Domain: Healthcare — Pathophysiology
Target concept: Hypotonic Dehydration and Cellular Morphological Changes

Video generation prompt: Place red blood cells in a hypotonic saline solution and dynamically observe their morphological changes under an optical microscope for 30 seconds.

Evaluation guide:
(i) Target concept: Osmotic lysis of erythrocytes in hypotonic extracellular fluid.
Minimum mechanism: Water must move into cells down its concentration gradient across an intact but permeable plasma membrane; membrane tensile limit must be exceeded to cause rupture; hemoglobin must be intracellularly contained pre-lysis and freely dispersible post-lysis.
(ii)Storyline: Frame 1–2: Intact biconcave red blood cells resting in saline drop. Frame 3–6: Cells lose concavity, edges round, diameter increases, maintaining red color and membrane continuity. Frame 7–9: Cells become perfect spheres under tension; surface smoothens slightly. Frame 10: One or more cells rupture: sudden loss of defined boundary, red content diffuses outward into saline; no rebound or resealing. Perspective: Fixed microscope field-of-view, top-down, shallow depth of field; all events occur within same focal plane; no off-screen actions affect outcome.

Manual:
Experimental Procedure
1. Place a drop of 0.3% saline solution on a clean microscope slide.
2. Add a small volume of diluted red blood cell suspension into the saline drop.
3. Cover with coverslip and observe under 40x objective for 30 seconds.
Observation of Experimental Phenomena
Red blood cells initially appear biconcave discs, then progressively swell into spheres, and finally undergo lysis (rupture) with release of hemoglobin into surrounding solution.
Summary of Experimental Principles
In hypotonic saline, water enters red blood cells via osmosis due to lower extracellular solute concentration, causing swelling and eventual membrane rupture — characteristic of hypotonic dehydration-induced cellular injury.

Prompt Grounding rubric:
level_1: No red blood cells, no saline droplet/slide, and no microscope field-of-view are shown; the scene depicts something unrelated to preparing or viewing a blood-in-saline wet mount, and there is no indication cells were ever introduced into a hypotonic solution.
level_2: Only one of the three required setup elements is present: e.g., red blood cells appear without any saline droplet or slide, or a slide/coverslip appears without recognizable cells, or a circular microscope-style field-of-view appears without any visible cell-in-saline content; if both cells and liquid appear, they are not shown in contact (cells sit on a dry part of the slide or float outside the droplet).
level_3: Red blood cells, a saline droplet on a slide (with or without coverslip), and a circular microscope field-of-view are all present; the cells are shown being added into, or already resting within, the saline droplet, establishing that contact between cells and the hypotonic solution occurs before any morphological change begins.
level_4: Everything in score 3 holds, and additionally the red blood cells are clearly submerged within the saline droplet rather than merely touching its edge or floating above it; the microscope's field-of-view is centered on the region of the droplet containing the cells; any pipette or dropper used to add the cell suspension has finished dispensing and does not obscure the cells once swelling begins.
level_5: Everything in score 4 holds, and additionally the microscope frame shows only the saline-and-cell region for the whole clip: no dry slide area, droplet edge, or unrelated structures crowd the view; the moment the cells enter the saline is fully visible on-screen (not cut away or implied), ending with every visible cell fully immersed; the focal plane, magnification, and framing of the droplet stay constant from that moment through the start of observation.

Scientific and Causal Correctness rubric:
level_1: No morphological transition is shown: red blood cells stay rigid biconcave discs throughout, or they shrink/crenate (a hypertonic-type response instead of hypotonic swelling), or they burst immediately without ever passing through a swollen spherical stage, or the intracellular red hemoglobin coloring disappears or shifts hue in a way inconsistent with hemoglobin staying inside the cell until rupture.
level_2: Cells sit in the saline droplet but show no visible shape change over the clip, or only a single end-state is shown (e.g., cells appear already spherical or already lysed from the first frame with no discoid stage beforehand), or the shape change moves in the wrong direction for a hypotonic environment (cells become smaller, crenated/spiky, or otherwise shrunken instead of swelling).
level_3: Cells begin as biconcave discs and are shown progressively losing their central dimple and rounding outward into spheres; the swelling is continuous and one-directional: no cell reverses toward a discoid shape or oscillates in size; cells remain uniformly red (hemoglobin still contained) throughout this stage, with no rupture yet shown.
level_4: Everything in score 3 holds, and additionally, once cells reach a fully spherical shape, at least one cell's membrane visibly ruptures (its outline disappears abruptly and red hemoglobin-colored content spreads into the surrounding saline), and this rupture occurs only after the spherical stage is reached, never while a cell is still partially discoid or mid-swelling.
level_5: Everything in score 4 holds, and additionally every red blood cell visible in the field follows the same discoid-to-sphere-to-rupture sequence; hemoglobin released from ruptured cells diffuses outward and blends into the surrounding saline rather than clumping into discrete blobs or settling as a separate layer; by the end of the clip no originally-tracked cell remains an intact discoid or sphere while others have already lysed.

Spatiotemporal Consistency rubric:
level_1: Severe spatiotemporal breaks: red blood cells jump to new positions between frames with no visible path connecting them, the microscope field abruptly cuts to a different magnification or angle, cells or the saline droplet vanish or appear from nothing, or the illumination flips between clearly different brightness or color casts from one frame to the next.
level_2: Noticeable but less severe breaks: a cell's position shifts slightly without a continuous swelling motion linking the frames, the focal plane snaps from sharp to blurred and back within one or two frames, a cell's apparent size or rotation changes in a way unconnected to swelling, or the droplet's illumination brightens or dims inconsistent with a single steady light source.
level_3: Red blood cells and the saline droplet keep the same relative positions and orientation to each other and to the frame edges; the swelling motion reads as smooth and gradual rather than jumpy; every cell visible at the start remains visible and traceable across the clip (none pops in or out of existence outside the rupture event itself); the focal plane and magnification stay locked on the same cells throughout.
level_4: Everything in score 3 holds, and additionally the swelling motion has no stutters, freeze-frames, or sudden jump-cuts; the saline droplet's edge and meniscus stay in place aside from the cells' own swelling; the swelling pace looks uniform rather than suddenly speeding up or slowing down partway through; cell outlines line up consistently from one frame to the next with no visible misalignment.
level_5: Everything in score 4 holds, and additionally every cell boundary stays a single closed, non-self-crossing outline while swelling; the droplet's edge curves smoothly and consistently; the rupture event is the only moment a cell's boundary disappears, it happens once per cell, and no ruptured cell's boundary reappears afterward; no two consecutive frames are identical duplicates, and no cell's motion contradicts the motion of the other cells in the same droplet.