Population

Question 1

Define ‘ecology’ .

Answer 1

Ecology is the study of the interactions of organisms with one another and with their environment.

Question 2

What is population ecology?

Answer 2

Is the study of populations in relation to the environment, including environmental influences on population density and distribution, age structure, and population size.

Question 3

What are the features used to describe a population?

Answer 3

Population size, population range, and population density

Question 4

Explain population size.

Answer 4

Is the number of individuals living in a population.
Denoted by letter N.

Question 5

What is population range?

Answer 5

Is the area within which the population is found.
Since range is an area, units would be either km2 or m2.

Question 6

What is population density? and state its formula.

Answer 6

Refers to the number of individuals that may be present in each unit area.
Formula: number of individuals divide by population range.

Question 7

What are the 2 factors that control the age structure of any population.

Answer 7

-Natality/birth rate
-Mortality/death rate

Question 8

Why do some organisms have very high mortality rate? and state how they overcome this situation. Also give an example of such species.

Answer 8

They live in unfavourable conditions or they have plenty predators or enemies example, mice.
They make up for the high mortality rate by having an equally high natality rate.

Question 9

What is the purpose of a survivorship curve?

Answer 9

It is a useful way of showing the natality and mortality rate of different populations. It is the ‘chance of remaining alive’.

Question 10

State 3 population dynamics.

Answer 10

-They rely on the same resources
- are influenced by similar environmental factors
- highly likely of interacting with and breeding with one another.

Question 11

Explain some limitations of a density-dependent population.

Answer 11

-competition- competition for resources increases as the population increases due to members of the population having identical resource needs.
- Parasitism and disease
-predation- predators have a good effect on the prey population as they prevent it from over- exploiting its habitat.
-toxic waste- toxic wastes within a population can limit the population itself e.g alcohol produced by yeast limits yeast production.

Question 12

Some factors limiting density- independent population.

Answer 12

Natural disasters
Fires
Drought
Frost
Cyclones.

Question 13

How does intraspecific competition regulate population size ?

Answer 13

By favouring the stronger and more adaptable individuals who are able to obtain most of the resources

Question 14

What do producers compete for?

Answer 14

light, space, minerals, water, and substrate

Question 15

What do consumers compete for?

Answer 15

Breeding sites, food, space, water and shelter.

Question 16

How does interspecific competition keep population size low?

Answer 16

Due to competition for similar resources between different species.

Question 17

What is the Gauze’s principle of competitive exclusion? and provide an example.

Answer 17

States that 2 organisms with the same niche cannot co-exist in the same area for very long . The one adapted better to the local conditions will out-number the other. The ‘loser’ species must shift niche, migrate or die. Example, two species of flour beetle cannot co-exist in the same jar of flour if forced to be in direct competition. However if the environment within the flour varies a a bit, example one part of the jar being warmer of damper than the others, then the 2 species can specialize in separate zones.

Question 18

What are some human threats to populations?

Answer 18

-Poaching (illegal hunting) threatens, turtles, tigers, African elephant, pandas to extinction.
-Hunting has reduced whale, tuna and hundreds of other animal population to dangerously low numbers.
-Demand for more animal goods such as ivory and turtle shells increase as their population become dangerously scarce.
- habitat loss to farms and settlements has driven off species to extinction and is pushing still more to the edge..