Lesson at a Glance | He Tirohanga Whakamua
Ngā Whāinga Ako | Learning Intentions
Students will know
- The structural differences between prokaryotic cells (bacteria, no membrane-bound nucleus, circular DNA and a peptidoglycan wall) and eukaryotic cells (plant, animal and fungal cells with nuclei and linear DNA). Plant walls contain cellulose, fungal walls contain chitin, and animal cells have no cell wall.
- The structure and specific biochemical function of key organelles: Mitochondria, Chloroplast, Endoplasmic Reticulum (Rough/Smooth), Golgi Apparatus, Ribosomes, Lysosomes, and Vacuoles.
- How organelle density reflects specific cellular function (e.g. muscle cells have dense cristae mitochondria; leaf Palisade cells have abundant chloroplasts).
Students will demonstrate
- By completing a comparative organelle structure-function matrix.
- By completing formative Section 1 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)
Cellular Organelle Prompt:
"Why do cells with a high energy demand, such as flight muscle cells, tend to contain more mitochondria than less active cells?"
Unpack: Mitochondria are the site of aerobic cellular respiration producing ATP energy. Tissues with extreme metabolic demand (like rapid wing muscle contraction) require a high density of mitochondria with folded inner membranes (cristae) to maximise ATP production rate.
Key Eukaryotic Organelles for Level 2 Biology (20 min)
🔋 Mitochondria
Double-membrane organelle. Inner membrane folded into cristae to maximise surface area for Electron Transport Chain enzymes. Matrix contains Krebs cycle enzymes.
☀️ Chloroplast
Double-membrane organelle in plant cells. Contains thylakoid stacks (grana) holding chlorophyll for light reactions, and fluid stroma for Calvin cycle.
🏗️ Endoplasmic Reticulum & Ribosomes
Rough ER: Studded with ribosomes for protein synthesis & transport.
Smooth ER: Lipid synthesis & toxin breakdown.
📦 Golgi Apparatus & Lysosomes
Golgi: Modifies, sorts, and packages proteins into vesicles for secretion.
Lysosomes: Membrane sacs of digestive enzymes breakdown waste.
Plant vs Animal Cells (10 min)
1. Cell Wall
Cellulose, outside the cell membrane, rigid. Gives the cell its fixed shape and stops it bursting when water floods in. Animal cells have none — which is why an animal cell in pure water lyses and a plant cell does not.
2. Chloroplasts
Double membrane, with stacked thylakoids (grana) inside. The site of photosynthesis. Present only in photosynthetic cells — a plant's root cells have none, which is a useful check on the lazy answer "all plant cells have chloroplasts".
3. Large Central Vacuole
Bounded by the tonoplast, filled with cell sap. Stores water and ions, and presses outwards against the wall to create turgor. Animal cells have only small, temporary vacuoles.
4. What animal cells have instead
Centrioles, used to organise the spindle in cell division. Animal cells are also typically rounded rather than boxy, precisely because there is no wall to hold a shape.
Mahi | Do this: Draw one plant cell and one animal cell side by side and label only the differences. Then answer in one sentence: both are placed in pure water — why does one survive?
📁 Formative Revision Exercise Book — Section 1: Organelle Structure & Function
Students complete Section 1 in their exercise book or class revision folder. This organelle map is formative evidence for kaiako feedback, not an NZQA submission. All required prompts are supplied below:
Section 1 Requirements:
1. Cell-type Matrix: Compare a bacterium, plant cell, fungal cell and animal cell for nucleus, membrane-bound organelles, DNA structure (circular vs linear), and cell wall composition (peptidoglycan, cellulose, chitin or no wall).
2. Organelle Structure-Function Map: Annotated diagrams of Mitochondria (cristae, matrix) and Chloroplast (grana, stroma, thylakoid) explaining how structural adaptations maximise biological rates.
3. Cell Specialisation Justification: 1-paragraph explanation of why plant Palisade mesophyll cells have high chloroplast density while root hair cells have zero.
Exit Verification | Ka Mutu Hoki (5 min)
Exit Check:
"My Section 1 contains annotated diagrams of mitochondria and chloroplasts showing structural adaptations for surface area."
Teacher Planning & NCEA Alignment
NCEA Level 2 Biology Alignment (4 Credits External):
- Organelle Specialisation: Demonstrate understanding of cellular structure, organelle functions, and membrane adaptations.
- Eukaryote vs Prokaryote: Compare structural organisation across cellular kingdoms.
Vocabulary: Prokaryote, eukaryote, mitochondria, cristae, matrix, chloroplast, thylakoid, grana, stroma, rough ER, Golgi apparatus.
Paired concept in Guided Media & Evidence: organelle structure & function →