TOPIC 7C - POPULATIONS IN ECOSYSTEMS

Question 1

Give the definition of a habitat.

Answer 1

The place where an organism lives.

e.g. a rocky shore or a field

Question 2

Give the definition of a population.

Answer 2

All the organisms of one species in a habitat.

Question 3

Give the definition of a community.

Answer 3

Populations of different species in a habitat make up a community.

Question 4

Give the definition of an ecosystem.

Answer 4

A community, plus all the non-living (abiotic) conditions in the area in which it lives. Ecosystems can be small, e.g. a pong, or large, e.g. an entire ocean.

Question 5

Give the definition of abiotic conditions.

Answer 5

The non-living features of the ecosystem.

e.g. temperature and availability of water.

Abiotic factors include the amount of light, water or space available, the temperature of the surroundings or the chemical composition of the surroundings. When abiotic conditions are ideal for a species, organisms can grow fast and reproduce successfully.

Question 6

Give the definition of biotic conditions.

Answer 6

The living features of the ecosystem.

e.g. the presence of predators or food.

Question 7

Give the definition of a niche.

Answer 7

The role of a species within its habitat.

e.g. what it eats, where and when it feeds.

Question 8

Give the definition of an 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. This increases their chances of survival when food is scarce.

Question 9

Explain a niche and give two examples of one.

Answer 9

(see page 170 in the revision guide)

Question 10

What are physiological adaptations?

Answer 10

Processes inside the organism’s 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 organism’s body.

Question 13

What is natural selection?

Answer 13

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

Question 14

Give 3 examples of organisms that have adapted to abiotic conditions.

Answer 14

(see page 171 in the revision guide)

Question 15

Give 3 examples of organisms that have adapted to biotic conditions.

Answer 15

(see page 171 in the revision guide)

Question 16

Give the definition of population size.

Answer 16

The total number of organisms of one species in a habitat.

Question 17

Give the definition of carrying capacity.

Answer 17

The maximum stable population size of a species that an ecosystem can support.

Carrying capacity varies as a result of both abiotic and biotic factors.

Question 18

How does the ideal temperature of a mammals surroundings affect their population size?

Answer 18

When the temperature of a mammal’s surroundings is the ideal temperature for metabolic reactions to take place, they don’t have to use up as much energy painting their body temperature. This means more energy can be used for growth and reproduction, so their population size will increase.

Question 19

How does the temperature when its not ideal of a mammals surroundings affect their population size?

Answer 19

When the temperature os a mammals surroundings is significantly lower or higher than their optimum body temperature, they have to use a lot of energy to maintain the right body temperature. This means less energy will be available for growth and reproduction, so their population size will decrease.

Question 20

What is interspecific competition?

Answer 20

When organisms of different species compete with each other for the same resourced.

e.g. red and grey squirrels compete for the same food sources and habitats in the UK.

Question 21

In interspecific competition, what happens to the population size of both species competing?

Answer 21

Decrease.

or

If one is better adapted, the other will be out-competed.

(see page 172 in the revision guide)

Question 22

What is intraspecific competition?

Answer 22

When organisms of the same species compete with each other for the same resources.

(see page 172 in the revision guide)

Question 23

How are predator and prey population sizes linked?

Answer 23

(see page 173 in the revision guide)

Question 24

What is predation?

Answer 24

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

e.g. lions kill and eat (predate on) buffalo.

Question 25

How can you investigate the population size of non-motile organisms?

Answer 25

(see page 174 in the revision guide)

Question 26

How can you investigate the population size of motile organisms?

Answer 26

(see page 174 in the revision guide)

Question 27

How can you investigate the environmental factors on species distribution?

What are the ethical issues?

What are the safety issues?

Answer 27

(see page 175 in the revision guide)

Question 28

What is primary succession?

Answer 28

This happens on land that’s been newly formed or exposed.

e.g. where a volcano has erupted to form a new rock surface, or where sea level has dropped exposing a new area of land.

There’s no soil or organic material to start with, e.g. just bare rock

Question 29

What is secondary succession?

Answer 29

This happens on land that’s been cleared of all the plants, but where the soil remains.

e.g. after a forest fire or where a forest has been cut down by humans.

Question 30

Describe the stages of primary succession.

Answer 30

(see page 176 in the revision guide)

Question 31

Describe the stages of secondary succession.

Answer 31

(see page 176 in the revision guide)

Question 32

Describe how bare rock can turn into woodland using primary succession.

Answer 32

(see page 176 in the revision guide)

Question 33

What is the climatic climax in an ecosystem?

Answer 33

The climax community for a particular climate.

see page 177 in the revision guide

Question 34

Give some examples of human activities that can prevent succession.

Answer 34

• mowing grass
• animals grazing
• managed fires

(see page 177 in the revision guide)

Question 35

What is conservation?

Answer 35

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

Question 36

What does sustainable mean?

Answer 36

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

Question 37

Read the orange, pink and blue box on page 178 and the green box on page 179 in the revision guide.

Answer 37

understand?