Lesson 8: Cellular Respiration | BIO 2.4

Lesson at a Glance | He Tirohanga Whakamua

Do NowHow rapid glycolysis and aerobic respiration overlap in a sprint10 min

Three-Stage ModelGlycolysis, Krebs cycle and electron transport15 min

Exercise-book SynthesisComplete Section 8: Respiration Pathway & ATP Energetics10 min

Core Concept CheckCompare 2 ATP net with the larger, variable aerobic yield5 min

Rua Kūmara ApplicationSeparate sourced storage evidence from biological hypotheses15 min

Ngā Whāinga Ako | Learning Intentions

Students will know

The overall chemical equation for aerobic respiration: $C_{6} H_{12} O_{6} + 6 O_{2} \to 6 {CO}_{2} + 6 H_{2} O + energy$ . Some of that energy is captured in ATP.
The 3 stages of aerobic respiration: Glycolysis (Cytoplasm), Krebs Cycle (Mitochondrial Matrix), and Electron Transport Chain (Mitochondrial Cristae).
The overlapping pathways: glycolysis yields 2 ATP net per glucose. In animal cells, reducing pyruvate to lactate regenerates NAD⁺ so glycolysis can continue when oxygen-supported ATP supply cannot meet demand. With oxygen, mitochondrial respiration makes much more ATP — commonly about 30–32 ATP total per glucose in eukaryotic cells, although the exact yield varies.

Students will demonstrate

By drawing a complete 3-stage respiration pathway map inside a mitochondria model.
By completing formative Section 8 in their class exercise book or revision folder.

Curriculum alignment

NZC (2007) · Science · Level 7 · Living World: “Explore the diverse ways in which animals and plants carry out the life processes.”

Do Now | Tīmatanga Whakaaro (10 min)

Sprint ATP Prompt:

"During a hard sprint, why can rapid glycolysis become more important even though aerobic respiration continues at the same time?"

Unpack: Muscle does not flip a single on/off switch between “aerobic” and “anaerobic” pathways. Both contribute, but ATP demand can rise faster than oxygen-supported mitochondrial production. Glycolysis supplies 2 ATP net per glucose quickly. Converting pyruvate to lactate regenerates NAD⁺, allowing glycolysis to continue. Fatigue is multifactorial — changes in inorganic phosphate, ion balance, metabolites and nervous-system drive all contribute — so lactate is not a toxic waste product that simply waits for an “oxygen debt” to be repaid.

3 Stages of Aerobic Respiration (15 min)

⚡ 1. Glycolysis (Cytoplasm)

Glucose (6C) is split into 2 Pyruvate (3C). Anaerobic step. Yields 2 ATP net and 2 NADH.

🔄 2. Krebs Cycle (Matrix)

Pyruvate enters mitochondrial matrix. Fully broken down releasing ${CO}_{2}$ gas. Yields 2 ATP, NADH, and ${FADH}_{2}$ .

🌊 3. Electron Transport Chain (Cristae)

NADH/ ${FADH}_{2}$ donate electrons to proteins on the inner mitochondrial membrane. $O_{2}$ is the final electron acceptor and water forms. Oxidative phosphorylation produces most of the ATP; a eukaryotic cell commonly gains about 30–32 ATP in total per glucose, with the exact yield varying between cells and conditions.

📁 Formative Revision Exercise Book — Section 8: Respiration Pathway & Energetics

Students complete Section 8 in their exercise book or class revision folder. This is formative classroom evidence, not an NZQA submission:

Section 8 Requirements:

1. Mitochondrion Respiration Map: Draw cytoplasm & mitochondrion (matrix, cristae) mapping Glycolysis, Krebs Cycle, and ETC inputs/outputs.

2. Anaerobic vs Aerobic Comparison Table: Compare location, oxygen availability, how NAD⁺ is regenerated, end products (lactate in animal cells; ethanol and carbon dioxide in yeast; carbon dioxide and water aerobically), and ATP yield (2 ATP net from glycolysis versus a much larger, variable aerobic total commonly around 30–32 ATP in eukaryotic cells).

3. Excellence Cristae Adaptation Rationale: 1 paragraph explaining why endurance muscle cells have highly folded cristae inner membranes.

Core Concept Check | Tirohia te Māramatanga (5 min)

Exit Check:

"My Section 8 map traces glycolysis in the cytoplasm yielding 2 ATP net, the Krebs cycle in the matrix, and oxidative phosphorylation on the inner membrane producing most of a larger but variable aerobic ATP yield."

Te Rua Kūmara: source evidence and a bounded respiration lens (15 min)

A kūmara pulled from the ground is still alive, and its cells are still respiring — burning the stored starch that was the whole point of growing it. Every day in storage, some of the harvest is consumed by the harvest.

What the source establishes. Te Ara's account of kūmara tools and storage pits says underground storage provided high humidity needed to preserve tubers and records many pit forms, including small rectangular pits, connected cave-like pits and larger roofed pits. Its pit-design evidence shows bank, bell-shaped and roofed forms, often with drainage channels. High humidity in the air is not the same as liquid water sitting around the tubers: drainage kept external water out while the enclosed store reduced drying.

The task (in pairs). Keep source evidence and biological inference in separate columns:

Write what a respiring kūmara cell consumes and releases: glucose and oxygen are consumed; carbon dioxide, water and usable energy are produced. Explain why the tuber loses stored carbohydrate over time.
Record only what Te Ara supports about humidity, drainage, enclosure and varied pit forms. Do not add a universal claim that every rua was “dry and ventilated”.
Use biology to propose testable consequences of two conditions: air with high humidity, and liquid water flooding the store. Consider water loss, gas diffusion, tissue damage and microbial decay; label each statement as a hypothesis.
Choose one documented feature and write a cautious causal chain. End with what evidence you would still need before claiming that respiration explains the design.

Then discuss. The respiration model can help test possible consequences of storage conditions. It cannot recover why a particular community selected a particular rua form, nor derive cultural engineering or tikanga from an equation. Those claims require historical evidence and the authority of the people who hold the practice.

Kaiako — mātauranga handoff. Rua kūmara design and kūmara tikanga vary by rohe, and the practices around planting, harvest and storage carry meaning beyond food preservation. The authoritative account belongs with kaiako Māori and local knowledge holders — please seek that before teaching, and let local practice lead.

Teacher Planning & NCEA Alignment

NCEA Level 2 Biology Alignment (4 Credits External):

Cellular Respiration: Demonstrate understanding of glycolysis, anaerobic fermentation, Krebs cycle, electron transport chain, and mitochondrial structural adaptations.
Energy Yields: Compare ATP output between aerobic and anaerobic pathways.

Vocabulary: Cellular respiration, glycolysis, pyruvate, anaerobic fermentation, lactate, NAD⁺, Krebs cycle, matrix, electron transport chain, cristae, oxidative phosphorylation, ATP yield.

Paired concept in Guided Media & Evidence: cellular respiration →

Lesson 8: Cellular Respiration: Glycolysis, Krebs Cycle & Electron Transport Chain