NCERT Solutions Class 12 Biology Chapter 13

NCERT Solutions Class 12 Biology Chapter 13

The science of the study of all living things including plants, animals and microbes is referred to as Biology. Biologists generally study the structure, function, growth, origin, evolution and distribution of living species. Some scientific disciplines are intertwined with others. Biology is vital because it enables us to comprehend how living things function and interact on several levels. There was formerly an English term for biology called lifelore, but it is no longer used.

The 13th chapter of Class 12 Biology is Organisms and Populations. New ideas about organisms, populations, biomes and communities will be introduced in this chapter. When it comes to ecology, an organism’s definition and other terminology are different. Our planet has a diversified ecosystem that provides a haven for a wide range of flora and wildlife. Understanding what constitutes an ecosystem and how these words are linked will be essential.

New conceptual chapters are introduced in the Biology Class 12 syllabus. Chapter 13 is an important chapter in this syllabus. The teachers at Extramarks are aware of the questions and doubts young students may have about this chapter. Hence, they have introduced Class 12 Biology Chapter 13 NCERT Solutions. Chapter 13 Class 12 Biology NCERT Solutions helps students grasp the intricate details of the chapter.

Extramarks has a wide range of study material for students. In addition to Biology Class 12 Chapter 13 NCERT Solutions, students can use the Extramarks website to access several other study tools. For example, NCERT books, CBSE revision notes, CBSE sample papers, CBSE previous year question papers and other materials are available to students.

Key Topics Covered NCERT Solutions Class 12 Biology Chapter 13

Listed below are the key topics that are covered in NCERT Solutions Class 12 Biology Chapter 13- Organisms and Populations:

Let us look at in-depth information on each subtopic in NCERT Solutions Class 12 Biology Chapter 13 given by Extramarks. 

Introduction to Ecology

The branch of biology which studies the interactions between organisms and their surroundings is referred to as Ecology. The biological organisation is divided into four tiers:

• Organisms
• Populations
• Communities
• Biomes 

NCERT Solutions Class 12 Biology Chapter 13 discusses the two levels of the organisation- Organisms and Populations in the section below.

Organism and Environment

NCERT Solutions Class 12 Biology Chapter 13 states that a continuous biological system in an environment can adapt and keep specific structures and behaviour as an organism. Fungi, bacteria, plants, animals and people are all part of it. A group of organisms forms a population. The population is organised into a community that manages the ecology. The Biotic and Abiotic components together constitute the ecosystem.

Due to genetic differences, all organisms have the potential to adapt to a variety of environmental situations. They have a better probability of surviving because of this. Polar bears have a variety of characteristics that help in their adaptation to the freezing temperature of Antarctica. They are protected from the cold and predators by their thick fur coats. The waxy covering keeps the body warm while repelling water. These characteristics aid in their adaptation to the cold.

Some major Abiotic factors

NCERT Solutions Class 12 Biology Chapter 13 gives some major abiotic factors below:

• Temperature is an essential abiotic element that influences both the environment and organisms. The temperature at the poles is always lower than that at the equator. The Arctic region’s temperature fluctuates from sub-zero to >15°C in tropical deserts throughout the summer. The temperature impacts the body’s metabolism and physiology, just as it does on enzyme kinetics.
• Water, which is essential for life, is another critical abiotic element. Deserts are areas where there is a lack of water, and only creatures with adaptations will be able to survive. The content and pH of the water are critical for aquatic organisms. Some species have a high salinity range, referred to as euryhaline.
• Another major abiotic element is light, which is necessary for photosynthesis and may be seen in autotrophs. The sun is the universal source of light. Light intensity requirements differ from organism to organism, with some requiring high light intensity and others requiring low light intensity.
• Soil is another key abiotic element that impacts organisms and their populations. The nature and characteristics of soil vary based on the kind of climate, the weathering process, soil formation, soil movement, and if the soil is sedimentary.

Responses to Abiotic factors

Abiotic factors affect different creatures in different ways. In the following section, NCERT Solutions Class 12 Biology Chapter 13 presents numerous abiotic factor responses:

• Regulators: They are creatures that can maintain homeostasis and control, resulting in consistent body temperature, osmotic concentration and other factors.
• Conformers: They are creatures that cannot maintain a constant body temperature. The process of thermoregulation, which is an energy process, occurs when the body releases or absorbs heat, resulting in a rise or reduction in body temperature.
• Partial regulators: They are those species that can regulate themselves, but only to a limited extent, depending on the environment. When the organisms reach this limit, they are conformed.
• Migration: The transfer of animals from one location to another according to their needs.
• Spores: Certain microorganisms, such as bacteria and fungus can halt their development in unfavourable environmental circumstances.

Population and its Attributes

According to NCERT Solutions Class 12 Biology Chapter 13, a population is a collection of individuals or creatures of any species living in a well–defined geographic region at a certain moment capable of interbreeding. For instance, consider the deer population in a forest

Some Attributes of Population

• Birth rate: The total number of people born in a population in a certain period of time is the birth rate of that population.
• Death rate: Death rates are the total number of people of the population who die in a certain period of time.
• Sex ratio: The total number of females and males per 1000 people is the sex ratio.
• Age pyramid: A plot representing the age distribution is called an age pyramid.

Population Growth and Growth Models

The rise in the number of people in a population is called population growth. This is dependent on several circumstances including the weather, food supply, predator pressure and so on. The density of the population fluctuates because of the following factors:

• Natality: Natality refers to the birth of individuals in a given population. The “natality rate” is calculated as the number of individuals produced per female in a given unit time.
• Morality: Mortality is the number of people who die in a certain period.
• Emigration: The number of people who relocated to a different environment in a certain period.
• Immigration: The number of people who have arrived in the habitat from other places.

 NCERT Solutions Class 12 Biology Chapter 13 states that Population Growth involves two models: Exponential Growth and Logistic Growth.

Exponential Growth Model

The creation of exponential growth occurs when the nutrients available are in excess amount. If N is the population size, b is the birth rate (per capita births, not total births), and d is the death rate, then the rise or decrease in N over time period t will be (dN/dt).

dN/dt = (b-d)*(N)

Let (b-d) = r, then

dN/dt = rN

The ‘intrinsic rate of natural growth is referred to as r in this equation. The exponential growth pattern, also known as the geometric growth pattern causes the population to form a J-shaped curve. The following is the final equation that is obtained:

Nt = N0ert

Nt = population density after time t

N0 = population density at time zero

r = intrinsic rate of natural increase

e = the base of natural algorithms

t= time

Logistic Growth

When the number of nutrients and other available resources are restricted, population expansion is called Logistic Growth or Verhulst-Pearl Logistic Growth. As a result of this state, there will be increased competition among species. As a result, a lag phase will occur in the face of finite resources, followed by exponential growth, slowing, and eventually asymptote.

The logistic growth curve will be either S-shaped or sigmoid in form. Verhulst-Pearl Logistic Growth is depicted in the equation below:

dN/dt = rNk – N/K

r = intrinsic rate of natural increase

K = carrying capacity.

In the above section, NCERT Solutions Class 12 Biology Chapter 13 has discussed two models of Population Growth. All study material related to these is available on the Extramarks website. Register today to experience learning like never before.

Population Interaction

The interplay of diverse populations is referred to as Population Interaction. There are a variety of ways for people to interact with one another. NCERT Solutions Class 12 Biology Chapter 13 explains some of them:

• Predation: Predator-prey interaction in which the predator kills the prey. This is critical for the survival of the prey and predator species. Herbivores play the role of predators in the case of plants. Various adaptations have been discovered in certain plants that assist them in protecting themselves from prey. For example, thorns as a defence or defensive agents such as caffeine, nicotine, quinine and other commercially available substances might be utilised.
• Competition: The interaction between organisms in which they compete for resources such as food, water, shelter, etc. The organisms may be of the same species or other species. When resources are few, this interaction happens.
• Parasitism: It is a relationship in which one species relies on the other, resulting in one species benefiting while the other suffers. Ectoparasites are parasitic parasites that feed on the host organism’s outer surface.
• Commensalism: It is a species interaction in which one species benefits while the other species receives neither benefit nor damage.
• Mutualism: It is the interaction in which both species benefit from one another. Lichens (a reciprocal and symbiotic connection between algae and fungus) and mycorrhiza are two examples (symbiotic relationship between fungi and the roots of the higher plants).
• Amensalism: It is an organism interaction in which one species suffers harm while the other suffers neither gain nor injury.

NCERT Solutions Class 12 Biology Chapter 13 Exercise and Solutions

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By getting access to NCERT Solutions Class 12 Biology Chapter 13, students can easily understand all the concepts of Organisms and Populations.

Key Features of NCERT Solutions Class 12 Biology Chapter 13

Students are frequently advised to read through NCERT questions when studying for board examinations. These NCERT questions are an excellent combination of all the chapter’s concepts. Extramarks NCERT Solutions have been produced so that students can comprehend every concept of any difficult chapter with ease. Here are some of the benefits of using Extramarks:

• These solutions are a time saver for all students. They are easy to grasp and go.
• Organism and Population NCERT Solutions help students clear all their doubts and understand the manner in which the answers need to be written in the final exam.
• These solutions can help students build confidence and prepare them for the actual examination eventually.