Agar Diffusion Lab Results

AP Bio Lab Short Answer Responses (formatted) 1) what do the agar blocks represent? claim: The agar blocks model cells. Evidence: Dye removed where vinegar diffused from outside in. Explanation: Agar surface cell membrane; diffusion into agar models exchange across membrane. 2) what might the diffused volume represent? claim: Diffused volume = portion reached by the diffusing molecule (e.g., 02). Evidence: Loss of pink color indicates reagent reached region. Explanation: In cells, corresponds to cytoplasm that received molecules during the time. 3) Implications for cells with different % diffused volume: claim: Higher diffused -> faster exchange by diffusion. Evidence: 1x1x1 had 100% diffused; 4x4x4 had ~27%. Explanation: High diffused means diffusion can supply interior; low % requires transport systems or special shapes. 4) Did any other blocks lose all color? Answer: No, only 1xixi lost all color because diffusion from faces met at center. 5) Relationship: distance diffused vs size: claim: Distance diffused is smaller in larger blocks. Evidence: avg d decreases with larger blocks (0.50 0.20 cm). Explanation: Fixed exposure time limits penetration; larger interior remains beyond reach. 6) Relationship: diffused volume vs surface area: claim: diffused correlates with surface-area-to-volume ratio. Evidence: Higher SA:V (1x1x16) -> higher % diffused (100%). Explanation: More surface area per volume allows diffusion to reach larger fraction of interior. 7) Efficient respiring cube: Answer: 1x1x1; SA:V6, % diffused = 100%, so 02 would reach the whole cell quickly. 8) Two adaptations increasing SA:V: Microvilli (intestinal epithelial cells): increase apical membrane to boost nutrient absorption. - Root hairs (plant root epidermal cells): tubular outgrowths increase surface for water/mineral uptake.