BIO - Ecosystems

Question 0

Gene pool

Answer 0

Described as the combination of all the versions of all genes in a population

Question 1

Define a population

Answer 1

A population is a group of individuals from one species that interbreed with each other in a particular place.

Question 2

Species

Answer 2

A group of organisms that have similar structural characteristics, can interbreed under natural conditions to produce fertile offspring

Question 3

What do members of the same species share or have in common?

Answer 3

Members of the same species…

• share a common gene pool
• are genetically isolated from other species
• have similar DNA

Question 4

What method is used to test if asexually reproducing organisms it prokaryotic cells are from the same species?

Answer 4

DNA hybridisation

Question 5

Community

And how are areas named?

Answer 5

A community is defined as all populations of living organisms found in a particular area or place.

The area in which the community exists is named after the dominant (by number) species in the area

Question 6

What are population interactions called?

Answer 6

Tropic structures

Question 7

Tropic structures

Role of producers

Answer 7

Autotrophs which produce the food for the ecosystem eg. Plants through photosynthesis

Question 8

Tropic structures

Role of consumers

Answer 8

Organisms that feed on the producers (herbivores) and organisms that feed on other animals (carnivores)

Question 9

Tropic structures

Role of decomposers

Answer 9

Organisms that break down dead materials and recycle the nutrients (very important)

Note: only nutrients and not energy can be cycled

Question 10

Ecosystem

Answer 10

An ecosystem refers to all the communities (all the living organisms) that inhabit a particular areA, how they interact with one another and how they are affected by the non-living environment around them eg. Water levels, sunlight, weather patterns

ALSO: the affect that living organisms have on the non-living environment

Question 11

Species interaction

Competition

Answer 11

Competition occurs between organisms competing for the same resource (biotic or abiotic) eg. Light, space, food

Most intense: amongst organisms from the same species as looking for the exact same requirements eg. Acacias competing for space in a scrubland

Less intense: amongst organisms from different species as they will not have the exact same requirements eg. Snakes and eagles may compete for food but will not compete for space as one lives on ground and the other in trees

Question 12

Species interaction

Predation

Answer 12

Predation is where one organism feeds on another. Can be an animal feeding on a plant or an animal feeding on another.

Predation has profound effects on the overall number of organisms, the biodiversity of a community and the evolution of a species.

Question 13

Predation strategies

Answer 13

Strategies displayed by predators are usually obvious eg. Cats are fast, agile, strong and have sharp teeth

Question 14

Predator avoidance strategies

Plants

Answer 14

Chemical:

• many plants contain a vast array of chemicals to deter herbivores eg. Poison oak
• some simply taste bad and some are extremely toxic eg. Milkweed

Physical:

• thorns to protect themselves from large predators eg. Roses
• waxy layers to protect themselves from insects eg. Aloe Vera

Question 15

Predator avoidance strategies

Animals

Answer 15

Coloration:

• bright colours usually displayed by insects to suggest that they are toxic and to be left alone
• camouflage: used to conceal themselves eg. Cuttlefish, chameleon

Chemical:
-many have chemical defences to either deter or kill predators
Eg. Toxic butterflies, bees and spiders

Question 16

Species interaction

Symbiosis

Answer 16

A distinct relationship between two different organisms

• mutualism
• commensalism
• parasitism

Question 17

Mutualism

Answer 17

Both species benefit from the interactions
Eg. Lichen is a plant which is the association of two species. Alga provides oxygen and therefore food, and fungus provides a moist environment

Question 18

Commensalism

Answer 18

One species benefits and the other in unharmed but does not benefit
Eg. Birds making nest in trees. This benefits bird as the risk of predation is lower and the tree is unharmed

Question 19

Parasitism

Answer 19

One organism benefits and the other is harmed but not usually killed
Eg. Ticks feeding on blood of animals and tapeworms feeding on the material of an organism’s intestinal tract

Question 20

What are trophic levels?

Answer 20

Food chains. Ie. an organism’s trophic level is the location it has on a particular food chain.

Question 21

Three types of trophic levels/trophic structure

Answer 21

Producers
Consumers
Decomposers

Question 22

Food webs

Answer 22

Communities are made of many food chains, resulting in a food web

Food webs shape the numbers of species in a community

Question 23

Effect of environmental factors on communities

Answer 23

The composition of a community (types and populations) is a direct result of the environmental conditions of the habitat. This occurs because over time the species adapt to exist within a particular environment.
Eg. Different regions which have similar environmental conditions usually show species with similar characteristics

Question 24

Types of environmental factors Sunlight

Answer 24

The energy source for producers Too much sunlight results in adaptations to reduce water loss Too little sunlight (rainforest) results in fast growing/large leafed plants

Question 25

Types of environmental factors Water

Answer 25

Low levels of water in deserts result in producers with adaptations to reduce water loss eg. Small leaves, water stroking leaves Animals in arid environments are adapted for the same reason eg. Big ears to cool blood, body shapes to collect water

Question 26

Types of environmental factors Low water and high sun

Answer 26

Harsh conditions, so sparse populations

Question 27

Types of environmental factors High water and medium sun

Answer 27

Good conditions, dense populations

Question 28

Types of environmental factors Temperature

Answer 28

Enzyme action for all species requires specific temperatures, therefore species found in the desert will be different than those found in mountain ranges

Question 29

Types of environmental factors Wind

Answer 29

Strong winds will drive the adaptation of small plants

Question 30

Types of environmental factors Salinity

Answer 30

Coastal plants show adaptations to excrete salt from their roots

Question 31

Biotic resources

Answer 31

Biotic resources relate to living resources and the measure of thee in a community as termed the productivity of the community

Question 32

Productivity

Answer 32

The effectiveness of the members of the community to convert energy from the sun into biomass (living matter) Measured in grams per metre squared

Question 33

Biomass

Answer 33

The mass of living biological organisms in a given area or ecosystem at a given time Areas where conditions are much more favourable for plant growth eg. Rainforest, will show a larger biomass and therefore productivity than harsher areas eg. Deserts

Question 34

Why is the carbon cycle important/why do organisms require carbon??

Answer 34

Because we need macromolecules such as lipids

Question 35

Why is the phosphorous cycle important?

Answer 35

Need for nucleic acids, membranes, ATP/ADP

Question 36

Why are decomposers important?

Answer 36

All organisms contain contain: carbon, nitrogen, phosphorus and calcium When organisms die, decomposers are able to recycle these elements back into the community They release the "trapped" inorganic elements back into the soil to be taken up by producers Elements are therefore cycled through ecosystems, energy is not cycled

Question 37

Why is the nitrogen cycle important?

Answer 37

Organisms need ATP, nucleic acids, proteins

Question 38

Features of energy flow in an ecosystem

Answer 38

-uni-directional (starts at Sun, can't be recycled), non-cyclic -losses at each transfer from one trophic level to another (as heat from respiration, and from inefficiencies in processing eg. Cellulose) This decline of 90% as transfer to the next trophic level is made is what limits the number of tropic levels.

Question 39

Primary production/productivity (PP)

Answer 39

Primary production is the rate of accumulation of biomass. Gross primary production (GPP) is the total amount of energy produced by vegetation per unit area in Kg/metre squared/year The level of energy available may limit the productivity in a community

Question 40

What powers primary productivity

Answer 40

Photosynthesis (abiotic based). The more photosynthesis, the more energy in the system and the larger the biomass The annual productivity in an area is determined primarily by sunlight, temperature and moisture.

Question 41

Biological succession Why do species occupy a habitat? And explain succession.

Answer 41

Species occupy a habitat because their specific needs are met in that habitat. Therefore, as the habitat changes, the composition of a community will also change. This change can be over time or space and is called succession.

Question 42

Define succession

Answer 42

Succession is defined as the gradual changes that occur over time or space and include the species composition in the community. Like organisms, communities tend to evolve from simple to complex. One type of community changes the ecosystems so that the next, more complex community can develop. Succession is like the evolution of communities over long periods of time.

Question 43

How could organisms cause succession?

Answer 43

- changing the soil structure and providing more organic matter, thus recycling more nutrients. - trapping the suns energy and providing food for consumers - providing shelter for other organisms

Question 44

Two types of biological succession Primary succession

Answer 44

This is when organisms establish themselves in a NEW environments where resources are very limited. Eg. Sand dunes, newly formed volcanic islands

Question 45

Two types of biological succession Secondary succession

Answer 45

This is when changes occur in communities, starting in an area where a community has been before. Often due to damage to the communities by humans, eg. Fires, interference by urbanisation and logging

Question 46

Why do succession communities start with autotrophs?

Answer 46

Autotrophs are small and thus they can survive off little nutrients.

Question 47

Early succession community features

Answer 47

-small number of species that are fast reproduces

Question 48

Reproductive strategies Opportunistic (r) strategists

Answer 48

-short life -produce many offspring -high reproductive effort -generally found in areas that are new, harshly damaged, or changing -colonise the areas quickly -tolerant to low nutrient conditions Eg. Weeds in crops and gardens, grasshoppers

Question 49

Equilibrium (K) strategists

Answer 49

As succession or changes occur in the ecosystem, the environment changes so that the conditions are far more stable for those organisms that survive better in a stable environment. - low reproductive effort - long life - small number of offspring (produce slowly and care for them) - bigger in size

Question 50

Balance between K and r selected species

Answer 50

- r species colonsise areas very quickly, but this is unstable - the combination of large populations and low resources usually results in a boom/bust - K species cannot survive in low resource areas and therefore rely on r species to raise resource enough to allow them to colonise - The ruse in resources provided by K species allows r species to survive

Question 51

Extremes in species

Answer 51

r and K selected species are extremes on a continuum

Question 52

Biodiversity

Answer 52

Biodiversity refers to he variety of ecosystems and species of organisms in the community - important to maintain biodiversity at different levels in the community - genetic diversity is vital to surviving changing conditions in the environment - maintaining a wide range of species in the community allows for stability as conditions change

Question 53

Reproductive isolation

Answer 53

- maintains separate species - biological feature which prevents gene flow between species - Barriers could be pre-zygotic (two organisms cannot physically mate) or post-zygotiv (unequal chromosome number) - or physical features eg. Bird dances

Question 54

Energy input and output

Answer 54

For any ecosystem the amount of energy input will always be approximately the same as the total energy output. Energy cannot be created or destroyed, it can only change form

Question 55

Biological evolution

Answer 55

This is the gradual change in the characteristics of a species of organisms over time Theory first proposed by Charles Darwin Fossil evidence and DNA similarities support this theory of evolution

Question 56

Natural selection

Answer 56

Survival of the fittest | This means that organisms that survive all competition produce the most offspring

Question 57

Evolution VCR Variation

Answer 57

- individual organisms within a population vary considerably in characteristics - some variation is directly due to environmental characteristics - much due to inheritable genetic differences - genetic variation important in evolution

Question 58

Sources of genetic variation in sexually reproducing organisms

Answer 58

1. Mutation - source of all new genes and therefore all new characteristics 2. Crossing over - of homologous chromosomes during meiosis (mixing of genes) 3. Random assortment - of chromosomes during meiosis (independent assortment) 4. Random fusion - of gametes during fertilisation

Question 59

Evolution VCR Competition

Answer 59

Some organisms die, those that are best suited to their environment survive and reproduce The factors that lead to some living and some dying are called selecting agents and can be either biotic or abiotic. They lead to adaptations in species over time. Often called "survival of the fittest"

Question 60

Evolution VCR Reproduction

Answer 60

Organisms possessing certain characteristics will have a greater chance of survival and reproduction as they are better suited to their environment. If these characteristics have been inherited by the offspring we say these genes have been selected. The favourable characteristics have been passed on to the offspring.

Question 61

Selection

Answer 61

Evolution occurs when the gene pool changes significantly. Gene pools may be altered by: mutation and natural selection, or migration.

Question 62

Speciation is the process of one species becoming two. Outline the steps in this process.

Answer 62

1. Two parts if a population become separated by a geographical barrier (can take thousands of years) eg. River, mountain range, desert 2. Interbreeding between the two groups stops 3. The gene pools separate and there is little or no gene flow between them. 4. If the two environments differ, then selective pressures will be different for each group ie. the selecting agent will be different 5. After many generations of natural selection the two populations can become quite different (if the selecting agents are different) 6. The two (or more) populations will not be capable of interbreeding should they mix again. 7. They show reproductive isolation and are now considered separate species and will be named accordingly.

Question 63

Examples of reproductive behaviours

Answer 63

Pre-zygotic - incompatible courting behaviours - incompatible genitals - incompatible gametes - different mating times Post-zygotic - incompatible chromosome numbers - incompatible genes

Question 64

Explain how resistant strains of bacteria can evolve by natural selection

Answer 64

Antibiotics work in a number of ways: Interfering with cell wall production Blocking proteins synthesis Affecting the function of cell membranes Work as a selecting agent and over time many bacteria have developed resistance to many antibiotics, causing changes to the gene pool The increase in resistant bacteria in recent years is thought to be related to the misuse of antibiotics by the general public

Question 65

Define homologous structures

Answer 65

Homologous structures are those that have a common origin but not necessarily a common function Eg. Limb bones of mammals - different sizes for different functions - occurs from mutations

Question 66

Convergent evolution

Answer 66

Different, unrelated organisms develop similar structures through natural selection in similar environments with similar selecting agents. Convergent evolution describes the acquisition of the same biological trait in unrelated lineages Eg. The wing Flying insects, birds and bats have all evolved the capacity of flight independently, thus they have all "converged" on this trait

Question 67

Evidence for evolution - the fossil record

Answer 67

The fossil record provides evidence for a change in species over time It helps biologists to sort out evolutionary relationships between organisms Eg. Fossil fish contain complete remains of another species of fish

Question 68

Evidence for evolution - protein sequences

Answer 68

The order of amino acids in a protein can be determined By comparing sequences for proteins (eg. Haemoglobin) from different organisms, evolutionary relationships can be deduced

Question 69

Evidence for evolution - DNA hybridisation

Answer 69

DNA extracted from an organism and heated The two complementary strands separate The temperature is lowered and the two complementary strands rejoin If DNA from two different species is mixed, heated then cooled, hybrid DNA molecules may reform Each hybrid contains a strand from each species This will only occur if some of the DNA from the two species is complementary The % hybridisation can be measured and used as an indication of how similar the genes of two species are Evolutionary relationships can be deduced

Question 70

What rate is it estimated that human impacts have increased the rate if extinction by

Answer 70

It is estimated that human impacts have increased the rate of extinction by 10,000 times

Question 71

What is the best way to preserve species?

Answer 71

The best way to maintain species is to maintain their habitat. Species are best suited to their habitats after many generations of natural selection as they have already evolved to exist comfortably. -provides homes for species -maintains soil structure -photosynthesis -already adapted

Question 72

What areas cause the major impacts upon species diversity

Answer 72

``` Pollution Introduced species Mining Climate change Harvesting Habitat clearance ```

Question 73

Habitat clearance

Answer 73

Single most contributing factor to the extinction of species in Australia Clearances for farming and other human activities Disruption is caused by either: -removing entire habitats -habitat fragmentation (smaller fragments hold fewer species)

Question 74

Introduced species

Answer 74

Become problem in Australia as many don't have natural predators Brought in for a variety of reasons, such as hunting or to kill other invasive species Eg. Cats, dogs, foxes (prey on land dwelling animals that initially had few predators), cane toads, European carp (destroy waterways) ``` Cause problems by: Preying on native species Transmitting infectious diseases Taking over nesting sites and burrows Destroying vegetation ```

Question 75

Extinctions

Answer 75

Occurs when populations do not have the ability to overcome rapid environmental changes and die Eg. Hunting and over harvesting: saber tooth tiger, dodo, whales, sharks Habitat loss: Bengal tiger

Question 76

Over harvesting

Answer 76

Overfishing and clearance of native forests | In both of these the rate if harvesting exceeds the rate if regrowth and/or replacement

Question 77

Mining

Answer 77

Mining leads to the destruction of native habitat, removing vegetation and topsoil and hence dramatically altering the native habitat eg. Take out whole area as dirty and guessing This can also lead to various forms of pollution eg. CO2 and CO

Question 78

Pollution

Answer 78

Can come In many forms including: nuclear waste, chemicals from industry and factories, human synthetic chemicals (unable to be broken down by normal biochemical pathways), insecticides, pesticides, acid rain, food additives, greenhouse gas emissions (increased CO2) and destruction of ozone layer (caused by CFCs) The use of fossil fuels and overproduction of carbon dioxide and methane have led to the increased temperature and this global warming is called the enhanced greenhouse effect.

Question 79

Human overpopulation

Answer 79

Humans in developed countries have a huger demand on all resources Use of fossil fuels, water, soil and land availability all have finite limits There are accumulations of waste from humans, contibuting to diseases The huge demand is reducing global biodiversity at an alarming rate and alternatives need to be found