Responses of plants and animals to their external environment

Practice

Recall it first, then use it — testing yourself builds the memory, where rereading the notes above only feels easier.

Recall and application shuffled together — you have to work out what each item wants before you can answer it, which is the part the exam actually tests. Both kinds feed the same spacing schedule, so anything you miss comes back sooner.

Say the answer out loud before flipping — that attempt is where the learning happens, even when you get it wrong.

Exam-style only. Instant feedback, shuffled each attempt, best score saved on this device.

What actually comes up

Every paper transcribed here asks exactly three extended-response questions: one on plant responses, one on animal orientation or rhythms, and one on social behaviour — each built around a real, often unfamiliar species. Marking is holistic per question (evidence points cut at roughly 8/13/18 of 24 across the three questions), not per lettered part, so the bands below summarise what a Describe- / Explain- / Discuss-level answer needs, not a single correct sentence. Every Excellence band ends on the words reproductive success — see the ⭐ answer chain in the first section.

Across 4 years

The pattern — what to prepare

The 2022 paper ↗ Marking schedule ↗

Question One — Intraspecific relationships in the hihi

The hihi (stitchbird) defends a territory in the mating season, has a known dominance hierarchy (older over younger, males over females except at the nest), and males sing and perform flight displays to court females; hihi also nest in pairs or groups.

• describe Describe hierarchy, predation, territory, and group nesting. Achieved
• explain Explain WHY courtship (singing, flight displays) is an advantage (signals energy/fitness, enables female choice, confirms correct species) AND a disadvantage (costs energy, attracts predators, risk of injury), and explain the advantage of group nesting and of defending a territory only during the mating season. Merit
• discuss Discuss how group nesting and defending the territory in the mating season together outweigh their costs to maintain population size, for full Excellence also linking hierarchy and courtship into the same fully-connected explanation of more (and fitter) young surviving. Excellence

Question Two — Migration of the indigo bunting

The indigo bunting migrates about 2000 km each way between North American breeding grounds and Central American wintering areas, flying only at night.

• describe Define migration, identify the rhythm shown as circannual, describe the environmental cue (shortening day length / dropping temperature), and describe a navigation method usable at night (stellar navigation, or the Earth's magnetic field). Achieved
• explain Explain why migration lets the bunting avoid unfavourable conditions year-round, why its night navigation method must not depend on the sun, how it likely combines an internal (pineal gland) and external (stellar) cue, and why using multiple methods reduces the risk of going off course. Merit
• discuss Comprehensively discuss the costs of migration (getting lost, predation, starvation, energy depletion before breeding) against the benefits (favourable temperature, constant food, larger energy reserves, more surviving offspring, reduced disease/parasitism, genetic mixing), concluding the benefits outweigh the costs, increasing overall reproductive success. Excellence

Question Three — Golden dodder parasitism and synchronised flowering

The golden dodder is a leafless, rootless parasitic plant that winds around a host using a haustorium to draw water and nutrients, and synchronises its flowering with its host's flowering time regardless of whether the host is a short-day or long-day plant.

• describe Describe the parasitic (interspecific) relationship between dodder and host, describe positive thigmotropism as the growth response responsible for winding around the host, and describe what makes a plant a short-day plant versus a long-day plant. Achieved
• explain Explain how the dodder benefits while the host is harmed, explain the auxin mechanism behind the thigmotropic winding response, and explain why synchronising flowering with either a short-day or a long-day host still ensures pollinators are present regardless of the season. Merit
• discuss Discuss fully how positive thigmotropism (with the auxin mechanism named) lets the dodder parasitise a host for more energy, AND how synchronising flowering with both short-day and long-day hosts increases pollination success — both routes concluding in greater reproductive success and survival of the species. Excellence

The 2025 paper ↗ Marking schedule ↗

Question One — Phytochrome system

Poinsettia are short-day plants; New Zealand natives are mostly long-day plants that flower in summer. Growers use the phytochrome system to make short-day plants like poinsettia flower during a New Zealand summer.

• describe Define photoperiodism, short-day plant and long-day plant, name the phytochrome system (Pr / Pfr), and define critical day/night length. Achieved
• explain Explain how Pr and Pfr interconvert with light and dark, why critical night length matters, and how flowering is triggered in a short-day plant versus a long-day plant. Merit
• discuss Give a detailed account of the photoperiodic response AND justify both grower techniques for forcing poinsettia to flower in a New Zealand summer — extending the night, and interrupting the night with red light followed by far-red light. Excellence

Question Two — Honey bee behaviour

Honey bees forage on a rhythm linked to their circadian clock, using the Sun as a compass, and can still find their way home under cloud. Foraging activity was compared between a normal day and a day with a total solar eclipse.

• describe Describe diurnal behaviour and circadian rhythm, and the cues honey bees use for homing — landmarks, the sun compass, polarised light, scent, and (some evidence for) Earth’s magnetic field. Achieved
• explain Explain why the circadian rhythm is linked to the sun compass, which cues work on sunny versus overcast days, and describe the foraging pattern on a normal day compared with an eclipse day. Merit
• discuss Discuss why the circadian rhythm is entrained but does not react instantly to a sudden change, so the abrupt darkness of the eclipse does not immediately register as night for every bee — individual variation in responsiveness (or reliance on the still-present magnetic field) explains why some bees keep foraging. Excellence

Question Three — Behaviour in grey wolves

Grey wolves live in packs of roughly 2–20 with a hierarchy (alpha, beta, delta, omega). Agonistic behaviour — dominance and submissive displays, threats — maintains the hierarchy; only the alpha pair breeds.

• describe Define hierarchy and territory, and describe how the pack hierarchy is maintained. Achieved
• explain Explain at least two ways the hierarchy is maintained, why pack members show kin selection, and give one advantage and one disadvantage of living below the alpha pair, each linked to a cost or benefit. Merit
• discuss Discuss how the hierarchy is maintained AND why wolves show kin selection to increase reproductive success, then weigh the advantages against the disadvantages of living in the pack versus alone, concluding the advantages outweigh the costs. Excellence

The 2024 paper ↗ Marking schedule ↗

Question One — Relationships in the forest

Nocturnal kauri snails (pūpū-rangi) eat earthworms and small snails and lay about six eggs, three times a year. Nocturnal possums and hedgehogs both prey on the snail; hedgehogs also hibernate.

• describe Describe the relationship between possum and snail (predation) and between possum and hedgehog (interspecific competition), plus one advantage and one disadvantage of the snail being nocturnal. Achieved
• explain Explain how nocturnal activity gives the snail more food and less desiccation risk but more predator exposure, why hibernation raises the hedgehog’s survival chances, why laying three times a year raises the snail’s reproductive success, and how possum nocturnality reduces its competition with the hedgehog. Merit
• discuss Discuss all three relationships together, in each case tracing the mechanism through to increased reproductive success for the species that benefits. Excellence

Question Two — Bumblebees and kōwhai

Kōwhai flowers in late winter or early spring and is pollinated by bumblebees, which also live in the Arctic; actograms recorded two bumblebees foraging under 24-hour Arctic daylight.

• describe State whether kōwhai is a short-day or long-day plant with evidence, name the kōwhai shoot’s tropic response (negative geotropism) and the bumblebee’s movement response to nectar (positive chemotaxis / trophotaxis), and describe a named biological rhythm. Achieved
• explain Explain the short-day evidence via critical night length, the advantage of negative geotropism and of positive chemotaxis, the auxin mechanism behind the geotropic response, and how the actograms show an entrained, endogenous rhythm in the bumblebee. Merit
• discuss Discuss why flowering timed to avoid frost and drought, and synchronised with bumblebee foraging (itself endogenous — evidenced by the Arctic actograms under constant light), increases cross-pollination and so reproductive success for both species. Excellence

Question Three — Cooperative breeding

Chestnut-crowned babblers live in groups of up to about 25, cooperatively finding food, preening, nesting, and breeding. One large clutch is raised by roughly 4 breeding males and up to 12 non-breeding helper-males; unrelated females do not help raise chicks.

• describe Define territory and kin selection, and describe one advantage of group foraging and one of mutual preening. Achieved
• explain Explain how a defended territory raises survival and reproduction chances, why kin selection predicts helper-males (who share alleles with the chicks) will help while unrelated females will not, and give two named benefits of social behaviour. Merit
• discuss Discuss how territory defence and cooperative food-gathering and preening raise chick survival and reproductive success, then discuss kin selection specifically — helper-males pass on shared alleles by raising related chicks even without breeding themselves, while unrelated females have no shared alleles to gain from helping. Excellence

The 2023 paper ↗ Marking schedule ↗

Question One — Abiotic responses

Tulips are pollinated by wind or animals and show thermonasty, photonasty, negative geotropism, and positive phototropism — even after being cut and placed in a vase.

• describe Define tropism and nastic response, and give one advantage each of negative geotropism and positive phototropism. Achieved
• explain Explain the advantage of negative geotropism (keeps a cut stem upright) and positive phototropism (light for photosynthesis and pollination), and explain thermonasty and photonasty as flower-opening responses tied to pollination. Merit
• discuss Discuss the tropic and nastic responses working together — flowers open only in warm, sunny conditions when pollinators are active — and link the resulting increase in pollination to greater reproductive success, genetic variation, and population size. Excellence

Question Two — Aggressive behaviour

The Chillingham wild cattle are a small (40–60), genetically closed herd with a bull dominance hierarchy. The alpha bull ("king") settles most challenges by ritualised display, occasionally escalating to full-contact fighting.

• describe Define hierarchy, and describe one advantage each for the king and for the females of having a hierarchy. Achieved
• explain Explain how the hierarchy raises the king’s and the females’ chances of reproductive success, how intraspecific competition ensures only the fittest bulls breed, why ritualised rather than full-contact fighting avoids injury, and when fighting escalates. Merit
• discuss Discuss ritualised and full-contact fighting together as strengthening the herd overall, including the advantages to the king and the females, and discuss why escalation to full-contact fighting is costly — it can remove alleles from an already small gene pool, reducing survival and reproductive success. Excellence

Question Three — Salmon homing behaviour

Masu salmon home back to the stream they hatched in to spawn, apparently guided by imprinting on chemicals from that stream. After spawning, many adults die, and there is no parental care.

• describe Describe one navigation method used to find the stream (e.g. chemical / scent cues, the magnetic field) and one taxic response used to move up it (positive rheotaxis), and describe one advantage of homing. Achieved
• explain Explain the homing mechanism and its advantage, the navigation method and its advantage, and the advantage of producing a very large number of young. Merit
• discuss Discuss why successful homing to the natal stream matters for the survival of the young and the species, and discuss the r-strategy — producing huge numbers of young with no parental care — as a successful reproductive strategy given mass mortality at every stage. Excellence

Grades above are the schedule’s Describes / Explains / Discusses columns condensed to their essentials, not the literal evidence-point count — the real cut is holistic across all three questions (roughly 8/13/18 of 24 marks). Read the full schedule via the links above before treating any single sentence here as the only correct answer.

Past exams & resources

⏱ Timed opens the paper and starts a countdown matching the exam length. Official NZQA PDFs. If a link 404s, that year’s paper may sit under a slightly different code: browse the NZQA subject page.