Chapter 35 - Population

Question 1

What is a population?

Answer 1

A group of organisms of the same species living in the same area at the same time.

Question 2

Explain food supply as a factor affecting the rate of population growth.

Answer 2

An increase in number of organisms in a population causes competition for food and the strong&fitter will survive and the weaker will die of starvation. Food will become limited when the population demand more food than what their habitat can supply.

Question 3

Explain predators as a factor affecting the rate of population growth.

Answer 3

Of prey is plentiful, the number of predators will increase. As they increase, they require more food and will kill more of their prey whose numbers will then decrease.

Question 4

Explain diseases as a factor affecting the rate of population growth.

Answer 4

As population numbers increase, it gets easier for disease to spread rapidly across densely populated areas, especially in members of the same species. Increasing cases of disease will reduce population numbers.

Question 5

Explain size of ecosystem as a factor affecting the rate of population growth.

Answer 5

The larger the size of an area,the larger the population can grow, if there is sufficient resources. The competition for space to establish territories is a behavioral mechanism that may restrict population growth.

Question 6

Explain competitors as a factor affecting the rate of population growth.

Answer 6

Other organisms may require the same resources from the environment and so reduce population growth. Competition for mates can also drastically reduce the growth of individual organisms.

Question 7

What is a community?

Answer 7

It is all the populations of different species living in an ecosystem.

Question 8

What is an ecosystem?

Answer 8

A self-contained area including all the living organisms and their environment.

Question 9

Name the 2 growth curves.

Answer 9

Exponential / J-shaped
Sigmoid / S-shaped

Question 10

Name the 3 phases of a sigmoid population growth curve.

Answer 10

Lag phase
Log (exponential) phase
Stationary phase

Question 11

Explain the lag phase of a sigmoid growth curve.

Answer 11

It is the slow-growing phase of a population, the period where individuals adapt and acclimatize to the new environment or conditions. The new population takes time to settle and mature before breeding begins.

Question 12

Explain the log phase in a sigmoid growth curve.

Answer 12

It is the period of rapid increase in population size due to improved availability and other requirements will little or no competition. All conditions are favourable and there are no limiting factors such as predation. Natalities and immigration exceeds mortality and emigration.

Question 13

Explain the stationary phase in a sigmoid growth curve.

Answer 13

This is when the growth are becomes stable and the population remains constant because mortality is equal to natality. Disease spread faster and predators hunt more successfully as the population increases. Resources become scarce when a population is large, which increases competition and limiting factors. Population growth is zero at this phase, because it has reached its carrying capacity.

Question 14

Name factors affecting human population growth.

Answer 14

When natality is greater than mortality, the population increase in size & vice versa.
When natality is equal to mortality, there is zero population growth.
Immigration increase and emigration decreases population size.
Factors like poverty, fertility rate and socio-economic factors can also affect human pop. size.

Question 15

Name how fewer diseases occur in the human population.

Answer 15

• sewage treatment
• hygienic handling of food
• general standards of cleanliness
• immunization against infectious disease reduces infection rates
• antibiotic is used to treat bacterial diseases

Question 16

Name how more food is available in the human population.

Answer 16

• more and more land has been brought under cultivation
• agriculture has become more efficient because of modern technology
• the use of fertilisers increase crop yield considerably
• the use of pesticides controls diseases and pests so fewer crops are destroyed

Question 17

Name some social implication of the current human population.

Answer 17

• greater demands on education and health care
• abundant food supplies can lead to more people becoming obese with cause
• if we don’t control human birth rate, famine, war and disease may increase death rate
• more population/overcrowding an more unemployment, means fewer jobs available
• increased pressure on the environment and less land available for agriculture
• global climate change
• water isn’t a infinite renewable source
• increased demand for raw materials and minerals

Question 18

Name the two population pyramids.

Answer 18

• LEDCs
• MEDCs

Question 19

What is population pyramids?

Answer 19

It is a graphical illustration that shows the distribution of various age groups in a population, which forms the shape of a pyramid when the population is growing.

Question 20

Explain the pyramid of LEDCs.

Answer 20

It has a wide base and a narrow tip, which shows a high natality rate.
Youth levels are wide meaning future pressure on jobs and housing needs.
Narrow tip could mean that there is difficult living conditions, precarious health care service and short life expectancy.

Question 21

Explain the pyramid of MEDCs.

Answer 21

Narrow base shows natality isn’t high.
Pyramid shows a stabilized human population.
Adult age ranges generally higher than infantile ranges, so no population growth.
Quality of life is high, good nutrition and has access to healthcare services, as there is proportionally a high number of older individuals