Domain: Natural Science — Microbiology
Target concept: Rhizopus Detection (Malt Extract-Phenol Red Colorimetric Method)

Video generation prompt: Prepare a phenol red malt extract broth in a test tube, inoculate with Rhizopus using a sterile inoculating loop, and cultivate under warm conditions while observing changes in the medium over time. Clearly demonstrate the inoculation process, the cultivation procedure, and the comparison with the uninoculated control.

Evaluation guide:
(i) Target concept: Visual demonstration of differential pH-dependent color change in phenol red broth induced exclusively by Rhizopus inoculation, validated via side-by-side control.
Minimum mechanism: Rhizopus must be present as viable, morphologically authentic saprophytic mold; phenol red must be functional and embedded in malt extract broth; acid production must occur post-inoculation and manifest as irreversible yellow coloration only in the inoculated tube; control tube must remain chemically and visually unchanged.
(ii)Storyline: Frame 1–2: Static wide shot showing two upright, identical test tubes filled with amber/orange broth, side-by-side in same plane. Frame 3–4: Sterile inoculating loop (shiny, thin metal) approaches and contacts white, fuzzy Rhizopus colony. Frame 5–6: Loop moves continuously into first tube, submerging tip; no contact with second tube. Frame 7–10: Final frames show clear dichotomy — first tube broth is uniformly yellow, second tube broth remains amber/orange; both tubes fully visible, stationary, under consistent lighting; no motion or artifact obscures color distinction. Perspective: fixed frontal viewpoint, centered on tube pair, no zoom or pan.

Manual:
Experimental Procedure
1. Place two identical test tubes containing phenol red malt extract broth side-by-side.
2. Sterilize inoculating loop, cool, then touch Rhizopus colony (white, fuzzy mycelium).
3. Streak loop into first tube; leave second tube untouched as control.
4. Observe: inoculated tube turns yellow; control remains amber/orange.
Observation of Experimental Phenomena
- Inoculated tube: broth changes from amber/orange to uniform yellow.
- Control tube: broth remains amber/orange with no color shift or cloudiness.
- Rhizopus appears as dry, cottony, white aerial mycelium on source.
Summary of Experimental Principles
Rhizopus metabolizes maltose → produces organic acids → lowers pH → phenol red indicator shifts from orange (neutral) to yellow (acidic). Control lacks inoculum, so no acid production occurs.

Prompt Grounding rubric:
level_1: No test tube is visible; no phenol red malt extract broth is present; no sterile inoculating loop is shown; no Rhizopus colony source is visible; only one tube (not a paired inoculated/control pair) appears; none of preparing the broth, inoculating a tube, and comparing it with a control is depicted.
level_2: At least one test tube is present, but its broth is missing or an implausible color (not amber/orange); the inoculating loop is shown but never touches the Rhizopus colony or a tube; only the inoculated tube or only the control tube appears, not the pair together; the loop is held or moved but with no visible connection to the colony or a tube.
level_3: Two test tubes with amber/orange broth appear together in the same shot; a sterile inoculating loop contacts a fuzzy, white, cottony Rhizopus colony and is then inserted into one tube while the other tube is left untouched; the broth setup, the inoculation gesture, and the paired comparison are each shown at least once, in a sensible order.
level_4: Everything in score 3 holds, and additionally: the loop looks clean and residue-free before it touches the colony; the Rhizopus source is recognizably a fuzzy, cottony mold rather than a smooth, glossy, or liquid-like growth; the two tubes are positioned so a viewer can tell which one received the loop and which is the control; nothing blocks the view of the loop, tubes, or colony during these key actions.
level_5: Everything in score 4 holds, and additionally: the loop touches the Rhizopus colony before it ever enters the inoculated tube, and it never touches the control tube; both tubes stay in place and fully visible for the whole clip; the two tubes sit at matching height, angle, and lighting so the only visible difference between them is what happens to the broth; at no point is it unclear which object is the loop, which is the colony, or which tube was inoculated.

Scientific and Causal Correctness rubric:
level_1: Neither tube's broth changes color, or both tubes end up the same color; a color change is shown happening before the loop ever reaches that tube; there is no visible timing link between the loop entering a tube and any subsequent color shift.
level_2: One tube's broth changes color, but to a hue inconsistent with an acid-driven phenol red shift (e.g., blue, purple, or dark brown instead of yellow); the untouched control tube also changes color; or the broth turns cloudy or forms a precipitate without any color shift, offered as if that were the expected result.
level_3: The tube that received the loop turns yellow while the untouched tube stays amber/orange; the yellow appears only in frames after the loop has entered that tube, never before; the color difference between the two tubes is clear and holds through the final frames.
level_4: Everything in score 3 holds, and additionally: the yellow in the inoculated tube is an even, clean yellow (no green tinge, no browning, no patchy mix of yellow and orange); the control tube shows no haze, sediment, or partial shift toward yellow; nothing implausible for a broth culture occurs (no boiling, bubbling, or an instantaneous single-frame color flip).
level_5: Everything in score 4 holds, and additionally: the yellow spreads through the inoculated broth as a visible, gradual change (e.g., starting near where the loop entered and spreading through the tube) rather than snapping instantly from orange to yellow in one frame; the control tube never shows even a partial shift toward yellow at any point; every frame after inoculation stays consistent with acid production occurring only in the tube that was touched by the loop.

Spatiotemporal Consistency rubric:
level_1: A tube or the loop vanishes from one frame and turns up elsewhere in a later frame; the broth surface changes shape or level with no visible cause; the shot cuts to a clearly different camera angle or framing mid-action; the loop or a tube visibly deforms or breaks with no cause; an abrupt lighting shift occurs (e.g., the scene suddenly goes from bright to dark, or the reverse, with no visible cause).
level_2: The two tubes drift apart or shift relative to each other with nothing touching them; the loop's motion stutters or reverses direction more than once on its way from the colony to the tube; the broth surface shows a ripple or wave that matches no visible motion; the room's brightness flickers noticeably more than once for no reason; the inoculating loop rotates more than about 90° with no visible hand motion causing it.
level_3: Both tubes stay in the same position and orientation throughout; the loop moves in one continuous path from the colony to the inoculated tube without disappearing partway; the broth surface stays still or only settles gently after the loop enters, matching the insertion motion; the scene's overall brightness and the direction the shadows fall stay about the same from one frame to the next; nothing stretches, bends, or passes through another object.
level_4: Everything in score 3 holds, and additionally: the loop keeps a consistent thickness and metallic sheen throughout its motion; when the loop passes in front of a tube it consistently blocks the same part of that tube rather than jumping; the loop finishes contacting the colony before it starts moving toward the tube, never the reverse; any condensation on a tube builds up gradually rather than appearing all at once.
level_5: Everything in score 4 holds, and additionally: the loop's path from colony to tube is smooth, with no backtracking, pausing, or overshoot at the end; the loop looks appropriately smaller when farther from the camera and larger when closer, with no sudden change in apparent size; any motion blur matches how fast the loop is moving; the rims of the tubes, any labels, and the liquid line stay aligned from frame to frame; the two tubes keep their side-by-side, same-plane arrangement in every frame.