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Practice population-ecology with 20 free MCQ questions covering environment-and-ecology. Detailed explanations in English and Hindi, perfect for UPSC, SSC, and competitive exam preparation.
Attempt the quiz above first, then review every question with its correct answer and a short explanation below.
Q1.Unlike an individual organism which has births and deaths, a population exhibits which of the following attributes?
Explanation: NCERT Class 12 Biology Chapter 13 states: 'An individual organism has births and deaths, but a population has birth rates and death rates. Another attribute characteristic of a population is sex ratio.'
Q2.If in a pond there were 20 lotus plants last year and through reproduction 8 new plants are added, what is the birth rate of the population per year?
Explanation: NCERT Chapter 13 calculates this birth rate: Change in numbers / Initial numbers = 8 / 20 = 0.4 offspring per lotus per year.
Q3.If 4 individuals in a laboratory population of 40 fruit flies died during a specified week, what is the death rate of the population per fruit fly per week?
Explanation: NCERT Chapter 13 calculates this death rate: Number of deaths / Initial population = 4 / 40 = 0.1 individuals per fruit fly per week.
Q4.What does a triangular-shaped age pyramid with a broad base represent for a human population?
Explanation: NCERT Class 12 Biology ponders age structures: A triangular age pyramid indicates a high proportion of pre-reproductive individuals (young children), which means the population is expanding and will grow rapidly in the future.
Q5.A bell-shaped age pyramid, where the pre-reproductive and reproductive age cohorts are nearly equal in size, represents which population status?
Explanation: In a stable population, the number of individuals entering the pre-reproductive phase is roughly equal to those in the reproductive phase, resulting in a bell-shaped pyramid and a stable population size over time (NCERT Chapter 13).
Q6.When the pre-reproductive age group is smaller than the reproductive age group, the resulting urn-shaped age pyramid indicates that the population is:
Explanation: An urn-shaped age pyramid is characterized by a narrow base (fewer pre-reproductive young individuals) than middle reproductive levels, indicating a declining population size (common in developed countries like Japan).
Q7.In which of the following cases is counting absolute numbers NOT the most meaningful way to measure population density?
Explanation: NCERT Class 12 Biology states that if 200 Parthenium (carrot grass) plants grow in an area containing a single huge banyan tree, stating that the density of Parthenium is higher is misleading because the banyan tree has a vastly higher biomass and covers a larger percent area. In such cases, biomass or percent cover is a more meaningful measure.
Q8.For which of the following animals is the population density estimated indirectly by counting pugmarks and fecal pellets, rather than direct counting?
Explanation: NCERT Class 12 Biology notes: 'The tiger census in our national parks and tiger reserves is often based on pugmarks and fecal pellets.' This is an indirect method used because tigers are elusive and hard to spot directly.
Q9.Which type of survivorship curve is characteristic of species (like humans and large mammals) that have high survival rates in early and middle life, followed by a rapid decline in survivorship in old age?
Explanation: Type I survivorship curves are flat in early and middle life (indicating high survival rate of offspring due to high parental care) and drop steeply at old age. This is typical of large mammals and humans.
Q10.Type III survivorship curves, showing extremely high mortality among young offspring followed by high survival rates for the few individuals reaching adulthood, are typical of:
Explanation: Type III species produce massive numbers of offspring but provide no parental care (e.g. oysters releasing millions of eggs). Most offspring die early due to predation or environmental factors, but the survivors that grow shells/reach size have very low mortality.
Q11.The scientific study of the human population, including its size, structure, distribution, and changes over time, is called:
Explanation: Demography is the statistical study of human populations. It analyzes attributes such as birth rates, death rates, migration patterns, and age structure shifts.
Q12.Which of the following dispersion patterns is the most common in nature, where resources are localized and individuals live in groups?
Explanation: Clumped dispersion is the most common pattern in nature. Individuals aggregate in patches where food, water, or shelter are concentrated, or due to social behavior (herds, flocks, schools). Uniform is rarer (due to territoriality/competition), and random occurs where resources are uniform.
Q13.What is the term for the average number of children a woman is expected to have during her reproductive years in a given population?
Explanation: The Total Fertility Rate (TFR) represents the average number of children that would be born to a woman over her lifetime if she were to experience the current age-specific fertility rates throughout her childbearing years.
Q14.In a laboratory experiment, if you measure the fish population density in a lake by counting the number of fish caught per trap, this represents what type of measurement?
Explanation: NCERT Class 12 Biology states: 'Sometimes, for certain ecological investigations, there is no need to know the absolute population densities; relative densities serve the purpose equally well. For instance, the number of fish caught per trap is a good measure of their total population density in the lake.'
Q15.When plotting an age pyramid, which age group is placed at the bottom-most level?
Explanation: In an age pyramid, the youngest age group (pre-reproductive) is placed at the bottom, followed by the reproductive age group in the middle, and the post-reproductive (oldest) group at the top.
Q16.A population is defined in ecology as a group of individuals of the same species that:
Explanation: NCERT Class 12 Biology states that in ecology, a population is a group of individuals of the same species residing in a defined geographic area, sharing resources, and potentially interbreeding (which includes both sexual and asexual reproduction groups in ecology).
Q17.Which of the following factors represents a density-independent limit on population size?
Explanation: Density-independent factors affect the population size regardless of how dense it is. Catastrophic weather events (droughts, floods, volcanic eruptions, forest fires) kill individuals without regard to population density. In contrast, disease, competition, and predation are density-dependent.
Q18.The constant death rate and mortality patterns observed in songbirds and Hydra over their entire life span represent which type of survivorship curve?
Explanation: Type II survivorship curves represent a constant mortality rate throughout the organism's life. Individuals have an equal chance of dying at any age. This diagonal straight line is typical of Hydra, some rodents, and songbirds.
Q19.If the age pyramid of a human population has a very narrow pre-reproductive cohort at the base, it indicates that the population will soon experience:
Explanation: A narrow pre-reproductive base means fewer children are being born. As this cohort moves into reproductive ages, the total number of breeding individuals will drop, causing the population size to shrink (decline) over time.
Q20.In demography, what does the 'Replacement Level Fertility' value represent, which is typically around 2.1 in developed nations?
Explanation: Replacement level fertility is the level of fertility at which a population exactly replaces itself from one generation to the next without migration. It is slightly above 2.0 (around 2.1) to account for childhood mortality before reaching reproductive age.
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