Life processes in the biosphere

Question 1

what is a range of tolerance

Answer 1

for a specific condition or factor organisms can survive within a relatively narrow range, can survive environmental changes

Question 2

why are populations with large gene pools more likely to survive environmental change

Answer 2

some individuals will become adapted to new conditions, more survivors to breed and rebuild population and offspring would be adapted

Question 3

name 4 important abiotic factors

Answer 3

light, pH, water, mineral nutrients

Question 4

name 8 important biotic factors

Answer 4

food supply (high abundant reliable allow smany animals to survive) / seed dispersal (moved by wind or by animal , plants produce seeds that intend to attract animals) / pollination / disease / avoiding predators (creates defence mechanisms or camouflage) / symbiotic nutrition (species evolve to assist each other) / nutrient supply

Question 5

what is ecological succession

Answer 5

change in structure and species composition of a community overtime

Question 6

why is ecological succession important

Answer 6

necessary to avoid extinction, as changing conditions make current location unsuitable for survival

Question 7

what is a sere

Answer 7

a stage in succession

Question 8

what is a climax community

Answer 8

long-term stable community at the end of succession

Question 9

state the developments that occur to create a climax community

Answer 9

soil creates a pioneer species / larger plant species grow, brought in by wind or animal / increasing levels of organic matter, eg humus, hold soil together / trees begin to grow, shade out shrubs creating shade tolerant plants / animal communities develop due to succession, biodiversity increases as succession proceeds

Question 10

what is a pioneer species

Answer 10

first colonisers for succession eg mosses and lichens dying and decomposing in soil

Question 11

what are the 3 types of succession

Answer 11

primary (development where no organisms have grown before) / deflected (situation where climax community cannot be achieved) / secondary (community develops on previously colonised area, generally faster than primary as soil already exists)

Question 12

name the 5 methods of maintaining plagioclimax communities

Answer 12

grazing / mowing / burning / coppicing / pollarding

Question 13

what is coppicing

Answer 13

when trees are cut down to ground level with a different area is cut each year on a regular cycle, allows more light and rain to reach woodland floor, allowing wildflowers to grow = food for insects

Question 14

what is a plagioclimax

Answer 14

human activity deflecting climax community so natural climax community doesn’t have time to reform

Question 15

what is pollarding

Answer 15

branches are cut back rather than the trunk, keeps regrowing shoots out of reach for animals that would eat them, cut branches left to prove organic matter for decomposers, also prolongs tree life so less likely to be damaged by wind

Question 16

describe the ecological succession of the hydrosere

Answer 16

freshwater is created and quickly colonised by single celled algae / birds and ducks deposit spores and algae seeds / lake edges colonised by rooting plants / more area colonised produces food and shelter so animals colonise / plants die and fill lake with dead organic matter and soil sediment, water becomes shallower allowing rooted plants to survive, emergent plants w leaves out outcompete submerged plants which die / soil accumulates and sediments fill lake, supports weight of bigger organisms eg trees / transpiration of trees remove water from sediments so drier conditions, allows growth of new tree species / community dominated by larger trees and other plants and animals

Question 17

describe the ecological succession of the lithosere

Answer 17

species develop on bare rock, algae and simple autotrophs colonise first / dead organic matter and rock fragments accumulate / moss and thin soil layer accumulates, plant nutrients are more available / seddlings are produced / pollinating insects colonise so flowering plants can colonise / soil becomes deep enough for trees to establish, first trees have wind blown seeds then animals colonise and spread seeds

Question 18

why is it tricky to create a climax community in a lithosere

Answer 18

abiotic conditions are very harsh and unsuitable for most organisms, temperature is extreme and water availability is limited and there is no soil

Question 19

describe the ecological succession of the psammosere

Answer 19

plants succeed in colonising, binds sand particles together, nutrient supply increases and organic matter builds up, water becomes more available / sequence of change in a community brings colonisation of animals

Question 20

why is it difficult to create a climax community in a psammosere

Answer 20

starts on sand where nutrients aren’t readily available, drainage is rapid so water supplies are poor and moving sand makes it difficult for plants to establish

Question 21

what causes a population increase

Answer 21

if reproduction rate is higher than the death rate

Question 22

what causes population decrease

Answer 22

if death rate is higher than reproduction rate

Question 23

what are r-related species

Answer 23

can respond rapidly to low survival rates, reach sexual maturity quickly, produce many young and disperse wildly

Question 24

what are k-selected species

Answer 24

recover slowly from decline in population, reach sexual maturity at an older age, produce few young but live for a long time, chnage in death rate by human exploitation or change in habitat could cause population crash

Question 25

what factors affect morality rates

Answer 25

density independent factors: factors where population density has no effect on chances of survival of an indiviual eg drought, flood / density dependant factors: factors where chances of survival depend upon population density of a species eg disease, food supply

Question 26

what is the carrying capacity

Answer 26

greatest population that an area can support indefinitely without damaging or over-exploiting the environment - mortality rate in a population changes if population size is above or below carrying capacity

Question 27

describe what happens in a predator prey relationship

Answer 27

prey population rises, lots of food for predator, so their population rises. higher predator population decreases prey population. low prey population lowers food for predator so their population declines, so prey population can rise again

Question 28

when is artificial population control necessary

Answer 28

if breeding rate of endangered species is low, captive breeding and release programme is needed / non-indigenous species is introduced, reducing population of indigenous / indigenous predator has been removed so indigenous prey species become over populated

Question 29

what is taxonomy

Answer 29

science of grouping organisms according to similarities in their features

Question 30

what is species

Answer 30

group of closely related organisms that resemble each other more than members of other groups, form reproductively isolated group that breed to produce fertile offspring

Question 31

what is evolution

Answer 31

process that changes the gene pool of a species, separating gene pools can eventually become two or more species. driven by increased chance of survival and can vary in different areas. evolution can produce isolated populations, creating closely related but not the same species

Question 32

what is habitat

Answer 32

area or location where a species or community of species live

Question 33

what is an ecological niche

Answer 33

a role that a species plays in its habitat eg pollination or seed dispersal

Question 34

what is population

Answer 34

includes all individuals of a single species that live in a particular area

Question 35

what is a community of species

Answer 35

includes all members of a species that live on an area

Question 36

what is an ecosystem

Answer 36

combination of abiotic and biotic features in an area, includes community of species and their inter-relations with each other and their relationship with the physical environment

Question 37

what is a biome

Answer 37

large geographical region with specific climate conditions within which characteristic community species lives

Question 38

what is the biosphere

Answer 38

all of planet earth that is inhibited by living organisms, including land surface, soil, water and atmosphere