Topic 7 Difficult

Question 1

what factors are species influenced by?

Answer 1

biotic:
availability of food
new predators
new pathogens
competition – one species may outcompete another = numbers not sufficient to breed

abiotic:
light intensity
temperature
moisture levels
soil pH & mineral content
wind intensity & direction
CO2 concentration for plants
O2 concentration (for aquatic animals)

Question 2

how is a species impacted by these factors?

Answer 2

impact distribution & abundance (population size) of a species
= change the community.
if # of population decreases too much, they are unable to breed & may be lost from community

Question 3

what causes competition?

Answer 3

to survive & reproduce, organisms need a supply of materials from their surroundings (which is limited) and other organisms which leads to competition

Question 4

the larger the sample size

Answer 4

the more reproducible, reliable & valid

Question 5

why do organisms lose biomass?/why is not all biomass transferred to next trophic level?

Answer 5

1. not all ingested material is absorbed - some is egested via faeces
2. some absorbed material is lost as waste e.g. CO2 & H2O in respiration (for heat & movement) & H2O & urea in urine
3. large amounts of glucose are used in respiration
4. not all of the organism is consumed e.g. bones or roots

Question 6

why are materials recycled?

Answer 6

to provide the building blocks for other organisms

Question 7

what are materials?

Answer 7

elements that make up other organisms e.g. carbon, hydrogen, oxygen, nitrogen that make lipids, carbs & proteins (= organic compounds)

Question 8

what processes recycle materials?

Answer 8

photosynthesis, respiration, combustion

Question 9

why are decomposers important? (2)

Answer 9

1. return carbon to atmosphere as CO2 through respiration = for photosynthesis
2. return mineral ions to soil for plants to use = magnesium & nitrate

Question 10

describe the water cycle

Answer 10

1. evaporation of water from earth falls as precipitation
2. absorption of water by plants via osmosis into roots
3. transpiration by plants releases H2O into atmosphere
4. production of urine, sweat & faeces by animals
5. respiration by all organisms produces H2O

Question 11

what do decomposers do?

Answer 11

break down dead plant & animal matter by secreting enzymes into environment, which break down large molecules in dead organisms into small & soluble food molecules that diffuse into the microorganism = used to make larger molecules or in respiration

Question 12

what is decomposition?

Answer 12

process by which living organisms remove materials from the environment for growth

Question 13

what is the impact of environmental change?

Answer 13

affect distribution of a species in ecosystem

Question 14

what are the environmental changes?

Answer 14

1. temperature
2. availability of H2O
3. composition of atmospheric gases e.g. O2, CO2, CH4  greenhouse gases –> global warming

Question 15

how does moisture level affect rate of decay?

Answer 15

higher moisture, greater rate of decay because decomposers do not dry out & easier to digest wet organisms & microorganisms grow faster in moist conditions