populations and sustainability

Question 1

give examples of density dependant factors

Answer 1

biotic:
- predation
- competition
- disease
- CO2 conc. (for plants)

Question 1

what is density independent factor and give examples

Answer 1

factors that cause death regardless of number in population
e.g. abiotic factors
- climate change
- fire
- volcanic eruption

Question 2

what are k strategist species controlled by

Answer 2

density dependant factors

Question 3

features of k strategist species

Answer 3

• controlled by density dependant factors
• invest highly in parental care
• large
• fewer offspring
  e.g. chimpanzees

Question 3

features of r strategist populations

Answer 3

• population exceeds carrying capacity before limiting factors have an effect, causing death phase due to lack of resources.
• low likelihood of surviving to adulthood
• smaller
• produce rapid offspring
  e.g. fish

Question 4

how does intraspecific predation effect population of a species?

Answer 4

competition for same food, water, territory slows down growth so population enters stationary phase and fluctuates around carrying capacity

Question 5

what is preservation

Answer 5

protecting species/area of land by restricting human activity and keeping it the way it is.
Lead to CLIMAX COMMUNITY

Question 6

what is conservation

Answer 6

active maintenance of biodiversity and ecosystems by humans which will lead to DEFLECTED SUCCESSION

Question 6

state 4 methods of control of fish production

Answer 6

• limiting number of fish caught
• limiting fishing to certain times in a year
• set out areas where fishing is banned
• education

Question 7

state 2 difficulties of controlling production of fish

Answer 7

• area too large to manage
• monitoring can be obstructed by weather

Question 8

describe small scale rotational coppicing as a method of sustainable timer production

Answer 8

• cut trunk close to ground
• protect young trees from grazers
• allow some trees to grow full size
• repeat process after 9 years

Question 9

what are 3 benefits of rotational coppicing

Answer 9

• less big trees means more light for smaller plants to grow
• roots remain in soil so prevent soil erosion
• prevents succession

Question 10

name 3 types of large scale felling

Answer 10

clear felling, selective felling, and strip felling

Question 11

what are problems of large scale felling

Answer 11

• loss of biodiversity
• disrupting food chains
• soil erosion

Question 12

how can timber be produced sustainably?

Answer 12

• limit area felled
• replant trees
• allow time for young trees to mature

Question 13

state the equation to calculate number of bacteria grown over a certain length of time

Answer 13

N = N0 x 2n

0 = initial number
n = number of divisions

Question 14

why are the number of predators generally smaller?

Answer 14

because they are higher up the food chain

Question 15

describe the relationship between predator and prey

Answer 15

when the prey population is high, there is more food source available for predators to eat, so pop of prey decline and predator pop increase,

However, now due to lack of prey, there is limited food source so predator pop lowers, and prey pop increases, this cycle repeats.

Question 16

predator-prey relationships are often more complex - describe the 3 other factors that effect their populations.

Answer 16

• the higher the species diversity in an ecosystem, the more difficult it is to see predator-prey relationships
• if a predator eats several kinds of prey, then it can switch to another if first prey pop declines.
• correlation does not always mean causation, it may be (intraspecific) competition for food, space, mates

Question 17

why is there a delay before predator population can increase?

Answer 17

because it takes time for birth rate to respond to changing conditions

Question 18

competitive exclusion

Answer 18

if two species have same niche, one will always outcompete the other, which then dies out.

Question 19

niche partioning

Answer 19

one species may be pushed into another niche.

Question 20

when does population level out?

Answer 20

at carrying capacity

Question 21

why is lag phase slow

Answer 21

• acclimatising to habitat
• genes switching on
• only small population

Question 22

economic reasons for conservation

Answer 22

• growth of timber, wood, and fuel
• detoxification and recycling of wastes
• source of medicines

Question 23

how to prevent succession

Answer 23

burning, grazing, coppicing