Ecology and the environment, The organism in the environment

Question 2

definition of population

Answer 2

group of organisms of same species living in the same place at the same time

Question 3

definition of community

Answer 3

all the populations living in same area at same time

Question 4

ecosystem definition

Answer 4

all the biotic factors and all abiotic factors that interact within an area at 1 time

Question 5

definition of habitat

Answer 5

place where organism lives

Question 6

what is the method for the practical to investigate population size

Answer 6

1- use a tape measure to lay out a survey area in chosen habitat

2- use random number generator to create a set of coordinates to place first quadrat

3- count number of chosen species found inside quadrat

4- estimate population size using equation : total area / area sampled x number of specie found

Question 7

what is a quadrat

Answer 7

a square frame made out of wood or wire which marks out an area to then estimate population size

Question 8

what is a limitation to the practical for investigating population size

Answer 8

easy to miss out an individual organism

Question 9

what is biodiversity

Answer 9

the range and variety of different species of organisms on Earth, or within an ecosystem

Question 10

why is biodiversity crucial

Answer 10

because it ensures the stability of an ecosystem by reducing the dependance of one species on another for one of these 3 things:
- food
- shelter ( birds nests on trees)
- maintenance of physical environment

Question 11

what is the method for the practical to measure biodiversity

Answer 11

1- lay out first survey area
2- use random number generator to create set of coordinates for first quadrat
3- count number of chosen species inside the quadrat
4- record on a table using the species key and repeat until you recorded the number of different species for 10 quadrats
5- repeat in 2nd survey area

Question 12

abiotic means

Answer 12

non living

Question 12

biotic means

Answer 12

living

Question 12

what is the limitation of the practical for measuring biodiversity

Answer 12

it can be hard to distinguish or identify species so use a species key

Question 13

how do abiotic factors affect population size and distribution (6)

Answer 13

• light intensity (is needed for photosynthesis and the growth of plants)
• temperature ( affects photosynthesis rate)
• moisture levels (plants and animals need water to survive)
• Soil pH and mineral content (different species are adapted to different pHs and concentrations)
• Wind intensity & direction (affect transpiration are which affects photosynthesis rates)
• CO2 levels for plants (affects rate of photosynthesis)
• oxygen levels for aquatic animals ( some can only survive in water with high oxygen concentrations)

Question 14

how biotic factors affect population size and density (4)

Answer 14

• Availability of food (more food means higher chance of survival and reproduction)
• new predators ( in balanced ecosystems, predators catch enough prey to survive but not wipe out the population, if a new one is introduced, they might get wiped out)
• New pathogens (if a new pathogen enters the ecosystem, the animals won’t be immune to it and so find it more difficult to fight it and so die)
• competition ( if 2 species compete for the same resources, the more advantaged and adapted one will gain them all, making the other one eventually die out)