3.7.4 Populations in ecosystems Flashcards Preview

SHHS - Science - NEW AQA A-Level Biology (Year 2) > 3.7.4 Populations in ecosystems > Flashcards

Flashcards in 3.7.4 Populations in ecosystems Deck (71)
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1

define community

all living organisms of all species found in a given area/habitat/ecosystem at a given time

2

define ecosysytem

self contained area including all the living (all the communities within it) and non living factors interacting with one another

3

define niche

describes how an organism fits into the environment/its role in the ecosystem - no organism can occupy the same niche

4

define succession

used to describe changes that occur over time, in the species that occupy a particular area

5

define abiotic

non living factor in the environment of an organism e.g temperature, oxygen concentration, pH, light

6

define biotic

the living factors in the environment of an organism e.g. disease, predation, competetion

7

define population

all of the organisms of one particular species in a given habitat/area at the same time

8

What conditions are necessary in order for the mark release recapture investigations to be valid? what assumptions are made?

1. markings dont make organism visible to predators
2. markings dont harm the organism
3. No migration/immigration
4. sample large
5. no reproduction
6. no births or deaths
7. markings are nor easily rubbed off/worn off
8. marked individuals in 1st sample distribute themselves evenly back into the population

9

Name two types of competition

interspecific and intraspecific

10

Define intraspecific competition

competition between organisms of the SAME species

11

Define interspecific competition

competition between organisms of DIFFERENT species

12

What is a pioneer species?

the first organism to colonise in the first stage of succession - it can with stand hostile environments

13

define a climax community

A stable community/no further succession.
All the organisms that make up the final stage of succession - animals and plants

14

define a habitat

place where a habitat where an organism lives

15

define carrying capacity

The population size of a species that an be supported by the ecosystem

16

within an ecosystem which 2 major processes occur

1. flow of energy through the system
2. recycling of nutrients within the system

17

define population size

the number of individuals in the population

18

what do we call factors that limit the size of the population

limiting factors - they can be abiotic or biotic

19

Give examples of abiotic factors that limit the size of a population

light, temperature, pH, water, humidity

20

give examples of biotic factors that limit population size

availability of food, predation, disease

21

The growth and size of the human population depends on

birth rate v death rate - its the balance between these two that determines if if increases, decreases or remains the same (also includes immigration and migration)

22

define immigration

when people move into a population from outside

23

define emmigration

when people move out of a population and leave

24

In a stable population what can be said about birth and death rates?

they are equal

25

In an increasing population what can be said about birth and death rates?

birth rates are higher than death rates

26

define predation

where one organism is consumed by another

27

Define prey

An organism that is consumed/hunted by another organism

28

Define a predator

An organism that hunts and feed on other organisms

29

Why is it impossible to count every organism when investigating populations?

too many to count, too time consuming, would probably damage the habitat

30

How do we ensure the samples we take are representative when investigating populations

Take large sample, sample at random