🌸Chapter 11
Organisms & Populations
(2 Marks)
1.
Define
population.
Answer: A population is a group of individuals of the same species
living in a particular area at a given time.
2.
What
is population density?
Answer: Population density is the number of individuals per unit area
or volume.
3.
What
is population dispersion?
Answer: Dispersion is the spatial arrangement of individuals
within a population.
4.
Name
three types of population dispersion.
Answer: Clumped, uniform, and random.
5.
Define
natality.
Answer: Natality is the birth rate of a population, i.e., number
of births per 1000 individuals per year.
6.
Define
mortality.
Answer: Mortality is the death rate, i.e., number of deaths per
1000 individuals per year.
7.
What
is immigration?
Answer: Immigration is the arrival of individuals into a
population from other areas.
8.
What
is emigration?
Answer: Emigration is the movement of individuals out of a
population to other areas.
9.
Give
the formula for change in population size.
Answer: ΔN = (B – D) + (I – E), where B = births, D = deaths, I = immigration,
E = emigration.
10.
Define
carrying capacity (K).
Answer: Carrying capacity is the maximum population size that an
environment can sustain indefinitely.
11.
What
is exponential growth?
Answer: Exponential growth occurs when resources are unlimited
and population grows rapidly (J-shaped curve).
12.
What
is logistic growth?
Answer: Logistic growth occurs when population growth slows down as
it reaches carrying capacity (S-shaped curve).
13.
Define
age structure of a population.
Answer: Age structure is the distribution of individuals in
different age groups: pre-reproductive, reproductive, and post-reproductive.
14.
Which
age group contributes directly to population growth?
Answer: Reproductive age group.
15.
What
is the significance of age pyramids?
Answer: Age pyramids help predict population growth trends.
16.
Give
one example of clumped dispersion.
Answer: Elephants in herds.
17.
Give
one example of uniform dispersion.
Answer: Penguins in breeding grounds.
18.
Give
one example of random dispersion.
Answer: Dandelions in a field.
19.
Define
intraspecific competition.
Answer: Competition among individuals of the same species for
resources.
20.
Define
interspecific competition.
Answer: Competition between individuals of different species for
resources.
21.
Give
one example of mutualism.
Answer: Lichen (alga + fungus).
22.
Give
one example of commensalism.
Answer: Cattle egret and cattle.
23.
Give
one example of amensalism.
Answer: Penicillium secreting antibiotic affecting bacteria.
24.
Give
one example of parasitism.
Answer: Tick on dog.
25.
Give
one example of predation.
Answer: Lion hunting deer.
26.
What
is density-dependent factor?
Answer: A factor whose effect increases with population density,
e.g., disease, competition.
27.
What
is density-independent factor?
Answer: A factor that affects population regardless of density,
e.g., floods, fire.
28.
Define
population growth rate.
Answer: The rate of change in population size per unit time.
29.
What
is zero population growth?
Answer: When birth rate = death rate, population size remains
constant.
30.
Define
ecological niche.
Answer: Ecological niche is the role and position of a species in
an ecosystem.
31.
Give
one example of physiological adaptation.
Answer: Hump of camel storing fat and water.
32.
Give
one example of morphological adaptation.
Answer: Thorns of cactus.
33.
Give
one example of behavioral adaptation.
Answer: Nocturnal activity of desert animals.
34.
What
is lag phase in population growth?
Answer: Initial period of slow growth as population adjusts to
new environment.
35.
What
is log/exponential phase in population growth?
Answer: Phase of rapid population increase due to abundant
resources.
36.
What
is stationary phase in population growth?
Answer: Phase when population stabilizes near carrying capacity.
37.
Define
emigration rate.
Answer: Number of individuals leaving a population per unit time.
38.
Define
immigration rate.
Answer: Number of individuals entering a population per unit time.
39.
Why
is clumped dispersion common in animals?
Answer: For protection, social interaction, or resource availability.
40.
Why
does uniform dispersion occur?
Answer: Due to territoriality or competition for resources.
41.
Why
does random dispersion occur?
Answer: When resources are evenly distributed and interactions
are negligible.
42.
Name
two factors that regulate population.
Answer: Density-dependent and density-independent factors.
43.
Give
one example of density-independent regulation in plants.
Answer: Flood affecting tree seedlings.
44.
Give
one example of density-dependent regulation in animals.
Answer: Disease spreading in crowded rabbit population.
45.
Define
pre-reproductive age group.
Answer: Individuals not yet capable of reproduction.
46.
Define
post-reproductive age group.
Answer: Individuals beyond reproductive age.
47.
Give
one example of interspecific competition in animals.
Answer: Lion and hyena competing for prey.
48.
Give
one example of intraspecific competition in plants.
Answer: Trees of same species competing for sunlight.
49.
What
is the effect of predation on prey population?
Answer: It reduces prey population, maintaining ecosystem
balance.
50.
Why
is carrying capacity important?
Answer: It limits population size and prevents over-exploitation
of resources.
