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Biology - IGCSE > Ch 19 - (Organisms and the environment) > Flashcards

Ch 19 - (Organisms and the environment) Flashcards

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1
Q

What is the main principal source of energy?

A

The sun

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2
Q

how does energy flow through organisms?

A
  • Light energy from sun and chemical energy in organisms
  • energy is transferred to the environment as heat
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3
Q

what does a food chain?

A

Transfer of energy from om organism to organism

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4
Q

What do arrows in the food chain show?

A

Transfer of energy from one trophic level to another

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5
Q

How is energy transferred from one organism to another?

A

Ingestion

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6
Q

define producers

A
  • organisms that produce their own organic nutrients usually using energy from sunlight
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7
Q

Define herbivore

A

animal that gets its energy from eating plants

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8
Q

Define carnivore

A

an animal that gets its energy by eating other animals

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9
Q

Define primary consumers

A

herbivore - they feed on producers (plants)

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10
Q

Define secondary consumers

A

predators that feed on primary consumers

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11
Q

Define tertiary consumers

A

predators that feed on secondary consumers

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12
Q

Define decomposers

A

Bacteria and fungi that get their energy from feeding off dead and decaying organisms and undigested waste

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13
Q

What is a food web?

A

Network of interconnected food chain

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14
Q

What does a food Web show?

A
  • Show connections between organisms
  • animals rarely exist on just one type of food source
  • show interdependence on how a specie affects another
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15
Q

Why do most change in populations happen?

A
  • human impact
  • overharvesting of food species
  • introduction of foreign species to a habitat
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16
Q

What do change in population do die to interdependence?

A

Long lasting knock on effects

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17
Q

What does a pyramid of numbers show?

A

How many organism there are are

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18
Q

What does the width of a box show in a pyramid?

A

Number of organisms

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19
Q

Why may some pyramids not be pyramid shaped?

A

Size of organism is also important

20
Q

What are the rule to remember when drawing a pyramid of numbers

A
  1. You cannot change trophic levels of organisms
  2. Larger an individual organism is, the less of them there are
21
Q

What does pyramid of biomass show?

A

how much mass the creatures at each level would have without including all the water that is in the organisms

22
Q

How are biomass pyramids like, and why?

A
  • ALWAYS pyramid shaped
  • cuz mass of an organism has to decrease as you go up a food chain
  • provide better idea of quantity
23
Q

How is energy passed on?

A

Has to be consumed (eaten)

24
Q

What happens to energy in energy of pyramids?

A
  • not all of the energy grass plants receive goes into making
  • only the energy that is made into new cells remains with the organism to be passed on
25
Q

Is the energy that is made into new cells consumed?

A
  • No
  • energy is stored in these parts and so it does not get passed on
26
Q

What is majority of energy in an organism used?

A
  • making waste products
  • as movement
  • as heat
  • as undigested waste
27
Q

How is the human energy transfer in food chain?

A
  • omnivore
  • choice of what we eat
  • impact on what we grow
28
Q

What nutrients does the carbon cycle involve?

A

Carbon and nitrogen

  • recycled
29
Q

What happens to carbon in the cycle?

A
  • Carbon is taken out of the atmosphere in form of CO2 for plants to be sued in photosynthesis
  • passed onto organisms by feeding
  • returned as CO2 thru respiration
  • decomposed dead organisms form fossil fuels
  • burnt fossil fuels releases CO2
30
Q

What are the main issues causing an increase in CO2?

A
  • increased use of fossil fuels
  • mass deforestation by reducing the amount of procedures
31
Q

What is nitrogen?

A

An element required to make proteins

32
Q

Why can’t plants or animals absorb N2?

A
  • very stable
  • cannot be broken down
33
Q

what are 2 ways that nitrogen can be converted into a usable form?

A
  1. Nitrogen fixing bacteria - lives in the soil
  2. Lightening - splits the bonds between N and turns into nitrous oxide
34
Q

Explain how nitrogen is transferred?

A
  • plants absorb nitrogen in form of nitrates from soil
  • animals eat plants, so it is passed up by food chain
  • waste send nitrogen out of the body
  • waste and dead species decay and nitrogen group is broken into ammonia
  • plants can’t absorb ammonium compounds so nitrifying bacteria concerts it to nitrites then nitrates
35
Q

What does denitrifying bacteria do?

A
  • takes nitrates out of soil
  • reduces soil fertility
36
Q

Define population.

A

A group of organisms of one species living in the same area at the same time

37
Q

Define a community

A

All of the populations of different species in an ecosystem

38
Q

Define an ecosystem.

A

a unit containing the community of organisms and the environment interacting together

39
Q

What do all living organisms compete with each other for?

A

Flood, water and living space.

40
Q

What are the 3factors required for population growth?

A
  1. Food supply
  2. Predation
  3. Disease
41
Q

What are the 4 stages of a population growth curve?

A
  1. Lag phase
  2. Log phase (exponential phase)
  3. Stationary phase
  4. Death phase
42
Q

What happens in lag phase?

A
  • organism adapting to the environment

-

43
Q

What happens in log phase or exponential phase?

A
  • food supply is abundant
  • birth rate is rapid
  • death date is low
  • growth is exponential
44
Q

What happens in stationary phase?

A
  • populations level out
  • due to nutrient factor in environment
  • birthrate becomes limited
45
Q

What happens in death phase?

A
  • population decrease
  • food supply is short
  • metabolic waste produced by population builds up to toxic levels
46
Q

What are organisms in a natural environment unlikely to show rapid growth unlike sigmoid growth curve?

A

Other factors

47
Q

What’s re the factors that’s effect population growth

A
  • changing temperature or light
  • predators
  • disease
  • immigration (individuals moving into area)

-emigration (individuals moving out of area)

Biology - IGCSE (19 decks)

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