Domain: Natural Science — Cell & Developmental Biology
Target concept: Phagocytosis of colored beads by macrophage-like cells

Video generation prompt: Macrophage-like cells in a dish were observed under a microscope over time after red and green plastic beads were added to the surrounding liquid.

Evaluation guide:
(i) Target concept: Phagocytosis as an active, stepwise cellular uptake mechanism requiring physical particle recognition, membrane deformation, and vacuole sealing.
Minimum mechanism: Particles must be inert, non-digestible solids; cells must be motile, polarizable, and capable of actin-driven membrane protrusion; internalization requires complete topological enclosure, not adhesion or partial wrapping.
(ii)Storyline: Frame 1–2: Static baseline, cells and beads coexist in dish with liquid medium, no contact. Frame 3–4: Initiation, pseudopods extend from cell periphery toward nearby red/green beads. Frame 5–6: Contact, bead touches cell membrane with visible indentation. Frame 7–8: Engulfment, membrane progressively flows over bead surface, maintaining continuous contour. Frame 9–10: Completion, bead fully enclosed, surrounded by intact membrane, residing in cytoplasm; both red and green variants must appear in at least one valid internalization event. Perspective: Fixed microscopic viewpoint; all events occur within single focal plane; no zoom, pan, or focus shift; beads and cells remain fully visible and unoccluded throughout.

Manual:
Experimental Procedure
1. Place macrophage-like cells in a petri dish with clear liquid medium.
2. Add red and green plastic beads evenly into the liquid surrounding the cells.
3. Observe under microscope over time as cells extend pseudopods and engulf beads.
Observation of Experimental Phenomena
- Red and green plastic beads are initially free-floating in liquid.
- Macrophage-like cells extend dynamic pseudopods toward beads.
- Beads make direct contact with cell membrane.
- Membrane flows around beads and fully encloses them.
- Internalized beads reside inside cells, retaining original color and solid appearance.
Summary of Experimental Principles
Phagocytosis is a receptor-mediated, actin-dependent process where macrophage-like cells recognize, bind, and internalize solid particles (e.g., plastic beads) via pseudopod extension and vesicle formation.

Prompt Grounding rubric:
level_1: No macrophage-like cells are visible; no red or green plastic beads are present; no dish or liquid medium is shown; nothing resembling bead engulfment is depicted.
level_2: Macrophage-like cells are present but stay static; either red beads or green beads appear, but not both; the beads float freely with no contact with any cell; no bead ever appears inside a cell.
level_3: Both red and green plastic beads are present in the same view; macrophage-like cells are present and at least one bead of either color touches a cell's membrane; no bead is yet visibly inside a cell; the dish and surrounding liquid medium are clearly identifiable.
level_4: Every requirement for a 3-level score holds, and additionally: at least one red bead and at least one green bead are each in direct contact with a macrophage-like cell, whether the same cell or different cells; at least one bead of either color becomes fully enclosed inside a cell, visible as intracellular; the dish and liquid medium stay visible throughout.
level_5: Every requirement for a 4-level score holds, and additionally: red and green beads appear with equal visual prominence; for at least one macrophage-like cell, a red bead and a green bead are visible at the same time, one fully internalized and the other still touching the membrane from outside; the camera framing, spatial arrangement of dish and cells, and the progression from contact to internalization all stay coherent throughout.

Scientific and Causal Correctness rubric:
level_1: The beads look metallic, gelatinous, or organic rather than plastic; the macrophage-like cells show no phagocytic behavior (no pseudopod extension, membrane stays rigid and spherical); engulfment is replaced by the bead fusing into, dissolving into, or being absorbed by the cell rather than being physically enclosed; bead colors are wrong, e.g., a red bead appears blue or a green bead appears yellow.
level_2: Bead colors are correct but their material looks biological (e.g., resembling bacteria or a vesicle) rather than plastic; the macrophage-like cells extend pseudopods but never actually contact a bead; a bead that ends up inside a cell still shows part of its outline poking through the cell edge or overlapping it unnaturally.
level_3: Red and green plastic beads are visually distinct with correct colors; macrophage-like cells extend pseudopods that contact the beads; at least one bead of either color becomes fully enclosed within a cell's membrane, with a clear membrane outline visible around it; nothing violates the mechanics of engulfment (no bead splitting apart, no bead vanishing on its own).
level_4: Every requirement for a 3-level score holds, and additionally: both a red bead and a green bead are each fully enclosed inside a cell, whether the same cell or different cells, in at least one frame; no bead changes color, shape, or transparency during contact or engulfment; no internalized bead keeps a visible outer contour or halo that would be inconsistent with sitting inside the cytoplasm.
level_5: Every requirement for a 4-level score holds, and additionally: internalized red and green beads keep their original solid color with no blurring, fading, or bleeding into the cytoplasm; the membrane forms a smooth, continuous, single outline around each internalized bead with no gaps or double edges; the sequence follows one unbroken causal chain, contact then membrane extension then enclosure then full internalization, with no stage skipped or reversed.

Spatiotemporal Consistency rubric:
level_1: Objects teleport between frames, e.g., a bead disappears and then reappears already inside a cell with no visible contact step in between; a macrophage-like cell's position or orientation changes abruptly with no motion shown; the dish or liquid background flickers, shifts, or vanishes; the lighting changes discontinuously, e.g., bright, then dark, then bright again in consecutive frames.
level_2: Beads or cells move in a jerky, non-fluid way; a cell's membrane extends or retracts with visible skipping or stutter; the liquid surface or dish edges warp or distort across frames; spatial relationships shift inconsistently, e.g., a bead appears on the opposite side of a cell with no visible path crossing between.
level_3: Macrophage-like cells stay in fixed relative positions within the dish; beads move continuously, never jumping, as they approach a cell; contact happens through a smooth approach; internalization proceeds as a gradual flow of membrane over the bead surface; nothing crosses outside the dish or liquid area; the implied light source and any shadow on the beads or membrane stay constant in direction and brightness.
level_4: Every requirement for a 3-level score holds, and additionally: pseudopod motion is continuous and looks anatomically plausible, with no rigid rotation or straight-line translation of the whole membrane; a bead stays fully visible throughout internalization until it is completely enclosed; the bead is never partially hidden behind an unrealistic patch of opacity or blur.
level_5: Every requirement for a 4-level score holds, and additionally: motion between frames is smooth throughout, with no sudden speed spikes or pauses; the same cell-bead pairings stay in place with no unexplained rearrangement; there is no perspective drift or parallax shift; the time spent on contact and on internalization stays plausibly proportioned to each other; no ghosting, smearing, or motion blur degrades the visible edges of beads or cells.