Population Growth

Question 1

1.A population is a?
2.Give an example?

Answer 1

1.Group of individuals of the same species living in a particular habitat
2.pop of starlings which roost in Dungannon park

Question 2

Population dynamics looks at how?

Answer 2

Pop size changes over a period of time

Question 3

1.Much of the research in this area has been done using?
2.In what conditions? E.g in a?
3.As these organisms? (3)

Answer 3

1.Micro-organisms (yeast and bacteria)
2.closed conditions, beaker/conical flask
3. Multiply quickly,are easy to keep and easy to count

Question 4

1.What diagram shows the pattern of population growth?
2.And how can it be divided?

Answer 4

1.Sigmoidal (S-shape) growth curve
2.Into 4 distinct phases

Question 5

What are the four distinct phases for population growth?

Answer 5

Lag, Exponential (log),Stationary(stable),Decline

Question 6

Lag phase- there is a? In the no. of the organisms(1)
- (no.s may even?)(1)
-This is due to?(1)
-What might this involve? (4)

Answer 6

• very slow increase
  -( decline)
  -the time needed to adapt to the environment
  -nutrient assimilation (making the appropriate enzymes to digest food),egg production, egg and larval development, gestation period (in mammals).

Question 7

-Exponential (log/growth) phase,population no.s increase by the?
-Reproduction creates? Which add to? (?) -E.g?
-There is (what kinda)? competition, since?
-The numbers increase by a value called(grows to?)(?)
- the population is illustrating its?

Answer 7

-Same factor in each time unit
-new members of the population
-which add to the population’s reproductive capacity(?ability to reproduce)
-E.g a bacterium divides to produce 2 bacteria, each of which produces 2, to give a total of 4 bacteria and so on.
- Little competition since there are sufficient resources
-the intrinsic rate of natural increase (grows to max rate) (designated r)
- biotic potential(the max reproductive potential (rate) of a population living under optimal environmental conditions

Question 8

Stationary (stable) phase: 1.population numbers ?
2.For all populations exponential growth cannot?
3.The environmental factors that eventually stop population growth (prevent?) are known as? E.g?
4.As population numbers increase resources become? And competition? And there may be a ?( particularly in?)
5.There is a decline in ? So new so new individuals are added to the population Via?Is equal with?
6. The population reaches its ? (Which is ?) This is very much determined by the? E.g

Answer 8

1.remain relatively stable
2. continue for an unlimited time
3.(the pop from remaining at its biotic potential), environmental resistance,e.g competition,disease, predation,and an unfavourable climate.
4. Limiting, increases and there may be a mixture of waste (paticularly in laboratory populations)
5. Birth rate combined with an increase in death rate, via births/ possibly immigration) is equal with losses (via deaths, and possibly emigration).
6. Carrying capacity( designated K), the maximum population number that an environment can support under a particular set of conditions, resources available e.g food.

Question 9

Decline phase- 1.population no.s?
2. The population has exhausted the? And/or there’s an? So that? And pop no.s?
3.The? Shaped curve (which the population would follow if it was at its?) becomes? This shape is caused when the population?due to? Eventually the curve?

Answer 9

1. Decrease rapidly
2. Resources and or/there’s an accumulation of toxic waste so that the birth rate falls to zero and the death rate increases - pop no.s crash
   3.J,biotic potential, s-shaped,when the population encounters environmental resistance due to one or more limiting factors. Eventually the curve levels off and the population reaches the carrying capacity of the environment.

Question 10

Environmental resistance- 1.the?
2.It can be due to?
3. The factors that influence populations can be divided into 2 categories?

Answer 10

1.Restriction by the environment on the population reaching its max growth rate and its biotic potential.
2. nutrient shortage or accumulation of waste but also climate , competition from other organisms, predation and disease.
3. Biotic and abiotic

Question 11

Biotic factors- definition? Name 2 factors?

Answer 11

Organisms are affected by other organisms of the same or different species e.g food supply or predation

Question 12

Abiotic factors- 1.Organisms are dependant upon what type of factors(?) that make up their?
2.Name 3 factors?

Answer 12

1.Organisms are dependant upon the physical and chemical factors,(non-living), that make up their environment
2.climatic, edaphic (soil),other factors

Question 13

Abiotic factors- 1.climatic?
2.Edaphic (soil) factors?
3.Other factors?

Answer 13

1.light intensity , temp, rain fall, wind , water, currents etc.
2.ph,moisture, mineral availability, texture etc
3. CO2 and O2 concentration

Question 14

Temp isn’t a? But will determine the? And so the?
For example in lab populations it can be demonstrated that the rate of increase (in the exponential phase) will rise from?
However higher temps won’t influence the size of the?
This will be determined by?

Answer 14

Resource, metabolic rate in organisms, rate at which they develop.
higher temperatures.
Maximum population in the stationary phase (carrying capacity)- This will be determined by?resources such as the availability of food.

Question 15

The stationary and decline phases will depend on whether the resources are?

Renewable- definition?, e.g?
The populations will tend to remain in its? phase.

Non renewable -definition? e.g?
The populations will have an? phase followed by? as the?

Answer 15

Renewable/non renewable,

Resources are continually being replaced and made available to the organism,
trees continually fall in woodland and provide food for wood lice, stationary

Non renewable
Resources are initially available but not replaced , Yeast grown in a lab batch culture will eventually run out of nutrients, exponential, rapid decline, resources are consumed.

Question 16

In this example resource availability is a key determinant of the growth pattern.

J shaped growth curve for an algal population over the course of a year- there’s a ? In spring as there’s abundant?
Temp and light levels are? and there are relatively few? At this time of year.
However in mid summer the pop often?(with ?) and ? As the nutrient supply becomes? But also because herbivores (zoo plankton) ?and because?

Answer 16

Very rapid period of growth, nutrient availability in water, increasing, herbivores in the water.
Crashes, (no stationary phase), rapidly falls largely, exhausted, increase in no., waste accumulates.

Question 17

Population dynamics- what happens to the number of individuals making up natural populations over time?
Populations:? Increase in size through?
And decrease in size through?
Population growth=?
In favourable conditions , the population will grow if?
In unfavourable conditions , the population will decrease if?
A population in equilibrium (no growth) will have an equation:

Answer 17

Fluctuates over time.
Increase in size through births and immigration (movement into the population)
Decrease in size through deaths and emigration (movement out of the population.
Births(B) - deaths(D) + (immigration(i) -emigration(E))
If the no.of births and Immigrants is greater than the number of deaths and emigrants.
If the number of births and immigrants is less than the number of deaths and the number of emigrants.
B+I= D+E

Question 18

Other factors affecting population size-

Factors that increase population size?

Factors that decrease population size?

Answer 18

Plentiful suitable space available, good food supply, good water supply, ability to resist disease, small numbers of predators, ability to avoid predation , high reproductive rate, favourable light , stable abiotic conditions

Suitable space unavailable or limited, inadequate food supply, inadequate water supply , inability to resist disease , inability to avoid predation, low reproductive rate , too much or too little light, unstable abiotic conditions.

Question 19

R -selected and k-selected species-
A populations main aim is to ensure?
and so reproductive strategies are of?
If we consider the fact that the production of offspring requires energy,which is better? (More,small offspring/fewer large offspring) Answer “it depends “
The favourite alternative is the one in which the offspring have the? This may come from?
Often the environment is the?
Two variables govern the growth of populations which are?
Species can be characterised by the relative importance of r and K in their?

Answer 19

Survival
great importance
Greatest summed reproductive value
A few offspring each with a high reproductive value or from many offspring each with a lower reproductive value.
deciding factor
The intrinsic rate of natural increase (r) and the carrying capacity (k).
Life cycles

Question 20

R-selected species

These are species with a?
The populations of the species increase?, as a resource becomes? And? as a resource is?
? With repeated cycles of ?
Their emphasis is on? Rather than?
Due to the importance of the intrinsic rate of natural increase (r), such species are called ? Or are said to have an ?
Examples include?

Answer 20

These are species with a high intrinsic capacity for population increase.
Rapidly as a resource becomes available and crash as the resource is used up, boom and bust
Reproduction and the colonisation of new areas , survival.
R-selected species
R-strategy
Bacteria, insects, weeds , mice and rats.

Question 21

K-selected species- these species have more? and they usually remain at the?
Their emphasis is more on? rather than?
Such species are called? or are said to have a?
Examples include?
K-selected species are more prone to? As they can’t?
Most organisms have Reproductive patterns between these 2 extremes E.g?

Answer 21

stable populations, carrying capacity (K) of the environment .
survival and dominance, expanding the population or colonising new areas
k-selected species, k-strategy.
Elephants, humans and trees.
Extinction, respond well to environmental disaster
sea turtles have large and long life spans (k-selected) but their offspring are unnurtured (r-selected)

Question 22

Population interactions- individual organisms do not live in ? They are continually interacting?
Different populations within a habitat may affect each other’s?

Answer 22

Isolation in a community, with each other, population growth,

Question 23

symbiosis?
If both species benefit from the interaction its called? I.e it’s?

Answer 23

A relationship between 2 or more organisms living in close association.
Mutualism
Beneficial

Question 24

Nitrogen-fixing bacteria receive? What’s in the root? E.g
The plant receives?

Answer 24

Protection and nutrients within the root, nodule tissue of leguminous plants e.g clover
Nitrogen-containing compounds (nitrates)

Question 25

Lichens are organisms that live on?
They consist of?
The fungi does what? Which the (?) can use.
The algae carry out? and provide the fungi with? ( fungi have no? And so cant?)

Answer 25

The surface of rock ,wood etc. Fungi that harbour green algae around their hyphae
Absorbs water and nutrients, algae.
Photosynthesis, sugar (fungi have no chloroplasts and so cannot photosynthesise).

Question 26

Cellulose digestion in many herbivores is a?
The bacteria possess the? required to hydrolyse?
The herbivore (e.g cow) benefits as they can use a?
The bacteria gain? and are maintained at a what temperature?ensuring?

Answer 26

Result of mutualism between the herbivores and bacteria in their gut.
cellulases, cellulose.
very abundant source of food not accessible to many other animal species.
A ready supply of food, high and constant, rapid metabolic activity

Question 27

Predation is used here to include all?
This includes?

Answer 27

+/- interactions in which one organism consumes all or part of another.
Predator-prey, grazing and parasitism

Question 28

A predator-prey relationship is defined as?
An abundance of prey will mean that? And so the predator pop?
Large numbers of predators will reduce?
Little available prey would then not support the? Which would ?
The resulting predator-prey interaction will often produce?
The oscillations produced will show?

Answer 28

The way in which numbers of a predator and its prey depend upon each other.
More of the predator population can be supported, will grow
The prey population
Large numbers of predators ,later fall
Oscillations
changes in the predator population which lag behind changes in the prey population.

Question 29

The predator peaks and troughs (low activity) what ?
The length of the predator cycle is usually?
The number of predators is significantly lower than the number of? At?

Answer 29

Lag Behind the prey peaks and troughs.
similar to the length of the prey cycle
Prey individuals, at equivalent points on the cycle.

Question 30

Grazing?
This is a very similar process to a? in that the

Answer 30

The eating of plants by herbivorous animals.
predator-prey relationship in that the populations of plants and animals will affect each other.

Question 31

Parasitism
A parasite is an?
The parasite uses the resources of its host, e.g?
The host receives?

Answer 31

Organism that lives outside (ectoparasite) /inside (endoparasite) its host benefiting from it and causing harm over an extended period of time
Food,shelter,warmth.
No benefit at all and is usually harmed.

Question 32

Parasites differ from predators in the following ways:
Examples of parasites are?

Answer 32

The parasite lives in/on the host,the parasite causes harm to the host over an extended period of time, the parasite is usually smaller than the host, the parasite rarely kills the host(or if it does it is a very slow process)
Fleas on a cat and a tapeworm in a human.

Question 33

Competition
Resources are limited and so organisms have to?
Plants compete for?
Animals compete for?
The effect of the competition is to?

Answer 33

compete for them
Space,light and mineral nutrients.
Food,shelter and a mate
Reduce the growth rate of individuals and their reproductive capacity to a lower level than they could achieve if there was no competition.

Question 34

Inter-specific competition between the populations of ?
occurs when they?
Both species may?

Answer 34

two different species
require a common resource which is in limited supply.
share the same role or at least, display role overlap.

Question 35

An ecological niche is?(?)

The characteristics of competition are:

Both species do? When competing for the resource

The weaker competitor? and is? Which will ? (?)

The winner may ?and so be ? or it may have some feature which allows it to?e.g ?

The outcome of competition may be determined by the? e.g ? but not if it is?

Answer 35

The role of an organism in the ecosystem (what it feeds on /nutrient needs, competition with other organisms, its temperature , water and other requirements).

Both species do less well when competing for the resource

The weaker competitor dies and is eliminated by the best competitor, which will take over the habitat completely (competitive exclusion principle)

The winner may utilise the resource more efficiently and so be more successful or it may have some feature which allows it to compete more effectively e.g one species of water plant has air sacs which allow it to float above other plant species and so can absorb more of the available sunlight.

The outcome of competition may be determined by the environmental conditions e.g one species of beetle outcompetes another when conditions are warm and humid but not if it is cold and dry.

Question 36

Competitive exclusion principle states:
This has been demonstrated to some extent in laboratory experiments using
organisms such as Paramecium( a?

Answer 36

2 species can’t share the same role without one species being eliminated.
(single-celled, ciliated protozoan that feeds on bacteria).

Question 37

When (cultured/grown) in isolation the population density of each species of Paramecium?
In mixed culture, competition for food, space and other minerals results in the? of P. Caudatum after about 20 days:the more rapidly reproducing P. Aurelia (does what to) ? its rival.

Answer 37

increases rapidly and then levels off .
Elimination
Outcompetes

Question 38

However, caution needs to be?:
two species of grass might require the same mineral ions but obtain these at different levels in the soil as?; two species of plant would require light but?

Two species of flour beetle, tribolium confusum and tribolium cataneum were placed in some flour and the number of adult beetles were plotted over a period of time. The population of T. Castaneum always rose and then oscillated , while that of T.confusum gradually?

Answer 38

Exercised, one has longer roots than the other, avoid competition by growing at different times in the year
fell until it died out altogether.

Question 39

Suggest reasons for the changes in population size for Tribolium confusm? In nature competitive exclusion is?
While owls and foxes may compete for a? there are?
Role overlap is said to be?

Answer 39

The T.confusum population rises rapidly at first, as food is plentiful and there is little competition.
As the population of T. Castaneum also increases, inter-specific competition for food (or other resources) increases.
T. Confusum is outcompeted by T.castaneum. Individuals are less likely to survive and reproduce , and so the population falls and , at around 600 days , dies out.
Rare
A common food source, alternative sources of food available.
minimal

Question 40

Biological control

A pest is any organism that?
Examples Include?

Answer 40

Competes with or damages a population of plants or animals that are of economic importance to humans
Weeds competing with crops such as wheat and barley , animals such as rabbits eating crops , insects such as aphids damaging plants and mosquitoes spreading malaria and other diseases .

Question 41

Such pests may be controlled by ? Elaborate ?
Another factor is called? Elaborate?

Answer 41

chemical control-Spraying with a chemical substance that kills the pest
biological control-By making use of another organism to kill the pest

Question 42

Biological control aims to achieve?
A biological control method involves? (?) that will?
Parasites are ? ultimately? Most have a?
Pathogens? They? And are?
Predators? For example? As they can?

Answer 42

Permanent control of pest populations without the dangerous side-effects associated with chemical pesticides.

the introduction of a parasite, pathogen, or predator(the biological control agent) that will target the pest and reduce its numbers to a point below the economic damage threshold

Species whose immature stage develops on or within a single host , ultimately killing the host. Most have a very small host range.

Are disease-causing organisms including bacteria,fungi and viruses. They kill or weaken their host and are relatively specific to certain insect groups.

Are mainly free living species that consume a large number of prey during their lifetime. For example, ladybird beetles are used for attacking aphids (green fly) as they can eat their own weight in aphids in a single day.

Question 43

Features of effective Biological control-
A biological control programme will require?
For example the control agent should?

Answer 43

much research to ensure a successful outcome.
Target only the pest species (small prey range)
To not become a pest itself by destroying other species
Survive and reproduce in its new environment
Not introduce any diseases
Simultaneous action with pest life cycle ( it should be present when the pest emerges)
Efficient search ability-able to locate pest even when it is in short supply.

Question 44

Advantages of biological control over chemical control

Pesticides are?
Biological control agents are more likely to target?
Biological control agents do not have a?
The development of resistance of pests to biological control is?
Biological control agents reproduce and so are?
Biological control is? while the initial research may be?, the predator or parasite does not have to be? (whereas pesticides must be?).

Answer 44

Expensive,difficult to handle safely , dangerous to non pest species and pests can often develop resistance to them.
only the pest species (specific).
negative effect on biodiversity i.e no bioaccumulation in food chains
unlikely
keeping themselves alive (self perpetuating) over time.
relatively cheap since, costly, reintroduced (re-applied often).

Question 45

Disadvantages of biological control

Biological control is a ? and it cannot cope with ?
? may need to be used in such circumstances
If the biological control agent has no potential predators in its new environment, this may result in an?
The biological control agent may disrupt?
The biological control agent will probably not?

Answer 45

Biological control is a ? slower method, sudden surges in pest numbers (takes time for control agent to reproduce and increase in numbers).
Pesticides.
uncontrolled population explosion of them.
food webs as it may eat or compete with other species
entirely destroy the pest, but will maintain its population at a low level.

Question 46

An ecological community consists of?
Definition of an ecological community?
An ecosystem consists of?
Examples of ecosystems include?
Definition of an ecosystem?

Answer 46

Populations of different species which live in the same place at the same time and interact with each other
The biotic component of an ecosystem and involving interactions between autotrophic and heterotrophic populations
A habitat and its associated community, including abiotic and biotic components, the interactions within and between them
Ponds, lakes , forests and sea shores.
A community of different species which are interdependent and interact with each other and their abiotic environment, involving energy flow, nutrient and gas exchanges.

Question 47

Abiotic?
Biotic?

Answer 47

Non living
Living

Question 48

Succession- the process of community development

Ecosystems constantly?
with new species?
If land is laid bare as a result of a? it will?
The vegetation that?
succession is?
Succession involves?
And there’s? Between these 2 components.

Answer 48

change
entering the community and others being lost.
landslide, erosion, the eruption of a volcano or some other phenomenon
if the environment is not too harsh, slowly become covered with vegetation and its accompanying animal life.
initially colonises the bare land is usually replaced in the course of time by a second type, which may eventually be replaced itself.
This process of progressive change in the species composition of a community over a period of time
Changes to the community and the abiotic environment
important Interaction

Question 49

There are 2 kinds of succession which are?

Answer 49

Primary and secondary

Question 50

Primary succession takes place in a?
Examples include?

The exposed land provides a? for life. There will be? to support plants.

Answer 50

Previously uncolonised substrate.

Bare rock in a disused quarry , volcanoes erupting and depositing lava which hardens into rock,
landslides exposing rocks,
sand being piled into dunes by sea or wind etc.

The exposed land provides a very harsh and hostile environment for life. There will be no soil present to support plants.

Question 51

A small number of colonising species become the?
These new species are known as?
These organisms can ?
For example ?
The algae (which are part of the?) can?
while the fungi hyphae can? This forms the?

Answer 51

new community e.g lichens
pioneer species
survive the hostile conditions and penetrate the rock surface.
lichen can grow without soil and can resist desiccation (drying out).
lichen, photosynthesise and make organic compounds, while the fungi hyphae can penetrate small cracks in the rock and release acidic compounds to weather(crack/break down) the rock surface (also aided by the climate e.g frost action)
embryonic soil

Question 52

Initially the soil will?
The death and decay of several generations of these pioneer species (?) ?
More water and nutrients gradually become? so?

Answer 52

accumulate in the cracks in rocks.
(lichens) add to the humus content of the accumulating soil
available in the soil, that it can support other species e.g mosses.

Question 53

Primary succession

Other organisms, both plants and animals , then?
These are usually?
These communities alter the?
Making the environment more?

Answer 53

enter the community
r-strategists specialised in dispersal(movement) to (e.g spores are carried in the wind) and colonisation of exposed areas.
abiotic environment (change the conditions of light, humidity, soil composition etc), making the environment more favourable for the establishment of new species

Question 54

Primary succession

This process continues through a number of stages (called? until a final community is reached- this is known as the?

The climax community is a ?

Answer 54

seres) until a final community is reached- this is known as the climax community.
relatively stable end-stage of a Succession and is in equilibrium with its environment

Question 55

Primary succession on Bare Rock

Pioneer-
Successive seres-
Climax-

Answer 55

Pioneer? Colonisation by lichens, breakdown of rock and production of dead organic material
Successive seres? growth of moss, further breakdown and the beginnings of soil formation.
Growth of small plants such as grasses and ferns, further improving soil.
Larger herbaceous plants can grow in the deeper and more nutrient-rich soil
Climax? Climax community dominated by shrubs and forest trees

Question 56

1.Type of interaction: mutualism: effect on pop growth? comment?
2.Type of interaction: predation : effect on pop growth? comment?
3.Type of interaction: competition : effect on pop growth? And comment?

Answer 56

1.++,both species gain and interaction may be necessary for both
2.+|-, the predator species gain and the prey species loses
3.-/- both species lose while interacting, the species most effected is eliminated from its role.

Question 57

Features of r selected and k selected species

R selected species:features? Length of life cycle?, generation time?, number of offspring?, pop density?, dispersal (ability to migrate)?, competitive ability?, body size?, amount of parental care?, habitat?, examples?

K selected species:features?
Length of life cycle?, generation time?, number of offspring?, pop density?, dispersal (ability to migrate)?, competitive ability?, body size?, amount of parental care?, habitat?, examples?

Answer 57

R selected species:short- quick to mature, short, many, highly changeable - often surpasses K resulting in boom and bust fluctuations
,high- species migrate readily and are able to recolonise easily, weak competitor, small, little or no parental care , unstable or disturbed,
bacteria,insects,weeds and mammals such as small rodents (mice)

K selected species:long- takes times before individuals mature, long ,few, less changeable usually near k, low- recolonisation is uncommon, strong competitor, large, considerable parental care, stable, elephants, trees, humans, whales