D4 Continuity and Change of Ecosystems

Question 1

Polymorphic trait

definition

Answer 1

a trait that has more than 2 but less than 4 genetic variations (can eb at a phenotypic or genotypic level)

Question 2

directional selection

definition

Answer 2

when a trait has two or 3 categorical phenotypes and natural selection favours one

Question 3

stabalising selection

definition

Answer 3

when there is a continuum of phenotypes for a trait and natural selection favours the average not the extremes

Question 4

disruptive selection

define

Answer 4

either extreme phenotypes are prefered to the average on a continuum of phenotypes for a trait (can be the begining of speciation)

Question 5

genetic equalibrium

define

Answer 5

when there is no change in allele frequencies over time, usually in reference to one trait/gene

Question 6

conditions needed for a population to be in genetic equalibrium

Answer 6

1. large population size
2. no immigration or emigration (gene flow)
3. no favoured phenotype
4. no sexual selection (random mating)
5. no generation of new alleles that change the phenotype by mutation

Question 7

ecosystem sustainability

define

Answer 7

the ecosystem can support itself without outside influences. Allowed when changes to an ecosystem are slow enough that organisms can still adapt to and thrive

Question 8

tipping point

define

Answer 8

the point where an ecosystem has endured too much damage and can no longer be self-sufficient or sustained

Question 9

requirements for an ecosystem to remain stable

Answer 9

1. sufficient energy supply
2. nutrient recycling
3. enetic diversity
4. good response to climate change

Question 10

keystone species

define

Answer 10

a species that has a disproportunate effect on the ecosystem

Question 11

trophic cascade

define

Answer 11

when a top predator is removed and consequently destabalises the lower trophic levels and ecosystem balance

Question 12

soil erosion

define

Answer 12

the loss of nutrient rich topsoil by excess rain or wind

Question 13

leaching

define

Answer 13

when rain or irrigation water disolves nutrients in the soil and pulls it down past plant roots so that they can’t be absorbed by roots

Question 14

agrochemicals

define

Answer 14

chemicals like pesticides and fertilisers used by farmers, that lead to eutrophication and water pollution

Question 15

carbon footprint

definition

Answer 15

the total amount of greenhouse gasses that is generated by an activity

Question 16

tillage

definition

Answer 16

preperation of soil for crops that uses machinery that emitt carbon emissions

Question 17

eutrophication

definition

Answer 17

an abundance of nutrients running into water causing algae to overgrow on surface, increase in decomposers, decrease in oxygen, decrease in fish

Question 18

biochemical oxygen demand

definition

Answer 18

the amount of oxygen needed by bacteria decomposers in water to carry out cellular respiration

Question 19

biomagnification

definition

Answer 19

when there are traces of toxins in the water that get passed up trophic levels

Question 20

macroplasitcs

size

Answer 20

larger than 5mm

Question 21

microplastics

size

Answer 21

smaller than 5mm

Question 22

pioneer species

definition

Answer 22

the first species to exist in a newly established ecosystem

Question 23

climax community

definition

Answer 23

a stable point of peak biodiversity and population in an ecosystem

Question 24

cyclical succession

definition

Answer 24

when an ecosystem does not reach one stable climax community but many in a repeating cycle

Question 25

permafrost ## Footnote definition

Answer 25

the soil in very cold climates below the surface that is frozen solid

Question 26

albedo ## Footnote definition

Answer 26

the ability of a sureface to reflect light (dark object = low albedo)

Question 27

landfast ice ## Footnote defintion

Answer 27

a frozen layer of seawater that is attached to the land, important in some organisms breed here

Question 28

ocean stratification ## Footnote definition

Answer 28

the layers of the ocean where warmer less salty water floats on the top of the cold, nurtient dense layer

Question 29

carbon sequestration ## Footnote definition

Answer 29

the capture and storage of carbon that can happen naturally or to combat climate change

Question 30

phenology ## Footnote definition

Answer 30

the study of the timing of periodic events in living organisms

Question 31

photoperiod ## Footnote definition

Answer 31

the number of hours a day when the sun is shining

Question 32

trophic mismatch ## Footnote definition

Answer 32

when an abiotic change disrupts the annual cycle of a species, causing it to fcall out of sync with other species

Question 33

microevolution ## Footnote definition

Answer 33

tracing changes over time in a syngle phenotypic trait (often using hardy weinburg)

Question 34

polymorphism ## Footnote definition

Answer 34

when there are two or more phenotypes for a trait that are equally present and neither provides an advantage