Population Attributes Questions in English

(N/A) Age composition refers to the relative abundance of organisms of different age groups within a population at a given time. It is a key attribute of a population that helps in understanding the growth status (expanding,stable,or declining) of the population.

(N/A) Census refers to the complete count of individuals within a specific area. In the context of human populations,it is conducted systematically after every $10$ years to gather demographic data.

(D) The death rate is calculated as the number of deaths per individual per unit time.
Formula: $\text{Death Rate} = \frac{\text{Number of deaths}}{\text{Initial population size}}$
Given:
Number of deaths = $8$
Initial population size = $80$
$\text{Death Rate} = \frac{8}{80} = 0.1 \text{ individuals per Drosophila per week}$.
Therefore, the correct option is $D$.

(A) In ecology,a group of individuals of the same species occupying a specific geographical area at a given time and interacting with each other is defined as a $Population$.
- $A$ $Community$ consists of populations of different species living in the same area.
- An $Ecosystem$ includes both biotic (living) and abiotic (non-living) components.
- $A$ $Biome$ is a large regional unit characterized by specific climate and vegetation.

(C) population is defined as a group of individuals of the same species living in a specific geographical area at a given time.
$1$. Individuals of a population belong to the same species ($A$ is correct).
$2$. They are reproductively isolated from other species ($B$ is correct).
$3$. They share a common gene pool and can interbreed ($D$ is correct).
$4$. Option $C$ is incorrect because individuals of the same species generally share similar morphological and anatomical characteristics,rather than being distinct from each other in these aspects.

(B) The birth rate is defined as the number of births per capita per unit time.
Formula: $\text{Birth Rate} = \frac{\text{Number of new offspring}}{\text{Initial population size}}$
Given:
Initial population $(N_0)$ = $30$
Number of new offspring $(B)$ = $10$
Calculation:
$\text{Birth Rate} = \frac{10}{30} = \frac{1}{3} \approx 0.33$ offspring per lotus per year.
Therefore, the correct option is $B$.

(D) The death rate is calculated as the number of deaths divided by the initial population size over a specific time period.
Death rate $= \frac{\text{Number of deaths}}{\text{Initial population size}}$
Given:
Number of deaths $= 10$
Initial population size $= 50$
Death rate $= \frac{10}{50} = 0.2$ individuals per fruit fly per week.
Therefore, the correct option is $D$.

(C) The age pyramid $P$ shows a broad base of pre-reproductive individuals,indicating an expanding population.
The age pyramid $Q$ shows pre-reproductive and reproductive individuals in almost equal proportions,indicating a stable population.
The age pyramid $R$ shows a narrow base of pre-reproductive individuals,indicating a declining population.
Therefore,$P$ represents an expanding population,$Q$ represents a stable population,and $R$ represents a declining population.

(A) Total population = $2000$.
Number of females = $1100$.
Number of males = Total population - Number of females = $2000 - 1100 = 900$.
Percentage of females = $(1100 / 2000) \times 100 = 55\%$.
Percentage of males = $(900 / 2000) \times 100 = 45\%$.
Therefore,the sex ratio is Female - $55\%$ and Male - $45\%$.

(B) Population density $(N)$ is influenced by four basic processes:
$1$. Natality $(B)$: Number of births during a given period that are added to the initial density.
$2$. Immigration $(I)$: Number of individuals of the same species that have come into the habitat from elsewhere during the time period under consideration.
$3$. Mortality $(D)$: Number of deaths in the population during a given period.
$4$. Emigration $(E)$: Number of individuals of the population who left the habitat and went elsewhere during the time period under consideration.
In the provided diagram:
- $S$ represents Births $(B)$
- $P$ represents Immigration $(I)$
- $Q$ represents Deaths $(D)$
- $R$ represents Emigration $(E)$
Factors that increase population density are Natality $(B)$ and Immigration $(I)$,which correspond to $S$ and $P$ respectively. Therefore,$P$ and $S$ are responsible for the increase in population density.

(D) Organisms evolve different reproductive strategies to maximize their fitness based on environmental stability and resource availability.
$1$. Some organisms produce a large number of small-sized offspring (e.g.,Oysters,Pelagic fishes). This strategy ensures that at least a few survive despite high predation rates.
$2$. Other organisms produce a small number of large-sized offspring (e.g.,Birds,Mammals). This strategy focuses on providing better parental care and higher survival probability for each individual offspring.
Therefore,$I$ (Oysters) and $III$ (Pelagic fishes) produce many small-sized offspring,while $II$ (Birds) and $IV$ (Mammals) produce few large-sized offspring.
The correct matching is $I, III$ for many small-sized offspring and $II, IV$ for few large-sized offspring.

(C) Population density $(N)$ changes due to four basic processes: Natality $(B)$,Mortality $(D)$,Immigration $(I)$,and Emigration $(E)$.
Natality is the number of births during a given period in the population that are added to the initial density.
Immigration is the number of individuals of the same species that have come into the habitat from elsewhere during the time period under consideration.
Both Natality and Immigration contribute to an increase in population density.
Conversely,Mortality and Emigration contribute to a decrease in population density.
Therefore,the factors related to an increase in population density are Natality and Immigration.

(C) Statement $(A)$ is correct because population size changes over time due to births,deaths,immigration,and emigration.
Statement $(B)$ is incorrect because total number is not always the most appropriate measure. For example,in a large population with dense cover,counting individuals is difficult or meaningless; in such cases,biomass or percent cover is used.
Statement $(C)$ is incorrect because a population growing with unlimited resources exhibits exponential growth ($J$-shaped curve),which does not show deceleration or an asymptote. The description provided (lag,acceleration,deceleration,asymptote) refers to logistic growth ($S$-shaped curve) which occurs under limited resources.
Statement $(D)$ is correct as life history traits (like clutch size,age at first reproduction) are adaptations evolved to maximize fitness under the specific environmental constraints of the habitat.
Therefore,only statements $(A)$ and $(D)$ are correct.

(D) Population size is a dynamic parameter that changes over time depending on various factors such as food availability,climatic conditions,predation pressure,and competition.
$A$,$B$,and $C$ are direct factors that influence birth rates,death rates,and migration,thereby affecting population density.
$D$ (Morphological differences) refers to the physical appearance of individuals within a population. While morphological variation exists within a population,it does not directly determine the total size or growth rate of the population. Therefore,population size does not depend on morphological differences.

(D) An individual organism has a sex (male or female),but it does not have a sex ratio. $A$ sex ratio is a characteristic of a population,defined as the ratio of males to females in the population.
Similarly,an individual organism is either born or dies,but it does not have a birth rate or a death rate. Birth rate (natality) and death rate (mortality) are expressed as per capita births or deaths in a population over a specific period.
Therefore,all the given attributes are characteristics of a population and not of an individual organism.

(B) In population ecology,$Natality$ refers to the number of births during a given period in the population that are added to the initial density.
$Absolute$ $natality$ (or $Maximum$ $natality$) is the maximum number of births possible under ideal environmental conditions,where there is no competition and resources like food and water are abundant.
$Realized$ $natality$ is the actual birth rate observed under existing environmental conditions,which are usually limited by competition and resource availability.
Therefore,the correct term for births under ideal conditions is $Absolute$ $natality$.

(A) Organisms evolve towards the most efficient reproductive strategy based on the selection pressure in their environment.
Some organisms,like oysters,produce a large number of small-sized offspring (e.g.,$Oysters$ produce millions of eggs) to ensure that at least a few survive predation and environmental challenges.
Other organisms,like mammals,produce a small number of large-sized offspring and invest significant energy in parental care to ensure the survival of their young.
Both strategies are evolutionary adaptations to maximize fitness in their respective ecological niches.
Therefore,both statements $A$ and $B$ are correct.

(C) The tiger census in national parks and tiger reserves is often based on indirect methods because tigers are elusive,solitary,and nocturnal animals.
Specifically,the census relies on the identification and counting of pugmarks (footprints) and faecal pellets (scat) found in the habitat.
These signs provide reliable data to estimate the population density and distribution of tigers in a given area without requiring the direct sighting of every individual.

(B) The birth rate is defined as the number of new offspring produced per individual per unit time.
Birth rate = $\frac{\text{Number of new offspring}}{\text{Initial population size}}$
Given,birth rate = $4$ offspring/carp/year and initial population = $500$.
Therefore,the number of new offspring = $\text{Birth rate} \times \text{Initial population}$
Number of new offspring = $4 \times 500 = 2000$.
The total number of carp fish at the end of the year = $\text{Initial population} + \text{New offspring}$
Total population = $500 + 2000 = 2500$.

(D) The age pyramid for Hungary shows a narrow base and a wider middle/top section.
In this pyramid,the number of individuals in the pre-reproductive and reproductive age groups is smaller compared to the number of individuals in the post-reproductive age group.
This indicates a declining population,which represents negative growth.

(D) Absolute natality (or maximum natality) is the theoretical maximum number of births under ideal environmental conditions,where there is no competition or limiting factors.
Realised natality is the actual number of births that occur under existing environmental conditions,which are typically limited by resources,predation,and competition.
Since environmental conditions are rarely perfect,the actual number of births (realised natality) is almost always lower than the theoretical maximum (absolute natality).
Therefore,absolute natality is always more than realised natality.

(A) population is defined as a group of individuals of the same species living in a specific geographical area at a given time.
Key characteristics of a population include natality (birth rate),mortality (death rate),age distribution (represented by age pyramids),sex ratio,and population growth (e.g.,expanding,stable,or declining population).
Option $A$ describes the 'Transfer of energy from one form to another',which is a fundamental principle of thermodynamics and a characteristic of an ecosystem,not a population.
Therefore,it is not a characteristic of a population.

(B) The population density $(N)$ changes based on four primary factors: Natality $(B)$,Mortality $(D)$,Immigration $(I)$,and Emigration $(E)$.
The formula for population density at time $t+1$ is: $N_{t+1} = N_t + [(B + I) - (D + E)]$.
Population density decreases when the number of individuals leaving the population exceeds the number of individuals entering it.
Specifically,an increase in Mortality $(D)$ or an increase in Emigration $(E)$ leads to a decrease in population density.
Therefore,option $B$ is correct as it describes factors that reduce population size.

(D) Natality refers to the number of births in a population during a given period. It is defined as the number of births per unit area per unit time.
$1$. Immigration $(I)$ is the number of individuals of the same species that have come into the habitat from elsewhere during the time period under consideration.
$2$. Emigration $(E)$ is the number of individuals of the population who left the habitat and gone elsewhere during the time period under consideration.
$3$. Mortality is the number of deaths in the population during a given period.
$4$. Natality is the number of births in the population during a given period.
Therefore,the correct option is $D$.

(A) Mortality refers to the number of deaths in a population during a given period.
It is one of the key factors that decreases the population density.
In contrast,natality refers to the number of births in a population during a given period,which increases the population density.
Therefore,mortality is the rate of deaths of individuals in a population.

(C) In an age pyramid,the population is classified as declining when the proportion of individuals in the pre-reproductive age group is smaller than those in the reproductive and post-reproductive age groups.
This indicates that the birth rate is low and the population is not replacing itself,leading to a decrease in the total population size over time.
Therefore,the correct condition for a declining population is that the pre-reproductive age group is smaller than the reproductive age group.

(C) Population dynamics refers to the study of how and why population sizes and structures change over time. It involves analyzing factors such as birth rates,death rates,immigration,and emigration that influence the size and composition of a population. Therefore,the changing nature of a population is termed as population dynamics.

(B) The population density $(N)$ at time $t+1$ is calculated using the formula: $N_{t+1} = N_t + [(B + I) - (D + E)]$.
Where:
$B$ = Natality (birth rate)
$I$ = Immigration (number of individuals joining the population)
$D$ = Mortality (death rate)
$E$ = Emigration (number of individuals leaving the population)
Population density increases when the number of individuals added to the population $(B + I)$ is greater than the number of individuals lost from the population $(D + E)$.
Therefore,an increase in Natality $(B)$ and Immigration $(I)$ leads to an increase in population density.

(D) Population density $(N)$ is influenced by four primary factors: Natality $(B)$,Mortality $(D)$,Immigration $(I)$,and Emigration $(E)$.
The formula for population density at time $t+1$ is: $N_{t+1} = N_t + [(B + I) - (D + E)]$.
$1$. Natality $(B)$: Number of births in a population during a given period,which adds to the population density.
$2$. Immigration $(I)$: Number of individuals of the same species that have come into the habitat from elsewhere during a given period,which adds to the population density.
$3$. Mortality $(D)$: Number of deaths in a population during a given period,which reduces the population density.
$4$. Emigration $(E)$: Number of individuals of the population who left the habitat and gone elsewhere during a given period,which reduces the population density.
Therefore,population density increases when Natality $(B)$ or Immigration $(I)$ increases,or when Mortality $(D)$ or Emigration $(E)$ decreases.

(A) The age pyramids represent the distribution of different age groups in a population:
$1$. Pyramid $C$ has a broad base of pre-reproductive individuals,indicating a growing population.
$2$. Pyramid $B$ shows a stable distribution where pre-reproductive and reproductive individuals are roughly equal,indicating a stable or steady population.
$3$. Pyramid $A$ shows a bell-shaped structure,also representing a stable population.
$4$. Pyramid $D$ has a narrow base of pre-reproductive individuals compared to the reproductive group,indicating a declining population.
Therefore,$A$ and $B$ represent stable populations,while $D$ represents a declining population. Comparing this with the options,$B$ and $D$ are declining is incorrect,but $A$ and $B$ are steady is correct. However,looking at standard interpretations: $A$ is stable,$B$ is stable,$C$ is growing,and $D$ is declining. Thus,$A$ and $B$ are steady populations.

(B) Population size,more technically called population density (designated as $N$),need not necessarily be measured in numbers only.
The tiger census in our national parks and tiger reserves is often based on pug marks and fecal pellets.

(B) In ecology,a population is defined as a group of individuals of the same species occupying a specific geographical area at a given time. These individuals are capable of interbreeding and sharing a common gene pool.

(D) The population density $(N)$ is influenced by four primary factors: natality $(B)$,mortality $(D)$,immigration $(I)$,and emigration $(E)$.
The formula for population density at time $t+1$ is given by: $N_{t+1} = N_t + [(B + I) - (D + E)]$.
Natality $(B)$ refers to the number of births in a population during a given period,which adds individuals to the population.
Immigration $(I)$ refers to the number of individuals of the same species that have come into the habitat from elsewhere during the time period under consideration,which also adds individuals to the population.
Since both natality and immigration contribute to an increase in the number of individuals,an increase in these rates will lead to an increase in the overall population density.

(B) The provided age pyramid shows a base (pre-reproductive age group) that is narrower than the middle section (reproductive age group).
This shape is characteristic of a declining population,where the number of individuals in the reproductive age group is higher than those in the pre-reproductive age group,leading to a decrease in the population over time.

(C) In the given diagram,the factors affecting population density $(N)$ are shown:
$I$ represents Immigration (adds to population,$+$).
$B$ represents Births/Natality (adds to population,$+$).
$D$ represents Deaths/Mortality (removes from population,$-$).
$E$ represents Emigration (removes from population,$-$).
Therefore,$P$ corresponds to Deaths $(D)$ and $Q$ corresponds to Emigration $(E)$.
Both $P$ and $Q$ represent factors that decrease the population density,so they are both marked with a negative sign $(-)$.
Thus,the correct option is $C$.

(C) Population density $(N)$ is affected by four basic processes. The two factors that contribute to an increase in population density are:
$1$. Natality (Birth-rate): The number of births during a given period in the population that are added to the initial density.
$2$. Immigration: The number of individuals of the same species that have come into the habitat from elsewhere during the time period under consideration.
Conversely,mortality (death rate) and emigration decrease the population density. Therefore,the correct option is $C$.

(A) The population density $(N_{t+1})$ at time $t+1$ is calculated using the formula:
$N_{t+1} = N_t + [(B + I) - (D + E)]$
Where:
$N_t$ = Initial population = $80$
$B$ = Birth rate = $4$
$I$ = Immigration = $6$
$D$ = Death rate = $2$
$E$ = Emigration = $3$
Substituting the values:
$N_{t+1} = 80 + [(4 + 6) - (2 + 3)]$
$N_{t+1} = 80 + [10 - 5]$
$N_{t+1} = 80 + 5 = 85$
Therefore,the population density is $85$.

(A) The given age pyramid shows a bell-shaped structure,which is characteristic of a stable population.
In a stable population,the proportion of individuals in the pre-reproductive and reproductive age groups remains relatively constant.
This indicates that the birth rate is roughly equal to the death rate,leading to a stable population size over time.
Therefore,the correct option is $A$.

(A) The death rate is calculated as the number of deaths divided by the initial population size over a specific time interval.
Death rate = $\frac{\text{Number of deaths}}{\text{Initial population size}}$
Death rate = $\frac{8}{80} = 0.1$ individual per individual per time interval.
Therefore, the death rate is $0.1$ individual/time interval.

(B) The formula for the net population change is: $\text{Net Increase} = (\text{Natality} + \text{Immigration}) - (\text{Mortality} + \text{Emigration})$.
Given values are: $\text{Natality} = 25$, $\text{Mortality} = 24$, $\text{Immigration} = 2$, and $\text{Emigration} = 3$.
Substituting these values into the formula:
$\text{Net Increase} = (25 + 2) - (24 + 3)$
$\text{Net Increase} = 27 - 27 = 0$.
Therefore, the net increase in the population is $0$.

(D) The correct answer is $D$.
Population size is not a static parameter; it keeps fluctuating due to various ecological factors.
$1$. Food availability: Limited resources restrict population growth,while abundance promotes it.
$2$. Predation pressure: High predation rates reduce the population size of prey species.
$3$. Adverse weather: Extreme conditions like droughts,floods,or severe winters can significantly decrease population density.
Therefore,all the mentioned factors are responsible for the dynamic nature of population size.

(A) The correct answer is $A$ (Declining).
The age pyramid shown in the image represents a declining population.
In this type of pyramid,the proportion of pre-reproductive individuals (at the base) is smaller than the proportion of reproductive and post-reproductive individuals.
This indicates that the birth rate is low and the population is shrinking over time.

(A) The correct answer is $A$ and $B$ only.
$A$ population is defined as a group of individuals of the same species that occupy a specific geographical area at a given time.
These individuals are capable of interbreeding and sharing or exchanging genetic information.
Option $(C)$ is incorrect because population density and dispersion are dynamic characteristics that change over time and space,rather than being constant or uniform.

(C) The population density of an area increases due to two main factors:
$1$. Natality $(B)$: It refers to the number of births during a given period in the population that are added to the initial density.
$2$. Immigration $(I)$: It refers to the number of individuals of the same species that have come into the habitat from elsewhere during the time period under consideration.
Therefore,both Natality and Immigration contribute to an increase in population density.