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BY4 > Populations - Finished > Flashcards

Populations - Finished Flashcards

1
Q

What is a population?

A

A group of organisms of the same species living in a particular area.

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2
Q

What does population size depend on?

A

Birth Death Immigration Emigration * DO NOT APPLY TO LABORATORY BASED EXPERIMENTS**

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3
Q

What is the definition of “Carrying Capacity”

A

Maximum population size that a particular envirionment can support.

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4
Q

What is the definition of “Population Density”

A

The number of organisms in a given space

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5
Q

What does intraspecific mean?

A

between members of the same species

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6
Q

What does interspecific mean?

A

Between members of different species

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7
Q

What shape is the Population Growth Graph?

A

Sigmoid

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8
Q

Where is the carrying capacity?

A

Following over the line at the Stationary Phase

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9
Q

What is the Lag phase?

A

A peroid of slow population growth

Bacteria are adapting to their new food supply e.g. producing enzymes to break down the substrates present

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10
Q

What is the Log (exponential) Phase?

A

This is a period of rapid cell division
Cell production exceeds cell death
Abundance of nutrients and the amount of toxic waste produced is very low.

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11
Q

What is the Stationary Phase?

A

Period where the number of cells produced is equal to the number of cells that die
Factors that limit population size (environmental resistance) have taken effect
Environment has reached carrying capacity

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12
Q

What is the death (decline) phase?

A

Period where cell death exceeds cell production

Many bacteria die due to shortage of nutrients and a build up of toxic waste products

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13
Q

What are density dependant factors?

A

As the population density increases these factors have stonger effects
A greater % of the population will die/emigrate if the population increases
Biotic factors

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14
Q

Name some density dependent factors that limit population growth

A
  • Food
  • Predation
  • Accumulation of toxic waste
  • Disease and Paracitism
  • Competition for resources
  • Oxygen Concentration
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15
Q

What are Density independant factors?

A

These factors affect the same proportion of the population no matter what its density
The same % of the population will die/emigrate regardless of the population size
Abiotic factors

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16
Q

Name some density independant factors that limit population growth?

A
  • Weather
  • Natural Disaster
  • Temperature
17
Q

What does Biotic mean?

A

Caused by living organisms

18
Q

What does Abiotic mean?

A

Caused by non living factors in the environment

19
Q

What is the definition of a pest?

A

An organism that people find undesirable - may cause harm economically or affect peoples health

20
Q

How can pests be controlled?

A

Chemical control

Biological control

21
Q

What is Chemical Control?

A

The use of a toxic chemical substance (pesticide) to kill pest organisms and reduce the pest population
• Insecticide - Kills pest insects
• Fungicide - Kills pest fungi
• Herbicide - Kills pest plants
May act onthe pest in different ways e.g. contact, ingestion, inhalation

22
Q

What is biological control?

A

The use of another living organism (predator, paracite, pathogen) to reduce the pest population
Target - Undesirable pest organism
Agent - Organism used to control pest numbers

23
Q

Why is it not desirable to completely eradicate a pest?

A

Because if would not leave a food source for the predator/ control agent which would then die out. If the pest then re-invaded at a later date it would be able to quickly increase its numbers to an economically damaging level.

24
Q

What are the Advantages and Disadvantages of Biological control?

A

Advantages
• Usually species specific
• CAn provide long term control if equilibrium is established
Disadvantage
• The Control agent may be too slow to build up in number to be effective (if the pest numbers increase)
• Detailed knowledge of the lifecycle of the target and agent is required. Background research into this takes time and money.
• Control agent may kill non-target organisms and become a pest itself

25
Q

What are the advantages and disadvantages of Chemical control?

A

Advantages
• Can be applied on a small scale ad do not need a high level of skill or knowledge
• Can result in effective and quick eradication of pests.
Disadvantages
• Persistant pesticides may accumulate in body tissues and become concentrated in food chains, reaching toxic levels which cause harm to top predator.
• Long Term exposure may harm humans
• not species specific
• May kill Fish/birds/mammals by contaminating thier food
• Pests may become resistant

26
Q

What are sacrobionts/Sacrophytes?

A

microorganisms that obtain its food from the dead/decaying remains of another organism

BY4 (8 decks)

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