U1T4 - Keywords (1)

Question 1

Population

Answer 1

Group of organisms of same species living in particular habitat.

Question 2

Lag Phase

Answer 2

Pop nums remain relatively constant or decline/slow increase in nums. Nutrient assimilation + reproduction.

Question 3

Exponential/Log Phase

Answer 3

Pop nums increase by same factor each time unit. Each new member reproduces so rapid growth as low competition as sufficient resources + little waste. Increase by intrinsic rate of natural increase (r) as pop exhibits biotic potential.

Question 4

Stationary Phase

Answer 4

Increased pop numbers result in environmental resistance due to waste accumulation, lack resources + increased comp. Reduced birth rate + increased death rate so pop stays constant. Reaches carrying capacity (k). Most pops stay at this stage.

Question 5

Decline Phase

Answer 5

Lack resources + increase in toxic waste means birth rate 0 + high death rate. Steep decline/crash in pop nums.

Question 6

Biotic Potential

Answer 6

Max growth/repro rate of pop under optimum conditions.

Question 7

Carrying Capacity

Answer 7

Max pop size that can be supported by available resources. Max num organisms ecosystem can support.

Question 8

Intrinsic Rate of Natural Increase

Answer 8

The rate at which a population increases in size if there are no density-dependent forces regulating the population. Births - deaths per generation time.

Question 9

Environmental Resistance

Answer 9

Sum of environmental factors which restrict biotic potential of population + limit increase.

Question 10

Renewable Resource

Answer 10

Resource which can be used repeatedly + replaced naturally.

Question 11

Non-renewable Resource

Answer 11

Resource that doesn’t renew itself at sufficient rate for sustainable economic extraction in human time-frames.

Question 12

Detritivores

Answer 12

An animal which feeds on dead organic material.

Question 13

Survivorship Curve

Answer 13

Shows % of individuals surviving over a year/number of years.

Question 14

R + K Selection Theory

Answer 14

Relates to selection of traits which promote success in certain environments + originates from work on island biogeography by MacArthur + Wilson. Selective pressures are hypothesised to drive evolution in r or k directions.

Question 15

R Selected Species

Answer 15

Grow v. quickly as individual, pop size increases rapidly under ideal conditions, numbers decline rapidly in less favourable conditions, emphasis on reproduction + colonisation, less parental involvement, small, short life, high dispersal, not competitive, not specialised so adaptable, unstable habitats + high fecundity.

Question 16

K Selected Species

Answer 16

Stable pops, large, long life, more specialised so less resistant to environment change, stable habitats, pop close to carrying capacity, emphasis on survival + dominance, not colonisation, successful competition, more parental involvement, low fecundity, less able to migrate so more likely to become extinct.

Question 17

High/Low Fecundity

Answer 17

Many/Few Offspring at once.

Question 18

Intraspecific Competition

Answer 18

Competition between members of the same species. Becomes more severe as pop increases + resources become limited.

Question 19

Interspecific Competition

Answer 19

Competition between members of diff species’. Success of 1 species relates to adaptations of each species in current conditions.

Question 20

Competitive Exclusion Principle

Answer 20

Situation where, due to severity of competition for resources, 1 species is eliminated. Only occurs when overlap between niches as 2 species’ can’t occupy same niche.

Question 21

Boom + Bust Population Growth

Answer 21

Seen in R-Selected Species’. Emphasis on reproduction + colonisation, rather than survival. High birth rate in optimum conditions but when conditions less favourable, numbers decrease rapidly.

Question 22

Grazing

Answer 22

When a herbivore grazes on grass. Herbivore benefits whilst grass loses as it loses photosynthetic ability as leaves are eaten.

Question 23

Parasitism

Answer 23

Organisms which live on or in host organisms feed upon or within it, benefiting whilst the host suffers, ultimately ending in host death (not always but often)

Question 24

Predator/Prey Relationship

Answer 24

Predator gains food whilst prey suffers. These relationships lead to oscillating growth curves with peaks and lows. With more prey, numbers increase so prey decreases and numbers decrease. Predator + prey peaks and lows are similar lengths but predator lag behind prey in peaks + troughs, depending on reproduction time. Predators usually lower than prey. e.g. Snowshoe hare + Canadian Lynx

Question 25

Mutualism

Answer 25

Interaction where both partners benefit. Often, eventually, 1 species can't survive on its own.

Question 26

Pest

Answer 26

Species that competes with/adversely affects a valuable/commercial pop of crop species/animals causing economic damage.

Question 27

Biological Control

Answer 27

The use of natural enemies to reduce numbers in pops of pests, without the risks of chemicals. Aims to reduce numbers to where they don't cause economic damage rather than eradicate. Deliberately introduce predator species to target pest.

Question 28

Antagonists

Answer 28

Biological control agents of plant diseases. e.g. herbivores + plant pathogens.

Question 29

Pathogens

Answer 29

Disease causing organisms which kill/debilitate host + are relatively specific e.g. bacteria, fungi + viruses.

Question 30

Pest Resurgence

Answer 30

Numbers of pest dramatically increase due to elimination of natural predator by broad spectrum pesticide.

Question 31

Community

Answer 31

Biotic component of ecosystem which involves autotrophic + heterotrophic interactions. All populations of different species' living in same place at same time + interact with each other.

Question 32

Ecosystem

Answer 32

Natural unit consisting of all plants, animals + micro organisms (biotic factors) in area functioning together will all abiotic factors of environment. Many species interdependent on each other. Involves energy flow + nutrient + gas exchanges.

Question 33

Succession

Answer 33

Directional non-seasonal cumulative change in types of species that occupy given area through time. Involves changes to community, abiotic environment + interaction between these. Involves colonisation, establishment + extinction which act on participating plant species.

Question 34

Seres

Answer 34

Stages in a succession which can be recognised by collection of species that dominate at that point in the succession.

Question 35

Primary Succession

Answer 35

In previously uncolonised, newly formed barren land areas. Newly exposed land/rock provides harsh + hostile environment for life + no soil present to support plants. e.g sand dunes

Question 36

Secondary Succession

Answer 36

Happens following destruction of existing ecosystem.

Question 37

Pioneer Species

Answer 37

Usually R-Selected species with high levels of dispersal. e.g. lichens

Question 38

Climax Community

Answer 38

Stable end of succession which is in equilibrium with environment. e.g. Broadleaf deciduous forests or moorland

Question 39

Biotic Climax

Answer 39

Community where stable end stage of succession is maintained by biotic factors e.g. shading trees, heavy animal tramping. Differs from any other climax community.

Question 40

Climatic Climax

Answer 40

Culminating stage of plant succession for given environment, vegetation has reached stable condition so long as environment stays same or changes only in response to climate/soil substrate changes which are slow relative to rate of plant succession. Dictated by climate.

Question 41

Haemocytometer

Answer 41

An instrument for visual counting of the number of cells in a blood sample or other fluid under a microscope.

Question 42

Lincoln Index

Answer 42

Statistical measure to estimate num of cases that haven't yet been observed, based on 2 independent sets of observed cases.

Question 43

R

Answer 43

Intrinsic rate of natural increase (biotic potential)

Question 44

K

Answer 44

Carrying capacity.

Question 45

Parasite

Answer 45

An organism that lives in or on another organism (host) benefiting from it and causing it harm over an extended period of time.

Question 46

Resource

Answer 46

Supply of materials + other assets that can be drawn on by someone to function.

Question 47

Competition

Answer 47

Striving to gain something by defeating others.