19. Organisms and their environment

Question 1

What is photosynthesis (carbon cycle)?

Answer 1

synthesis of chemical energy from light energy using water and carbon dioxide

Question 2

What is respiration (carbon cycle)?

Answer 2

chemical process inside cells that releases energy

Question 3

What is feeding (carbon cycle)?

Answer 3

ingesting organic matter from other organisms

Question 4

What is decomposition (carbon cycle)?

Answer 4

breakdown of dead organic matter into simple nutrients/molecules that can be recycled back into the ecosystem

Question 5

What is fossilisation (carbon cycle)?

Answer 5

dad organic matter compressed under optimum conditions into fossil fuels after millions of years

Question 6

What is combustion (carbon cycle)?

Answer 6

complete oxidation of organic matter such as fossil fuels and biomass

Question 7

What is decomposition (nitrogen cycle)?

Answer 7

proteins to ammonium ions

Question 8

What is nitrification?

Answer 8

ammonium ions to nitrate ions

Question 9

What is denitrification?

Answer 9

nitrate ions to nitrogen gas

Question 10

Which organisms carry out nitrification?

Answer 10

nitrifying bacteria

Question 11

What is a necessary condition for denitrification?

Answer 11

no presence of oxygen

Question 12

For _______ to occur, no oxygen must be present.

Answer 12

denitrification

Question 13

What is nitrogen fixation?

Answer 13

nitrogen gas to nitrates

Question 14

Which organisms carry out decomposition?

Answer 14

by bacteria and fungi (decomposers)

Question 15

Which organisms carry out nitrogen fixing? Where are they located?

Answer 15

nitrogen fixing bacteria
found in root nodules of legume plants

Question 16

Which organism absorbs nitrate ions?

Answer 16

plants

Question 17

What substance do plants absorb?

Answer 17

nitrate ions

Question 18

What process can also carry out nitrogen fixation?

Answer 18

lightning

Question 19

How do nitrates from lightning reach the soil?

Answer 19

rainwater

Question 20

Where are amino acids/proteins made?

Answer 20

plants

Question 21

Plants are responsible for producing which substance which is part of the nitrogen cycle?

Answer 21

amino acids/proteins

Question 22

How are proteins transferred from producers to herbivores?

Answer 22

feeding

Question 23

What is feeding?

Answer 23

process in which proteins transfer from producer to herbivore by ingestion

Question 24

What happens once a herbivore feeds on a plant?

Answer 24

it will gain protein from the plant, digest it into amino acids, then used to make proteins.
carnivores eat herbivores and process restarts.

Question 25

Which organisms carry out denitrification?

Answer 25

denitrifying bacteria

Question 26

Define ‘population’.

Answer 26

a group of organisms of the same species, living in the same area at the same time

Question 27

Define ‘community’.

Answer 27

all of the populations of different species in an ecosystem

Question 28

Define ‘ecosystem’.

Answer 28

community interacting with abiotic factors in the environment

Question 29

What are 4 factors that affect the rate of population growth for a population of an organism?

Answer 29

food supply
competition
predation
disease

Question 30

State, in order, the phases of population growth (sigmoid curve).

Answer 30

lag phase
log phase
stationary phase
death phase

Question 31

What happens in the lag phase? Why is population growth very slow in this phase?

Answer 31

• although abiotic factors are optimum, there are too few individuals, making it hard to find compatible mates

Question 32

What are some examples of abiotic factors being optimum?

Answer 32

low competition for resources
high food + water availability
low spreading of diseases

Question 33

What happens in the log phase? Why is population growth exponential in this phase?

Answer 33

• there are enough individuals to mate
• optimum conditions for reproduction
• no limiting factors

Question 34

What happens in the stationary phase? Why is population growth stationary in this phase?

Answer 34

the high number of individuals increases competition for resources and mates
diseases spread more quickly
this keeps population stable

Question 35

In terms of birth, death, emigration and immigration, what is a declining population?

Answer 35

death and emigration > brith and immigration

Question 36

In terms of birth, death, emigration and immigration, what is an increasing population?

Answer 36

birth and immigration > death and emigration

Question 37

What 4 factors can be used to calculate population growth?

Answer 37

birth,
immigration,
death,
emigration

Question 38

What is the ‘formula’ for population growth?

Answer 38

births - deaths + immigration - emigration

Question 39

What happens in the death phase? Why is population growth declining in this phase?

Answer 39

• struggle for survival as resources become limiting (used up)
  individuals die

Question 40

What are some limiting factors in population growth? (not in syllabus, ignora Anna <3)

Answer 40

resources
food
water
mates/partners
space
shelter