Domain: Natural Science — Ecology & Evolutionary Biology
Target concept: The tender shoots of indoor plants bend toward lateral light sources within a few days.

Video generation prompt: Place a potted plant on a table and position a bright light on one side; record the changes in the plant at fixed time intervals for several consecutive days.

Evaluation guide:
(i) Target concept: Phototropic curvature of etiolated or young plant shoots in response to unilateral light exposure.
Minimum mechanism: Intact apical meristem; functional auxin transport system; absence of mechanical obstruction or competing tropisms (e.g., no gravity override, no touch stimulus); light wavelength within photosensitive range (400–500 nm blue peak).
(ii)Storyline: Frame 1–2: Plant upright, stem vertical, leaves symmetrically arranged; light off or ambient-only. Frame 3–4: Light activates on one side; no immediate motion. Frame 5–7: Apical region begins gentle curvature toward light; young leaves reorient incrementally. Frame 8–10: Curvature intensifies visibly; stem arc becomes continuous; light-facing leaf count exceeds shaded-side count; all motion occurs within fixed frontal view with stable lighting geometry.

Manual:
Experimental Procedure
1. Place a potted indoor plant (e.g., coleus or bean seedling) upright on a flat table.
2. Position a bright, focused light source on one side of the plant—left or right—not in front, behind, or above.
3. Record continuously from a fixed frontal viewpoint for 10 seconds.
Observation of Experimental Phenomena
The plant"s tender shoot and young leaves gradually curve toward the lateral light source; stem bends smoothly; more leaves face the lit side than the shaded side.
Summary of Experimental Principles
Phototropism: plant shoots bend toward unilateral light due to auxin redistribution, causing differential cell elongation on shaded vs. lit sides.

Prompt Grounding rubric:
level_1: No potted plant visible; no lateral light source present; no table surface shown; no fixed viewpoint established; none of the three required objects (plant, pot, light) appear together in same scene.
level_2: Exactly one of the three core objects appears (potted plant OR bright light OR table); if present, object is misidentified (e.g., lamp labeled as sun, vase as pot, floor as table); spatial arrangement shows no lateral relationship (light not positioned to one side of plant).
level_3: All three core objects present: potted plant on table surface, bright light source placed adjacent to plant on one side only; viewpoint is fixed and frontal; no teleportation or object insertion/removal mid-sequence; plant remains stationary relative to table and light throughout.
level_4: All conditions for score 3 satisfied AND light source is visibly distinct from ambient illumination (e.g., directional beam, brighter intensity halo, non-diffuse appearance); pot has visible soil and green foliage; table surface is continuous and planar beneath both plant and light base.
level_5: All conditions for score 4 satisfied AND light source is unambiguously positioned on the left or right side of the plant (not front/back/above); plant stem and leaves are fully visible and oriented toward the light side; pot sits stably centered on table with no tilt; no occlusion between plant, pot, light base, and table surface at any frame.

Scientific and Causal Correctness rubric:
level_1: No observable directional response by plant; stem remains vertically straight or bends away from light; new growth or leaf orientation shows no lateral asymmetry; all foliage faces upward or randomly: no consistent bias toward light source.
level_2: Stem shows bending but direction is inconsistent (e.g., first toward light, then away); bending occurs only in uppermost leaf or single petiole without involvement of main stem or multiple leaves; no temporal progression implied (e.g., static bent pose without prior upright reference).
level_3: Stem or primary shoot exhibits clear curvature toward the lateral light source; at least two leaves or leaf pairs show asymmetric orientation: more leaves facing light side than opposite side; curvature is smooth and continuous, not jagged or segmented; no reversal or oscillation in direction.
level_4: All conditions for score 3 satisfied AND curvature originates near the apical meristem (visible tip region) and extends downward along stem; younger leaves (smaller, lighter green) show stronger orientation bias than older leaves; no contradictory motion (e.g., simultaneous bending away at base while tip bends toward).
level_5: All conditions for score 4 satisfied AND curvature increases progressively across visible frames (i.e., more pronounced bend in later frames than earlier ones within the 10s sequence); leaf petioles on light-facing side are visibly shorter and more taut than those on shaded side; no wilting, yellowing, or necrosis: foliage remains uniformly healthy green.

Spatiotemporal Consistency rubric:
level_1: Plant or light abruptly appears/disappears; table surface discontinuously shifts position or vanishes; lighting changes inconsistently (e.g., ambient brightness flickers unrelated to light source activation); shadow of plant or light base jumps discontinuously across frames.
level_2: One major spatiotemporal break: either plant rotates >45° without intermediate frames, or light source moves laterally without smooth translation, or table edge warps/bends unnaturally; camera viewpoint drifts significantly (e.g., zooming, panning, tilting) violating fixed-viewpoint requirement.
level_3: No object teleportation; no structural deformation of plant, pot, table, or light fixture; lighting and shadows remain consistent in direction and softness; camera remains fixed in position and orientation; all objects maintain stable spatial relationships across frames.
level_4: All conditions for score 3 satisfied AND plant motion is smooth and fluid (no stutter, freeze, or frame duplication); shadow of plant consistently falls opposite the light source; no parallax violation (e.g., light base stays aligned with table surface across all frames).
level_5: All conditions for score 4 satisfied AND motion of stem curvature is biomechanically plausible: gradual, continuous, and accelerating slightly toward light side; no unnatural rigidity (e.g., hinge-like joint at base) nor excessive flexibility (e.g., whip-like snap); inter-frame motion vectors align with natural gravitropic-phototropic coupling.