<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="1:1">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, sans-serif;
      background: #f8fafc;
      color: #1e2945;
      padding: 12px;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }

    /* Tabs */
    .tabs {
      display: flex;
      gap: 6px;
      justify-content: center;
    }
    .tab-btn {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 6px;
      padding: 5px 10px;
      font-size: 13px;
      font-weight: 600;
      color: #475569;
      cursor: pointer;
      box-shadow: 0 1px 2px rgba(0,0,0,0.05);
    }
    .tab-btn.active {
      background: #0284c7;
      color: #ffffff;
      border-color: #0284c7;
    }

    /* Graph Section */
    .graph-card {
      background: #ffffff;
      border-radius: 8px;
      border: 1px solid #e2e8f0;
      padding: 8px 8px 4px 8px;
    }
    svg {
      width: 100%;
      height: auto;
      display: block;
    }

    /* Enzyme Cards */
    .enzyme-row {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 8px;
    }
    .enzyme-card {
      background: #ffffff;
      border: 2px solid #e2e8f0;
      border-radius: 8px;
      padding: 8px;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      transition: border-color 0.2s, box-shadow 0.2s;
    }
    .enzyme-card.highlight {
      border-color: #0284c7;
      box-shadow: 0 0 0 1px #0284c7;
    }
    .enzyme-card.denatured-highlight {
      border-color: #ea580c;
      box-shadow: 0 0 0 1px #ea580c;
    }
    .card-title {
      font-size: 13px;
      font-weight: 700;
      margin-bottom: 4px;
      display: flex;
      align-items: center;
      gap: 4px;
    }
    .enzyme-svg {
      width: 100%;
      max-width: 150px;
      height: 90px;
    }
    .status-tag {
      font-size: 12px;
      font-weight: 600;
      margin-top: 4px;
      padding: 2px 8px;
      border-radius: 4px;
    }
    .tag-fit { background: #dcfce7; color: #166534; }
    .tag-nofit { background: #fee2e2; color: #991b1b; }
  </style>
</head>
<body>

  
  <div class="tabs">
    <button class="tab-btn" onclick="setStage('low')">10°C (Slow)</button>
    <button class="tab-btn active" onclick="setStage('opt')">30°C (Optimum)</button>
    <button class="tab-btn" onclick="setStage('denat')">48°C (Denatured)</button>
  </div>

  
  <div class="graph-card">
    <svg viewBox="0 0 360 145">
      
      <line x1="45" y1="115" x2="345" y2="115" stroke="#94a3b8" stroke-width="1.5" />
      <line x1="45" y1="15" x2="45" y2="115" stroke="#94a3b8" stroke-width="1.5" />
      
      
      <text x="12" y="65" font-size="11" font-weight="600" fill="#475569" transform="rotate(-90 12 65)" text-anchor="middle">Photosynthesis Rate</text>
      <text x="195" y="140" font-size="11" font-weight="600" fill="#475569" text-anchor="middle">Temperature (°C)</text>

      
      <text x="45" y="127" font-size="10" fill="#64748b" text-anchor="middle">0</text>
      <line x1="105" y1="115" x2="105" y2="118" stroke="#94a3b8" />
      <text x="105" y="127" font-size="10" fill="#64748b" text-anchor="middle">10</text>
      <line x1="165" y1="115" x2="165" y2="118" stroke="#94a3b8" />
      <text x="165" y="127" font-size="10" fill="#64748b" text-anchor="middle">20</text>
      <line x1="225" y1="115" x2="225" y2="118" stroke="#94a3b8" />
      <text x="225" y="127" font-size="10" fill="#64748b" text-anchor="middle">30</text>
      <line x1="285" y1="115" x2="285" y2="118" stroke="#94a3b8" />
      <text x="285" y="127" font-size="10" fill="#64748b" text-anchor="middle">40</text>
      <text x="345" y="127" font-size="10" fill="#64748b" text-anchor="middle">50</text>

      
      <line x1="225" y1="20" x2="225" y2="115" stroke="#cbd5e1" stroke-dasharray="3,3" />

      
      <path d="M 45 114 C 105 112, 165 92, 215 30 C 225 18, 233 18, 245 35 C 275 80, 295 112, 333 115" 
            fill="none" stroke="#0284c7" stroke-width="3" stroke-linecap="round" />

      
      <rect x="195" y="4" width="60" height="15" rx="3" fill="#0284c7" />
      <text x="225" y="15" font-size="9.5" font-weight="700" fill="#ffffff" text-anchor="middle">Optimum</text>

      
      <circle id="graphDot" cx="225" cy="22" r="6" fill="#0284c7" stroke="#ffffff" stroke-width="2" />
    </svg>
  </div>

  
  <div class="enzyme-row">
    
    <div id="cardNormal" class="enzyme-card highlight">
      <div class="card-title" style="color: #166534;">30°C Normal</div>
      <svg class="enzyme-svg" viewBox="0 0 140 85">
        
        <path d="M 52 14 L 88 14 L 88 28 L 78 28 L 78 38 L 62 38 L 62 28 L 52 28 Z" fill="#8b5cf6" stroke="#6d28d9" stroke-width="1.5"/>
        <text x="70" y="25" font-size="8" font-weight="700" fill="#ffffff" text-anchor="middle">CO₂</text>
        
        
        <path d="M 20 45 C 20 38, 45 38, 50 38 L 50 50 L 90 50 L 90 38 C 95 38, 120 38, 120 45 C 120 78, 100 80, 70 80 C 40 80, 20 78, 20 45 Z" 
              fill="#bae6fd" stroke="#0284c7" stroke-width="2"/>
        <text x="70" y="68" font-size="10" font-weight="700" fill="#0369a1" text-anchor="middle">Enzyme</text>
      </svg>
      <div class="status-tag tag-fit">✓ Substrate fits active site</div>
    </div>

    
    <div id="cardDenat" class="enzyme-card">
      <div class="card-title" style="color: #c2410c;">48°C Denatured</div>
      <svg class="enzyme-svg" viewBox="0 0 140 85">
        
        <path d="M 85 8 L 115 8 L 115 20 L 107 20 L 107 28 L 93 28 L 93 20 L 85 20 Z" 
              fill="#8b5cf6" stroke="#6d28d9" stroke-width="1.5" transform="rotate(25 100 18)"/>
        <text x="100" y="17" font-size="7.5" font-weight="700" fill="#ffffff" text-anchor="middle" transform="rotate(25 100 18)">CO₂</text>

        
        <path d="M 22 52 C 15 35, 42 42, 58 48 C 65 52, 75 42, 88 46 C 105 50, 122 36, 116 58 C 110 76, 92 80, 68 78 C 38 76, 26 62, 22 52 Z" 
              fill="#fed7aa" stroke="#ea580c" stroke-width="2"/>
        <text x="70" y="68" font-size="10" font-weight="700" fill="#c2410c" text-anchor="middle">Enzyme</text>
      </svg>
      <div class="status-tag tag-nofit">✗ Active site deformed</div>
    </div>
  </div>

  <script>
    const points = {
      low: { cx: 105, cy: 110, color: '#64748b' },
      opt: { cx: 225, cy: 22, color: '#0284c7' },
      denat: { cx: 320, cy: 100, color: '#ea580c' }
    };

    function setStage(stage) {
      // Update Buttons
      const btns = document.querySelectorAll('.tab-btn');
      btns.forEach((b, i) => {
        b.classList.remove('active');
        if ((stage === 'low' && i === 0) || (stage === 'opt' && i === 1) || (stage === 'denat' && i === 2)) {
          b.classList.add('active');
        }
      });

      // Update Dot on Curve
      const dot = document.getElementById('graphDot');
      const pt = points[stage];
      dot.setAttribute('cx', pt.cx);
      dot.setAttribute('cy', pt.cy);
      dot.setAttribute('fill', pt.color);

      // Highlight Cards
      const cNorm = document.getElementById('cardNormal');
      const cDenat = document.getElementById('cardDenat');
      
      cNorm.classList.remove('highlight', 'denatured-highlight');
      cDenat.classList.remove('highlight', 'denatured-highlight');

      if (stage === 'opt' || stage === 'low') {
        cNorm.classList.add('highlight');
      } else {
        cDenat.classList.add('denatured-highlight');
      }
    }
  </script>
</body>
</html>

Factors Affecting the Rate of Photosynthesis

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <title>Rate of Photosynthesis vs Light Intensity</title>
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      width: 100%;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      padding: 10px 12px;
      user-select: none;
      -webkit-user-select: none;
    }

    .graph-container {
      position: relative;
      width: 100%;
      max-width: 580px;
    }

    svg {
      width: 100%;
      height: auto;
      display: block;
      overflow: visible;
    }

    .axis-line {
      stroke: #64748b;
      stroke-width: 2.5;
      stroke-linecap: round;
      stroke-linejoin: round;
    }

    .grid-line {
      stroke: #f1f5f9;
      stroke-width: 1.5;
      stroke-dasharray: 4 4;
    }

    .axis-label {
      font-size: 13px;
      font-weight: 700;
      fill: #1e2945;
    }

    .axis-tick {
      font-size: 11px;
      fill: #64748b;
      font-weight: 500;
    }

    .curve-path {
      fill: none;
      stroke: #16a34a;
      stroke-width: 4;
      stroke-linecap: round;
      stroke-linejoin: round;
    }

    .curve-bg {
      fill: none;
      stroke: rgba(22, 163, 74, 0.12);
      stroke-width: 14;
      stroke-linecap: round;
    }

    .plateau-line {
      stroke: #94a3b8;
      stroke-width: 1.5;
      stroke-dasharray: 5 4;
    }

    .region-box {
      cursor: pointer;
      transition: opacity 0.2s ease;
    }
    .region-box:hover {
      opacity: 0.85;
    }

    .pt-marker {
      cursor: pointer;
      transition: stroke 0.2s ease, fill 0.2s ease;
    }
    .pt-marker:hover circle.outer {
      fill: rgba(34, 183, 255, 0.25);
    }
    .pt-marker.active circle.core {
      fill: #0284c7;
      stroke: #ffffff;
      stroke-width: 3px;
    }
    .pt-marker.active circle.outer {
      fill: rgba(2, 132, 199, 0.2);
    }

    .info-panel {
      width: 100%;
      max-width: 580px;
      margin-top: 8px;
      padding: 10px 14px;
      background: #f8fafc;
      border: 1.5px solid #e2e8f0;
      border-radius: 10px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 12px;
      min-height: 58px;
    }

    .info-text {
      font-size: 13px;
      line-height: 1.4;
      color: #334155;
    }

    .info-text strong {
      color: #0f172a;
      display: inline-block;
      margin-right: 4px;
    }

    .nav-buttons {
      display: flex;
      gap: 6px;
      flex-shrink: 0;
    }

    .btn-step {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      color: #475569;
      padding: 6px 10px;
      border-radius: 6px;
      font-size: 12px;
      font-weight: 600;
      cursor: pointer;
      transition: all 0.15s ease;
    }
    .btn-step:hover {
      background: #f1f5f9;
      color: #0f172a;
      border-color: #94a3b8;
    }
    .btn-step.active {
      background: #0284c7;
      color: #ffffff;
      border-color: #0284c7;
    }

    .tag-bubble {
      font-size: 11px;
      font-weight: 700;
      letter-spacing: 0.3px;
    }
  </style>
</head>
<body>

  <div class="graph-container">
    <svg viewBox="0 0 540 330" id="graphSvg">
      <defs>
        <marker id="arrow" viewBox="0 0 10 10" refX="6" refY="5" markerWidth="6" markerHeight="6" orient="auto-start-reverse">
          <path d="M 1 1 L 9 5 L 1 9 z" fill="#64748b" />
        </marker>
        <linearGradient id="shadeGrad" x1="0%" y1="0%" x2="100%" y2="0%">
          <stop offset="0%" stop-color="#16a34a" stop-opacity="0.18"/>
          <stop offset="45%" stop-color="#16a34a" stop-opacity="0.08"/>
          <stop offset="100%" stop-color="#38bdf8" stop-opacity="0.06"/>
        </linearGradient>
      </defs>

      
      <path id="curveArea" fill="url(#shadeGrad)" />

      
      <line x1="65" y1="75" x2="495" y2="75" class="plateau-line" />
      <text x="70" y="68" class="axis-tick" fill="#94a3b8">Maximum achievable rate</text>

      
      <line x1="260" y1="75" x2="260" y2="275" stroke="#cbd5e1" stroke-width="1.5" stroke-dasharray="4 4" />

      
      
      <line x1="65" y1="280" x2="65" y2="35" class="axis-line" marker-end="url(#arrow)" />
      
      <line x1="60" y1="275" x2="510" y2="275" class="axis-line" marker-end="url(#arrow)" />

      
      <text x="54" y="292" class="axis-tick">0</text>

      
      <text x="285" y="315" class="axis-label" text-anchor="middle">Light Intensity →</text>
      <text x="-160" y="24" class="axis-label" transform="rotate(-90)" text-anchor="middle">Rate of Photosynthesis →</text>

      
      <path id="curveGlow" class="curve-bg" />
      <path id="curveLine" class="curve-path" />

      
      <g class="region-box" id="regA">
        <rect x="75" y="125" width="165" height="38" rx="6" fill="#f0fdf4" stroke="#86efac" stroke-width="1.2" />
        <text x="83" y="141" class="tag-bubble" fill="#15803d">REGION A</text>
        <text x="83" y="155" font-size="11px" font-weight="600" fill="#166534">Light intensity is limiting</text>
      </g>

      <g class="region-box" id="regB">
        <rect x="290" y="105" width="180" height="38" rx="6" fill="#f0f9ff" stroke="#7dd3fc" stroke-width="1.2" />
        <text x="298" y="121" class="tag-bubble" fill="#0369a1">REGION B (Plateau)</text>
        <text x="298" y="135" font-size="11px" font-weight="600" fill="#0c4a6e">Light is no longer limiting</text>
      </g>

      
      <g id="bottleneckTag" transform="translate(290, 42)">
        <rect x="0" y="0" width="215" height="26" rx="5" fill="#fef2f2" stroke="#fca5a5" stroke-width="1" />
        <text x="8" y="17" font-size="11px" font-weight="600" fill="#991b1b">⚠️ Bottleneck: CO₂ or Temperature</text>
      </g>

      
      <g id="pointsGroup"></g>
    </svg>
  </div>

  
  <div class="info-panel">
    <div class="info-text" id="statusText">
      <strong>Point 1 (Steep Rise):</strong> Light is limiting. Increasing light intensity directly speeds up photosynthesis.
    </div>
    <div class="nav-buttons">
      <button class="btn-step active" id="btn1">1</button>
      <button class="btn-step" id="btn2">2</button>
      <button class="btn-step" id="btn3">3</button>
    </div>
  </div>

  <script>
    // Exact mathematical curve coordinates: R(x) = Rmax * (1 - e^(-k*x))
    // Graph mapping: x from 0 to 420 -> SVG X from 65 to 485
    // Y max plateau at y=75, origin at y=275. Height span = 200.
    const originX = 65;
    const originY = 275;
    const maxY = 75;
    const amplitude = originY - maxY; // 200px
    const k = 0.0115; // saturation rate factor

    function getCurveY(xVal) {
      return originY - amplitude * (1 - Math.exp(-k * xVal));
    }

    // Build SVG path data dynamically to ensure 100% mathematical precision
    let pathD = `M ${originX} ${originY}`;
    let areaD = `M ${originX} ${originY}`;
    const maxX = 425;

    for (let x = 1; x <= maxX; x += 3) {
      const px = originX + x;
      const py = getCurveY(x);
      pathD += ` L ${px.toFixed(1)} ${py.toFixed(1)}`;
      areaD += ` L ${px.toFixed(1)} ${py.toFixed(1)}`;
    }

    areaD += ` L ${(originX + maxX).toFixed(1)} ${originY} Z`;

    document.getElementById('curveLine').setAttribute('d', pathD);
    document.getElementById('curveGlow').setAttribute('d', pathD);
    document.getElementById('curveArea').setAttribute('d', areaD);

    // Interactive Key Points on the Curve
    const interactivePoints = [
      {
        xVal: 55,
        title: "Point 1 (Region A - Linear Rise):",
        desc: "Light is the limiting factor. Each extra photon directly increases photosynthetic rate proportionally."
      },
      {
        xVal: 155,
        title: "Point 2 (Transition Curve):",
        desc: "Light is becoming abundant. Rate still increases, but begins slowing down as enzymes reach maximum capacity."
      },
      {
        xVal: 330,
        title: "Point 3 (Region B - Plateau):",
        desc: "Light is no longer limiting. Graph flattens because CO₂ level or temperature is now the bottleneck."
      }
    ];

    const ptsGroup = document.getElementById('pointsGroup');
    const statusText = document.getElementById('statusText');
    const buttons = [
      document.getElementById('btn1'),
      document.getElementById('btn2'),
      document.getElementById('btn3')
    ];

    let activeIndex = 0;
    const markerElements = [];

    interactivePoints.forEach((pt, i) => {
      const cx = originX + pt.xVal;
      const cy = getCurveY(pt.xVal);

      const g = document.createElementNS("http://www.w3.org/2000/svg", "g");
      g.setAttribute("class", "pt-marker" + (i === 0 ? " active" : ""));
      g.setAttribute("id", `marker-${i}`);

      g.innerHTML = `
        <circle class="outer" cx="${cx.toFixed(1)}" cy="${cy.toFixed(1)}" r="14" fill="rgba(34, 183, 255, 0.01)" />
        <circle class="core" cx="${cx.toFixed(1)}" cy="${cy.toFixed(1)}" r="6" fill="${i === 0 ? '#0284c7' : '#ffffff'}" stroke="#16a34a" stroke-width="2.5" />
      `;

      g.addEventListener('click', () => selectPoint(i));
      ptsGroup.appendChild(g);
      markerElements.push(g);
    });

    function selectPoint(index) {
      activeIndex = index;
      const pt = interactivePoints[index];
      
      statusText.innerHTML = `<strong>${pt.title}</strong> ${pt.desc}`;

      markerElements.forEach((m, idx) => {
        const core = m.querySelector('.core');
        if (idx === index) {
          m.classList.add('active');
          core.setAttribute('fill', '#0284c7');
          core.setAttribute('stroke', '#ffffff');
          core.setAttribute('stroke-width', '3');
          core.setAttribute('r', '7');
        } else {
          m.classList.remove('active');
          core.setAttribute('fill', '#ffffff');
          core.setAttribute('stroke', '#16a34a');
          core.setAttribute('stroke-width', '2.5');
          core.setAttribute('r', '6');
        }
      });

      buttons.forEach((btn, idx) => {
        btn.classList.toggle('active', idx === index);
      });
    }

    buttons.forEach((btn, idx) => {
      btn.addEventListener('click', () => selectPoint(idx));
    });

    document.getElementById('regA').addEventListener('click', () => selectPoint(0));
    document.getElementById('regB').addEventListener('click', () => selectPoint(2));
    document.getElementById('bottleneckTag').addEventListener('click', () => selectPoint(2));
  </script>
</body>
</html>

UK-GCSE-SCIENCE-BIO-PS-02-04

Aligned learning resources

Related diagrams