Populations in Ecosystems (complete)

Question 1

What is a population in an ecosystem?

Answer 1

A group of individuals of the same species living in a specific area.

Question 2

What is carrying capacity of an environment?

Answer 2

The maximum number of individuals of a species that an environment can support.

Question 3

What is the difference between biotic and abiotic factors?

Answer 3

Biotic factors are living components of an ecosystem, while abiotic factors are non-living components.

Question 4

What is the formula for calculating population growth rate?

Answer 4

Population Growth Rate = (Births - Deaths) / Total Population.

Question 5

What is an ecosystem?

Answer 5

A community of living organisms interacting with their physical environment.

Question 6

What is a trophic level?

Answer 6

The position an organism occupies in a food chain.

Question 7

What is the difference between primary and secondary succession?

Answer 7

Primary succession occurs in lifeless areas, while secondary succession occurs in areas where a disturbance has destroyed a community without destroying the soil.

Question 8

What is a climax community?

Answer 8

A stable community that no longer goes through major ecological changes.
The organisms that make up the final stage of ecological succession (balanced equilibrium)

Question 9

What is a trophic pyramid?

Answer 9

A graphical representation of the energy or biomass at each trophic level in an ecosystem.

Question 10

Name a method used to estimate population size.

Answer 10

Mark and recapture method.

Question 11

What is the role of decomposers in an ecosystem?

Answer 11

They break down dead organic matter, returning nutrients to the soil.

Question 12

What is a habitat?

Answer 12

The natural home or environment of an organism.

Question 13

Define an invasive species.

Answer 13

A non-native species that spreads widely in a new habitat.

Question 14

What is a food web?

Answer 14

A complex network of feeding relationships between organisms in an ecosystem.

Question 15

What is a mutualistic relationship?

Answer 15

A mutually beneficial interaction between two different species.

Question 16

What is the difference between primary and secondary producers?

Answer 16

Primary producers produce their own energy, while secondary producers consume primary producers.

Question 17

Define ecological niche.

Answer 17

The role and space an organism fills in an ecosystem.

Question 18

What is the role of apex predators in an ecosystem?

Answer 18

They help maintain the structure of the ecosystem by controlling populations of other species.

Question 19

Define trophic efficiency.

Answer 19

The percentage of energy transferred from one trophic level to the next.

Question 20

What is the primary method of energy transfer in ecosystems?

Answer 20

Through food chains and food webs.

Question 21

Define the term ‘extinction’.

Answer 21

The permanent loss of a species from the planet.

Question 22

What is the significance of wetlands in ecosystems?

Answer 22

They provide habitat for wildlife, filter pollutants, and help regulate water cycles.

Question 23

Define a niche

Answer 23

• how an organism fits into the environment, where it lives and the abiotic and biotic factors that may affect it.

Question 24

Give the difference between a realised niche and a fundamental niche.

Answer 24

• Realised - the actual niche occupied by an organism
• Fundamental - mich wider than a realised niche, the whole of the potential niche of an organism.

Question 25

Name some abiotic factors that affect a species niche/population.

Answer 25

- Light intensity - Temperature - Water - Space - Nutrients - Soil pH - Wind speed

Question 26

Name some biotic factors that affect a species niche/population.

Answer 26

- Food - Mates - Disease - Human Interaction - Predators

Question 27

How does Temperature affect the niche/population of a species?

Answer 27

- Enzymes - Too cold enzymes slow down, metabolic rate decreases, growth slower; Too hot enzymes denatured so population growth slower. - For warm-blooded animals, lots of energy expended trying to maintain body temperature if too far from optimum, so population growth slows.

Question 28

How does light affect the niche/population of a species?

Answer 28

- Photosynthesis rates will decrease if too low of a light intensity, so slower plant growth.

Question 29

How does pH affect the niche/population of a species?

Answer 29

- Enzyme activity affected if pH too far from optimum. - When pH optimum for enzymes, population will be larger.

Question 30

How does water/humidity affect the niche/population of a species?

Answer 30

- If very little water, population sizes smallest. - Changes in humidity affect transpiration rates of plants, so affecting plant growth.

Question 31

Define introspection competition

Answer 31

- Competition that occurs within members of the same species. - e.g: for space/food.

Question 32

Define interspecific competition

Answer 32

- Where different species compete cor the same resource at the same trophic level. - e.g: for light, food

Question 33

Name some reasons for conservation of ecosystems and biodiversity

Answer 33

- Ethical - respect for living things, other species should be able to coexist. - Economic - living organisms have a high gene pool and may have the capacity to make millions of substances. - Cultural and Aesthetic - habitats enrich our lives. - Personal - to maintain our planet and therefore out life support system.

Question 34

Define succession

Answer 34

- the term used to describe the changes, over time in the species that occupy a particular area.

Question 35

Describe the first stage of succession.

Answer 35

Pioneer Species: - Pioneer species colonise a hostile environment. - Allow for new species to exist in the previously hostile environment.

Question 36

Name some adaptations of pioneer species to survive in hostile environments.

Answer 36

- Production of wind dispersed seeds to easily reach isolated areas. - Rapid germination of seeds. - Ability to photosynthesise. - Ability to fix nitrogen from atmosphere. - Asexual reproduction to build up population quickly. Tolerance to extreme conditions.

Question 37

Name the stages of succession.

Answer 37

- Barren land (Hostile environment) —> Primary colonisers —> Secondary colonisers —> (Tertiary colonisers) —> Scrubland —> Climax community.

Question 38

How does a land alteration affect the succession?

Answer 38

- The area will undergo succesion to return to a stable climax community, however this type doesn’t begin with a pioneer species.

Question 39

Name some common features of any succession.

Answer 39

- The non-living environment becomes less hostile. - A greater number and variety of habitats. - Increased biodiversity - Competition - More complex food webs - Increased biomass - Climax community

Question 40

Describe and explain how succession occurs

Answer 40

- Hostile environment —> Pioneer species colonise - Pioneer species die and decompose —> Release nutrients and organic matter into soil - Change in abiotic factors. - New species able to survive due to less harsh environment. - New species out compete pioneer species —> Change in biotic factors and increase in biodiversity - Cycle continues until species in climax community begin growing. - Now less hostile environment and climax community reached.