Populations and ecosystems (BIOL4)

Question 0

Define population

Answer 0

All organisms of one species in a habitat

Question 1

Define habitat

Answer 1

Part of an ecosystem in which organisms live

Question 2

Define ecosystem

Answer 2

All organisms living in a particular area and all the non-living conditions

Question 3

Define abiotic conditions

Answer 3

Non-living features of the ecosystem (temp, water availability)

Question 4

Define biotic conditions

Answer 4

Living features of the ecosystem (predators, food)

Question 5

Define niche

Answer 5

Role of a species within its habitat

Question 6

Define adaptation

Answer 6

Feature that species have that increases their chances of survival and reproduction

Question 7

Define abundance

Answer 7

No. of individuals of a species in an area

Question 8

Define frequency

Answer 8

No. of samples species is recorded in

Question 9

Define percentage cover

Answer 9

How much of an area is covered by a species

Question 10

Define distribution

Answer 10

Where a species is within an area

Question 11

What the the two types of sampling techniques?

Answer 11

Random and systematic

Question 12

What is random sampling?

Answer 12

You don’t make a conscious decision of where samples are taken; prevents bias

Question 13

How are random samples taken?

Answer 13

Divide land into grid, use random no. generator to select coordinates

Question 14

What is systematic sampling?

Answer 14

Samples are decided

Question 15

How is the number of individuals in an area estimated?

Answer 15

Mean x size area

Question 16

What are the different types of quadrats?

Answer 16

Frame - square frames placed

Point - random no. generator to determine placement. Drop needle in hole, count what it touches

Question 17

What are the different types of transects?

Answer 17

Line - record species touching tape at intervals

Belt - quadrats along belt, record percentage cover/abundance

Question 18

What is the mark-release-recapture method?

Answer 18

Capture sample and count

Mark in harmless way

Release back into habitat

Take 2nd sample from same population

Count how many are marked

Question 19

How do we estimate total population from mark-capture-release? (Lincoln Index!)

Answer 19

Total population = (no. caught in s1 x no. caught in s2) / no. marked in s2

Question 20

What assumptions does the mark-release-recapture method rely on?

Answer 20

Sample had time to mix w/ population

Marking hasn’t affected chances of survival

Changes in population (deaths/births/migration) are small

Question 21

What factors effect variation in population size?

Answer 21

Abiotic factors

Biotic factors

Predation

Question 22

How do abiotic factors affect variation in population size?

Answer 22

When abiotic cond. ideal, organisms grow fast and reproduce or undertake metabolic reactions successfully

Question 23

How do biotic factors contribute to variation in population size?

Answer 23

Interspecific competition - different species compete for same resources (food/space), results in out-competition due to one being better adapted

Intraspecific competition - same species; population inc. when resources plentiful; more organisms compete.

Resources become limited; population declines. Small population = less competition = population inc.

Question 24

How does predation contribute to variation in population size?

Answer 24

Prey inc, more food for predators –> predator population inc.

More prey eaten –> prey population falls, less predator food –> predator population falls

Question 25

Define species

Answer 25

Group of similar organisms that can reproduce to give fertile offspring