Review and Consolidation I

Term 1, Week 6, Lesson 4

Year 9 biology review consolidation thermoregulation tropisms endotherm ectotherm heat transfer plant responses Western Australia

Do Now

Quick recall — no notes. Answer each question in one sentence or less:

1. Name the two types of thermoregulation strategy and give one WA example of each.
2. What is the hormone responsible for phototropism, and where is it produced?
3. Name all four mechanisms of heat transfer.
4. What is the difference between a tropism and a nastic movement?
5. Which direction does gravity cause auxin to move in a horizontal seedling — and what effect does this have on the shoot?

You have 4 minutes.

Daily Review

Answer the following 5 multiple choice questions in your book:

1. A plant root detects a moisture gradient and grows toward the wetter zone. This is an example of:
   • 1. Negative geotropism
   • 2. Thigmotropism
   • 3. Positive hydrotropism
   • 4. Photonasty
2. A tendril on a WA climbing vine wraps tightly around a wire fence. This is an example of:
   • 1. Positive hydrotropism
   • 2. Positive thigmotropism
   • 3. Nastic movement
   • 4. Negative phototropism
3. Both endotherms and ectotherms use evaporation to lose heat. Which of the following is an example of evaporative cooling in a WA endotherm?
   • 1. A dugite snake resting under a cool flat rock
   • 2. A red kangaroo licking its sparsely furred forearms
   • 3. A bobtail lizard basking on warm bitumen
   • 4. A bilby huddling in its burrow
4. Which of the following statements correctly compares phototropism and geotropism?
   • 1. Both are driven by uneven light distribution across the shoot tip
   • 2. Both result in shoots growing upward and roots growing downward
   • 3. Both are caused by uneven auxin distribution, but each is triggered by a different stimulus (light vs gravity)
   • 4. Phototropism is permanent; geotropism reverses when the stimulus is removed
5. A lizard in the Kimberley flattens its dark-coloured back toward the morning sun. Which heat transfer mechanism is it primarily using to gain heat?
   • 1. Conduction
   • 2. Convection
   • 3. Radiation
   • 4. Evaporation

NoteAnswers

1. C 2) B 3) B 4) C 5) C

Learning Intentions

Today we are learning to synthesise the key concepts from Weeks 5 and 6 into a coherent understanding of how organisms detect and respond to environmental change, and to apply these concepts to explain organism behaviour in new, complex scenarios.

Success Criteria

You will be successful if you have:

• Constructed or contributed to a concept map that accurately links stimulus–response, endotherm/ectotherm thermoregulation, heat transfer mechanisms, and plant tropisms
• Analysed a multi-organism scenario and identified at least four distinct response mechanisms across different organisms
• Compared the stimulus–response pathway in an animal (thermoregulating endotherm) and a plant (tropism) — identifying similarities and differences in how the response is coordinated

Keywords

No new keywords today — consolidation of all terms from Weeks 5 and 6.

Key terms to review: stimulus · receptor · coordinator · effector · response · homeostasis · endotherm · ectotherm · thermoregulation · conduction · convection · radiation · evaporation · tropism · auxin · phototropism · geotropism · hydrotropism · thigmotropism · nastic movement · positive tropism · negative tropism

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Learning Activities

Activity 1 — I DO: Building the Big Picture — Concept Map

The Connecting Idea

Over the past two weeks, every organism and every mechanism we have studied shares one underlying logic:

All living things must detect changes in their environment and respond in ways that maintain conditions for survival.

Whether it is a dugite detecting a hot rock surface and seeking shade, a kangaroo’s hypothalamus triggering sweat glands as core temperature rises, or a banksia root following a moisture gradient through dry laterite soil — the structure is always the same: stimulus → detection → processing → response.

Class Concept Map

Concept map biology organisms respond environmental change thermoregulation tropisms stimulus response Year 9

As a class we will build the following concept map on the board. Copy it into your book as we go.

Central node: All organisms respond to environmental change

Branch 1 — Animals:

• Stimulus–response pathway (stimulus → receptor → coordinator → effector → response)
  • Example: heat → thermoreceptors in skin → hypothalamus → sweat glands → sweating (endotherm)
  • Example: heat → skin receptors → nervous system → muscles → movement to shade (ectotherm)
• Thermoregulation
  • Endotherms: maintain stable temperature; use evaporation + insulation as primary mechanisms
  • Ectotherms: temperature varies with environment; use conduction + radiation as primary mechanisms
• Heat transfer: conduction · convection · radiation · evaporation
  • Different proportions in endo vs ecto
  • Both types use all four mechanisms

Branch 2 — Plants:

• Stimulus–response (no nervous system; hormone-mediated; growth-based)
  • Example: unilateral light → photoreceptors in shoot tip → auxin redistribution → differential elongation → shoot bends toward light
• Tropisms (permanent, directional growth)
  • Phototropism (light → auxin → differential growth in shoot)
  • Geotropism (gravity → auxin → opposite effect in shoot vs root)
  • Hydrotropism (moisture gradient → root cap detection → root curves toward water)
  • Thigmotropism (contact → differential growth → wrapping)
• Nastic movements (non-directional, reversible)
• Circadian rhythms (stomata, leaf movements)

Connecting threads:

• All responses serve survival and reproduction (link to adaptations from Weeks 3–4)
• The stimulus–response model applies to both plants and animals — just with different mechanisms
• WA context: almost every example we’ve used is a WA species in a WA ecosystem

Comparing Animal and Plant Response Pathways

Feature	Animal response (e.g. endotherm thermoregulating)	Plant response (e.g. phototropism)
Speed	Seconds to minutes (nervous system)	Hours to days (growth-based)
Coordinator	Brain / hypothalamus / nervous system	Hormones (auxin, ABA, etc.)
Effector	Muscles, glands, blood vessels	Zones of dividing/elongating cells
Reversibility	Mostly reversible (muscle can relax; sweat stops)	Mostly irreversible (new cell walls are permanent)
Precision	High — specific muscles activated	Lower — involves broad growth zones

Key similarity: Both require detection of the stimulus by a specialised receptor (thermoreceptors in skin; photoreceptors and root-cap cells in plants) and a signal that carries information to the effector (nerve impulses in animals; hormone gradients in plants).

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Activity 2 — WE DO: Extended Scenario — A Summer Heatwave in the South-West

South-west Western Australia jarrah forest summer heatwave landscape ectotherm endotherm plant responses

The scenario:

It is January. The south-west WA jarrah forest has experienced 10 consecutive days of temperatures above 40°C with no rainfall. The following organisms are all present in the same patch of forest:

• A red kangaroo resting in the shade of a large jarrah tree, occasionally licking its forearms
• A bobtail lizard that has retreated under a cool granite boulder
• A jarrah tree (Eucalyptus marginata) with lateral roots extending through dry laterite soil; its stomata closed since noon
• A banksia seedling that germinated six weeks ago near the base of a dead tree trunk, competing for a shaft of light filtering through the canopy

In groups of three or four, answer the following questions. Be ready to share with the class.

Question 1 — Thermoregulation (Endotherm): Describe three heat transfer mechanisms the red kangaroo is using at this moment. For each mechanism, state whether the kangaroo is gaining or losing heat, and explain why the mechanism is effective.

Question 2 — Thermoregulation (Ectotherm): The bobtail lizard is pressed under the granite boulder. Identify the primary heat transfer mechanism it is using, and explain why sheltering under a rock is a more effective cooling strategy for the bobtail than for the kangaroo. (Hint: think about each animal’s heat source.)

Question 3 — Plant Responses (Jarrah tree): The jarrah tree’s stomata have been closed since noon. Explain this response using the stimulus–response model:

• What is the stimulus?
• How does the plant detect it?
• What is the response?
• What is the adaptive benefit?

Question 4 — Plant Tropisms (Banksia seedling): The banksia seedling is competing for the shaft of light near the dead tree trunk. Over the past six weeks, identify two tropisms the seedling has used — one to establish its roots and one to orient its shoot — and explain each using the auxin mechanism.

Question 5 — Synthesis: Both the kangaroo and the banksia seedling are responding to the same environmental condition (extreme heat and dryness). Compare their response strategies:

• Which response is faster?
• Which response is reversible?
• What fundamental feature do all these responses have in common?

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Activity 3 — YOU DO: Integrated Review

Year 9 biology review worksheet thermoregulation heat transfer tropisms consolidation integrated questions

Complete the worksheet: 164-review-and-consolidation-you-do.docx

The worksheet integrates all topics from Weeks 5 and 6: stimulus–response, endotherm/ectotherm strategies, heat transfer mechanisms, and plant tropisms. It includes a concept map completion task, scenario analysis, and one extended-response question.

Work independently. You have 12 minutes.

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Notes

Use this space to write any important points from today’s lesson.

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Reflection

1. The stimulus–response model applies to both plants and animals. Which of the following correctly describes the main difference in how each type of organism coordinates its response?
   • 1. Animals use chemical hormones; plants use nerve impulses
   • 2. Animals use nerve impulses and/or hormones for fast responses; plants use hormones that cause slow, growth-based responses
   • 3. Animals can only respond to temperature; plants can only respond to light
   • 4. Both use identical mechanisms — the only difference is speed
2. A kangaroo is sweating and a banksia root is growing toward a moist patch of soil. These responses are similar in that both:
   • 1. Involve the hormone auxin redistributing in response to a stimulus
   • 2. Are responses to the same stimulus (water deficit) that help the organism maintain internal conditions suitable for survival
   • 3. Are coordinated by a hypothalamus detecting changes in core body temperature
   • 4. Are examples of negative feedback homeostasis in endotherms
3. Which of the following best describes the adaptive significance of all the organism responses studied in Weeks 5 and 6?
   • 1. They allow organisms to evolve faster in response to environmental change
   • 2. They allow organisms to detect environmental changes and respond in ways that improve their chances of survival and reproduction
   • 3. They reduce the need for structural adaptations in WA organisms
   • 4. They only function in extreme environments such as deserts and polar regions
4. A student says: “Tropisms are different from animal responses because plants don’t have a nervous system.” Which of the following is the most accurate and complete response to this student?
   • 1. The student is wrong — plants do have a simple nervous system made of specialised cells
   • 2. The student is correct; therefore tropisms are not true stimulus–response pathways
   • 3. The student is correct that plants lack a nervous system, but tropisms still follow a stimulus–response pattern — the coordination is chemical (hormonal) rather than neural
   • 4. The student is correct, but only phototropism is a true stimulus–response — other tropisms are purely mechanical
5. Extended short answer: Choose one organism from the heatwave scenario in the WE DO activity. Describe two responses it is using to cope with the extreme heat, and for each response: (a) identify the stimulus, (b) describe the mechanism, and (c) explain the adaptive benefit. Use correct scientific vocabulary.

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Home-study

Review for the unit test (if applicable). Using your notes and today’s concept map, create a one-page summary of the key concepts from Weeks 5 and 6. Your summary should cover:

• The stimulus–response model (with one animal and one plant example)
• Endotherm vs ectotherm thermoregulation (including heat transfer mechanisms)
• At least three plant tropisms and their mechanisms
• At least two WA examples for each category