Test: Organisms & Populations - 1 - NEET MCQ

• Births and deaths: These are characteristics of a population as they reflect the overall population dynamics rather than individual organisms.



• Birth rates and death rates: Population-level data on birth and death rates provide insights into the growth or decline of a population, which is not applicable to individual organisms.



• Sex ratio: While sex ratio can vary among individuals, it is more commonly used to describe the distribution of males and females in a population as a whole.



• Age distribution: Age distribution, such as the proportion of individuals in different age groups, is a population-level characteristic that helps understand the structure of a population.

In summary, characteristics such as birth rates, death rates, sex ratio, and age distribution are more relevant to populations as a whole rather than individual organisms. These factors provide valuable insights into the dynamics and structure of a population, highlighting the importance of studying populations as distinct entities from individual organisms.

In the given scenario, the laboratory population of fruit flies consists of 40 fruit flies, and during a specified time interval, 4 individuals died. To calculate the death rate, we divide the number of deaths by the total population.

Number of deaths = 4
Total population = 40

Death rate = Number of deaths / Total population
= 4 / 40
= 0.1 individuals per fruitfly per week

Option a) "0.1 individuals per fruitfly per week" is the correct answer because it accurately represents the death rate calculated based on the given information.

Natural selection operates on the population level to evolve desired traits. While individual organisms have to cope with changes in their environment, it is at the population level that natural selection acts to shape the genetic composition and traits of the population over time.

Population ecology, links ecology to population genetics and evolution. It is at the population level that variations in traits occur due to genetic diversity and interactions with the environment. Individuals with traits that confer advantages in survival, reproduction, and adaptation are more likely to pass on those traits to the next generation through interbreeding.

An age pyramid with a wide base and narrow top indicates a population that is growing rapidly.

In an age pyramid, the width of each age group represents the proportion or percentage of individuals in that specific age group. A wide base indicates a larger population of young individuals, while a narrow top indicates a smaller population of older individuals.

When the base of an age pyramid is wide and the subsequent age groups gradually decrease in width towards the top, it suggests that there is a higher proportion of young individuals compared to older individuals. This is indicative of a population that is growing rapidly because there is a high birth rate.

• Our intestine is a unique habitat for hundreds of species of microbes. Digestion is important for breaking down food into nutrients, which the body uses for energy, growth, and cell repair.
• Food and drink must be changed into smaller molecules of nutrients before the blood absorbs them and carries them to cells throughout the body.
• The intestines are a long, continuous tube running from the stomach to the anus. Most absorption of nutrients and water happen in the intestines.
• The intestines include the small intestine, large intestine, and rectum.

A population's birth rate refers to the number of births per capita. A population has birth rates and death rates, and these rates are expressed as changes in numbers (increase or decrease) with respect to members of the population.

To calculate the birth rate, the number of births is divided by the population size or the number of individuals in the population. The birth rate per capita provides a measure of the average number of births per individual in the population.

Carrying capacity of a habitat is the maximum number of individual that can survive in given habit. There is a limitation of food, water and space in a habitat so only limited numbers of individual survive.

Interactions between different species living within a particular area may be useful as in case of mutualism, fatal as in case of parasitism or neutralin which no one is harmed.

Interacting members of species live close to each other in commensalism, predation and parasitism.

A majority of organisms are restricted to narrow range of temperature. Such organisms are called stenothermal species. The distribution range of these species will be adversely affected if average global temperature keeps increasing.

Ecology is the study of the relationships between living organisms and the abiotic (physico-chemical factors) and biotic components (other species) of their environment. Ecology encompasses the interactions and relationships between organisms and both their non-living (abiotic) and living (biotic) environment. It examines how organisms interact with factors such as climate, water, soil, and other organisms.

Therefore, option a) Abiotic and biotic components accurately describes the scope of ecology.

Interactions between species can have different outcomes. In mutualism, both species benefit from the interaction. This means that there is a mutually beneficial relationship where both species gain advantages, such as access to food, protection, or reproductive assistance.

Option d) Mutualism is the correct answer because it accurately identifies the type of interaction where both species involved benefit from each other.

Thermoregulation refers to the ability of an organism to regulate its body temperature. It is the process by which organisms maintain a relatively constant internal temperature despite fluctuations in the external environment. This is achieved through physiological and behavioral mechanisms.

The levels of organization are described below from the smallest to the largest:

• A species is a group of individuals that are genetically related and can breed to produce fertile young. Individuals are not members of the same species if their members cannot produce offspring that can also have children. The second word in the two word name given to every organism is the species name. For example, in Homo sapiens, sapiens is the species name.
• A population is a group of organisms belonging to the same species that live in the same area and interact with one another.
• A community is all of the populations of different species that live in the same area and interact with one another. A community is composed of all of the biotic factors of an area.
• A biome is a community of plants and animals that have common characteristics for the environment they exist in. They can be found over a range of continents. Biomes are distinct biological communities that have formed in response to a shared physical climate.

Hence, Option A is correct.

The principle that states that the superior competitor eliminates the inferior one in competition is the Competitive Exclusion Principle. This principle suggests that when two species compete for the same limited resources in an ecological niche, the species that is better adapted or more efficient at utilizing those resources will eventually outcompete and eliminate the other species from that particular niche.

The correct answer is option a) Competitive exclusion principle. This principle highlights the competitive interactions between species and how competition can lead to the exclusion of one species by another in certain ecological niches.

Exponential growth pattern in population results into j-shaped curve. During exponential growth faster growth occurs and j-shaped curve is formed when time v/s growth is drawn.

In predation and parasitism one species is benefitted while other is harmed. Parasite obtain food from host by harming them.

Populations grow through births and immigration and decline through deaths and emigration.

When resources become progressively limiting for a population, the growth pattern turns logistic. This means that initially, the population may experience exponential growth when resources are abundant and unlimited.

However, as resources start to become scarce and limiting, the growth rate of the population slows down and eventually levels off. This pattern is known as logistic growth.

• Exponential growth (option b) refers to a rapid and unrestricted increase in population size without resource limitations.
• Constant growth (option c) implies a steady and consistent growth rate over time, regardless of resource availability.
• Declining growth (option d) suggests a decrease in population size over time, often due to factors like limited resources or environmental disturbances.

Commensalism is interaction in which one species is benefited by other is neither benefited nor harmed. Orchids growing on mango tree do not harm the mango plants but get shelter.

Population ecology is an important area of ecology because it links ecology to population genetics and evolution. At population level natural selection operates to evolve desired traits.

Inter-specific competition could be most intense and strongest as it occurs between organisms having same types of requirement of food, water etc. They may have competition for food, shelter, water, space or mat also.

Intrinsic rate of natural increase (r) is a measure of the inherent potential of a population to grow.

The intrinsic rate of natural increase refers to the rate at which a population grows under ideal conditions, assuming unlimited resources and without any limiting factors such as predation, competition, or environmental constraints. It is a measure of the population's ability to reproduce and survive.

• Birth rate (option b) refers to the rate at which individuals are born in a population.
• Death rate (option c) refers to the rate at which individuals die in a population. While these factors are important in determining population dynamics, the intrinsic rate of natural increase specifically measures the potential for population growth under optimal conditions.
• Carrying capacity (option d) refers to the maximum number of individuals that an environment can sustainably support based on the available resources.

The interaction where one species benefits and the other is unaffected is called commensalism. In this type of interaction, one organism benefits from the association, while the other remains unaffected. Commensalism is characterized by a relationship in which one species gains an advantage or benefit, such as shelter, transportation, or access to food, without causing any harm or benefit to the other species involved.

The correct answer is option d) Commensalism. This type of interaction allows one species to benefit without affecting the other species positively or negatively.

The birth rate of a population = new individual added / previous population. Here birth rate= 7/23=0.3043. Hence, birth rate of Salvinia plants is equal to 0.3.

Sex ratio is the no of female available per thousands of male in a population. Sex ratio is decline due to female feticides alarmingly in some part of India.