Domain: Natural Science — Biochemistry & Molecular Biology
Target concept: Red Blood Cell Agglutination Mediated by Surface Glycoprotein Antigens

Video generation prompt: On a glass slide, two drops of human red blood cell suspension were placed. Anti-blood group serum was added to the left side, and physiological saline to the right side. The slide was gently agitated under the microscope camera.

Evaluation guide:
(i) Target concept: Antigen-antibody mediated RBC agglutination is a binary, bivalent, surface-restricted phenomenon requiring specific molecular complementarity and multivalent cross-linking.
Minimum mechanism: Agglutination requires (a) intact RBC membrane glycoproteins bearing A/B antigens, (b) functional IgM-class anti-A/B antibodies in serum, (c) absence of competing inhibitors (e.g., soluble antigens), and (d) isotonic environment; saline alone cannot induce lattice formation.
(ii)Storyline: Frame 1–2: Static glass slide with two identical RBC suspension drops. Frame 3–4: Serum added to left drop (visible liquid contact), saline added to right drop (visible liquid contact). Frame 5–8: Sustained gentle agitation applied to both drops *in parallel*, inducing immediate differential response: left drop develops coarse, static aggregates; right drop retains fluid homogeneity. Frame 9–10: Agitation ceases; aggregates in left drop remain fixed and non-dispersing; right drop shows no residual structure. Perspective: Fixed overhead microscope view; full slide in frame; no occlusion; all events occur within same continuous shot.

Manual:
Experimental Procedure
1. Place two separate drops of human red blood cell suspension side-by-side on a clean glass slide.
2. Add anti-blood group serum to the left drop; add physiological saline to the right drop.
3. Gently agitate both drops simultaneously under fixed microscope camera view.
Observation of Experimental Phenomena
Left drop (anti-serum) shows irreversible clumping into irregular aggregates; right drop (saline) remains uniformly dispersed with no clumping.
Summary of Experimental Principles
Red blood cell agglutination is mediated by specific binding of surface glycoprotein antigens (e.g., A/B antigens) to corresponding IgM antibodies in anti-blood group serum — a calcium-independent, lattice-forming reaction absent in saline controls.

Prompt Grounding rubric:
level_1: No glass slide is shown; no drop of red blood cell suspension is visible; neither anti-blood-group serum nor saline is added; the two drops never appear side by side; no agitation motion occurs; the shot is not framed as a microscope view.
level_2: A glass slide is visible but holds only one drop instead of two; anti-serum or saline (or both) is never added to a drop; the two drops are stacked, overlapping, or shown in separate shots instead of side by side; no agitation motion is visible.
level_3: The glass slide holds two separate drops side by side; one drop visibly receives anti-blood-group serum and the other visibly receives physiological saline; a gentle agitation motion (fluid surface moving or mixing at the interface) is visible; the fixed microscope-style framing keeps both drops in view.
level_4: Everything score 3 requires still holds, and on top of that, the left drop is clearly the one that received the anti-serum and the right drop is clearly the one that received the saline (the order of addition is visible on-screen), and no scene cut or object duplication separates the addition step from the agitation step.
level_5: Everything score 4 requires still holds, and on top of that, the left/right arrangement of the two drops never changes throughout the video, both drops stay fully inside the frame during agitation with no drift, zoom, or repositioning of the camera, and no extra objects (fingers, a pipette left in frame, or labels) enter the shot once agitation begins.

Scientific and Causal Correctness rubric:
level_1: Neither drop shows any clumping: both drops look like uniformly dispersed red blood cell suspension throughout, with no visible difference between the anti-serum (left) and saline (right) drop at any point.
level_2: Clumping shows up in only one drop, but it is the saline (right) drop rather than the anti-serum (left) drop; or both drops clump at the same time; or both drops develop the same uniform clumping with no contrast between them.
level_3: Only the anti-serum (left) drop develops visible clumped, grainy aggregates that stand out from the smooth background suspension, while the saline (right) drop stays fluid and evenly dispersed; this contrast is still visible after the agitation stops.
level_4: Everything score 3 requires still holds, and on top of that, the clumps in the left drop do not break apart or re-disperse when agitation continues or pauses, the right drop never shows even a brief moment of clustering or settling during agitation, and the clumps in the left drop are visibly coarser and larger than the fine grain of a normal, unclumped suspension.
level_5: Everything score 4 requires still holds, and on top of that, the clumping in the left drop shows both dense central clusters and looser aggregates around them (not just one uniform blob), the right drop stays visually smooth with no settling band or clustering forming at any point in the video, and neither drop shows a false clump caused by a stray bubble or piece of debris.

Spatiotemporal Consistency rubric:
level_1: The slide vanishes and reappears between frames; either drop jumps to a different position without visibly moving there; the scene brightness swings by more than 50% within one or two frames; the agitation motion starts or stops instantly with no ramp-up or slow-down.
level_2: The slide shifts sideways by more than 10% of the frame width between key moments; the left and right drops swap or drift out of their original positions; the agitation motion reverses direction abruptly several times in a jerky way; the lighting flickers on and off; the image blurs and sharpens abruptly as if the focus jumped.
level_3: The slide drifts less than 5% of the frame width and in one consistent direction; the agitation motion is continuous with at most one brief pause; the ambient lighting changes gradually rather than suddenly; the focus stays acceptably sharp throughout; no drop or object disappears or duplicates.
level_4: Everything score 3 requires still holds, and on top of that, the moving liquid edges stay visibly defined rather than smearing into an unnatural blur for the agitation speed shown, the boundary of each drop stays in about the same place from one frame to the next with no visible jump or misalignment, and the agitation is never shown happening before the serum or saline is added.
level_5: Everything score 4 requires still holds, and on top of that, the slide itself never appears to bend, warp, or tilt in perspective across frames, the edges of each drop look stable and free of visible shimmer or crawl as the liquid moves, the agitation follows one smooth back-and-forth or circular motion without stalling or sudden speed changes, and no new bright glare or spreading shadow appears on the slide partway through.