NCERT Solutions for Class 12 Biology Chapter 13
NCERT Solutions for Class 12 Biology Chapter 13 Organisms and Populations to Study Online or download FREE in PDF file format updated for new academic session 2020-21 based on latest NCERT Books 2020-2021.NCERT Solutions 2020-21 based on latest NCERT Books are also given to download in PDF format. Explore Your Knowledge with the others via Discussion Forum.
NCERT Solutions for Class 12 Biology Chapter 13
|Chapter 13:||Organisms and Populations|
Class 12 Biology Chapter 13 Solutions in English
NCERT Solutions for Class 12 Biology Chapter 13 is given below to download in PDF format free updated for new academic session 2020-21 based on latest NCERT Books. Download Offline Apps based on new NCERT Solutions 2020-2021 following the latest CBSE Syllabus 2020-2021. Join the Discussion Forum to ask your doubts and discuss the questions asked by the other users.
Important Terms related to Chapter 13
1. Organisms: Organisms form the basic unit of study in ecology.
2. Species: Organisms with similar features and the potential to interbreed among themselves and produce fertile offspring, constitute a species.
3. Populations: Population is a group of individuals of the same species, inhabiting in a given area. Interspecific competition for basic needs operate among the individuals of population.
4. Biological Community: Biological community is constituted by an assemblage of the populations of all different species that live in an area and interact with each other. A biotic community has a distinct species composition and structure.
A branch of science that studies interactions among organisms and their physical environment. Ecology is basically concerned with four levels of biological organisation – Organisms, population, communities and biomes. Ramdeo Mishra is called as the Father of Ecology in India.
1. Ecosystem: Is a biological system in nature and composed of a biotic community integrated with its physical (abiotic) environment through the exchange of energy and recycling of the nutrients.
2. Biomes: Biomes is a very large unit, constituting of a major vegetation type and associate fauna found is a specified zone. Annual Variations is the intensity, duration of temperature and precipitation account for the formation of major biomes like desert, rain, forest and Tundra.
3. Habitat: Habitat is the place where an organism lives.
Major Biomes of India: Tropical rain forest, deciduous forest, desert, sea coast. Regional and local variations within each biome lead to formation of a wide variety of habitats.
1. The ecological niche of an organism represents the range of conditions that it can tolerate the resources it utilises and its functional role in the ecological system. Each species occupies a distinct niche and no two species occupy the same niche.
2. Biosphere: It is the sum total of all the biomes on the earth.
3. Environment: Environment is a sum total of all biotic and abiotic factors that surround and potentially influence an organism. Temperature, water, light and soil are the major abiotic factors.
Important Questions on 12th Biology Chapter 13
Hibernation or winter sleep is a resting stage where in animals escape winters (cold) by hiding themselves in their shelters. They escape the winter season by entering a state of inactivity by slowing their metabolism. The phenomenon of hibernation is exhibited by bats, squirrels, and other rodents.
Morphological defence mechanisms:
Cactus leaves (Opuntia) are modified into sharp spines (thorns) to deter herbivores from feeding on them.
Sharp thorns along with leaves are present in Acacia to deter herbivores.
In some plants, the margins of their leaves are spiny or have sharp edges that prevent herbivores from feeding on them.
Chemical defence mechanisms:
All parts of Calotropis weeds contain toxic cardiac glycosides, which can prove to be fatal if ingested by herbivores.
Chemical substances such as nicotine, caffeine, quinine, and opium are produced in plants as a part of self-defence.
A population can be defined as a group of individuals of the same species residing in a particular geographical area at a particular time and functioning as a unit. For example, all human beings living at a particular place at a particular time constitute the population of humans.
A community is defined as a group of individuals of different species, living within a certain geographical area. Such individuals can be similar or dissimilar, but cannot reproduce with the members of other species.
Three important characteristics of a population are:
Birth rate (Natality): It is the ratio of live births in an area to the population of an area. It is expressed as the number of individuals added to the population with respect to the members of the population.
Death rate (Mortality): It is the ratio of deaths in an area to the population of an area. It is expressed as the loss of individuals with respect to the members of the population.
Age Distribution: It is the percentage of individuals of different ages in a given population. At any given time, a population is composed of individuals that are present in various age groups. The age distribution pattern is commonly represented through age pyramids.