Skip to main content

CBSE class 12th biology notes Population and Population Growth

CBSE class 12th biology notes Population and Population Growth

There are four variables/ causes that govern the population growth/population size:
  1. Birth rate(Natality): It is defined as a number of births per 1000 individuals in one year.
  2. Death rate (Mortality): It is defined as a number of death per 1000 individuals per year.
  3. Immigration: Entry of individuals in a given population.
  4. Emigration: Exit of individuals from a given population.
A population gains individuals by birth and immigration and loses them by deaths and emigration.
Thus, population change = (Births + Immigration) – (Deaths + Emigration)
Effect of Age Distribution on Population growth
In many organisms, the generations overlap. It is shown, from a theoretical point of view, that competition between the different ages classes in such organisms will have important population dynamics consequences. Strong competition between age classes can be either a stabilizing or destabilizing force depending on the stage of the life cycle—juvenile survival or adult survival/reproduction—at which density dependence occurs. When juvenile survival is density dependent, competition has a stabilizing effect. On the other hand, when reproduction is density dependent, strong competition tends to be destabilizing, i.e. it will cause population density to fluctuate. It is also shown that delayed effects on reproduction, caused by strong competition as the adults grow up, tend to be destabilizing. These findings have interesting implications for the population dynamic behavior in organisms with different types of life cycles, and these theoretical findings might be relevant to the interpretation of patterns of population dynamic behavior.
For School courses, live classes, Professional courses, and Digital Marketing courses, Class 12 Science Online Classes kindly visit www.takshilalearning.com 

Labels:

Comments

Post a Comment

Thank you we will contact ASAP.

Popular posts from this blog

Lessons-Worksheets-Question Papers-CBSE Class 2 English

Lessons-Worksheets-Question Papers-CBSE Class 2 English CBSE 2nd Class English – One and Many  In this blog, we share the spelling rules used in the concept of  One  and Many. When there is only one of a naming word (noun), it is said to be a  singular noun . When a noun shows more than one, it is said to be in the  plural . We can add  –S, -es, -ves or ies  to show that there is more than one noun.  For example,  we say many birds, four biscuits, six brushes. But for the students of  Class 2 , it’s very difficult and confusing to understand where to use  s , es, ves or ies  in the form of many. Don’t worry, it looks difficult, but it is very easy as in grammar each concept has a set of rules that need to practice. Noun ending with  –s, -x, -o, -sh, -ch, and –ss  form plurals by taking  –es. Look at these pairs of words: Bus – Buses Brush – Brushes Continue ..... Click here ...
Post a Comment
Read more

Class 3 English Practice Grammar Worksheet -The Adverb

 Class 3 English Practice Grammar Worksheet -The Adverb Class 3 English – The Adverb – Kinds of Adverb Fill in the blanks with suitable Adverbs of place. Choose from the box.  Up               outside                       everywhere                 back                down      away          here                           there                     ...
Post a Comment
Read more

Bhakti Movement NCERT Class 12 History

Bhakti Movement NCERT Class 12 History The Bhakti movement was an effort to achieve salvation and emancipation by devotion to God. In Hindi, the word bhakti refers to fervent devotion to God. This movement, which stressed a single-minded, ardent devotion to God, is seen as the most characteristic act of religious progress during the Middle Ages. In the 12th and 13th centuries, Kabir Das was a key figure in the Bhakti Movement. As a result of the movement, Kabir Das' poems and religious writings attained widespread fame. Kabir Das was raised up by a Muslim family. However, his religious beliefs were influenced by his Hindu teacher Ramananda, who regarded Rama as the highest God. The first Sikh guru and the founder of Sikhism was Guru Nanak. He vehemently opposed prejudice based on customs, rivalry, and caste in religion. Nanak was raised in a Hindu household and from an early age began to exhibit spiritual tendencies. He helped the indigent and underprivileged. His followers began r...
Post a Comment
Read more