19. Organisms and their environment

Question 1

Consumer

Answer 1

An organism that gets its energy by feeding on other organisms. They may be classed as primary, secondary, tertiary and quaternary according to their position in a food chain

Question 2

Herbivore

Answer 2

An animal that gets its energy by eating plants

Question 3

Carnivore

Answer 3

An animal that gets its energy by eating other animals

Question 4

Decomposer

Answer 4

An organism that gets its energy from dead or waste organic material

Question 5

Trophic level

Answer 5

The position of an organism in a food chain, food web or ecological pyramid

Question 6

Organisms

Answer 6

Any living biological entity, such as an animal, plant, fungus, or bacterium

Question 7

Respiration

Answer 7

Chemical reactions in cells that break down nutrient molecules to release energy

Question 8

Carbohydrates

Answer 8

Compounds found in living things composed of carbon, hydrogen and oxygen

Question 9

Biological systems

Answer 9

A group of organisms or organs that work together to carry out a particular task

Question 10

Biomass

Answer 10

The dry mass of living material in each organism. If multiplied by the total number of organisms at that trophic level you get the total biomass of a species in that system

Question 11

Detrivores

Answer 11

Animals that eat dead plants and animals

Question 12

Detritus food chains

Answer 12

Food chains that start with dead organic materials

Question 13

Efficiency of biomass transfer

Answer 13

(biomass in higher trophic level / Biomass in lower trophic level) * 100

Question 14

Ecosystem

Answer 14

A unit containing the community of organisms and their environment, interacting together

Question 15

Food chain

Answer 15

Showing the transfer of energy from one organism to the next, beginning with a producer

Question 16

Food web

Answer 16

A network of interconnected food chains

Question 17

Removing Carbon Dioxide from air (CC)

Answer 17

Photosynthesis

carbon dioxide + water → glucose + oxygen

Question 18

Feeding and decomposition in living cycles (CC)

Answer 18

Animals eat plants –> Digest carbon compounds.
Decomposers feed on dead animals + waste materials –> digest carbon compounds.

Question 19

Returning carbon dioxide to the air (CC)

Answer 19

Respiration - glucose + oxygen → carbon dioxide + water
Combustion - Burning of fossil fuels (compressed organisms) / trees + plants releases carbon

Question 20

Where is carbon stored

Answer 20

Atmosphere (Gas)
Ocean (Carbon dioxide dissolves in water - bicarbonate salt)
Land Biomass (Dry matter in organisms (plants + animals))
Fossil Fuels

Question 21

What is nitrogen used for?

Answer 21

To create amino acids.
To create nitrate ions, ammonium ions –> minerals needed for living organisms.

Question 22

Nitrogen Fixation (NC)

Answer 22

Nitrogen fixation is the process by which unreactive nitrogen gas is converted into more reactive forms of nitrogen.

Lightning - Energy makes nitrogen gas combine with oxygen forming nitrogen dioxide / nitric oxide. Dissolve in rain –> wash into soil.

Nitrogen-fixing bacteria - Bacteria that convert nitrogen gas or ammonium ions (in soil) into nitrates to be used by plants. Live freely in soil or inside nodules of leguminous plants (beans/plants).

Question 23

Denitrification (NC)

Answer 23

Process that converts nitrates from the soil into nitrogen gas.

Denitrifying bacteria in soil.

Question 24

How do animals consume nitrogen?

Answer 24

We eat plants that have consumed nitrogen from soil / nitrogen fixing bacteria.

Question 25

Plant absorbtion (NC)

Answer 25

Plants absorb nitrate ions through root hair cells + active transport. –> use this to make amino acids –> make proteins –> transferred to animals been eaten –> digested to form amino acids –> make proteins etc.

Question 26

Nitrogen from animals to plants (NC)

Answer 26

Deamination - The removal of the nitrogen-containing part of amino acids to form urea.
Excess amino acids transported to liver for deamination. Urea excreted through kidneys in urine.
Decomposition - Decomposers break down plants and animal protein to form ammonium ions –> can be nitrified to form nitrate ions. –> either absorbed by plants or dentrified.

Question 27

Nitrification (NC)

Answer 27

Ammonium ions in soil converted to nitrate ions using nitrifying bactera in soil.

Question 28

Population

Answer 28

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

Question 29

Community

Answer 29

All of the populations of different species in an ecosystem.

Question 30

Factors affecting population growth rate.

Answer 30

Food supply - Enough food/shortages.
Predation - too many/too few predators in relation to prey
Disease - Epidemics can cause fall in population
Competition - for resources (water, food, territory)

Question 31

Population factors affecting growth curve

Answer 31

Number of births - Increases size
Immigration - Increases size
Number of deaths - Decreases size
Emigration - Decreases size

Question 32

Stable population

Answer 32

number of births + immigration = number of deaths + emigration

Question 33

Sigmoid curve of population growth

Answer 33

An s-shaped curve that plots the change in population as it varies due to environmental factors.

Question 34

Sigmoid curve - Lag phase

Answer 34

Slow increase in population, after a new species has been introduced to an environment.

Question 35

Sigmoid curve - Exponential (log) phase

Answer 35

Resources are plentiful –> individuals reproduce at a high rate –> exponential increas in population size

Question 36

Sigmoid curve - Stationary phase

Answer 36

Maximum size of population reached (carrying capacity) –> competition for resources is high –> not all individuals will get teh resources they need to survive.

Question 37

Sigmoid curve - Death phase

Answer 37

Rapid decrease in the size of population. Caused by new predator, disease, competing species, drought etc.

Question 38

Carrying Capacity

Answer 38

The maximum population size of a species that can be sustained by its environment.

Question 39

Limiting Factor / Environmental Resistance Factors

Answer 39

The variable in the environment that controls the rate, growth or abundance of a biological processes. For instance, temperature can be the limiting factor in the growth of a plant.