Population Size And Ecosystem

Question 1

Population growth curve

Answer 1

Lag
Log stationary
Death/decline

Question 2

Density dependent

Answer 2

Biotic (living)
Competition for resources
Predation
Disease

Question 3

Density independent (non living)

Answer 3

Light intensity
Temp
Water supply
Nutrient supply
Humidity
Wind speed
Day lenght
Rainfall

Question 4

How can results be used to determine the relationship between chosen factor and the percentage cover

Answer 4

Use a statistical test
Eg Pearson linear correlation
Spearman’s rank

Question 5

What is species diversity

Answer 5

Number of diff species in a community and the relative abundance of each population

Question 6

What is advantage of random sampling

Answer 6

Prevents selective sampling from causing bias
Eg. Researcher bias

Question 7

What type of graph is used to represent the distribution of a species along a transect

Answer 7

A kite diagram

Question 8

To asses biodiversity

Answer 8

1. Number of different species in that area
2. Number of individuals of each species

Question 9

To asses biodiversity what is used to estimate data

Answer 9

Random sampling

Question 10

In random sampling

Answer 10

Species must have equal chnace of being included in sample
Sampling method ensures that sample is representative of the whole population of each species
This reduces subjectivity and bias from data collected

Question 11

Quadrat

Answer 11

Used to collect population sizes of organisms that do not move or move slowly

Question 12

What does quadrat size depend on

Answer 12

1. Area being sampled
2. Size of organisms

Question 13

Small quadrat

Answer 13

Area is narrow
Area of high level diversity

Question 14

Large quadrat

Answer 14

Counting trees
(10x10m^2) quadrats may be used

Question 15

What is biodiversity

Answer 15

Species richness and species eveness

Question 16

Importance of taking large sample

Answer 16

Ensures sample is representative of whole area
Avoids bias
Ensures reliability of results

Question 17

Controls

Answer 17

Sample area which has not been excluded
Ensure environmental conditions are same in both areas

Question 18

Simpsons diversity

Answer 18

D= N(N-1)/{n(n-1)

Question 19

Carbon cycle

Answer 19

1. Plants take in co2 and use it in photosynthesis to make organic molecules passed to food chains
2. Plants and animals respire and excrete co2
3. Combustion releases co2
4. Decomposers respire excreting Co2
5. The formation of fossil fuels

Question 20

Decomposers

Answer 20

Bacteria and Fungi

Question 21

Decomposition rate is affected by

Answer 21

Temp slower when cold
Ph slower when acidic
O2 availability slower with less oxygen

Question 22

What’s wrong with water logged soil

Answer 22

Lacks oxygen
This favours denitification and slows nitrification
Insectivorous plants live in water logged area

Question 23

What is done to fix water logged soil

Answer 23

Ploughing introduces air into soil encouraging nitrification
Drainage ditches reduce water logging and denitrification

Question 24

Losses are through ?

Answer 24

Leaching
Soluable ammonium, nitrate and nitrite ions dissolve in ground water and drain away

Question 25

Eutrophication

Answer 25

Excessive plant and algal growth due to increased availability of one or more limiting growth factors needed for photosynthesis

Question 26

What does leaching cause

Answer 26

Excess nutrients flow into lakes and rivers from leaching causing eutrophication causing growth of algal bloom This blocks sunlight from bottom dwelling plants which die When algae die Decomposers population increases As they are aerobic more o2 than usual is utilised out of water Increased demand for oxygen Fish and aquatic invertebrates die and decompose

Question 27

What are nitrifying bacteria

Answer 27

Nitrosomonas - convert ammonium to nitrite Nitrobacter convert nitrite into nitrate

Question 28

Nitrogen fixing bacteria

Answer 28

Azobacter free living in soil Rhizobium in root nodules of legumes symbiotic

Question 29

Denitrifying bacteria

Answer 29

Convert nitrate to nitrogen gas Pseudomonas thrive in water logged soil

Question 30

Why is draining agriculture bad

Answer 30

Means that species rich wetlands are lost This loss of habitats and niches reduces species diversity

Question 31

Rhizobium - symbiotic relationship with legumes

Answer 31

It fixes nitrogen gas into ammonium ions and makes amino acids which exports into legume Legume makes root nodules for the rhizobium and provides carbohydrates and micro anerobic conditions needed for nitrogen fixation Legumes live in poor nitrate soil Clover is example of legume planted to provide extra nitrogen containing compounds

Question 32

What does simpsons index show

Answer 32

It’s a measure of diversity Shows number of species present And relative abundance of each species