Biology (9-1) - 0970 CIE

Populations

Gbogbo ọrọ náà

Put a few yeast cells in sugar solution and come back in a week: where there were dozens, there are now millions, and then, just as suddenly, the numbers crash. Almost every population, from bacteria to buffalo, follows the same S-shaped story, racing upward and then hitting the limits of its world.

In this lesson you will define population, community and ecosystem, name the factors that drive numbers up and down, and read the four phases of the sigmoid growth curve. You will learn to explain each phase in terms of food, competition, predation and disease, the same limiting factors that decide how many of any species a habitat can hold.

Ebumnobi

Describe a population as a group of organisms of one species, living in the same area, at the same time
Describe a community as all of the populations of different species in an ecosystem
Describe an ecosystem as a unit containing the community of organisms and their environment, interacting together
Identify and state the factors affecting the rate of population growth for a population of an organism, limited to food supply, competition, predation and disease
Identify the lag, exponential (log), stationary and death phases in the sigmoid curve of population growth for a population growing in an environment with limited resources
Interpret graphs and diagrams of population growth
[Supplement] Explain the factors that lead to each phase in the sigmoid curve of population growth, making reference, where appropriate, to the role of limiting factors

Akọmọ Ojú-ẹkọ

Population growth shapes everything in ecology, including the human population itself. Knowing why numbers rise, level off and fall lets you predict the effect of a new predator, a disease outbreak or a richer food supply. Exam questions almost always show a sigmoid curve and ask you to label its phases and explain them using limiting factors, so the reasoning here is directly examinable.

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Ayẹwo Ẹkọ

Ekele diri gi maka imecha ihe karịrị na Populations. Ugbu a na ị na-enyochakwa isi echiche na echiche ndị dị mkpa, ọ bụ oge iji nwalee ihe ị ma. Ngwa a na-enye ụdị ajụjụ ọmụmụ dị iche iche emebere iji kwado nghọta gị wee nyere gị aka ịmata otú ị ghọtara ihe ndị a kụziri.

Ị ga-ahụ ngwakọta nke ụdị ajụjụ dị iche iche, gụnyere ajụjụ chọrọ ịhọrọ otu n’ime ọtụtụ azịza, ajụjụ chọrọ mkpirisi azịza, na ajụjụ ede ede. A na-arụpụta ajụjụ ọ bụla nke ọma iji nwalee akụkụ dị iche iche nke ihe ọmụma gị na nkà nke ịtụgharị uche.

Jiri akụkụ a nke nyocha ka ohere iji kụziere ihe ị matara banyere isiokwu ahụ ma chọpụta ebe ọ bụla ị nwere ike ịchọ ọmụmụ ihe ọzọ. Ekwela ka nsogbu ọ bụla ị na-eche ihu mee ka ị daa mba; kama, lee ha anya dị ka ohere maka ịzụlite onwe gị na imeziwanye.

A population is best described as: A. all the living things in an area B. a group of one species in the same area at the same time C. organisms plus their environment D. all the consumers in a food web Answer: B
Which is NOT a factor affecting the rate of population growth? A. food supply B. predation C. disease D. the colour of the soil Answer: D
In the sigmoid curve, the phase of most rapid growth is the: A. lag phase B. exponential phase C. stationary phase D. death phase Answer: B
During the stationary phase of population growth: A. there are no births B. birth rate equals death rate C. death rate is zero D. the population doubles each hour Answer: B
An ecosystem is: A. one species in an area B. all populations of different species C. a community plus its non-living environment D. only the producers Answer: C