Organisms & environment

Question 1

Define ecosystem

Answer 1

• cycles of energy
• habitat
• food web
• interacting organisms

Question 2

What do plants need

Answer 2

• water H2O
• Nitrates NO3-
• phosphates Po4-
• Magnesium Mg2+
• potassium K+
• Carbon dioxide Co2

Question 3

ideally, what would be the best pyramid to show trophic levels

Answer 3

Pyramid of Productivity
(looking at what has been eaten instead of what is eating)

Question 4

What can disrupt a food web?
What would disruption cause?

Answer 4

• pesticides
• invasive species
• overpopulation
• pollution
• lack of natural resources
• damaged habitat/ ecosystem
• biomagnification

Question 5

Why is human population increasing so much

Answer 5

industry/tech ≠ predation
agricultural revolution ≠ extreme lack of food
medicine ≠ diseases

Sadly we still have competition, e.g. war and poverty

Question 6

Define : Population

Answer 6

group of organisms of some species

Question 7

Define : Community

Answer 7

populations of several species, both plants and animals

Question 8

Define : Ecosystem

Answer 8

communities + the environment they live in

Question 9

What is carrying capacity

Answer 9

the amount of organisms a habitat/environment can sustain

Question 10

What is the biological balance equation that represents changes in population

Answer 10

n. of birth + immigration = n. of death + emigration

This needs to be balanced, otherwise there will be an increase or decline in population

Question 11

How efficient is energy transfer from organism to organism

Answer 11

Only 10%

🤯

Whaaaaat? Crazyyy!!!

Question 12

What is light energy converted into

Answer 12

chemical energy

Question 13

What are the differences, advantages and disadvantages of pyramid of numbers or biomass

Answer 13

NUMBERS :
represents energy transfer and number of organisms on each trophic level
disadvantage: doesn’t show values of energy transfer or biomass

BIOMASS :
represents transfer of biomass on each trophic level.
We can work out percentages of transfer efficiency.
disadvantage: doesn’t show quantity of organisms or energy distribution

Question 14

What is biomass

Answer 14

Total dry mass of living matter and chemical energy

Question 15

What is a detrital food chain and a detritivore ?
What is decomposer?

Answer 15

Starts with dead material instead of sunlight

Detritivores eat dead material (like dead leaves)

Decomposer decays bodies of dead organisms

Question 16

Define :
Trophic level
Decomposer
Food chaine
producer
consumer
Herbivore
carnivore

Answer 16

EMPTY

Question 17

What level of organism do all organisms rely on?

Answer 17

Producer

Question 18

What is the name of the process of amino-acids -> urea

Answer 18

Deamination

Question 19

Respiration / Photosynthesis
What are equations which produces raw biomass?
(plant-based material used as fuel)

Answer 19

Photosynthesis

Oxygen + glucose —> water + carbon dioxide
carbon dioxide + water —> oxygen + glucose
I
Sunlight

Question 20

Define Biomagnification

Answer 20

Accumulation of chemicals
mostly affects higher on food chain

Question 21

In population growth, what is the:
1. lag phase
2. exponential phase
3. transitional phase
4. plateau phase

Answer 21

1. Species introduced to new habitat. Takes time to adjust.
2. plenty of resources, food, space, barely no factor limiting growth. rapide increase.
3. no longer enough resources, increase in predators and diseases, growth rate falls, death rises, but still overall slow increase
4. carrying capacity reached. Constant population self balancing (see population notes)

Question 22

Why is carbon always moving places in nature

Answer 22

it is constantly going through organisms as glucose, in the atmosphere as CO2 and is generally always part of a cycle.

Question 23

What is the carbon cycle

Answer 23

The cycle in which carbon is absorbed and assimilated by organisms ans released back into the atmosphere

Question 24

What are the processes in the carbon cycle

Answer 24

–> Carbon dioxide in air
–> Photosynthesis
–> Respiration in plants (back to air)/feeding & assimilation
–> Respiration in animals/death/egestion
–> decomposition (and then decomposers respire and carbon goes back into air)/fossilisation
–> combustion (carbon released back into air)

Question 25

Describe the nitrogen cycle

Answer 25

• Nitrogen gas in air
• Can be fixed into nitrates by lighting, root nodule bacteria and some fertilisers
• Plants absorb nitrates and assimilate it
• Animals ingest plants, digest plant proteins to amino acids then assimilate them to make their own proteins
• Either animals die, or perform egestion or excretion, and proteins are broken down to amino acids which are transferred to urea in the body
• Urea is decomposed to ammonia by decomposers e.g. decomposing bacteria
• Ammonia is nitrified by nitrifying bacteria into nitrites then nitrates
• The nitrates are either denitrified by denitrifying bacteria or absorbed by plants again

Question 26

What are the 4 bacteria in the nitrogen cycle

Answer 26

nitrification (oxidation) bacteria - ammonia —> nitrate
denitrification bacteria - nitrate —> nitrogen
nitrogenific root nodule bacteria - nitrogen —> nitrate
decomposing bacteria - urea —> ammonia

Question 27

What are the benefits of root nodule bacteria?
(for both in symbiosis)

Answer 27

Plants get nitrate
bacteria gets glucose and protection

Question 28

What type of process happens in root nodules

Answer 28

mutualistic/ symbiotic process:
Nitrogen fixing
nitrogen —> nitrates

Question 29

What happens between dead organic material and absorption of nitrate by plants
(nitrogen cycle)

Answer 29

Dead matter → protein → amino-acids →ammonia → nitrates → absorbed by plants
_____________________________________________________ _______________________________
↓ ↓
Decomposition by decomposers like worms or nitrified by nitrification bacteria
decomposing bacteria