13.1 Food chains and energy transfer Flashcards

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1
Q

How is sunlight the ultimate source of energy

A

. Sunlight is conserved as chemical energy by plants

. Plants use sunlight to make organic compounds from CO2 in air, or water that surrounds them

. These organic compounds are mostly used as substrates for respiration, and remainder make other groups of biological molecules

. Biological molecules form biomass of plants

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2
Q

What are producers

A

. Photosynthetic organisms that manufacture organic substances using light energy, water, mineral ions and CO2

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3
Q

What are consumers

A

. Organisms that obtain their energy by feeding on other organisms rather than using the energy of the sunlight directly

Eg animals are consumers

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4
Q

What are the 3 types of consumers

A

. Primary consumers directly eat producers eg green plants, and are first in chain of consumers

. Secondary consumers eat primary consumers

. Tertiary consumers eat secondary consumers

Secondary and tertiary are usually predators but they may also be parasites or scavengers

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5
Q

What are sabrobionts

A

Decomposers are a group of organisms that break down complex materials in dead organisms into simple ones

In doing so they release valuable minerals and elements in a form that can be absorbed by plants and so contribute to recycling

Majority of this work is carried out by fungi and bacteria

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6
Q

What is a food chain

A

It describes a feeding relationship where primary consumers eat producers
Then secondary consumers eat primary consumers
Then tertiary consumers eat secondary consumers

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7
Q

What is a trophic level

A

. In a food chain where one thing eats another, each stage is a trophic level

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8
Q

What are food webs

A

. Most animals don’t rely on a single food source and within a single habitat many food chains are linked together to form a food web

They are complex but more likely than food chains in an ecosystem

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9
Q

What is biomass

A

The total mass of living material in a specific area at a given time

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10
Q

What makes measuring biomass unreliable

A

. Although it is easy to access fresh mass, the presence of varying amounts of water make it unreliable

. So to do it you would have to dry the organism out and kill them
. Because of this it is only done on a small scale so isn’t representative

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11
Q

What is biomass measured in

A

Biomass is dry mass per given area

  • Grams per metre squared
    g/m^2
    Where an area of land is being sampled eg grassland
  • It is grams per metre cubed for volume eg ocean or pond
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12
Q

What is a better way to measure biomass

A

Calorimetry

In bomb calorimetry, sample of dry material is weighed and burnt in pure oxygen within a sealed chamber called a bomb

The bomb is surrounded by a water bath and the heat of combustion causes a small temperature rise in this water

As we know the specific heat capacity of water, the temperature rise, and the volume of water
We can use q=mcat to measure amount of energy released from the mass burnt

In units eg kJkg^-1

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