3.7

Question 1

define population

Answer 1

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

Question 2

define community

Answer 2

all the populations of the different species
living at the same time
at the same place

Question 3

define ecosystem

Answer 3

the community + all the non-biotic conditions of the environment

Question 4

define niche

Answer 4

role a species plays within its habitat

Question 5

what determines the niche occupied by a species within the habitat

Answer 5

adaptations

abiotic/biotic factors

Question 6

define carrying capacity

Answer 6

maximum stable population size

an ecosystem is able to support

Question 7

how can abiotic factors affect population size

Answer 7

ideal conditions for species

= species can grow fast, reproduce successfully

Question 8

explain how population size can vary due to interactions between living organisms

Answer 8

interspecific competition
-reduces resources available
-better adapted species outcometes less one
intraspecific competition
-smaller pop size = less competition = better for growth + reproduction
predation
-increased predator size pop=decreased prey size pop=less food for predators= predator size falls= prey size increases= predator size increases again

Question 9

describe how you would estimate the size of a plant population in a given area

Answer 9

Randomly placed quadrats
- Use a grid / split area into squares
Obtain random coordinates using a random number generator / calculator
- place quadrat at coordinates
Deciding the number of quadrats to use to collect representative data:
- Calculate running mean
- When enough quadrats, this shows little change in mean
- Count frequency of species in quadrat
- Calculate mean per quadrat
- Calculate population size by multiplying the mean by the number of quadrats
that would cover the entire area of the habitat

Question 10

describe how you woulde measure the change in distibution of a plant species across a habitat

Answer 10

• lay tape measures from one area to another
• place quadrats at regular intervals from the line
• count frequency

Question 11

describe how you could estimate the population size of a mobile organism

Answer 11

• capture, mark, release
• leave enough time for organisms to randomly disperse
• population= total from first pop x total from second / total recaptured

Question 12

assumptions made during mark release capture method

Answer 12

1. no emigration/migration
2. no births/death occur
3. marking doesn’t affect survival
4. sufficient time for individuals to mix within population