6.6 Populations

Question 1

describe the lag phase

Answer 1

few individuals acclimatise to their habitat. rate of reproduction and growth in population is slow

Question 2

describe the log phase

Answer 2

resources are plentiful and the conditions are good. pop size increases rapidly and reproduction rate exceeds mortality rate

Question 3

describe the carrying capacity

Answer 3

this is when the habitat cannot support a larger population. reproduction and mortality rate is equal. limiting factors come into play

Question 4

what are the two types of limiting factors

Answer 4

density dependant
density indépendant

Question 5

describe density independent factors

Answer 5

act strongly regardless of pop size e.g low temp will kill same proportion of individuals regardless of pop size

Question 6

describe density independent factors

Answer 6

factor influences pop more strongly as pop size increases e.g availability of food water and light, when pop size increases there are higher levels of parasitism and predation

Question 7

describe k strategists and examples of them

Answer 7

pop size is determined by carrying capacity- limiting factors have significant effects

birds, larger mammals (humans, elephants, lions, larger plants)

Question 8

define characteristics of k strategists

Answer 8

• low reproduction rate
  -slow development
  -late reproductive rate
  -long lifespan
  -large body mass

Question 9

describe r strategists and examples of them

Answer 9

pop size exceeds carrying capacity before limiting factors have effect
after carrying capacity is exceeded there are not enough resources for survival and reproduction so build up of waste products may poison species “boom and bust”

mice, insects, spiders, weeds

Question 10

define characteristics of r strategists

Answer 10

-high reproductive rate
-quick development
-young reproductive rate
-short life span
-small body mass

Question 11

identify the differences between r and k strategists

Answer 11

r strategist species tend to have rapid reproduction rate and quick pop growth so they can colonise disturbed ground before k strategists

K are more likely to be members of a climax community because the r are likely to have reached carrying capacity and dispersed to other habitats

Question 12

describe the predator and prey effect on pop size

Answer 12

1- predator pop gets bigger, more prey is eaten
2- prey pop gets smaller, less food for predators
3-less food so predator pop gets smaller
4-less predators, less prey eaten so pop increases
5- more prey, predator pop increases and cycle repeats

Question 13

define interspecific competition

Answer 13

competition between individuals of different species

Question 14

define infraspecific competition

Answer 14

competition between two individuals of the same species

Question 15

define the competitive exclusion principle

Answer 15

more overlap between two species niches’ results in more intense competition. If 2 species have the same niche, one is outcompeted by the other and dies out or becomes extinct in that habitat

Question 16

example of competitive exclusion principle

Answer 16

2 species of paramecium grown both separately and together
when together, competition for food and after 20 days one species died out and the other increased and was left as the only remaining species

Question 17

define conservation

Answer 17

maintenance of biodiversity including diversity between species, genetic diversity within species and maintenance of a variety of habitats and ecosystems

Question 18

define preservation

Answer 18

maintenance of habitats and ecosystems in their present condition minimising human impact

Question 19

why is a conservation a dynamic process

Answer 19

needs constant adaptation to changes within the ecosystem

Question 20

what does conservation involve

Answer 20

-maintaining genetic diversity
-maintainance of habitats
-managing areas of land
-taking steps to encourage new habitats
-removing animals to captivity
-growing plants in cultivation
-reclamation of damaged or destroyed ecosystems

Question 21

what does preservation involve

Answer 21

-protecting ecosystems so they are kept exactly as they are
-nothing removed from a preserved area
-visitation is limited

Question 22

describe reasons organisms become extinct

Answer 22

H-habitat destruction
I- invasive species
P-predation
P-pollution
O-overharvesting

Question 23

why can human population threaten biodiversity

Answer 23

-overexploitation of wild populations for food
-habitat disruption and fragmentations as result of intensive agricultural practices/pollution/widespread building
-species introduced to an ecosystem by humans that outcompete other native species

Question 24

describe conservation strategies

Answer 24

-raise carrying capacity by providing extra food
-more individuals to enlarge populations or encourage natural dispersion of individuals by developing dispersal corridors of appropriate habitat
-restrict dispersal of individuals by fencing
-control predators and poachers
-vaccinate individuals against disease
-preserve habitats by preventing pollution or disruption or intervene to restrict the process of succession

Question 25

describe economic reasons for conservation

Answer 25

-natural ecosystems provide services such as regulation of atmosphere and climate, formation and fertilisation of soil, recycling nutrients, growing of timber, food and fuel
- natural environments are a valuable source of beneficial organisms (medicinal drugs)
-natural predators of pests can act as biological control agents
-ecotourism

Question 26

describe ethical reasons for conservation

Answer 26

-species become extinct as a result of human action
-humans have responsibility to maintain species, ecosystems and habitats for future generations
-all organisms have a right to survive and live in the way which they have become adapted

Question 27

describe social reasons for conservation

Answer 27

-people enjoy visiting wild places and observing wild life
-wellbeing: physical, intellectual and emotional health

Question 28

how did the terai region make resource more sustainable

Answer 28

by creating forest corridors, counteracting poachers and illegal felling, introducing biogas plants and wood efficient stoves, constructing waterholes, monitoring endangered species and eradicating invasive species

Question 29

how did the Maasai mara make resource more sustainable

Answer 29

by creating conservancies that allow limited grazing and tourism opportunities to co exist

Question 30

similarities between terai region and Maasai mara

Answer 30

both strategies adopted acknowledged the importance of local people and work with them and both have conservation with development aspects

Question 31

differences between the terai region and Maasai mara

Answer 31

Maasai are responsible for large areas of land, where as indigenous terai just work on land owned by government

Question 32

what are the positive consequences of the Terai region

Answer 32

forests provide local people with a sustainable source of fuel, animal feed, food, building materials, agricultural and household tools, as well as medicines. Tiger population appears to be increasing.

Question 33

what are the negative consequences of the terai region

Answer 33

increasing tiger populations might tempt back poachers

Question 34

what are the positive consequences in the Maasai region

Answer 34

positive partnerships between conservancies and tourism organisations. sustainable farming and tourism opportunities for locals

Question 35

what are the negative consequences in the Maasai region

Answer 35

land owners are forced to move their livestock out of the conservancies during the tourist season and can be forced to resettle elsewhere

Question 36

what are the main threats to native species on the Galapagos islands

Answer 36

habitat disturbance, over exploitation of resource, effects of introduced species

Question 37

how do goats pose a problem to conservation on the Galapagos islands

Answer 37

goats feed on Galapagos rock-purslane, a species unique to the islands, trample and feed upon giant tortoises food supply and disrupt their nesting sites. On northern Isabella island, the goat has also transformed the forest into grassland, leading to soil erosion.

Question 38

how does the management of the marine reserve around the Galapagos islands provide a model for effective conservation

Answer 38

it shows how local stakeholders can work together to sustainably manage a resource

Question 39

how is protection of krill important to the antarctic ecosystem

Answer 39

because they are a key component of a large number of food chains and a number of their predators are unable to adapt to find krill elsewhere if their numbers are low

Question 40

describe factors which work against conservation

Answer 40

-human population growth
-climate change
-pollution
-growth in ecotourism
-continued exploitation of natural resources

Question 41

describe strategies which help in conservation

Answer 41

-limit size of local population
-control local industry
-pollution levels and exploitation of natural resources
-control number of tourists and where they can go in ecosystem

Question 42

describe conflict in the Lake District

Answer 42

-spruce and pine in conifer plantations support limited biodiversity
-invasive species escaped from gardens and spread into woodland out competing native species
-rare ferns grow well in the fissures of limestone pavement and rare butterflies thrive in this habitat

Question 43

describe solutions to conflict in the Lake District

Answer 43

-recent initiatives have generated more varied planting and felling patterns, giving a mosaic of smaller strands of different aged trees
-physically removed by conservation workers
-the pavement is legally protected through the limestone pavement orders

Question 44

describe conflict in snowdonia

Answer 44

-farmers dig open drainage ditches to dry the land- rain flows quickly through habitat- increases flood risk
-conifers are planted as cash crops- this dries out the moorland as the trees absorb water, roads have to be built to carry wood away, compacting the land
-old heather burns easily and so accidental fires can be a high risk

Question 45

describe solution to conflict in snowdonia

Answer 45

-drainage ditches can be blocked by hay bales
-when trees are cut down, branches are used to block drainage ditches to slow water flow and keep the land moist
-burning controlled fired before heather gets too old and dry to prevent damage to habitat

Question 46

describe main threats to woodlands

Answer 46

-easily converted to agricultural land
-development (housing)
-logging
-pollution- acid rain from coal burning
-global warming- may change rainfall patterns

Question 47

describe uses of timber

Answer 47

-building construction
-fencing
-fuel
-paper
-furniture

Question 48

describe small scale production

Answer 48

pollarding- cut trees high up
coppacing- cut lower almost at stump

Question 49

describe large scale production

Answer 49

clear felling- destroys habitat, causes erosion of soil and nutrient loss
selective felling- cuts out largest, most valuable trees and replant them so habitat is broadly unaffected

Question 50

describe the process of coppicing

Answer 50

-trunk cut close to ground level
-several new shoots grow from cut surface
-protect young shoots from grazers
-process repeated after certain time
-broadleaved species
-rotational species
-can be repeated indefinitely

Question 51

describe benefits of coppicing

Answer 51

-new stems grow more rapidly than saplings
-lifespan of tree extended
-provides variety of light levels
-fewer large trees means more light for smaller plants
-provides variety of habitats
-roots prevent soil erosion

Question 52

what do fisheries need to do to manage fish stock sustainably

Answer 52

-maintain fish populations at their carrying capacity
-fishing quotas
-minimum catch size net sizes

Question 53

what are the pros of aquaculture

Answer 53

-stable supply of fish
-relief for wild aquatic animals
-protection of habitats
-mitigation of the endangered species problem
-local income source
-employment opportunities
-feed growing world population

Question 54

what are the cons of aquaculture

Answer 54

-use of antibiotics
-use of growth hormones
-genetic manipulation
-water pollution
-problems if farm fish escape and breed with wild fish
-regarded to as unnatural
-conditions in fish farms are poor
-ecosystems are altered