treated (left) vial fluoresces once the lamp is on, in a yellow-green color, and only after the esterase has been added; the right vial stays dark under the same lamp.
level_4: In addition to the above, the left vial's glow stays steady for as long as the lamp illuminates it, without flickering or cutting out; the right vial shows no glow, halo, or reflected light that could be mistaken for fluorescence; neither vial shows an off-color tint (no purple, cyan, or red glow).
level_5: In addition to the above, the glow stays confined to the liquid inside the left vial rather than spreading to the vial's outer wall or beyond the liquid, and the right vial otherwise looks like an identical twin of the left one before illumination (same clarity, same liquid level), confirming that both vials started from the same state and differ only because of the esterase.

Spatiotemporal Consistency rubric:
level_1: A vial disappears and reappears between shots; the lamp appears or vanishes abruptly rather than being carried in; the esterase is shown flowing upward into its own dropper; the lighting changes for a reason other than the lamp turning on; a vial's shape changes between frames.
level_2: The lamp switches from off to fully on with no visible transition; a vial shifts position partway through the clip; the esterase droplet's path into the vial looks broken or splits unnaturally; a frame freezes or repeats briefly.
level_3: Both vials stay in the same place and orientation throughout; the lamp moves the way a handheld object would, without floating or snapping into position; the esterase visibly descends into the left vial in one continuous motion; the glow begins only once the lamp is near and steady, but one small hiccup remains, such as a single brief stutter in the lamp's motion.
level_4: In addition to the above, the room lighting changes only when the lamp itself turns on or off, with nothing brightening or dimming on its own, and both vials keep a consistent glassy highlight and liquid-surface curve before, during, and after illumination.
level_5: In addition to the above, the lamp shows the small natural wobble of being held by hand rather than moving in a perfectly straight line, the liquid surface in the left vial settles smoothly after the esterase is added rather than jumping straight to its post-addition look, and the glow inside the left vial's liquid looks evenly bright across its width (no obvious dark patch or hotspot), consistent with steady handheld illumination.