← Responses of plants and animals to their external environment

10 What actually comes up

Every paper here asks three long-answer questions, each built round a real, often unfamiliar species: one on a plant response, one on animal orientation, navigation or rhythms, and one on social behaviour. Each question is marked as one answer, from N0 to E8, so the site splits it into three tiers: describe (what an Achieved answer covers), explain (Merit) and discuss (Excellence). Each tier links a worked answer that builds on the one below it. Eleven of these twelve questions want the Excellence answer to end on survival or reproductive success; see the ⭐ answer chain in the first section.

Across 4 years

12 questions · 36 parts 12 Achieved 12 Merit 12 Excellence

The pattern — what to prepare

Topic	Appears in	Grade level	What to practise
Ending the discussion on survival or reproductive success	11 of 12 questions, 2022–2025	E	End every discussion paragraph with an explicit "…which increases reproductive success" link — see the ⭐ answer chain in "Reading the notation". The one exception, 2025’s poinsettia question, asked why growers change the light instead.
One plant-response question (tropism, nastic response, or flowering time)	4/4 years: Q1 in 2023 and 2025, Q2 in 2024, Q3 in 2022	A–E	Know tropism against nastic cold, with the sign (positive or negative) and the stimulus — see "Plant responses".
One rhythm, orientation or navigation question	4/4 years	A–E	Practise naming the specific taxis or rhythm, its cue or zeitgeber, and how the animal finds its way — see "Animal orientation behaviour", "Navigation" and "Biological rhythms".
One social-behaviour question (hierarchy, territory, kin selection, cooperative breeding)	4/4 years	A–E	Learn hierarchy, territory, agonistic behaviour, kin selection (always say the animals are related) and altruism precisely — see "Social behaviour & spatial behaviour".
A named real species in an unfamiliar scenario, never a generic "a plant" or "an animal"	Every question, every year	—	Practise transferring the definitions to an unfamiliar organism under exam pressure — the biology is the same, only the species changes.
Weighing costs against benefits before concluding	2022, 2023, 2025	E	An Excellence discussion is rarely one-sided — name at least one specific cost (energy, injury, predation risk) alongside the benefits, then conclude explicitly that the benefits outweigh it — see "Weighing a behaviour's cost against its benefit" in Social behaviour.
Short-day and long-day plants and the critical night length (the phytochrome system itself only in 2025)	2022, 2024, 2025	A–E	Know that it is the NIGHT length that is measured — see "Photoperiodism". Bring in P_r and P_fr only when asked: the 2022 and 2024 reports both note candidates writing about phytochrome when the question was about something else.
A named navigation method, and when it works (day, night, cloud, open sea)	2022, 2023, 2025	A–E	A sun compass works only when the Sun or the polarised sky can be seen; stars work at night with a clock; the magnetic field works anywhere — see "Navigation over long distances".
The auxin mechanism behind a named tropism	2022, 2024	A–M	Say which side auxin collects on (away from touch or light, on the lower side under gravity) and that it makes those cells elongate — see "Plant responses".
A relationship between species (predation, competition, parasitism)	2022, 2024	A–E	Name the relationship, say who gains and who loses, then link each to survival — see "Relationships between species" in Social behaviour.

not tried got it to review 2025 Poinsettia photoperiodism, honey bee navigation, and a wolf hierarchy 9 parts

The 2025 paper ↗ Marking schedule ↗

Question One — Phytochrome system

Poinsettia (Euphorbia pulcherrima) is a short-day plant. Most New Zealand native plants are long-day plants, which flower in summer, when days are long and nights short. Growers use photoperiodism and the phytochrome system to bring poinsettia into flower during a New Zealand summer. The paper’s Figure 2, greyed out in NZQA’s public copy, compares a short-day plant under several 24-hour patterns of light and dark, among them a short night, a long night, and a long night broken by red light and then far-red light.

Not tried yet: describe Describe photoperiodism, the difference between a short-day and a long-day plant (Figure 2), and the phytochrome system.Worked solution → Achieved
Not tried yet: explain Explain how the phytochrome system controls when a short-day plant and a long-day plant flower, and how growers could make poinsettia flower in a New Zealand summer.Worked solution → Merit
Not tried yet: discuss Discuss the phytochrome system, and justify why New Zealand growers change the light and dark hours to make short-day plants such as poinsettia flower in summer.Worked solution → Excellence

Question Two — Honey bee behaviour

The honey bee (Apis mellifera) is active by day, and its pollen foraging is tied to its circadian rhythm. Bees find their way around and back to the hive by cues from their surroundings, including the Sun’s position as a compass, and can forage 5 km out and still get home when cloud hides the Sun. In a total solar eclipse the Moon covers the Sun completely, so bees meet darkness at a time they normally would not. Biologists compared foraging on an ordinary day with the day of a total eclipse. Their graph (Figure 4) is greyed out in NZQA’s public copy; as the schedule reads it, ordinary-day foraging climbs through the morning to a peak near 1:30 pm and eases off slowly in the late afternoon, while on the eclipse day it is normal until the eclipse, falls to a handful of bees in totality, comes back only slowly, and stays under the ordinary day until after 3 pm, when it rises above it.

Not tried yet: describe Describe the honey bee’s diurnal circadian rhythm, the cues it uses to find its way home, and its foraging on a normal day and on the eclipse day.Worked solution → Achieved
Not tried yet: explain Explain how the circadian rhythm is linked to the sun compass, which homing cues bees use on sunny and on overcast days, and the foraging on each of the two days.Worked solution → Merit
Not tried yet: discuss Discuss the behaviour of honey bees on a normal day and on the day of a total solar eclipse, including why some bees kept foraging in the eclipse’s darkness.Worked solution → Excellence

Question Three — Behaviour in grey wolves

Grey wolves (Canis lupus) live in packs of about 2 to 20 closely related animals that form a hierarchy, in which agonistic behaviour (dominance displays, submissive displays and threats) matters. The paper’s figure ranks the pack. The alpha male and female lead decisions, including cooperative hunts and defence of the territory; they are monogamous and the only pair to breed. Betas, of either sex, are second in command and help keep order on hunts and in other pack activities. Deltas follow the alphas and betas, help hunt, look after pups and help defend the territory. Omegas rank lowest: they receive the most aggression, eat last and eat least.

Not tried yet: describe Define hierarchy and territory, and describe how the pack’s hierarchy is kept, how pack members show kin selection, and an advantage and a disadvantage of living in the pack below the alpha pair.Worked solution → Achieved
Not tried yet: explain Explain how the hierarchy is maintained, why pack members show kin selection, and an advantage and a disadvantage, for a wolf below the alpha pair, of living in the hierarchy rather than alone.Worked solution → Merit
Not tried yet: discuss Discuss the advantages and disadvantages of hierarchical behaviour in a wolf pack for the wolves below the alpha pair, compared with living alone.Worked solution → Excellence

2024 Kauri snail predation, kōwhai biological clocks, and babbler cooperation 9 parts

The 2024 paper ↗ Marking schedule ↗

Question One — Relationships in the forest

Kauri snails, or pūpū-rangi (Paryphanta spp.), are northern giant land snails that evolved in New Zealand before two nocturnal predators, possums and hedgehogs, were introduced. They live in fertile soil full of earthworms and can live 20 years or more. They are most active at night and spend the day under leaf litter or plants. Their droppings show they eat mainly earthworms and some small snails, whose shells supply calcium. They mate mostly from April to July, apparently set off by weather such as rain, and lay about six eggs three times a year, in a hole they dig or under leaf litter at the foot of a tree. Hedgehogs (Erinaceus europaeus) are also out at night and eat kauri snails; where it is cold they may hibernate for some months of the year, once the ground falls below 11 °C. Brushtail possums (Trichosurus vulpecula), also nocturnal, eat kauri snails too, spotting the slow snails from up in the trees.

Not tried yet: describe Describe the relationship between the kauri snail and the possum and between the possum and the hedgehog, an advantage and a disadvantage for the snail of being active at night, and the snail’s egg laying, the hedgehog’s hibernation and the possum’s nocturnal behaviour.Worked solution → Achieved
Not tried yet: explain Explain the advantage and the disadvantage of night activity for the snail, and how laying three times a year, hibernation and the possum’s nocturnal behaviour each support survival.Worked solution → Merit
Not tried yet: discuss Evaluate reasons for the coexistence and survival of these species in Northland.Worked solution → Excellence

Question Two — Bumblebees and kōwhai

The kōwhai (Sophora spp.) is a native New Zealand tree whose bright flowers open in late winter or early spring. Auxins act at every stage of its life, from root development to growth and flowering. Once it flowers, animals such as the bumblebee (Bombus terrestris) pollinate it. In New Zealand the bumblebee forages by day, but most actively in the cooler parts of the day. The same species lives in the Arctic too, where summer daylight lasts all 24 hours, and an experiment there recorded a colony’s foraging under that constant light. Figure 1, double-plotted actograms of when two of its worker bees foraged, is greyed out in NZQA’s public copy; as the schedule reads it, the bees foraged in distinct daily bouts rather than around the clock.

Not tried yet: describe Describe whether kōwhai is a short-day or a long-day plant, with evidence; the geotropic response of its shoots and the part auxin plays; the bumblebee’s movement response to the nectar; and the biological clocks of both species.Worked solution → Achieved
Not tried yet: explain Explain the evidence for kōwhai’s type of plant, the mechanism and the advantage of its shoots’ geotropic response, the advantage of the bumblebee’s response to the nectar, and whether both species have biological clocks entrained to environmental factors (Figure 1).Worked solution → Merit
Not tried yet: discuss Discuss how the control of life processes through biological clocks results in kōwhai success.Worked solution → Excellence

Question Three — Cooperative breeding

Australian chestnut-crowned babblers (Pomatostomus ruficeps) live in social groups of up to about 25, dust-bathing, preening and feeding together. They search for food as a group: insects, spiders, small amphibians, crustaceans and reptiles, and fruit and seeds. At night they crowd into one large central nest; when alarmed they huddle under thick foliage or fly up into the lower canopy, chattering loudly. Breeding runs from about July to November, with one large clutch from all the breeding pairs. The whole group builds the single nest, feeds the incubating females and defends the breeding territory, and a pair seldom tries to breed without help. There are often about 4 breeding males and as many as 12 helper-males that do not breed. Kin selection seems to matter: females will not help care for young they are not related to.

Not tried yet: describe Define territory and kin selection, and describe an advantage of finding food as a group and of preening each other, why the helper-males help with the chicks, and why the unrelated females do not.Worked solution → Achieved
Not tried yet: explain Explain how the territory and the group’s social behaviour help the babblers survive and breed, why the many helper-males support the population, and why the unrelated females do not help raise the young.Worked solution → Merit
Not tried yet: discuss Examine how social behaviour can lead to successful reproduction in the chestnut-crowned babbler.Worked solution → Excellence

2023 Tulip tropisms, cattle dominance, and salmon homing 9 parts

The 2023 paper ↗ Marking schedule ↗

Question One — Abiotic responses

Tulips flower in spring and are pollinated by the wind or by animals. Decades of study have shown how they respond to their abiotic surroundings: they show geotropic responses and both thermonasty and photonasty, and even when cut and standing in a vase they still show geotropism and phototropism.

Not tried yet: describe Define tropism and nastic response, and describe the tulip’s negative geotropism and positive phototropism, an advantage of each, and its thermonasty and photonasty.Worked solution → Achieved
Not tried yet: explain Explain an advantage to the tulip of negative geotropism and of positive phototropism, and how thermonasty and photonasty each help pollination.Worked solution → Merit
Not tried yet: discuss Discuss how these responses help to ensure the success of the tulip.Worked solution → Excellence

Question Two — Aggressive behaviour

No other cattle in the world have stayed as pure as the Chillingham wild cattle, which have never bred with an outside herd. They still roam their historic home, a 365-acre park in England walled off in the 13th century for food and hunting, and are thought to descend from the original wild oxen of England. They number only about 40 to 60, and that is the whole world population. The bulls form a dominance hierarchy whose alpha bull is called the “king”. A challenge is usually settled by ritualised fighting, a show of bellowing, pawing at the ground and flinging dirt and debris about, but now and then one escalates to a full-contact fight that ends in injury or death.

Not tried yet: describe Define a dominance hierarchy, and describe an advantage of the hierarchy for the king and for the females, ritualised fighting, and when fighting may become physical.Worked solution → Achieved
Not tried yet: explain Explain how the hierarchy benefits the king and the females, and why fighting is usually ritualised but sometimes escalates to a physical fight.Worked solution → Merit
Not tried yet: discuss Discuss the behaviours that have led to the success of the herd.Worked solution → Excellence

Question Three — Salmon homing behaviour

Masu salmon (Oncorhynchus masou) are native to north-east Asia. Like all salmon they home very well, coming back to breed in the stream they hatched in, apparently because as young fish they imprinted on chemicals in that stream. In the river the females release eggs and the males swim over them releasing sperm, which is spawning; many adults die afterwards, and neither the fertilised eggs nor the young get any parental care. The paper’s photos show the fish just hatched, very young, as young fish heading downstream to the sea, and as adults heading back upstream.

Not tried yet: describe Describe a navigation method the salmon uses to get from the sea to its stream, the taxic response that takes it upstream, an advantage of homing, and the salmon’s strategy of having a lot of young.Worked solution → Achieved
Not tried yet: explain Explain how the salmon navigates home and moves up its stream, an advantage of homing, and why having a lot of young is a successful reproductive strategy.Worked solution → Merit
Not tried yet: discuss Discuss how the homing behaviour of the salmon ensures their success as a species.Worked solution → Excellence

2022 Stitchbird hierarchy, indigo bunting migration, and golden dodder parasitism 9 parts

The 2022 paper ↗ Marking schedule ↗

Question One — Intraspecific relationships in the hihi

The stitchbird, or hihi (Notiomystis cincta), lives only in New Zealand, and now only on islands or on mainland sites it has been moved to, because of predators such as domestic cats. It breeds in an unusual way, nesting in pairs or in groups; the paper sets group nesting in bold. Hihi defend a territory in the mating season (also bold), which runs through spring and summer. Their dominance hierarchies are well known: older birds dominate younger ones, above all of their own sex, and males dominate females, except when there are chicks at the nest. From the start of the breeding season until egg laying ends, the males sing loudly, and at the nesting area they put on flight displays that show off their white and yellow colouring.

Not tried yet: describe Describe hierarchy, predation and territory, the hihi’s group nesting, and an advantage and a disadvantage of the males’ courtship.Worked solution → Achieved
Not tried yet: explain Explain how a courtship strategy such as singing or flight displays can be both an advantage and a disadvantage for the male hihi, and the advantage of group nesting and of defending a territory only in the mating season.Worked solution → Merit
Not tried yet: discuss Discuss how the hihi’s behaviours work together to support its population size, evaluating how the two bold behaviours maintain the population in protected areas.Worked solution → Excellence

Question Two — Migration of the indigo bunting

The indigo bunting (Passerina cyanea) makes a long journey every year, and migrates only at night. It flies roughly 2000 km each way between its breeding grounds in eastern North America and its wintering grounds, which stretch from southern Florida to southern Central America; the paper shows both on a map.

Not tried yet: describe Define migration, describe the biological rhythm shown and the likely environmental cue for it, and describe a navigation method the bunting could use at night.Worked solution → Achieved
Not tried yet: explain Explain a navigation method for the bunting’s night migration, and how the yearly journey helps the bunting.Worked solution → Merit
Not tried yet: discuss Discuss how, despite the difficulties of a long journey, the yearly migration has enabled the indigo bunting population to be maintained.Worked solution → Excellence

Question Three — Golden dodder parasitism and synchronised flowering

The golden dodder (Cuscuta campestris) has no leaves and no roots and lives off other plants. A growth response lets it wind up and around a host, branching into a tangle that can spread from the first host to the plants around it. It fixes itself to the host with a special organ, the haustorium, which grows into the host’s tissues and draws water and nutrients from them. When it flowers is critical to its reproduction. It picks up environmental cues, night length above all, but little is known about what starts it flowering; it is known that its hosts include both short-day and long-day plants, and that it seems to flower when its host does.

Not tried yet: describe Identify and describe the relationship between the dodder and its host and the growth response that lets it wind around the host, and describe short-day and long-day plants.Worked solution → Achieved
Not tried yet: explain Explain how auxin lets the dodder grow up and wind around its host, how the dodder benefits from its host, and what flowering at the same time as its host does for it.Worked solution → Merit
Not tried yet: discuss Discuss reasons for the success of the dodder, through living off other plants and flowering at the same time as its short-day and long-day hosts.Worked solution → Excellence

Each tier asks the paper’s question at one column of the schedule; its worked answer gives a model answer at that depth and, under “What the marker wanted”, that column’s points in our words. The three questions add up to 24: Achieved from 8, Merit from 14, Excellence from 19 (in 2023, Achieved from 9). A model answer is one good answer, not the only one: read the schedule through the links above.

Practice for this standard covers the whole topic — flashcards and quiz.