Find the best tutors and institutes for Class 12 Tuition
Q10:
List any three important characteristics of a population and explain.
Solution :
Definition of Population Attributes
A population is defined as a group of individuals of the same species occupying a specific geographical area at a given time, sharing or competing for similar resources, and potentially interbreeding. Unlike an individual, a population possesses unique attributes that emerge from the collective statistics of its members. The three critical characteristics are Population Density, Natality/Mortality (Birth and Death Rates), and Age Distribution.
Step 1: Population Density ($N$)
Population density is a quantitative measure of the number of individuals of a species per unit area or volume at a given time. It is the most vital metric for assessing the success of a species in a habitat.
- Formula: $D = \frac{N}{S}$, where $N$ is the total number of individuals and $S$ is the space (area/volume).
- Significance: It reflects the population's interaction with the environment, resource availability, and potential for competition. High density often triggers density-dependent factors such as increased disease transmission or resource depletion [Per the Principle of Density-Dependent Population Regulation].
Step 2: Natality and Mortality
These metrics define the dynamic change in population size over a specific period.
| Characteristic | Definition | Mathematical Expression |
|---|---|---|
| Natality (Birth Rate) | Number of births per capita per unit time. | $B = \frac{\Delta N_b}{N \cdot \Delta t}$ |
| Mortality (Death Rate) | Number of deaths per capita per unit time. | $D = \frac{\Delta N_d}{N \cdot \Delta t}$ |
These two factors operate in opposition; while natality increases population size, mortality decreases it. The net change is calculated by $(B - D)$ [Per the Exponential Growth Equation Model].
Step 3: Age Distribution (Age Pyramids)
A population is composed of individuals at different developmental stages: pre-reproductive, reproductive, and post-reproductive. The proportion of these groups is represented graphically as an Age Pyramid.
Analysis of Pyramids:
- Expanding: Pre-reproductive individuals significantly outnumber reproductive individuals.
- Stable: The proportions of pre-reproductive and reproductive age groups are roughly balanced.
- Declining: Post-reproductive individuals are the largest cohort, indicating a shrinking future population.
Final Solution: The three fundamental characteristics of a population are 1) Population Density, which measures the number of individuals per unit area; 2) Natality and Mortality, which denote the rates of birth and death determining population flux; and 3) Age Distribution, which utilizes age pyramids to predict future population growth trajectories and demographic stability.
More Questions from Class 12 Biology Organisms and Populations EXERCISES
- Q1: List the attributes that populations possess but not individuals.
- Q1: List the attributes that populations possess but not individuals.
- Q2: If a population growing exponentially double in size in 3 years, what is the intrinsic rate of increase (\(r\)) of the population?
- Q2: If a population growing exponentially double in size in 3 years, what is the intrinsic rate of increase ((r)) of the population?
- Q3: Name important defence mechanisms in plants against herbivory.
- Q3: Name important defence mechanisms in plants against herbivory.
- Q4: An orchid plant is growing on the branch of mango tree. How do you describe this interaction between the orchid and the mango tree?
- Q4: An orchid plant is growing on the branch of mango tree. How do you describe this interaction between the orchid and the mango tree?
- Q5: What is the ecological principle behind the biological control method of managing with pest insects?
- Q5: What is the ecological principle behind the biological control method of managing with pest insects?
- Q6: Define population and community.
- Q6: Define population and community.
- Q7(a): Define the following terms and give one example for each: (a) Commensalism
- Q7(a): Define the following term and give one example for it: Commensalism
- Q7(b): Define the following terms and give one example for each: (b) Parasitism
- Q7(b): Define the following term and give one example for it: Parasitism
- Q7(c): Define the following terms and give one example for each: (c) Camouflage
- Q7(c): Define the following term and give one example for it: Camouflage
- Q7(d): Define the following terms and give one example for each: (d) Mutualism
- Q7(d): Define the following term and give one example for it: Mutualism
- Q7(e): Define the following terms and give one example for each: (e) Interspecific competition
- Q7(e): Define the following term and give one example for it: Interspecific competition
- Q8: With the help of suitable diagram describe the logistic population growth curve.
- Q8: With the help of suitable diagram describe the logistic population growth curve.
- Q9: Select the statement which explains best parasitism.
- Q9: Select the statement which explains best parasitism.
- Q10: List any three important characteristics of a population and explain.
CBSE Solutions for Class 12 Biology Organisms and Populations
Chapters in CBSE - Class 12 Biology
- Reproduction in Organisms
- Human Reproduction
- Reproductive Health
- Principles of Inheritance and Variation
- Molecular Basis of Inheritance
- Evolution
- Human Health and Disease
- Strategies for Enhancement in Food Production
- Microbes in Human Welfare
- Biotechnology: Principles and Processes
- Biotechnology and Its Applications
- Ecosystem
- Biodiversity and Conservation
- Environmental Issues
Top Tutors who teach Organisms and Populations
Top Tutor
Air Force Area, Jodhpur
4 yrs of
Exp
1 student
50 hrs of classes completed
300
per hour
Online Classes
Tutor's home
I am a postgraduate and I have been associated with teaching over four years. I teach science and always able to motivate my students to study hard and make better future choices. I am a chaser for the least obvious path. I believe in creativity, which brings interest in gaining knowledge. As a teacher, one can help others and himself to upgrade life and society.
Top Tutor
Patel Nagar, Gurgaon
7 yrs of
Exp
550
per hour
Online Classes
Student's Home
Tutor's home
Super Tutor
Banjara Hills, Hyderabad
12 yrs of
Exp
37 students
1296 hrs of classes completed
800
per hour
Online Classes
Tutor's home
Although I haven't taught in schools or colleges, I have been invited to deliver guest lectures at reputed universities. These sessions allowed me to share my expertise with advanced learners and contribute to academic discussions. My focus has always been on delivering value through practical insights, making complex topics accessible and engaging for university students.
The experience is very good , give an detailed explanation with real life examples and also makes the concept easy to understand.
Top Tutor
Laxmi Vihar, Hisar
4 yrs of
Exp
11 students
267 hrs of classes completed
800
per hour
Online Classes
I'm a mathematics' teacher. My goal is to teach you how you can think out a solution rather than roboting your way out. We will dive deep into concepts of mathematics and come out as a well learned and scrupulous student. I am ready to clear your hurdles with most accurate way. I have taught at many academies for JEE preparations. In addition to it I have taught online in UrbanPro from past 4 years.
Suman is an awesome teacher and connects well with the student and gets them to grasp concepts and be interested in the subject. Highly recommend him for math.
Super Tutor
Panvel, Mumbai
12 yrs of
Exp
21 students
3260 hrs of classes completed
500
per hour
Online Classes
I provide private tuition for Physics and Mathematics for Class XI and XII (All Boards) Physics for Engineering Aspirants Physics for Medical Aspirants Class IX and X Mathematics and Science.
I am grateful that my son have been taught by you. Your dedication, knowledge, and passion for teaching make every class engaging and productive. You explain complex concepts in a simple and understandable manner. Thank you Sir .
