Populations and ecosystems-BP

Question 1

What is a species?

Answer 1

group of organisms with similar characteristics that can interbreed to produce fertile offspring

Question 2

What is a population?

Answer 2

all the individuals of a particular species in a habitat at a particular time

Question 3

What is a community?

Answer 3

all the population of different species in a habitat

Question 4

What is a habitat?

Answer 4

The place when organisms normally live which is characterised by the physical conditions and the other organisms present

Question 5

What is an ecosystem?

Answer 5

all the organisms living in a particular area and the non-living (abiotic) conditions

Question 6

What is ecological niche?

Answer 6

an organisms role/position in an ecosystem – in terms of its interaction with abiotic and biotic factors

Question 7

Why can 2 different species not occupy the same ecological niche?

Answer 7

• interspecific competition will take place for the limiting factors/resources (abiotic & biotic factors)
• better adapted species will out compete the other = competitive exclusion principle

Question 8

How to sample plant species over a large area?

Answer 8

 obtain a map of the area
 divide the map into grids
 select a large number of coordinates using a running mean
 select a random set of coordinates using a random number chart
 in each coordinate place a quadrat
 measure abundance of the plant species in each quadrat = frequency or percentage cover
 calculate average for the whole area

Question 9

How to sample plants species along a path?

Answer 9

 use a transect
 place a tape along the path, count number of plants touching tape (Line Transect)
 or
 place a tape along the path, at regular intervals along the tape place a quadrat, measure abundance within the quadrat (Belt Transect)

Question 10

How to sample animal species in an area?

Answer 10

1. collect the sample, mark and release them
2. method is non-toxic and it does not make them visible to predators
3. leave sufficient time for animals to re-distribute before collecting second sample
4. (no in 1st sample x no in 2nd sample) ÷ number of marked individuals recaptured

Question 11

Assumptions of Mark-release-recapture technique?

Answer 11

 no births or deaths
 no immigration or emigration
 marked animals mix evenly with population
 mark is not toxic
 mark does not come off
 large population

Question 12

What are the 3 stages of population growth?

Answer 12

 slow/lag phase: species becomes adapted to new environment
 rapid/log phase: species adapted, abundant resources, doubling with reproduction, birth rate>death rate
 stationary phase: resources become limited, intraspecific competition occurs, birth rate = death rate

Question 13

How are resources/limiting factors grouped?

Answer 13

 abiotic (non-living): light, temperature, water, O2/CO2, minerals, pH, living space
 biotic (living): predator, prey, mates, competition, disease

Question 14

What is competition?

Answer 14

when organisms compete for resources (abiotic and biotic)

Question 15

What are the 2 types of competition?

Answer 15

• intraspecific
• interspecific

Question 16

Describe the predator/prey relationship?

Answer 16

 prey increases in number
 more food available for predator
 predator increases in number (more energy available for reproduction & growth)
 predator eats more of the prey
 prey decreases in number
 less food available for predator
 predator decreases in number
 less of the prey are eaten
 prey increases in number [cycle repeats]

Question 17

What is succession?

Answer 17

• how an ecosystem changes over time (change in species diversity and habitat diversity)
• relies on environment being made less hostile by present species via death and decomposition leading to it being outcompeted and replaced by larger better adapted species

Question 18

What are the 2 types of succession?

Answer 18

primary (occurs on new land) and secondary (occurs on previously colonised land that has become bare e.g. after a forest fire)

Question 19

Describe Primary Succession?

Answer 19

• new land appears (glacier retreats exposing rock, lava cools, sand dunes)
• pioneer species settle [adapted to surviving in hostile conditions of bare land]
• the land then erodes and soil forms
• The pioneer species die and decompose, putting nutrients back into the soil.
• small plants can now grow
• they out compete the pioneer species
• over time more soil forms, small plants die and decompose adding more nutrients to the soil
• large plants can now grow, they out compete the small plants
• this process continues until the climax community is reached
• the climax community contains the best adapted species to the environment (they are the final community, there will be no more succession after them)

Question 20

Primary succession vs Secondary succession?

Answer 20

• secondary succession starts from small plants not pioneer species (soil and nutrients already present)
• secondary succession is faster (soil, nutrients and seeds already present)

Question 21

types of conservation?

Answer 21

• ex-situ conservation
• in-situ conservation

Question 22

ex-situ conservation?

Answer 22

individual endangered species within zoos

Question 23

in-situ conservation?

Answer 23

whole ecosystems and landscapes

Question 24

specialised features of pioneer species?

Answer 24

• produce large quantities of wind-dispersing seeds or spores- can spread easily to remote areas
• short dormancy/fast germination
• not dependant on animal species (must photosynthesise)
• nitrogen fixing - poor soil quality
• tolerant of challenging conditions

Question 25

common features of succession?

Answer 25

• abiotic factors become less hostile
• a greater number and variety of habitats
• increased biodiversity
• more complex food webs
• increased biomass

Question 26

what is intraspecific competition?

Answer 26

occurs between organisms of the same species, only occurs when resources become limited, leads to natural selection and adaptation

Question 27

what is interspecific competition?

Answer 27

occurs between organisms of different species, can happen at any time even if resources are not limited, leads to formation of climax communities

Question 28

What is a gene pool?

Answer 28

All the alleles in a population