2.1 species and population

Question 1

Ecosystem

Answer 1

A community of interdependent organisms (biotic) and their interactions with the physical environment (abiotic) they inhabit.

Question 2

Species

Answer 2

A group of organisms sharing common characteristics that can interbreed and produce offspring that also produce young.

Question 3

Limitations of species

Answer 3

• dosen’t classify extinct population
• dosen’t account for asexual organisms

Question 4

Habitat

Answer 4

Environment in which a species lives, where an organism can find food, shelter, protection, mates.

Question 5

Niche

Answer 5

The set of biotic and abiotic conditions and resources that an organism or population responds to (not just habitat, but how an organism interacts with others). No two species can have the same niche.

Question 6

Fundamental niche

Answer 6

Full range of conditions/resources an organism can survive and reproduce in.

Answer 7

Actual conditions a species exists in due to biotic interactions.
→ different niches can still share the same habitat due to space, behaviour patterns

Question 8

Abiotic factors

Answer 8

The nonliving, physical factors that influence organisms and ecosystems.
Eg. temperature, sunlight, pH, precipitation, soil, landscape/topography.

Question 9

Population interactions

Answer 9

when one animal or plant hunts and eats another organism.
→ predator-prey relationships are controlled by negative feedback mechanisms
→ as prey increases, after time so do predators. Increase in predators reduces number of prey.
→ predation benefits prey - removes old/sick individuals, leaving superior breeding pool
Eg. lemming and snowy owl, gray wolf and moose

Question 10

Herbivory

Answer 10

where an animal feeds on a plant - the animal is known as a herbivore.
→ the plants as a food source affect the carrying capacity of the environment for the herbivore
Eg. hippopotamus grazing on vegetation / zooplankton feeding on phytoplankton

Question 11

Parasitism

Answer 11

where one organism benefits at the expense of another (the host), type of symbiotic relationship
→ endoparasites live inside hosts, ecto parasites live on the surface of hosts
Eg. tapeworms (endoparasites) and ticks/mites (ectoparasites

Question 12

Mutualism

Answer 12

Another form of symbiosis where both species benefit
Eg. coral reefs: zooxanthellae live within coral animal (polyp; they photosynthesise to produce food for themselves and the polyp; in exchange they are protected.

Question 13

Disease

Answer 13

pathogen - can be bacteria, virus, fungi - reduces carrying capacity of infected organism.
Eg. Dutch elm disease, caused by fungus clogging vascular tissues in tree, preventing water movement.

Question 14

Competition

Answer 14

demand by individuals for limited environmental resources
→ can be intraspecific (within a species) or interspecific (between diff species)
→ the degree to which niches (inter) overlap determines the level of competitive exclusion

Question 15

Population

Answer 15

group of organisms in the same species living in the same area at the same time, capable of interbreeding.

Question 16

S population curve

Answer 16

Rapid initial growth, then slowing as carrying capacity is reached, where population fluctuates around K.
→ divided into lag phase, exponential growth phase, transitional phase, stationary phase

Question 17

J population curve

Answer 17

Increasingly rapid exponential growth with no signs of slowing, exhibited by organisms that produce rapidly.
→ controlled by favourable abiotic components, results in a population crash

Question 18

Limiting factors

Answer 18

Low population growth as carrying capacity is reached
Density-Dependent Factors - lower birth rate/raise death rate as population grows
Density-Independent Factors - affect a population regardless of density, abiotic factors