Domain: Natural Science — Biochemistry & Molecular Biology
Target concept: Cytochrome c solution changes color depending on its redox state (oxidized or reduced).

Video generation prompt: A transparent cuvette containing purified cytochrome c was filmed: a mild reducing agent was first added using a pipette, then an oxidizing agent was added with a second pipette after mixing.

Evaluation guide:
(i) Target concept: Redox-dependent visible color transition in purified cytochrome c solution mediated by sequential chemical addition.
Minimum mechanism: Cytochrome c must be in aqueous solution inside optically transparent container; reducing agent must donate electrons to convert Fe³⁺ → Fe²⁺; oxidizing agent must accept electrons to convert Fe²⁺ → Fe³⁺; both reactions must occur in solution phase with no precipitation or denaturation.
(ii)Storyline: Frame opens on static transparent cuvette containing orange-brown solution → first pipette enters frame, approaches and dispenses reducing agent into solution → solution color transitions uniformly to cherry-red and stabilizes → first pipette withdraws completely → second pipette enters frame, approaches and dispenses oxidizing agent → solution color transitions uniformly back to orange-brown → both pipettes exit frame; entire sequence viewed from fixed frontal angle with cuvette centered and fully visible; no occlusion of solution column at any point.

Manual:
Experimental Procedure
1. Place purified cytochrome c solution in transparent cuvette.
2. Add mild reducing agent via pipette; observe color change.
3. Add oxidizing agent via second pipette; observe second color change.
Observation of Experimental Phenomena
Solution changes from orange-brown (oxidized) to cherry-red (reduced) after first addition, then back to orange-brown after second addition.
Summary of Experimental Principles
Cytochrome c is a heme-containing protein whose iron center cycles between Fe³⁺ (oxidized, orange-brown) and Fe²⁺ (reduced, cherry-red); redox state dictates absorption spectrum and thus visible color.

Prompt Grounding rubric:
level_1: No transparent cuvette is shown; no pipette appears; no reagent addition is visible; no cytochrome c solution is present; there is no sequence of two distinct additions.
level_2: A transparent cuvette with liquid appears, but no pipettes are shown; or only one pipette appears and performs a single addition; or a pipette is shown without ever touching the cuvette; or the cytochrome c solution itself is missing (e.g., an empty cuvette, or the wrong container).
level_3: A transparent cuvette holding a visibly colored aqueous solution is shown; two pipettes appear one after the other — the first touches the cuvette and dispenses liquid, then the second does the same; the two pipettes look visibly distinct from each other and from the cuvette; no third reagent or extra tool is introduced.
level_4: Everything from the 3-point description holds, and in addition: both pipettes are handled consistently (same hand or grip style); the cuvette stays in place the whole time; the two additions happen in clearly separate moments rather than overlapping; no clutter (gloves, labels, stands) blocks the view of the cuvette.
level_5: Everything from the 4-point description holds, and in addition: the first pipette is fully pulled away before the second one enters the frame or starts moving; the cuvette sits centered in the foreground with an unobstructed side view of the full liquid column; both pipette tips are visibly inserted into the cuvette's open top while dispensing; no extraneous tools or props appear anywhere in the sequence.

Scientific and Causal Correctness rubric:
level_1: The cytochrome c solution stays a single color for the entire clip with no shift after either addition; or the sequence of colors contradicts redox chemistry (e.g., the solution turns green then purple with no red stage, or stays blue the whole time).
level_2: Only one of the two expected transitions happens, and even that one is chemically wrong (e.g., the solution turns red after the oxidizing agent instead of the reducing one, or stays colorless after the reducing agent is added); or a color shift happens with no matching pipette action nearby.
level_3: Two transitions happen in order: shortly after the first pipette's addition, the solution shifts to a reduced-state hue and holds there until the second addition; shortly after the second addition, it shifts to an oxidized-state hue; both hues look like a clear liquid solution's color, not opaque, metallic, or glowing; the starting and ending colors are visibly different from each other.
level_4: Everything from the 3-point description holds, and in addition: the first hue is distinctly cherry-red or reddish-brown (reduced cytochrome c) and the second is distinctly orange-brown or rust-colored (oxidized cytochrome c); no gray, purple, or green tone appears between the two stable states; the color stays within the liquid itself, without bleeding into the cuvette walls or the background.
level_5: Everything from the 4-point description holds, and in addition: the first color change finishes completely before the second pipette ever touches the cuvette; the second color change only begins once the second pipette's tip is in the solution and visibly dispensing; both hues stay even across the whole visible liquid column during their stable phases; nothing dulls, fades, or brightens apart from the expected hue shift.

Spatiotemporal Consistency rubric:
level_1: The cuvette blinks out of the shot and returns without any visible camera cut; the pipette snaps from one spot to another with no travel path shown; the liquid level jumps up or down with no addition actually happening; the frame's overall brightness or color balance jumps sharply between one instant and the next; or the cuvette suddenly looks rotated or flipped compared to how it started.
level_2: The cuvette shifts sideways or up/down by more than its own width between the two additions; the pipette's motion stutters, jumps, or moves with unnatural bursts of speed; the liquid surface splashes or churns more than gentle pipette dispensing would cause; a shadow or reflection on the cuvette appears or disappears suddenly with no clear cause.
level_3: The cuvette holds the same position and tilt for the entire clip; each pipette travels along a smooth, physically believable path toward and away from the cuvette; the liquid surface shows only a small meniscus disturbance while a pipette is actually dispensing; nothing flickers, vanishes, or bends unnaturally; the whole sequence plays out in a single, uncut shot from one fixed camera position, with no cut, zoom, or pan breaking it up.
level_4: Everything from the 3-point description holds, and in addition: each pipette visibly slows down right before contact and speeds up again as it withdraws; the meniscus disturbance is brief and symmetric and settles fully before the next action begins; the apparent distance between a pipette tip and the cuvette never jumps unexpectedly; the background stays fixed and unchanging; no blur or ghosting hides the edges of the pipette or cuvette.
level_5: Everything from the 4-point description holds, and in addition: the spatial relationship between each pipette tip and the cuvette's opening stays consistent from frame to frame, with no sudden perspective jump; the size of the meniscus disturbance matches the timing of the pipette entering or leaving the liquid; all motion moves in one direction without doubling back; nothing about the motion looks like a stutter, freeze, or repeated moment breaking the sense of continuous movement.