Domain: Natural Science — Biochemistry & Molecular Biology
Target concept: Aquatic plant (Elodea) releases oxygen bubbles under intense light.

Video generation prompt: Freshly cut Elodea stems were submerged in a transparent container and placed under bright light. A non-transparent card was briefly used to block the light, then removed.

Evaluation guide:
(i) Target concept: Light-dependent oxygenic photosynthesis in submerged vascular plants.
Minimum mechanism: Intact chloroplasts in Elodea mesophyll cells; functional photosystem II; dissolved CO₂ and H₂O available; light energy sufficient to drive photolysis; oxygen insolubility causing bubble nucleation at hydrophobic stem surfaces.
(ii)Storyline: Frame 1–3: Brightly lit container with submerged green Elodea stems, no bubbles. Frame 4–6: Non-transparent card moves into light path and fully occludes illumination → immediate cessation of new bubble formation; existing bubbles may detach but no new nucleation. Frame 7–10: Card fully retracts → light fully restored → new oxygen bubbles begin forming on stem surfaces within ≤1 visual interval and increase in density continuously; all events occur from fixed frontal viewpoint with container centered and Elodea fully in frame.

Manual:
Experimental Procedure
1. Place freshly cut green Elodea stems vertically in clear water inside a transparent container.
2. Illuminate container with bright directional light.
3. Briefly insert a non-transparent card to fully block light from reaching Elodea, then remove it.
Observation of Experimental Phenomena
Oxygen bubbles appear exclusively on Elodea stems only after light is restored; no bubbles form during light block.
Summary of Experimental Principles
Aquatic plant (Elodea) releases oxygen bubbles under intense light via photosynthesis; light deprivation halts O₂ production instantly.

Prompt Grounding rubric:
level_1: No Elodea stems visible; no transparent container present; no bright light source shown; no opaque card present; no light block/unblock action of any kind depicted.
level_2: At least one of Elodea, the transparent container, the bright light, or the opaque card is present, but there is no correct blocking-then-unblocking action (e.g., the card never moves, or the light stays constant throughout with no occlusion event).
level_3: Green Elodea stems sit submerged in a transparent, water-filled container under bright light, and an opaque card is present and moves toward the light path, but the block is never followed by a removal, or removal happens before the block completes, or the card's motion isn't aimed at the light path.
level_4: Green Elodea stems are fully submerged in a transparent, water-filled container lit by a bright directional light; an opaque card approaches the light path, fully blocks the light for a clearly visible stretch of time, then is fully withdrawn, all within one continuous shot.
level_5: All 4-point conditions are met, and additionally the card's motion stays confined to the light beam itself with no unnecessary drifting elsewhere in the frame, the Elodea stays fully submerged and anchored in place the whole time, the container keeps the same upright position, and the light's apparent brightness and color look the same before, during, and after the block (only the card's presence changes, not the light source itself).

Scientific and Causal Correctness rubric:
level_1: No oxygen bubbles ever appear; the Elodea looks dry, wilted, or brown, or is floating loose rather than rooted; the container holds no visible water, or nothing about the scene responds to the light being blocked.
level_2: Bubbles appear but aren't tied to the Elodea stems (e.g., they float free in the water or rise from the container's bottom or sides), or bubbles keep appearing at the same rate whether or not the light is blocked, or the Elodea shows no clear stem structure or green color.
level_3: Bubbles form on the Elodea stems and only after the light is restored, but the timing is sloppy: bubbling resumes only after a noticeable extra delay once the card is withdrawn, or bubbling doesn't fully stop while the card is blocking the light.
level_4: Bubbles appear only on the Elodea stem surfaces (never on the container walls or water surface); they stop forming while the card fully blocks the light and resume promptly once the card is withdrawn, continuing steadily afterward; the stems stay green and firm throughout.
level_5: All 4-point conditions are met, and additionally the rate of new bubbles visibly climbs from occasional to frequent as time passes after the card is withdrawn (reflecting a resuming photosynthetic rate), bubbles originate from multiple points along the stems rather than a single spot, and no bubbles appear anywhere during the entire period the card blocks the light.

Spatiotemporal Consistency rubric:
level_1: Severe violation: the Elodea, container, light source, or card teleports to a different position; the container changes shape or size abruptly; the light source jumps position or disappears; the card appears or disappears without moving; the water level jumps discontinuously.
level_2: Multiple moderate violations: the Elodea drifts sideways by more than half its own length with no current or disturbance to explain it, the card's motion stutters or reverses direction more than once, the light's cast shadow edge flickers erratically, or the container's reflections don't match the background consistently across the shot.
level_3: One minor flaw only: e.g., the Elodea sways slightly with no visible water current to explain it, or the card's slide briefly hesitates without reversing or jumping; nothing breaks structurally and no occlusion looks wrong.
level_4: Nothing teleports or breaks structurally; the card slides smoothly along a single path toward and then away from the light; the container and Elodea keep the same position and orientation throughout; the water's surface stays level and undisturbed.
level_5: All 4-point conditions are met, and additionally the reflections and highlights on the container's glass shift in a way that stays consistent with the one fixed camera angle (nothing floats free of its true reflection), the water surface shows at most a brief, natural ripple right as the card passes near the container and settles right back down, and the Elodea stems stay anchored at their base with no unexplained drifting or floating loose for the entire clip.