Plant & Animal
Demonstrate understanding of the responses of plants and animals to their external environment
Introduction and key word list
Guess what guys, this standard is about animals and plants. If only it was that easy. It is about all the major responses of living organisms to their external environment. You will need to first recap what an ecosystem is and a habitat is, learn the abiotic and biotic factors and then go from there. You will get 3 essay style questions at the end of the year that will be directed by bullet points. Below I have started to add some links that will help but it is only the beginnings. For this topic there seems to be a larger focus on understanding the niche than previous years so make sure you have a good grasp of what that is. Also Practice old exam questions, yes it has changed but not to a huge extent.
Remember to not apply anthropomorphism to you answers – giving organisms human qualities. Don’t say ‘the plants think that …’ because plants do not think but rather respond to the abiotic and biotic factors in the environment.
Stimuli to know (learn these)
a) Temperature thermo
b) Water hydro
c) Gravity geo or gravi
d) Touch thigmo
e) Light photo
f) Chemicals chemo (Many organisms including plant growth)
g) Water current Rheo (Salmon and some spawning fish)
Biotic and Abiotic Factors
A habitat is made of physical (abiotic) and living (biotic) factors. A habitat is not necessarily a geographic area — for a parasite it is the body of its host.
The ecological niche describes how an organism or population responds to the distribution of resources and competitors (for example, by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (for example, limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey). "The type and number of variables comprising the dimensions of an environmental niche vary from one species to another and the relative importance of particular environmental variables for a species may vary according to the geographic and biotic contexts".
This is super important to learn as this may be a major focus in questions this year!
- Its habitat (abiotic and biotic factors, including any if it's requirements)
- Its adaptations (any structural, physiological or behavioural traits that enable to survive in its habitat)
- Its role (e.g. producer, how it fits into a food web or interacts with other species
•Niche The limits, for all important environmental features, within which individuals of a species can survive, grow and reproduce.
The 'occupation' or 'profession' of an organism or species.
The ecological niche of the maggot is moist and dark, with a food supply for growth and development into an adult. For the maggot an adaptive advantage is that it can avoid light and possible desiccation or predation, but also it can locate dark places, which is likely to be where its food supply is (inside moist bodies).
The ecological niche of the barnacle is exposed, tidal, subject to wave action and often densely populated, with a fixed / sessile way of life. For the barnacle an adaptive advantage is being able to locate a suitable environment with other successful barnacles, reducing chances of predation within a dense population and being able to attach firmly to a substrate without being washed away.
For each response you will need to be able to describe:
- the process(es) within each response
- how the responses occur
- the adaptive advantage provided for the organism in relation to its ecological niche
- why the responses provide an adaptive advantage for the organism in relation to its ecological niche
Powerpoint of help Intro to interactions
orientation in space
tropisms - plants
(plants only) – growth towards or away from a stimulus coming from one direction.
towards = positive
away = negative
towards light a positive phototropism, away a negative phototropism
Responses of different parts of the plant
Describe the role of auxin in the control of plant growth
Interpret historical experiments, e.g Darwin and Went Interactive workshop
Describe the effects of other plant hormones (ethylene, abscissic acid, cytokinins) and know some applications of plant hormones in industry. Flash cards to help you learn
Explain how the growth response contributes to the plant’s survival
Analyse and interpret information to explain examples of responses
Auxin is sent from the growing tip. It collects on the lower surface of the shoot and promotes cell elongation on that side, so the shoot bends up. In the root, auxin has the opposite effect – cell elongation is inhibited. This results in the root growing down, instead of up. These responses suit the requirements of the different plant parts; the shoot must photosynthesise so must grow away from gravity, whereas the roots must stabilise the plant so grow down. In orbit there is little gravity to cause the differential in auxin concentration; therefore there is little differential growth so plants struggle with the gravitropic response-roots can’t anchor and shoots can’t get max sunlight / achieve max photosynthesis.
Root: positive gravitropism as it is growing towards gravity. • Shoot: negative gravitropism as it is growing away from gravity . Mechanism: • Auxin / IAA / plant hormone / phytohormone. Purpose: • Shoot: photosynthesis. • Root: stability/ more likely to find water Effect of microgravity: • Roots and shoots unable to detect stimulus / direction of gravity.
Early experiments with growth responses
Gibberellins promote stem elongation. They are not produced in stem tip. Gibberellic acid was the first of this class of hormone to be discovered.
Cytokinins promote cell division. They are produced in growing areas, such as meristems at tip of the shoot. Zeatin is a hormone in this class, and occurs in corn (Zea ).
promotes seed dormancy by inhibiting cell growth. It is also involved in opening and closing of stomata as leaves wilt.
Ethylene is a gas produced by ripe fruits. Why does one bad apple spoil the whole bunch? Ethylene is used to ripen crops at the same time. Sprayed on a field it will cause all fruits to ripen at the same time so they can be harvested.
Effect of wavelength
From Wiki - Phototropism in plants such as Arabidopsis thaliana is directed by blue light receptors called phototropins. Other photosensitive receptors in plants include phytochromes that sense red light and cryptochromes that sense blue light. Different organs of the plant may exhibit different phototropic reactions to different wavelengths of light. Stem tips exhibit positive phototropic reactions to blue light, while root tips exhibit negative phototropic reactions to blue light. Both root tips and most stem tips exhibit positive phototropism to red light. Cryptochromes are photoreceptors that absorb blue/ UV-A light, and they help control the circadian rhythm in plants and timing of flowering. Phytochromes are photoreceptors that sense red/far-red light, but they also absorb blue light. The combination of responses from phytochromes and cryptochromes allow the plant to respond to various kinds of light. Together phytochromes and cryptochromes inhibit gravitropism in hypocotyls and contribute to phototropism.
Apical growth in plants
nastic responses - plants
(plants) – this is a response to a stimulus which is independent of the direction of the stimulus, e.g. Photonastic - the opening and closing of flowers in response to changes in light intensity.
taxes - animals
In animals – a movement towards or away from a stimulus.
(animals and a few mobile plants) – movement of the whole organism towards or away from a stimulus coming from one direction. May be positive or negative.
Towards light – positive phototaxis, away – negative phototaxis
A taxis is where an animal moves away or towards a directional stimulus. The maggot’s behaviour is a negative phototaxis because it is a movement away from the light stimulus detected by different receptors. The barnacle behaviour is a positive chemotaxis. In this case the larva detects and moves towards the chemical, showing a positive response. On detecting the rocky environment its cement glands attach it to the rock. This is a thigmokinesis, as the attachment is as soon as the rock is touched (there is no change in rock intensity)
2 or more receptors which can simultaneously judge the intensity of the stimulus, the animal can find a balance between them. This allows the animal to move directly towards or away from the stimulus
kineses - animals
Rate of movement in an animal is affected by the intensity of a stimuli.
Rate of turning is determined by the intensity of a stimulus. Increased chance of an animal finding favorable conditions.
Speed of an animals movement is determined by the intensity of a stimulus. Increased chance of an animal finding favorable conditions
Ability of an animal to find its way home over unfamiliar terrain. Daylight cues are Daylength – from year to year this does not change. Unreliable is the Weather/temperature – this changes from day to day, year to year (e.g. a cold winter vs. a warm winter).
Migration is the movement of individuals from one geographic location to another.
Mechanisms for animal navigation
including sun compass, visual cues, magnetic field, chemical trails
Movement from a familiar landmark to another until an animal
reaches its destination.
Used over short distances using visual cues.
Animal can detect a compass direction and travel in a straight line
path until it reaches its destination.
Accomplished using magnetic field lines, chemical cues, sound
Determining one’s position relative to other locations.
Requires a map sense and a sense of timing
The ability to orient towards a target area without the use of landmarks and regardless of its direction
Map sense – ability to be aware of the latitude and longitude of an area.
Sense of timing – an internal clock that can compensate for the movement of the sun or stars.
Both are required for solar and stellar navigation.
Methods used for Navigation
Visual cues – animal learns its surroundings. Memorise the shape of coastlines, other topography of the area e.g. trees, streams, hills
e.g. digger wasps
Requires a precise internal clock
Use of the sun to navigate home/migrate. Sun always moves East to west.
Some animals can detect polarised (due to differential absorption, some of the light becomes polarized plane of polarization tells position of sun)
Enables them to detect where the sun is even with the smallest patch of blue sky.
e.g. honeybees – keep the sun on one ommatidium of their compound eye during the outward journey and on a corresponding opposite ommatidium on the return journey.
Bee indicates where a food source is to the hive, by doing one of two dances.
Round dance – points directly to a food source within 50m
Waggle dance – bee traces a figure 8. The axis of the waggle (in regards to the vertical nature of the comb in the hive) indicates the direction of the food in relation to the direction of the sun.
The number of waggles indicates the distance.
Fewer, slower waggles the further away the food is.
Birds – fly mainly during the day
Compensate for the changing direction of the sun related to time of day.
e.g. northern hemisphere bird flying south in autumn
Q9am flies 45º left of the sun
Q3pm flies 45º right of the sun
Retard internal clock with artificial light-dark cycles and the bird will fly in direction based on perceived time. Reset internal clock.
e.g. retard by 6 hours; bird released at 3pm sees sun at 9am and will fly west.
Star compass orientation similar to sun compass.
• Groups and geometric patterns of stars are important.
• Generally based on the brightest (northern stars) stars as they move the least during the night.
• Rotational axis of star field (around North and South celestial poles) is important
• Requires precise internal clock
• Animal has a magnetic compass
• Able to follow the magnetic field lines of the earth
• Direction and position derived from direction and inclination of field components
• Some animals have small amounts of magnetite in their brains these respond to magnetic fields and information is transferred to nerve endings and processed by brain
• Used by pigeons, whales, dolphins, turtles, salamanders, some bacteria, some bees
• Magnetic storms, over magnetic anomalies and orientation in room with manipulated magnetic field animals navigation disrupted
An excellent powerpoint covering this part.
Orientation in time
First make sure you understand circadian rhythms, a good link is here. If the rhythm were exogenous it would happen at any time of the year and not at the same time each year.
Diurnal, nocturnal, crepuscular
Crepuscular, nocturnal, and diurnal are all terms used to describe the time of day that certain animals are active. When an animal is said to be "crepuscular" it means that that animal is active during the twilight hours at dawn and dusk. Nocturnal animals are only active at night. Many of these animals have specially adapted vision to help them see in the dark, and they often have excellent hearing as well. Animals that are only active during the day are diurnal. This can have great advantages for animals that have poor visibility like humans.
A great PowerPoint covering this part of the topic. Credit to Hagley's 13 Biology teacher.
Astronomical cycles creates environmental cues
This is a rhythm that is controlled by the external environmental stimuli detected by the organisms.
Controlled by an internal Biological clock.
Circadian – daily activity period (24hrs)
Circatidal – Tidal period (12.4hrs)
Circasemilunar – spring/neap tide (14.7 days)
Circalunar – monthly activity (29 days)
Circannual – yearly activity (365 days)
This is a rhythm that is controlled by the external environmental stimuli detected by the organisms.
These are internal timing system which continue without external time cues.
They control the timing activities of plants and animals.
What they do?
Control of daily body rhythms such as sleep, blood pressure, temperature, blood cell count, alertness, urine composition, metabolic rate and sex drive.
Reproductive timing i.e. animals in heat, courtship rituals, simultaneous release of sperm and eggs into water.
Animals may migrate to and from breeding grounds twice a year, and have many annual cycles of reproduction and hibernation.
This is the way that animals survive over winter, usually by slowing down their metabolism. Small animals are particularly susceptible to the cold as they have a large surface area to their volume and can lose heat rapidly.
This is a form of summer hibernation. When the soil gets too dry, earthworms will dig down deep and curl into a ball, secrete mucus and will aestivate until the soil becomes moist again.
- Vary from person to person
- Children sleep about 12 hrs per night
- Teenagers sleep about 9 hrs per night
- Adults on average sleep about 7-8 hrs
- Elderly people make do with 6hrs (and nap during the day.)
This rises during the day and drops at night, the lowest point being at 3 am.
This keeps in step with temperature.
This varies during the day. We are more sensitive to the pain of a needle at noon, but are more sensitive to the pain of cold at night.
Birth and Death
You are most likely to be born or to die in the early morning
Some animals synchronise their behaviour with the phases of the moon.
The positions of the sun and moon generate our tidal patterns, so the response to these tidal changes during a 24hr period is considered to be a lunar cycle.
The ovulatory cycles of primate females is about 4 weeks long but there is no firm evidence that these are synchronised with the lunar month.
The spawning behaviour of certain marine worms is synchronised by the moon, which ensures that eggs and sperms will be released at the same time.
The spawning of the palolo worm is governed by a combination of tidal, lunar and annual rhythms.
- The Grunion is a fish that spawns on land. From April to June, on the 3 or 4 nights that the spring tide occurs at precisely high tide, the fish squirm onto the beach. The female buries her tail in the sand. The male wraps around her to release sperm. Then they catch the outgoing tide. By the time the tide next reaches that part of the beach, 15 days later, the young grunions have hatched and catch a ride out to sea.
- Arrhythmic ( No regular pattern) - These organisms are usually found in areas where changes in the micro-climate are negligible. E.g. in caves, deep under the ocean or soil.
The following video is by NZ teacher Chris Clay, excellent videos.
Understand entrainment, free running, period and phase shift
Biological clocks are self sustaining oscillators which will continue a period of free-running cycling even in the absence of external cues. However, clocks are usually linked to and can be reset by the environment via cues (i.e., Zeitgeber). Such entrainment keeps an organisms clock synched to its surrounding conditions.
Timing response in plants ie. photoperiodism
- Understand the control of flowering in short day, long day and day neutral plants in terms of the phytochrome system and the critical day length.
An excellent powerpoint can be found here
- Interpret experimental results on day/night length and flowering.
In plants the phytochrome system controls flowering. Pfr is converted from Pr during the day. Pfr formed during the day breaks down to Pr overnight. The longer the night, the lower the Pfr concentration. When the night length gets to a critical level the fuchsia flowers. In animals the SCN in the brain controls the biorhythm , detecting changes in daylength. When it gets to a critical length the tui will court and breed. / In diurnal animals the pineal gland produces the hormone melatonin to promote sleep / Biological clock produces an endogenous rhythm that controls internal timing and can be entrained by a zeitgeber such as daylight, temp or similar... By ensuring activities happen at a certain time of year the tui can maximise the resources available, eg young appear when fuchsia is flowering (providing food). Similarly the fuchsia guarantees pollination by flowering when many pollinators, such as tūi, are present.
Powerpoint covering biological clocks
Vernalization is the acquisition of a plant's ability to flower in the spring by exposure to the prolonged cold of winter, or by an artificial equivalent. After vernalization, plants have acquired the ability to flower, but they may require additional seasonal cues or weeks of growth before they will actually flower. Vernalization can also refer to herbal (non-woody) plants requiring a cold dormancy to produce new shoots and leaves. 
Many plants grown in temperate climates require vernalization and must experience a period of low winter temperature to initiate or accelerate the flowering process. This ensures that reproductive development and seed production occurs in spring and summer, rather than in autumn. The needed cold is often expressed in chill hours. Typical vernalization temperatures are between 5 and 10 degrees Celsius.
Vernalisation of the meristem appears to confer competence to respond to floral inductive signals on the meristem. A vernalised meristem retains competence for as long as 300 days in the absence of an inductive signal (Taiz and Zeiger, 2002) . It is possible to de-vernalise a plant by exposure to high temperatures subsequent to vernalisation (Lang, 1965; Taiz and Zeiger, 2002).
Competition for resources
Competition is an interaction Between organisms or species in which the fitness of one is lowered by the presence of another. Limited supply of at least one resource (such as food, water, and territory) used by both can be a factor.
Animation covering this topic can be found here
Excellent PowerPoint link
Powerpoint link - Competition
Both animals benefit from a relationship
- wrasse and some shrimp cleaning larger fish. Cleaner gets food, bigger fish have parasites removed.
- mixed herds grazing, one warns of danger all warned
- ants and aphids, ants get honeydew and aphids get protection
Mutualism involves an intimate association between two species that offers advantages to both.
birds pollinating plants while getting nectar
Cleaner fish getting food
Symbiosis (not part of the standard but an interesting interaction).
In commensal relationships two species form an association where one organism benefits and the other is neither harmed or helped.
Murica! An excellent video showing this though..
An organism produces one or more biochemicals that influence the growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have beneficial (positive allelopathy) or detrimental (negative allelopathy) effects on the target organisms. Allelochemicals are a subset of secondary metabolites, which are not required for metabolism (i.e. growth, development and reproduction) of the allelopathic organism. Allelochemicals with negative allelopathic effects are an important part of plant defense against herbivory.
Antibiosis (not part of the standard but an interesting interaction).
Antibiosis relationship where one is harmed and the other is indifferent
- human waste in rivers, humans unaffected, fish harmed
- fungi producing waste products the inhibit bacterial growth
Predation is a form of exploitation where a predator species feeds on living prey species.
•The parasite exploits the resources of the host (e.g. food, shelter, warmth) for its own benefit.
•The host is harmed but usually not killed
•For example caterpillar host to wasp larvae.
competition for resources
- Give examples and adaptive advantage for the inter-specific and intra-speciific interactions.
a) Intraspecific competition is said to be ‘density dependant”. Explain what this means: Intraspecific is at its greatest when populations are at their highest – if resources are limited.
b) Give an example of courtship behaviour shown by an animal and explain what the purpose of this behaviour is: Displays by the peacock – to show the penhen that we is
c) Describe how geese work together to reduce the amount of energy expended while flying: The geese take turns at flying at the front (expending the most energy) to reduce the amount of energy needed by the whole group.
d) Describe how penguins work together to reduce the amount of energy needed to survive cold winters: Each penguins spend some time on the outside of the huddle, where it is coldest. They then move towards the centre where it is warmer. If the penguins did not group all would die from the cold.
Describes the natural layering of ecosystems that occurs at distinct altitudes due to varying environmental conditions. In New Zealand the barnacle species show a good pattern of zonation at the rocky sea shore.
A video talking about the oceans zonation patterns.
There is vertical stratification in any ecological community. An ecosystem can be subdivided by the layers of its vegetation. Stratification is determined especially by the sizes and kinds of plants present.
A forest community typically includes a canopy, an understory layer, shrubs, an herb/ground layer, and the forest floor, including roots and soil.
- The canopy is the primary site of energy fixation. It influences the amount of sunlight that penetrates deeper into the forest.
- The understory typically includes tall shrubs and smaller trees. These must be shade-tolerant since they're growing under the canopy trees.
- The shrub layer varies depending on the kind of and location of the forest. For example, there may be differences in the shrub layer of north- vs south-facing slopes within the same forest.
- The types of plants in the herb layer vary depending on the soil humidity and the deepness of shade in an ecosystem.
- The forest floor is mainly a site of decomposition. Fallen leaves and dead plants and animals are returned to the soil.
aggressive behaviour towards another member of the same species involving threats, submissions, chases and physical combat. Agonistic behaviour is a contest to determine who gains access to a resource. (Does not include predatory aggression for obtaining food)
•Conflicts between members of the same species are usually resolved with ritualistic behaviour. This prevents serious injury to the combatants.
•Fighting to the death is non-adaptive to most animals. Only occurs when eliminating a stranger from another group.
•The more scarce the resource the more intense the fighting.
•Belligerent behaviour by an animal that threatens to harm or kill another animal with which it is competing.
•Combat is more likely to be physical if it is essential to the survival and reproductive success of the competitors.
•Natural selection favours a quick end to combat to prevent the winner from becoming too injured, to be able to take advantage of the resources won.
•Fighting between males for mates is common. Winner mates with female and passes on genes for successful fighting. Selection may cause males to become larger than females (sexual dimorphism).
•A territory is an area defended against other members of the same species.
•It provides food, water supplies, nesting areas, and refuges from danger.
•Ownership of a territory is signaled by vocalisations, scent marking, visual displays.
•Boundary marking warns against accidental intrusion by others of its species.
•Another animal is only likely to attempt to dislodge the owner of the territory if it has a chance of being successful.
•Territorial behaviour is reinforced by natural selection where the benefits to the species outweigh the risks and the energy costs of defending the territory.
•Territories help to regulate the population to a size that can be supported by the available resources.
•Territorial behaviour varies widely. Most animals have a definite home. The area the animal covers regularly in search of food and mates is the home range. This area is not defended.
•The part of the home range defended against others of the same species is the territory. •Aggressive behaviour is used to hold on territories.
Marking and Defending
Vocalisations – e.g. birds singing on boundaries of their areas at dawn and dusk
Scent – e.g. marking with urine (dogs and cats) or faeces
Scent glands – special glands produce chemo markers.
e.g.: on rump, between horns (deer), wrists (lemur), behind ears (cats)
Physical gesturing – crabs wave claws at edge of territory
a form of animal social structure in which a linear or nearly linear ranking exists, with each animal dominant over those below it and submissive to those above it in the hierarchy. Dominance hierarchies are best known in social mammals, such as baboons and wolves, and in birds, notably chickens (in which the term peck order or peck right is often applied).
In most cases the dominance hierarchy is relatively stable from day to day. Direct conflict is rare; an animal usually steps aside when confronted by one of higher rank. Temporary shifts occur; for instance, a female baboon mated to a high-ranking male assumes a high rank for the duration of the pair bond. An individual weakened by injury, disease, or senility usually moves downward in rank. Wiki article covering the following in detail. LINK
1. What is an “alpha” individual? The top ranked individual in a linear hierarchy.
1. What is a “subordinate”? Individuals ranked lower than the alpha individual in a linear hierarchy.
What does being a high rank individual get you? More food, more mates
Give examples and explain ways hierarchies are maintained: Displays, biting, pecking, showing teeth, sounds, postering submissive/dominant postures
What are the advantages of maintaining hierarchies? Reduced aggression, individuals that are not allowed to breed helping raise others young, more efficient food finding
Examples from previous exams
By working together, the pūkeko can hold a larger, better quality territory. This means more resources for all members of the group, including submissive members. Cooperative interaction involves all group members helping to rear young. The hierarchy and use of displays rather than actual fighting, reduces conflict and harm within the group, as well as ensuring the dominant individuals are selected prior to breeding. The dominant and stronger members will pass on stronger/ successful genotypes / alleles / genes and therefore phenotypes, meaning that the next generation is strong enough to maintain the territory. Cooperative raising of the young means that the chances of their survival into adults is improved and so is the survival of the entire group. Those who asist with raising the young may not be able to breed or may be less successful breeding within the hierachy, but they do get to pass on their genes via kin selection. All individuals are protected if the group is strong.
The baboon hierarchy is a complex social organisation and not linear, as there are subordinate groups and affiliations within the overall group, such as mating pairs and families and associations are constantly changing. There is an alpha male in overall charge. AND Eg the group structure allows greater opportunity to locate food and greater survival chances for individual group members when conditions are difficult, or in the presence of predators./ Dominant males usually mate with the strong females to ensure genes are passed on and strong leadership continues, which ensures more “fit” individuals are produced and are therefore more likely to survive./ The group provides greater care for young through social bonding and increases chances of survival of the individuals into adulthood.
Includes group formation, pair bond formation and parental care.
Requires a form of communication that can be visual, vocal, chemical or tactile.
Advantages of group behaviour
Hunting - work as a team to kill prey. E.g. wolves, lions, wild, dogs.
Defence – form defensive circles or post guards to watch for danger whilst rest of group feeds. E.g. Himalayan yaks (circles), baboons (guards).
Protection – Dolphins protect mothers during birth process and help carry baby to surface until it has learned to breathe. Baboons, mother and young in safest position in the pack (centre).
Insect societies – organisms specialised to carry out aspects of maintenance of nest or hive. Centred around a queen who co-ordinates group with pheromones.
Clumping – confuses predators, difficult to pick out individuals. E.g. shoals of fish, flocks of birds
Breeding – Many groups from for breeding purposes. Safest breeding sites are in the centre of the group.
E.g. penguins, gannets, gulls
Courtship and Pair Bond Formation
•Animals tend to keep an individual distance from each other, even those in groups. Invading another's space is a threat.
•Courtship behaviour often shows the conflicting tendencies to attack and yet allow the closeness of mating.
•Sex is adaptive as it requires:
Temporary suppression of aggressive behaviour
A system of communication, and species recognitiono reproductive behaviours,
Large numbers of gametes are released (an r- strategy) so that there are increased chances that reproduction will happen and some offspring will survive.