prac qs/model answers

Question 1

(dynamic) Equilibrium

Answer 1

refers to a state of balance or stability within a biological system where opposing processes occur at equal rates, resulting in a relatively constant overall condition over time. (eg intake of oxygen and output of carbon dioxide remain in relative equilibrium)

Question 2

carrying capacity

Answer 2

Carrying capacity can be defined as a species’ average population size in a particular habitat. The species population size is limited by environmental factors like adequate food, shelter, water, and mates.

Question 3

ecological niche

Answer 3

the role of a species in an ecosystem: the set of resources it consumes and habitats it occupies, as well as its interactions with other species. ecological niches exert selection pressures that push the populations in various directions.

Question 4

Outline two reasons why the cane toad has
successfully invaded many areas of Australia.

Answer 4

1. The cane toad produces toxins that deter potential predators and native species that haven’t co-evolved defences. This reduced predation allows cane toads to rapidly invade broader areas of Australia.
2. A single female cane toad can lay thousands of eggs at once, and their tadpoles develop quickly in Australia’s warm, humid conditions. This speedy growth allows them to mature rapidly, generating multiple generations in a short span. This accelerated reproductive cycle aids their colonization of new habitats and establishment of self-sustaining populations before local predators or rivals can adjust to their arrival.

Question 5

When were cane toads introduced into Australia?

Answer 5

Cane toads were introduced into Australia in June 193 5 by
Mr RW Mungromery of the Sugar Experiment Station at Meringa, Queensland.

Question 6

Why were cane toads introduced into Australia?

Answer 6

Cane toads were introduced into Australia to control insect pests that were threatening the sugar cane industry, particularly the native cane beetle Dermolepida albohirtum.

Question 7

Explain how it is believed the cane toad, an
amphibian, is able to spread across the arid areas of
Northern Territory.

Answer 7

The spread across the Northern Territory is believed to follow stock routes with the toads moving from cattle dung patch to cattle dung patch following a cattle drive. This way the amphibian can stay in moist environments in the arid environment of the Northern Territory.

Question 8

Explain why the cane toad is considered to be a pest
in Australia.

Answer 8

Cane toads are considered to be a pest in Australia due to their toxic skin secretions, lack of predators, and fast reproduction, causing ecological disruptions by harming native species and biodiversity.

Question 9

The arrival of the cane toad in the Kakadu National
Park is linked to a decline in the northern quoll
population. Suggest a reason for the decrease in
number of quolls.

Answer 9

Quolls are a predator. If the quolls attacked the cane toads as a food source, they could be poisoned and die. Thus quoll numbers would decrease.

Question 10

Assess how the experience with the cane toad impacted
on procedures for biological control in Australia.

Answer 10

The experience with the cane toad was highly important in
showing the need for adequate research and investigation before a species is introduced into Australia for biological control. There is not much evidence to show that the cane toad was successful in the job it was introduced to perform and since then it has become a pest itself. The experience of the cane toad shows that without thorough prior investigation an introduced species can have a major adverse impact on the environment, threaten biodiversity
and require large amounts of time, effort and money to be spent in attempts to solve the problem. From this experience a list of procedures was compiled to ensure that any future introduced biological control species would not repeat the cane toad example. Thus the cane toad experience has been highly significant in the history of biological control and has led to the development of
procedures to ensure biosecurity for Australian fauna, flora and agriculture.

Question 11

In 2008 it was suggested by Rick Shine when he
won the Macfarlane Burnet Award for Excellence
that a small number of tiny cane toads should be
released in advance of the invasion front. Outline
why this proposal would slow the invasion front of
the cane toad across Australia.

Answer 11

Releasing smaller toads in front of the invasion front could slow the invasion front for a couple of reasons - I. Predators in the area would have a higher chance of survival if they tried to eat a small cane toad and would learn cane toads are best avoided. 2. Smaller toads would occupy areas and mate with the advancing front producing smaller offspring at the invasion front. This reduces the ‘Olympic Village’ syndrome where the ‘best’ are mating with the ‘best’ producing bigger and faster offspring each generation.

Question 12

Outline how cane toad invasion has affected other
populations, e.g. red-bellied black snake populations.

Answer 12

Red-bellied black snakes from toad-infested areas would not eat the toads when in captivity, could more ably survive the toad poison and had smaller heads to body size and thus could not eat very large toads. Whereas red-bellied snakes from non-toad areas were likely to grab a toad when in captivity and die from the toad poison and had larger heads compared to body size and grabbed the larger and more dangerous toads.

Question 13

adaptation

Answer 13

a feature of an organism that makes it well suited to its environment. Adaptations enhance an organism’s chances of survival.

Question 14

Biodiversity

Answer 14

refers to the broad range of different kinds of life forms on Earth. ‘Bio’ means ‘living’; ‘diversity’ means ‘variety’.

Question 15

Explain what is meant by the term biological control

Answer 15

‘Biological control’ refers to the use of one organism to control the numbers of another, for example as
a predator.

Question 16

predict the possible consequence for the northern quoll as the cane toad population continues to increase in Australia

Answer 16

The northern quoll is currently listed as Critically Endangered. Further decreases in its numbers could
lead to extinction.

Question 17

summarise how environmental pressures have contributed to population change in Australian native species since the introduction of the cane toad

Answer 17

Cane toads compete with native species for both food and habitats. Their skin contains toxic venom that can also kill native predators, as well as transfer diseases to native frogs.

Question 18

list at least 3 types of adaptations that assist with thermoregulation in animals that live in hot or cold environments.
Explain how the adaptations assist the animal to survive in its environment. (Kangaroos in hot climates)

Answer 18

The large surface area to volume ratio of the kangaroo’s ears is a structural adaptation that allows heat to easily radiate from the surface of the ear, heat is lost from the capillaries (which come closer to the surface due to vasodilation which is a physiological adaptation) to the environment through radiation, thus reducing the internal body temperature of the kangaroo and cooling it down. During hot weather, kangaroos lick their forearms, which promotes heat loss by evaporation. This behavioural adaptation keeps them cool.

Question 19

Polar bears and penguins live in similar polar environments. They have both converged on certain structural features that help them remain warm in polar conditions. List three structural features that are similar in polar bears and penguins and describe how these features help them maintain a stable body temperature.

Answer 19

Layer of fat surrounding the body. This insulates the body and stops heat from being lost.
Outer structural insulation layer (bear, fur, penguins, feathers) insulation reduces heat loss from the body to the environment)
Low surface area to volume ratio. Both polar bears and penguins have a rounded squat shape. (Bears more than penguins) This reduces the surface area from which to lose heat

Question 20

How are selection pressures a driving factor of evolution

Answer 20

Selective pressures can have a significant impact on the genetic variation in a population. If a selective pressure favours a particular trait or genetic variation, individuals with that trait or variation are more likely to survive and reproduce. These favourable traits are transferred to future generations, while genes that are disadvantageous to survival and reproduction will become more rare. This change in the genetic makeup of a population is called evolution.

Question 21

Hibernation

Answer 21

An inactive state resembling deep sleep in which certain animals living in cold climates pass the winter. In hibernation, the body temperature is lowered and breathing and heart rates slow down. Hibernation protects the animal from cold and reduces the need for food during the season when food is scarce. It is a physiological and behavioural adaptation.

Question 22

Torpor

Answer 22

A temporary drop in body temperature and metabolic rate often accompanied by failure to eat or micturate/defecate, is an adaptation of endothermic vertebrates that enables them to survive the energetic demands of cold ambient temperature. It is a physiological adaptation.

Question 23

Give an example of selection pressures

Answer 23

White coloured pepper moths were higher in abundance before the industrial revolution. The industrial revolution released more carbon and soot into the environment, blackening tree trunks. Due to the selective pressure in the environment, the darker moth had the more desirable trait of being dark and could therefore camouflage to avoid predators and therefore have a higher survival rate than the white peppered moth.

Question 24

explain what is meant by gene flow

Answer 24

• the exchange of genetic material between different populations of a species, often by migration of members of the populations. In vertical gene transfer, the transfer of genetic material is from parents to offspring. It may be through sexual or asexual reproduction. In contrast, horizontal gene transfer is the movement of genetic material from a donor organism to a recipient organism that is not its offspring.

Question 25

explain what is meant by genetic drift

Answer 25

Genetic drift is the change in frequency of an existing gene variant in the population due to random chance.

Question 26

explain what is meant by natural selection

Answer 26

Natural selection is a process where genetic variation within a population leads to individuals having different traits in response to the change in an environment. The Galápagos finches are a classic example of natural selection. These finches have different beak sizes and shapes adapted to their food sources. During a drought, finches with larger beaks were better at cracking tough seeds, making larger beaks a desirable trait. These birds passed down the large beak trait to their offspring, resulting in large-beaked birds being more common in the finch population over time.

Question 27

does a smaller or a larger population favour evolution and why

Answer 27

Large populations favour genetic evolution because they contain a greater diversity of genetic variations. This diversity increases the chances of individuals possessing advantageous traits that help them survive and reproduce. As these traits are passed on to the next generation, they contribute to the overall genetic makeup of the population, driving evolutionary change. Additionally, large populations are less susceptible to genetic drift (random changes in allele frequencies), which can have a stronger impact on smaller populations. This combination of genetic diversity and reduced genetic drift in larger populations promotes the accumulation of advantageous traits and adaptations, ultimately favouring evolution.

Question 28

does random or assortative mating favour evolution and why

Answer 28

Assortative mating occurs when individuals with similar traits mate preferentially, leading to the concentration of specific traits in offspring. This can amplify certain traits, potentially enhancing a species' adaptation to the environment. For example, if individuals with similar beak sizes in birds tend to mate, and larger beaks are more efficient for a particular food source, assortative mating can lead to a higher occurrence of larger beak sizes in the population. This alignment between mates' traits and advantageous traits can help populations adapt more rapidly to changing conditions. In contrast, if mating was entirely random, the genetic diversity within the population would be maintained, but specific traits might not become as concentrated or prevalent. Assortative mating provides a mechanism for traits to become more pronounced in a population, thus favoring the evolutionary process by driving the spread of adaptive traits.

Question 29

does gene flow favour evolution? why or why not

Answer 29

Gene flow favours evolution by introducing new genetic variation into populations. This increased genetic diversity allows for the accumulation of beneficial traits and adaptations over time. As individuals from different populations interbreed, their genetic material is exchanged, and advantageous alleles can spread more rapidly throughout the population. This process enhances the population's ability to adapt to changing environments and promotes evolution.

Question 30

do mutations favour evolution? why or why not

Answer 30

Consider a population of Galápagos finches with different beak sizes due to mutations. If the environment changes, such as a drought leading to larger, tougher seeds becoming more prevalent, a mutation that results in slightly larger beaks might occur in some finches. Those with the mutation can more effectively crack the tougher seeds, gaining an advantage in obtaining food. As a result, they are more likely to survive and reproduce, passing on the beneficial mutation to their offspring. Over generations, the frequency of the larger beak trait increases in the population. Mutations introduce new traits that, when advantageous in certain environments, are favored by natural selection. By creating genetic diversity, mutations increase the likelihood of a species' survival in changing conditions, driving evolution. They are the primary source of variation and therefore favour evolution

Question 31

does natural selection favour evolution? why or why not?

Answer 31

Natural selection is a mechanism that drives the adaptation of species over time. Natural selection acts on heritable traits, promoting the survival and reproduction of individuals with favourable traits. This leads to the accumulation of these favourable traits in a population, resulting in evolutionary changes that have better adapted to the environment, and therefore natural selection favours evolution.

Question 32

identify a factor that tends to increase genetic variation in populations

Answer 32

Mutation increases genetic variation by introducing new genetic variants or alleles. These changes create diverse traits within a population, providing the raw material for natural selection. Beneficial mutations can lead to advantageous traits that improve survival and reproduction. In smaller populations, mutations can have a more significant impact due to genetic drift. Over time, accumulated mutations contribute to the evolution of species and the development of distinct characteristics and an increase in genetic variation.

Question 33

identify a factor that tends to decrease genetic variation in populations

Answer 33

Inbreeding decreases genetic variation by increasing the likelihood of offspring inheriting identical alleles from closely related parents, leading to reduced diversity and a higher prevalence of genetic disorders. Small populations can lead to a decrease in genetic variation through a process known as genetic drift. This phenomenon occurs when chance events have a pronounced impact on the frequencies of alleles within a population. For example, consider a small population of endangered birds residing on a remote island. Owing to their limited numbers, these birds possess restricted genetic diversity. In the event of a significant storm that drastically reduces their population, the alleles carried by the surviving individuals will exert a more significant influence on the overall gene pool. Consequently, specific alleles may become dominant while others are lost, diminishing the population's genetic variability. This reduced genetic diversity can impede the population's capacity to adapt to environmental changes, illustrating the implications of genetic drift in small populations

Question 34

Why do some animals, given the opportunity, move into new environments?

Answer 34

Some animals move into new environments when they experience extreme competition. An example of this is competition for resources. This occurs mainly between a group of the same species in the habitat. When the resources in the environment is smaller than the requirement of the population, one population moves out to look for more resources.

Question 35

plants are unable to move. How might plants disperse to new environments?

Answer 35

Plants disperse to new environments through different methods. Wind dispersal involves lightweight seeds carried by air currents. Animal dispersal happens when seeds attach to animals or are consumed and then deposited in new locations. Water dispersal occurs as seeds float on water surfaces. Self-dispersal involves seed pods that burst, projecting seeds away. Explosive dispersal occurs when seed pods forcefully release seeds. Some seeds attract ants, which carry them to nests (myrmecochory). Lastly, human activities unintentionally transport seeds to new areas, aiding plant migration and expansion.

Question 36

describe the amount of gene flow within a parent population prior to and during the expansion of a species range

Answer 36

Gene flow is the transfer of genetic material from one population to another/

Question 37

explain how cycles of climate change can cause large changes in sea level (up to 200 m)

Question 38

what kinds of physical barriers could isolate different parts of the same population

Answer 38

Physical barriers, such as mountains, bodies of water, deserts, canyons, glaciers, urban areas, vegetation zones, and geographical features, can isolate different parts of the same population. These barriers restrict movement and gene flow between populations, leading to genetic isolation. This can result in the independent evolution of distinct traits and potentially contribute to speciation processes

Question 39

how mighjt emigration achieve the same effect as geographical isolation

Answer 39

Emigration, the movement of individuals out of a population, can achieve effects similar to geographical isolation. By physically separating a group, emigration reduces gene flow between the main population and the emigrant group. This can lead to the founder effect, genetic drift, and local adaptation in the isolated group, fostering genetic differentiation similar to what occurs with geographical barriers. Over time, the physical distance between the emigrant group and the main population can further limit gene flow and promote genetic divergence.

Question 40

how might selection pressures differ for a population that becomes isolated from the parent population? Galapagos finches

Question 41

describe the general effect of the change in selection pressures on the isolated gene pool

Question 42

define speciation

Answer 42

speciation is the formation of a new species once one population becomes so diverse that they are unable to interbreed and produce viable and fertile offspring between species due to factors such as geographical isolation, and behavioural and physiological changes.

Question 43

what is the mechanism for instant speciation? explain why it is more common in plants than in animals

Question 44

in how niche preference could result in the formation of a new species

Question 45

define divergent evolution

Answer 45

w

Question 46

why do populations diverge to eventually form new species

Answer 46

w

Question 47

how would you describe the evolution of the trilobites

Answer 47

hen

Question 48

when was the trilobite group most diverse

Answer 48

e

Question 49

suggest why the trilobites diversified so quickly

Question 50

considering the trilobites existed from 521 million years ago to 252 million years ago, approximately what percentage of their time in existence was spent in the evolution of new trilobite orders

Question 51

how do we know there were so many different trilobites

Question 52

how does natural selection account for divergence

Question 53

what were the differences between darwins and wallaces theories of natural selection

Question 54

explain how the DNA for antibiotic resistance could have arisen

Question 55

explain why antibiotic resistance is proliferating now

Question 56

explain how failing to complete a course of antibiotics can lead to antibiotic resistance such as seen in MRSA

Question 57

explain why cane toads were able to establish so well in australia

Answer 57

y

Question 58

why is it an advantage for a species to reach anew area faster than other individuals *can use cane toads as example

Question 59

how can DNA hybridisation give a measure of genetic relatedness between species

Answer 59

d

Question 60

why do the double strands of DNA break when they are heated

Answer 60

w

Question 61

Hybrid DNA from species A and B comes apart at a lower temperature than that of species A and C. Which species is A most closely related to

Question 62

explain ecological niche

Answer 62

An ecological niche is the specific role a species plays in its ecosystem, including how it uses resources, interacts with other species, and adapts to its environment for survival and reproduction. It defines a species' unique place in its habitat.

Question 63

in what way could a realised niche be regarded as flexible

Answer 63

A realized niche is adaptable because it can change based on interactions with other species, environmental shifts, competition, and a species' own traits. This adaptability allows species to find ways to occupy a niche that avoids direct competition and makes the most of available resources and conditions. Galapagos finches, a group of bird species found on the Galapagos Islands, exemplify the concept of realized niche flexibility. These finches have evolved varying beak shapes and sizes to adapt to different food sources and ecological niches. For instance, some finches have beaks suited for cracking seeds, while others have slender beaks for insect feeding or probing flowers. When resources are abundant, each finch species can occupy its specialized niche. However, during periods of scarcity or changing conditions, some finches may adjust their feeding behaviours and switch to alternative food sources or habitats, showcasing their ability to be flexible within their realized niches.

Question 64

what factors might further constrain the extent of the realised ecological niche

Answer 64

Intense competition with other species for limited resources can restrict a species to a narrower realized niche. The presence of dominant competitors can force a species to avoid certain resources or habitats, leading to a more specialized niche. Human activities such as habitat destruction, pollution, and introduction of invasive species can constrain a species' realized niche by altering the availability of resources and suitable habitats.

Question 65

contrast the effects of interspecific competition and intraspecific competition on niche breadth

Answer 65

Interspecific competition, between different species, tends to narrow niche breadth as species specialize to avoid resource overlap. In contrast, intraspecific competition, within the same species, initially widens niche breadth in resource-abundant environments, but narrows it as competition among individuals increases with higher population density. Interspecific competition can be seen when lions and hyenas compete for the same prey resources. This competition narrows their respective niches. Intraspecific competition is evident among oak trees within a forest, where initially abundant resources lead to a wider niche breadth, but as trees grow and population density increases, niche breadth narrows due to competition for limited resources like sunlight and nutrients.

Question 66

WOMBAT AND GROUNDHOG briefly describe the adaptations of body shape, diet and locomotion that appear to be similar in both forms and the likely selection pressures that are acting on these mammals to produce similar body forms

Question 67

SUGAR GLIDER AND FLYING SQUIRREL briefly describe the adaptations of body shape, diet and locomotion that appear to be similar in both forms and the likely selection pressures that are acting on these mammals to produce similar body forms

Question 67

MARSUPIAL MOUSE AND DEER MOUSE briefly describe the adaptations of body shape, diet and locomotion that appear to be similar in both forms and the likely selection pressures that are acting on these mammals to produce similar body forms

Question 68

BILBY AND JACKRABBIT briefly describe the adaptations of body shape, diet and locomotion that appear to be similar in both forms and the likely selection pressures that are acting on these mammals to produce similar body forms

Question 69

The bottleneck effect describes when a population has a drastic selection pressure causing very few to survive - for example, a natural disaster. The survivors have essentially passed through a narrow bottleneck'. The traits that allowed the few individuals to survive will become more common in future generations of the population. Would instances of the bottleneck effect provide support for gradualism or punctuated equilibrium? Explain your answer.

Answer 69

Punctuated equilibrium → because they are strong selection pressure that drastically alters the genetic diversity in a population towards whatever trait allows survival, such events are more likely to result in rapid, rather than gradual change.

Question 70

A mass extinction event occurred during the Cretaceous period that led to over 50% of marine species becoming extinct, as well as many terrestrial animals and plants - including most dinosaurs. A large asteroid or comet hitting Earth is hypothesised to have been the cause. This extinction drastically changed access to resources, as well as the levels of predation and competition. Many surviving organisms changed around this time due to natural selection. Does this provide an example of gradualism or punctuated equilibrium? explain your answer

Answer 70

Punctuated equilibrium → an asteroid comet would have rapidly caused many extinctions, and the survivors would have had strong selection pressures applied to their gene pools. This would explain why Over 50% of marine species became extinct and surviving organisms with desirable traits reproduced and thrived.

Question 71

Compare interspecific and intraspecific competition and give an example each.

Answer 71

Interspecific competition involves competition between different species for the same resources, while intraspecific competition involves competition among individuals of the same species. Example of interspecific competition: Lions and hyenas competing for the same prey species in an African savannah. Both predators need the same resource (prey), which can lead to resource scarcity and intense competition between the two species. Example of intraspecific competition: Oak trees in a forest competing for sunlight and nutrients. As oak trees grow closely together, they vie for the same resources within their population, leading to competition for available space, light, and nutrients.

Question 72

explain how parasitism differs from mutualism. Give an example of each.

Question 73

Explain how a mass extinction can result in new species evolving

Answer 73

a

Question 74

What factors drive extinction

Question 75

define/example of allelopathy

Answer 75

Allelopathy is where a plant releases specific biochemicals that influence, either detrimentally or beneficially, the growth of other individual plants around it. Often, allelopathy involves plants releasing chemicals into the soil to prevent other plants from growing in the same space. Acacia trees, which are the main diet of giraffes, let off allelochemicals when they are eaten to warn nearby acacias that there is a grazing giraffe around, in which case they cut off their water flow to the leaves and become bitter/unpleasant and even poisonous.

Question 76

Competitive exclusion principle

Answer 76

the competitive exclusion principle states that two species cannot occupy the same ecological niche, as this will result in extinction or adaptation of the weaker species. Therefore, it is advantageous for each species to occupy a unique ecological niche.

Question 77

Explain how a mass extinction can result in new species evolving

Question 78

Describe the effects of competition on population with examples --> hares, white brown rabbits

Answer 78

as the

Question 79

define/example of commensalism

Answer 79

commensalism is a symbiotic relationship between two species in which one obtains benefits from the other without harming or benefiting it. Whales can carry barnacles into nutrient-rich waters as they latch onto the whale's body. This has no observable benefit to the whales and is therefore a commensal relationship.

Question 80

define/example of competition

Question 80

define/example of predation

Question 80

define/example of mutualism

Question 81

compare interspecific and intraspecific competition and give an example for each

Question 81

describe the effect of symbiosis on populations --> reintroductions,

Question 82

Effect of diseases on populations --> predator and prey relationships

Question 83

Predict what would happen to the aphid population if the ladybird population was removed from the vegetable garden

Question 84

what is niche breadth

Answer 84

Niche breadth refers to the range of resources, environmental conditions, and habitats that a species can effectively utilize and occupy within its ecosystem. A species with a broad niche breadth is adaptable and can exploit a wide variety of resources, while a species with a narrow niche breadth has specialized requirements and is limited to specific conditions and resources.

Question 85

Fossils don't form in volcanic rocks. Explain why radiometrically dating volcanic rocks can often give us a good idea of the age of fossils found nearby.

Question 86

what is parasitism? give an example

Answer 86

parasitism is a symbiotic relationship in which one organism benefits from another organism that is being actively harmed by the relationship. Tapeworms, for example, are flatworm parasites that attach themselves to the intestines of various animals, including humans. They lack a digestive system and absorb nutrients from their host's digested food. However, the host is harmed because the tapeworm's presence can lead to malnutrition, weakened immune response, and even physical damage to the intestinal lining.

Question 87

describe the ecological nice of a eucalypt tree

Question 88

what evidence does ice core drilling provide for past changes in ecosystems?

Question 89

predator prey dynamic refer to the diagram in jannath doc

Question 90

what is quadrat sampling used for what assumptions are we making when we use this method

Question 92

what is the tolerance range for abiotic factors

Question 93

describe the process of natural selection

Answer 93

abiotic/biotic factors x factors such as x allowed this species eg cane toads to do xxx like olympic village effect. this effected other species eg red bellied snake adapted bc of selection pressures with x feature were more favourable uhhh natural selection.

Question 94

define selection pressures

Answer 94

abiotic and biotic factors that effect an organisms ability to survive in a particular environment negative vs positive

Question 95

why do selection pressures drive evolution