Test: Population: Attributes & Growth - NEET MCQ

Mortality and emigration would necessarily decrease the density of a population in a given habitat.

Topic in NCERT: POPULATION DYNAMICS

Line in NCERT: "two (mortality and emigration) to a decrease."

Current human population growth appears to be J-shaped as we have either not yet met our population carrying capacity, or have exceeded the carrying capacity, but have not yet seen the population crash normally associated with J-shaped or exponential population growth. If the human population meets the carrying capacity it will closely resemble an S-shaped population curve.

Topic in NCERT: Population Growth Models

Line in NCERT: "The population density reaches the carrying capacity. plot of N in relation to time (t) results in a sigmoid curve. This type of population growth is called Verhulst-Pearl Logistic Growth."

Natality in population ecology is the scientific term for birth rate. Along with mortality rate, natality rate is used to calculate the dynamics of a population. They are the key factors in determining whether a population is increasing, decreasing or staying the same in size. Natality is the greatest influence on a population’s increase. Natality is shown as a crude birth rate or specific birth rate. Crude birth rate is used when calculating population size (number of births per 1000 population/year), whereas specific birth rate is used relative to a specific criterion such as age. By calculating specific birth rate, the results are seen in an age-specific schedule of births.

Topic in NCERT: Natality

Line in NCERT: "Natality refers to the number of births during a given period in the population that are added to the initial density."

Formula = the rate of change in population size) = (the contribution of each individual to population growth) x (the number of individuals in the population
dt/dN = rN,
where:
dN = change in number
dt = change in time
r = the per head maximum potiential growth rate
N = number of individuals in a population.
Topic in NCERT: Population Growth Models
Line in NCERT: "dN/dt = rN"

orrect option is

D

all of these

The rate of growth or decline of a population basically depends on four factors, including natality rate or births, mortality rates or death, and the emigration and immigration rates. These four factors affect the inflow and outflow of a population and hence, affects the growth and decline of a population.

So, the correct answer is 'All of these'

Topic in NCERT: Population Density

Line in NCERT: "two of which (natality and immigration) contribute to an increase in population density and two (mortality and emigration) to a decrease."

Exponential model is the one in which rate of change in anything is directly proportional to the number of the thing present. Exponential phase shows the exponential growth. Thus the size or the number increases at a constant growing rate.

Topic in NCERT: Population Density

Line in NCERT: "population density will increase if the number of births plus the number of immigrants (B + I) is more than the number of deaths plus the number of emigrants (D + E)."

S-shaped growth curve (sigmoid growth curve) A pattern of growth in which, in a new environment, the population density of an organism increases slowly initially, in a positive acceleration phase; then increases rapidly approaching an exponential growth rate as in the J-shaped curve; but then declines in a negative acceleration phase until at zero growth rate the population stabilizes.

Topic in NCERT: Logistic growth

Line in NCERT: "A population growing in a habitat with limited resources show initially a lag phase, followed by phases of acceleration and deceleration and finally an asymptote, when the population density reaches the carrying capacity. plot of N in relation to time (t) results in a sigmoid curve."

Solution:

1 - D: Population Density → The number of individuals per unit area or volume in a population.
2 - C: Exponential Growth → The rate of increase in a population's size under ideal conditions.
3 - A: Carrying Capacity → The maximum number of individuals an environment can support sustainably.
4 - B: Immigration → Movement of individuals into a population from another area.

The density of a population in a given habitat during a given period changes due to changes in four basic processes, two of which (natality and immigration) contribute to an increase in population density and two (mortality and emigration) to a decrease. In a zero population growth density natality is balanced by mortality. 
Topic in NCERT: Population Density

Line in NCERT: "Under normal conditions, births and deaths are the most important factors influencing population density."

Solution:

The logistic growth curve is considered more realistic because it accounts for the limitations imposed by the environment, such as limited resources and carrying capacity. In contrast, the exponential growth curve assumes unlimited resources, which rarely occurs in nature. Therefore, Option B is the correct answer as it reflects more realistic conditions for population growth.

Topic in NCERT: Logistic Growth Model

Line in NCERT: "the logistic growth model is considered a more realistic one."

The logistic growth equation is given by dN/dt = K N (1 - N/K), where N is the population size, K is the carrying capacity, and r is the intrinsic rate of natural increase. This equation models growth under resource limitations, leading to a sigmoid curve.

Topic in NCERT: Population Growth Models

Line in NCERT: "dN/dt = K N (1 - N/K)"

Statement 1 is correct because natality (birth rate) and immigration (arrival of new individuals) both lead to an increase in population size.
Statement 2 is incorrect as mortality (death rate) and emigration (leaving of individuals) both reduce the population size, not increase it.
Statement 3 is correct because natality refers to births per capita, while mortality refers to deaths in a population over a specified period.
Statement 4 is incorrect because immigration contributes to population growth, not a decrease.

Topic in NCERT: Population Dynamics

Line in NCERT: "two of which (natality and immigration) contribute to an increase in population density and two (mortality and emigration) to a decrease." "Natality refers to the number of births during a given period in the population that are added to the initial density." "Mortality is the number of deaths in the population during a given period."

Statement 1 is incorrect because exponential growth occurs only under conditions of unlimited resources, not limited resources.
Statement 2 is correct as logistic growth models describe population growth with limited resources, leading to a sigmoid curve.
Statement 3 is correct since natality, mortality, immigration, and emigration are the four key factors that influence population dynamics.
Statement 4 is incorrect because the intrinsic rate of natural increase (r) can vary depending on environmental factors like resource availability and competition.

Topic in NCERT: Population Growth Dynamics

Line in NCERT: "when resources are unlimited, the growth is usually exponential but when resources become progressively limiting, the growth pattern turns logistic." "The intrinsic rate of natural increase (r) is a measure of the inherent potential of a population to grow." "Natality, mortality, immigration, and emigration are the four main factors that influence population size."

Carrying capacity (K) refers to the maximum number of individuals a habitat can support given the available resources. Beyond this limit, the population will stop growing or may even decline due to resource depletion.

Topic in NCERT: Carrying Capacity

Line in NCERT: "In nature, a given habitat has enough resources to support a maximum possible number, beyond which no further growth is possible. Let us call this limit as nature's carrying capacity (K) for that species in that habitat."

Statement A is correct. Organisms with high reproductive rates (high r value) evolve to maximize their reproductive fitness by increasing their population size rapidly.
Statement B is incorrect. Organisms that breed only once in their lifetime, such as Pacific salmon, typically produce many small offspring, not large ones.
Statement C is incorrect. Life history traits are shaped by both biotic (living) and abiotic (non-living) factors in the environment, which constrain and influence their evolution.
Statement D is correct. The evolution of life history traits is heavily influenced by the abiotic and biotic components of the organism's habitat, ensuring that the traits align with environmental conditions.
Therefore, the correct answer is Option A and Option D are correct.

Topic in NCERT: Life History Variation

Line in NCERT: "Populations evolve to maximise their reproductive fitness, also called Darwinian fitness (high r value), in the habitat in which they live."