Population size and ecosystems

Question 1

What is a fugitive species

Answer 1

Cannot tolerate competition. They reproduce rapidly and spread out. They are able to invade new environments rapidly

Question 2

What is an equilibrium species

Answer 2

Control their population by competition in a stable habitat. Bacteria and rabbit populations show this type of growth

Question 3

What is the birth rate

Answer 3

The reproductive capacity of a population; the number of new individuals derived from reproduction per unit of time

Question 4

What is immigration

Answer 4

The movement of individuals into a population of the same species

Question 5

What is a population

Answer 5

The number of organisms of the same species living within a given area.

Question 6

What is the lag phase of a population growth chart

Answer 6

Population number increases very slowly because time is needed for enzyme synthesis

Question 7

What is the exponential phase of a population growth chart

Answer 7

Plenty of nutrients and few toxic by-products so there a no limiting factors to reproduction and population size increases rapidly

Question 8

What is the stationary phase of a population growth chart

Answer 8

Cells are reproducing but population is relatively constant as the rate of cell production = rate of cell death. The population has reached its carrying capacity because reduced resources and toxic by-products are now limiting factors

Question 9

What is the death phase of a population growth chart

Answer 9

More cells are dying that being produced so the population decreases. Death of cells is due to lack of oxygen, nutrients or toxicity of the medium

Question 10

What is the carrying capacity

Answer 10

the limit of a population, where the death rate is equal to the birth rate

Question 11

What is a population crash

Answer 11

Sudden decrease in population number

Question 12

What causes a population crash

Answer 12

When a population greatly increases its carrying capacity

Question 13

What happens after a population crash

Answer 13

The set carrying capacity us much lower as the environment is usually damaged beyond repair

Question 14

What is intraspecific competition

Answer 14

Competition within the same species

Question 15

What is interspecific competition

Answer 15

Competition between different species

Question 16

List factors that affect a population

Answer 16

Food supply
Competition
Predation
Living space
Parasitism
Weather

Question 17

What are biotic factors

Answer 17

Factors directly impacted by living things, eg. predation, disease and competition

Question 18

What are abiotic factors

Answer 18

Factors that are not affected by living things, eg. temperature, O2/CO2 concentration, nutrient/water availability

Question 19

Describe a predator-prey cycle

Answer 19

Predator peak is always lower than prey peak
Predator peak comes after prey peak
Occurs in a continuous cycle

Question 20

What is a population index

Answer 20

(birth rate + immigration) - (death rate + emigration)

Question 21

What are density dependant factors

Answer 21

Limit the carrying capacity as they weaken individuals and make them less likely to reproduce

Question 22

What are density independent factors

Answer 22

These are not linked to the population density, eg. natural disasters

Question 23

Explain mark, release recapture and tactics used to reduce its effect on the animals

Answer 23

Capturing an animal, marking it, and catching another load again every few hours. The way you mark them must be subtle otherwise it can inhibit their ability to catch prey or can increase their visibility an likelihood to be caught.

Question 24

What is a detrivore

Answer 24

feed on dead and decaying matter, increase surface area for saprophytes

Question 25

Why does only a little energy pass through each trophic level

Answer 25

some parts of the organism are inedible some parts of the organism cannot be digested heat energy lost via respiration

Question 26

What is gross primary productivity

Answer 26

the energy converted in plants into organic molecules

Question 27

What is net primary productivity

Answer 27

Plants use some of the energy in respiration, losing some as heat. The energy stored forms new biomass.

Question 28

Name disadvantages of pyramids of number

Answer 28

due to an often large number of organisms at the bottom it is almost impossible to draw to scale

Question 29

Name disadvantages of pyramids of biomass

Answer 29

This is very destructive as it requires killing organisms and so is generally considered unethical

Question 30

What is succession

Answer 30

gradual change over many years where plain ground goes from being empty to being able to grow more complex life

Question 31

What is a pioneer species

Answer 31

the first species to colonise a new area. They are usually very resistant to harsh abiotic factors

Question 32

What is a climax community

Answer 32

the most complex environment an area can grow to

Question 33

What is primary succession

Answer 33

the introduction of species to an area that was previously uninhabited

Question 34

What is secondary succession

Answer 34

the reintroduction of species into a bare habitat that was previously inhabited, ie, after a forest fire

Question 35

How does succession work

Answer 35

Each organism living there modifies the environment, usually improving soil quality and making more opportunities for other organisms to thrive

Question 36

What is a niche

Answer 36

the role and position a species has in its environment

Question 37

What are the stages of the nitrogen cycle

Answer 37

Deamination Nitrification Nitrogen Fixation Denitrification

Question 38

How do plants obtain nitrates

Answer 38

From the soil by active transport

Question 39

Explain what happens in deamination and the product formed

Answer 39

Saprophytic bacteria break down dead and decaying matter. Breaking them down releases ammonia. Nitrogen Compounds -> Ammonia

Question 40

Explain what happens in nitrification and the products formed

Answer 40

One type of nitrifying bacteria converts ammonia into nitrites, and another converts nitrites into nitrates. Ammonia - > Nitrites -> Nitrates

Question 41

Explain what happens in nitrogen fixing and the product formed

Answer 41

Nodules on legume plants contain bacteria with which they have a mutualistic relationship. The bacteria make ammonia to be turned in nitrates by nitrifying bacteria. Nitrogen -> Ammonia

Question 42

Explain what happens in denitrification and the product formed

Answer 42

Denitrifying bacteria in the soil convert nitrates back into nitrogen gas. This works against farmers who want to keep a maximum number of nitrates in the soil. Nitrate -> Nitrogen gas

Question 43

Name the four processes in the carbon cycle

Answer 43

Photosynthesis Respiration Combustion Decay

Question 44

How is carbon removed from the atmosphere

Answer 44

Photosynthesis removes CO2 from the atmosphere

Question 45

How is carbon returned to the atmosphere

Answer 45

Respiration - CO2 is a by-product of respiration Combustion - CO2 is released from the combustion of fossil fuels Decay - saprophytes break down organic molecules and release CO2