Paper 2: Topic 7 Ecology - Trophic levels in an ecosystem Flashcards Preview

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Flashcards in Paper 2: Topic 7 Ecology - Trophic levels in an ecosystem Deck (30)
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1

Define the term trophic level

The feeding stage of an organism within a food chain

2

Which type of organisms are always found on trophic level one?

Producers i.e. plants and algae

3

Explain why each trophic level can have more than one species in it

Each species within a trophic level carries out a specific role in the food chain

4

What is the first trophic level called and what organisms are found in it?

Level 1: Plants and algae make their own food and are called producers

5

What is the second trophic level called and what organisms are found in it?

Level 2: Herbivores eat plants/algae and are called primary consumers

6

What is the third trophic level called and what organisms are found in it?

Level 3: Carnivores that eat herbivores are called secondary consumers

7

What is the fourth trophic level called and what organisms are found in it?

Level 4: Carnivores that eat other carnivores are called tertiary consumers

8

Define the term ‘apex predator’

Apex predators are carnivores with no predators

9

Which trophic level normally has an apex predator

Fourth / Level 4

10

Explain why food chains rarely have more than 4 trophic levels

  • Energy is lost between each trophic level along the food chain
  • The energy that reaches level 4 is very small
  • So this means there is insufficient energy to support a 5th trophic level

11

State the two types of organisms that are decomposers

  • Bacteria
  • Fungi

12

Explain how decomposers contribute to the recycling of materials in the ecosystem

  • Decomposers break down dead plant and animal matter by secreting enzymes into the environment
  • Small soluble food molecules then diffuse into the microorganism

13

Why do scientist draw pyramids of biomass?

Pyramids of biomass can be constructed to represent the relative amount of biomass in each level of a food chain

14

Describe what happens to the amount of energy at each trophic level

It decreases as the energy flow along the food chain

15

Describe what happens to the amount of biomass at each trophic level

It decreases as the biomass flow along the food chain

16

Describe what happens to the number of organisms at each trophic level

It generally decreases when you move up a trophic level

17

Describe a situation when the numbers of organisms in a trophic level may be higher than the previous trophic level

Fleas living on a fox

18

Explain what each bar on a pyramid of number represents

The number of organisms feeding at that stage in the food chain in a given period of time

19

Explain what each bar on a pyramid of biomass represents

The biomass of the organisms feeding at that stage in the food chain in a given period of time

20

Define the term biomass

The relative mass of the living material within an organism

21

22

State 3 pieces of information that can be obtained from a pyramid of biomass

  1. The sequence of organisms in the food chain (read the pyramid from the base upwards)
  2. The amount of biomass available at each trophic level (the area of the bar)
  3. The amount of biomass lost between different trophic levels (calculate the difference between the area of the two bars)

23

State the typical energy transfer that occurs between the sun and producers

~1%

24

State 4 reasons why the energy transfer between the sun and the producers is so low

  1. Not all the light rays reach the Earth’s surface
  2. Not all the light rays hit plants (some hit roads, building etc)
  3. Some of the light rays are reflected from the surface of the leaf
  4. Some of the light rays pass straight through the leaf and do not hit a chloroplast

25

State the typical biomass transfer that occurs between producers and primary consumers (herbivores)

~10%

26

State 2 reasons why the biomass transfer that occurs between producers and primary consumers (herbivores) is so low

  1. The plant uses some of the biomass to produce biological molecules for its own growth
  2. The plant uses some of the biomass in respiration to release energy to produce fruits and seeds
  3. Not all of the plant is eaten by the herbivore e.g. roots, thorns

27

State the typical energy transfer that occurs between primary consumers (herbivores) and secondary consumers

~20%

28

State 6 reasons why the biomass transfer that occurs between primary consumers (herbivores) and secondary consumers is so low

  1. The plant uses some of the biomass to produce biological molecules for its own growth
  2. Some of the biomass is converted to waste products and excreted
  3. Some of the biomass is undigested and egested
  4. Some of the biomass is respired to release energy for movement
  5. Some of the biomass is respired to release energy for reproduction
  6. Some of the biomass is respired to maintain body temperature

29

List 3 waste products that are formed as part of an organism’s metabolism

  1. Carbon dioxide (from respiration)
  2. Water (from respiration)
  3. Urea (from deamination of excess amino acids)

30

Describe how to calculate the efficiency of biomass transfer

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