Populations in Ecosystems

Question 1

Habitat?

Answer 1

place where an organism lives

Question 2

Population?

Answer 2

all organisms of one species in a habitat

Question 3

Community?

Answer 3

populations of different species in a habitat make up a community

Question 4

Ecosystem?

Answer 4

a community, plus all the abiotic conditions in the area in which it lives

Question 5

Abiotic conditions?

Answer 5

non-living features of an ecosystem e.g. temp, availability of water

Question 6

Biotic conditions?

Answer 6

living features of an ecosystem e.g. presence of predators or food

Question 7

Niche?

Answer 7

the role of a species within its habitat - includes its biotic interactions (organisms it eats, those its eaten by) and abiotic interactions (O2 it breathes, CO2 it breathes out)

Question 8

Adaptation?

Answer 8

a feature that members of a species have that increases their chance of survival and reproduction
e.g. giraffes have long necks to help them reach vegetation that’s high up, increasing their chances of survival when food is scarce

Question 9

What happens if two species try to occupy the same niche?

Answer 9

they will compete with each other, one species will be more successful than the other until only one species is left
(every species has its own unique niche)

Question 10

What are physiological adaptations?

Answer 10

processes inside the body

Question 11

What are behavioural adaptations?

Answer 11

the way an organism acts

Question 12

What are anatomical adaptations?

Answer 12

structural features of the body

Question 13

What is natural selection?

Answer 13

organisms with better adaptations are more likely to survive, reproduce and pass on their alleles for their adaptations, so the adaptations become more common in the population

Question 14

3 examples of adaptations to abiotic conditions in an environment?

Answer 14

• Otters have webbed paws - they can walk on land and swim effectively, increasing their chances of survival because they can live and hunt both on land and in water
• Seal have a thick layer of blubber - helps keep them warm in the coldest seas, increasing chances of survival because they can live in places where food is plentiful
• Hedgehogs hibernate - they lower their rate of metabolism over the winter, increasing chances of survival because they can conserve energy during the coldest months

Question 15

3 examples of adaptations to biotic factors in an environment?

Answer 15

• Sea otters use rocks to smash open shellfish and clams, increasing chances of survival because it gives them access to another food source
• Male frogs produce mating calls to attract females, making sure they attract a mate of the same species, increasing chance of reproduction by making successful mating more likely
• Some bacteria produce antibiotics which kill other species of bacteria in the same area, increasing chances of survival because there’s less competition for resources

Question 16

What is population size?

Answer 16

the total number of organisms of one species in a habitat

Question 17

What is the carrying capacity?

Answer 17

maximum stable population size of a species that an ecosystem can support (varies as a result of abiotic and biotic factors)

Question 18

What are examples of abiotic factors?

Answer 18

light, water, space, temp of surroundings, chemical composition of surroundings

Question 19

How is population size affected when temp of an mammal’s surroundings is ideal?

Answer 19

ideal temp of surroundings for metabolic reactions to take place means they don’t have to use up as much energy maintaining their body temp. So more energy can be used for growth and reproduction, so population size increases

Question 20

How is population size affected when temp of an mammal’s surroundings is lower or higher than their optimum body temp?

Answer 20

they have to use a lot of energy to maintain the right body temp. So less energy available for growth and reproduction, so population size decreases

Question 21

What is interspecific competition?

Answer 21

competition between different species for the same resources

Question 22

Why would interspecific competition limit population sizes of both species?

Answer 22

if they share the same food source, there will be less available to both of them. Both populations are limited by a lower amount of food. They have less energy for growth and reproduction, so population sizes will be lower for both species

Question 23

What is the effect of interspecific competition if one species is better adapted?

Answer 23

the less well adapted species is likely to be out-competed - won’t be able to exist alongside the better adapted species

Question 24

What is infraspecific competition?

Answer 24

competition between organisms of the same species for the same resources

Question 25

What is the effect of infraspecific competition on population size?

Answer 25

1. population of a species increases when resources are plentiful, as population increases, more organisms competing for same amount of food and space 2. resources (food and space) become limiting - isn't enough for all organisms, population starts to decline 3. smaller population means less competition for space and food, which is better for growth and reproduction - population starts to grow again

Question 26

What is predation?

Answer 26

an organism (predator) kills and eats another organism (prey)

Question 27

Why are population sizes of predators and prey interlinked?

Answer 27

as the population of one changes, it causes the other population to change

Question 28

Describe a predator-prey cycle.

Answer 28

1. as prey population increases, more food for predators, so predator population grows 2. as predator population increases, more prey is eaten, so prey population begins to fall 3. less food for predators, so predator population decreases and so on

Question 29

Why are predator-prey cycles usually more complicated?

Answer 29

there are other factors involved, like availability of food for prey. e.g. population of prey might initially decrease because there's too many of them for the amount of food available, this is then accelerated by predation

Question 30

What is succession?

Answer 30

the process by which an ecosystem changes over time

Question 31

2 types of succession?

Answer 31

- primary | - secondary

Question 32

What is primary succession?

Answer 32

happens on land that's been newly formed or exposed (e.g. where a volcano has erupted to form a new rock face, or where sea level has dropped exposing a new area of land). Theres no soil or organic material to start with (e.g. just bare rock)

Question 33

What is secondary succession?

Answer 33

happens on land that's been cleared of all plants, but where the soil remains (e.g. after a forest fire or where a forest has been cut down by humans)

Question 34

Describe the process of primary succession. | -example of how some new species may change the environment so that it becomes less suitable for the previous species?

Answer 34

1. pioneer species colonise the area (adapted to live in harsh conditions) 2. pioneer species change the abiotic conditions - they die and microorganisms decompose the dead organic material (humus), this forms a basic soil. this makes conditions less hostile (basic soil helps to retain water) 3. so new organisms can move in and grow - they die and are decomposed, making soil deeper and richer in minerals 4. so larger plants that need more water can start to grow in deeper soil. soil continues to deepen as larger plants die an dare decomposed -e.g. sand sedge stabilises the sand through the growth of rhizomes (underground stems). this makes the conditions less suitable for marram grass, which needs constant reburial by sand in order to grow healthily

Question 35

Example - describe process of primary succession from bare rock to woodland.

Answer 35

1. pioneer species colonise the rocks e.g. lichens grow on and break down rocks, releasing minerals 2. lichens die and are decomposed helping form a thin soil, which thickens as more organic material is formed. this means other species such as mosses can grow 3. larger plants that need more water can move in as the soil deepens, e.g. grasses and small flowering plants. soil continues to deepen as larger plants die an dare decomposed 4. shrubs, ferns and small trees start to grow, out-competing the grasses and smaller plants to become the dominant species. Diversity increases. 5. finally, soil is deep and rich enough in nutrients to support large trees. these become the dominant species, and the climax community is formed

Question 36

What is the climatic climax?

Answer 36

the climax community for a particular climate

Question 37

What is the climatic climax in a temperate climate?

Answer 37

there's plenty of available water, mild temperatures and not much change between the seasons. the climatic climax will contain large trees because they can grow in these conditions once deep soils have developed

Question 38

What is the climatic climax in a polar climate?

Answer 38

not much available water, low temperatures and there are massive changes between seasons. large trees won't ever be able to grow in these conditions, so climatic climax contains only herbs or shrubs

Question 39

What is a plagioclimax?

Answer 39

the climax community when succession is stopped artificially

Question 40

What is conservation? | -what does it sometimes involve?

Answer 40

the protection and management of species and ecosystems in a sustainable way. -preventing succession in order to preserve an ecosystem in its current stage of succession

Question 41

Example - why are large areas of moorland in Scotland conserved?

Answer 41

- they provide habitats for many species of plants and animals - if moorland was left to natural processes, succession would lead to a climax community of spruce forest. this would mean loss of the moorland habitat and could lead to loss of some plants and animals that currently live there. preventing succession keeps moorland ecosystem intact

Question 42

What 2 ways is succession managed to conserve the moorland ecosystem?

Answer 42

1. animals allowed to graze on the land - animals eat the growing points of shrubs and trees, which stops them from establishing themselves and helps keep vegetation low 2. Managed fires are lit - after fires, secondary succession will occur on the moorland. species that grow back first (pioneer species) are the species that are being conserved, e.g. heather. larger species take longer to grow back and will be removed again the next time the moor is burnt

Question 43

What is conservation?

Answer 43

the protection and management of species and habitats (ecosystems) in a sustainable way

Question 44

What does sustainable mean?

Answer 44

enough resources are taken to met the needs of people today, without reducing the ability of people in the future to meet their own needs

Question 45

4 examples of conservation techniques: - plants? - fish? - areas? - species?

Answer 45

- seedbanks - stores of lots of seeds from lots of different plant species. if plants become extinct in the wild, stored seeds can be used to grow new plants - fishing quotas are limits to the amount of certain fish species that fishermen are allowed to catch - they help to conserve fish species by reducing the numbers that are caught and killed - national parks and nature reserves protect habitats (and the species that live in them) by restricting urban development, industrial development and farming - endangered species can be bred in captivity (zoo) to increase their numbers, then returned to the wild