Domain: Healthcare — Digestive Physiology
Target concept: Assay of Intestinal Lipase Activity (Lipolysis Method)

Video generation prompt: Prepare test tubes containing lipid substrates and buffer. Add lipase solution to the experimental tubes and inactive enzyme to the control tubes. Place the tubes in a water bath at near body temperature. Gently mix intermittently, then terminate the reaction for comparison.

Evaluation guide:
(i) Target concept: Enzyme-specific catalytic hydrolysis of emulsified lipids under physiological temperature, quantified by turbidity loss.
Minimum mechanism: Lipid substrate must be emulsified (visually milky); active lipase must be present and thermally activated; hydrolysis products must be more soluble → reduced light scattering → measurable clarity increase; inactive enzyme must produce no catalysis → no clarity change.
(ii)Storyline: Frame opens on water bath with two upright test tubes side-by-side, both containing identical milky suspension. First, a dropper adds a reagent to left tube (lipase); second, same dropper adds different reagent to right tube (inactive enzyme): visually distinct delivery. Tubes are then submerged. Intermittent swirling begins: smooth, small-amplitude rotational motion applied equally to both tubes. Over time, left tube content visibly transitions from opaque to translucent while right tube retains uniform opacity. Viewpoint remains static frontal close-up; no camera movement; lighting even and diffuse; all events unfold in fixed spatial context without interruption.

Manual:
Experimental Procedure
1. Place two identical test tubes in water bath at ~37°C.
2. Add lipid substrate + buffer to both tubes.
3. Add lipase solution to experimental tube; add heat-inactivated enzyme to control tube.
4. Gently swirl both tubes intermittently for 10 sec.
5. Observe turbidity difference.
Observation of Experimental Phenomena
Experimental tube gradually becomes clearer; control tube remains uniformly milky/opaque.
Summary of Experimental Principles
Lipase hydrolyzes triglycerides into fatty acids + glycerol, reducing light-scattering particles → decreased turbidity. Inactive enzyme causes no hydrolysis → no turbidity change.

Prompt Grounding rubric:
level_1: The two test tubes, the milky lipid-and-buffer suspension inside them, the lipase and heat-inactivated-enzyme reagents, and the water bath are all absent from the video; none of these core setup elements appear at any point.
level_2: Only a subset of the setup is shown: for example test tubes and a water bath appear but the tubes are empty or hold a clear (non-milky) liquid, or a single tube receives only one of the two reagents (lipase or inactivated enzyme) with no matched second tube shown, or the tubes are never placed into the bath.
level_3: Two test tubes holding an identical milky lipid-and-buffer suspension are shown; lipase solution is added to one tube and heat-inactivated enzyme to the other in two distinguishable additions; both tubes are then placed in a heated water bath and swirled intermittently. The paired tubes, the milky suspension, the two differentiated reagent additions, and the bath are all present, occurring in the order: reagent added, then tubes placed in the bath, then intermittent mixing.
level_4: Everything required at the 3-point level is shown, plus: the two tubes start with matching fill levels and suspension appearance before any reagent is added; the lipase addition and the inactivated-enzyme addition happen as two clearly separate actions rather than both reagents entering a single shared vessel; the intermittent swirling begins only once both tubes are already in the bath, not before; the frame contains no unrelated lab clutter (extra pipettes, racks, or labels) competing with the two tubes for attention.
level_5: Everything required at the 4-point level is shown, plus: the two tubes are kept together in one frame at matching height and orientation so their appearance can be directly compared; the reagent identity for each tube stays unambiguous throughout (e.g., visibly different dropper colors, separate labeled vials, or non-overlapping addition moments), so a viewer can tell which tube received active lipase and which received inactivated enzyme without inferring it from later effects; no hand, tool, or label ever obstructs either tube during reagent addition, bath placement, or mixing.

Scientific and Causal Correctness rubric:
level_1: No turbidity change indicating lipid hydrolysis is visible: both tubes stay uniformly milky throughout, or both clear at the same rate regardless of which reagent (active lipase vs. heat-inactivated enzyme) was added, so the reagent has no visible effect on either tube.
level_2: A turbidity change occurs but breaks the expected cause-and-effect: for instance the inactivated-enzyme tube clears faster than or as fast as the lipase tube, or the lipase tube begins clearing before it is placed in the warm bath, or clearing happens without the tubes ever being warmed.
level_3: After the tubes are warmed and swirled, the lipase tube's suspension becomes progressively less milky and more translucent while the inactivated-enzyme tube stays uniformly milky for the remainder of the clip; the difference, once established, does not reverse or oscillate before the video ends.
level_4: Everything required at the 3-point level holds, and additionally: the lipase tube's clearing is one-directional with no intervals of re-clouding once it starts to clear; the inactivated-enzyme tube shows no partial clearing, settling, or sedimentation anywhere in the tube; neither tube develops a yellow or brown tint that would suggest an unrelated chemical change rather than simple loss of emulsified lipid droplets.
level_5: Everything required at the 4-point level holds, and additionally: the lipase tube's rise in clarity reads as a smooth, continuous trend rather than a sudden jump concentrated in one moment of the clip; the inactivated-enzyme tube's milky appearance (hue, density, and uniformity) matches its own starting appearance from before mixing began; no bubbles, meniscus glare, or condensation on the tube walls obscures the turbidity comparison between the two tubes at any point.

Spatiotemporal Consistency rubric:
level_1: A tube's turbidity, fill level, or position on the rack abruptly changes from one moment to the next with no continuous transition shown, e.g., a cloudy tube suddenly looks clear (or vice versa) with no visible swirling in between, the water bath's liquid level jumps, or a tube's position on the rack changes without anyone moving it; a tube teleports to a different spot on the rack between frames, the room lighting abruptly switches between bright and dark with no visible cause, or a tube or reagent flickers in and out of view.
level_2: Motion is mostly continuous but has clear gaps: one tube visibly swirls while the neighboring tube stays perfectly still with no explanation; the water surface line in the bath shifts in a way that doesn't match how far the tubes have moved; a hand appears to swirl a tube without ever visibly touching it.
level_3: The two tubes keep the same spatial relationship to one another for the whole clip (side by side, neither drifting apart nor overlapping); the bath's liquid surface stays level and steady around the immersed tubes; the swirling motion looks like it's being driven by a wrist or hand rather than the tube floating or spinning on its own.
level_4: Everything required at the 3-point level holds, and additionally: neither tube drifts sideways or up/down while being swirled; no hand or tool crosses in front of a tube and then disappears without leaving the shot; the glass highlight/reflection on each tube shifts smoothly as the tube rotates rather than jumping or vanishing.
level_5: Everything required at the 4-point level holds, and additionally: no motion blur ever hides whether a tube's contents look clear or milky; the camera framing shows no perspective shift suggesting the camera itself moved; the whole sequence plays as one uninterrupted take with no visible cut, fade, or splice from reagent addition through the final turbidity comparison.