Find the best tutors and institutes for Class 12 Tuition
Q7(a):
Define the following terms and give one example for each:
(a) Commensalism
Solution :
Step 1: Core Definition of Commensalism
Commensalism is an interspecific population interaction [occurring between members of two different species] wherein one species derives a tangible ecological benefit, while the other species is neither benefited nor harmed.
Step 2: Ecological Interaction Matrix & Notation
In theoretical population ecology, interactions are categorized based on the functional outcome for the fitness of each species involved. Commensalism is designated algebraically as a $(+, 0)$ interaction.
- Species A (The Commensal): Assigned a positive value $(+)$, as it experiences an increase in fitness, resource acquisition, or survival rate.
- Species B (The Host): Assigned a zero value $(0)$, indicating absolute neutrality. Its survival, reproduction, and resource pool remain entirely unaffected by the presence of the commensal.
Step 3: Analytical Examples of Commensalism
To fully substantiate the theoretical model, we observe instances of commensalism in both zoological and botanical ecosystems. [Per standard ecological curriculum, detailing one primary example is required, though two are provided here for absolute clarity].
| Example Type | Interacting Species | Ecological Mechanism & Justification |
|---|---|---|
| Zoological | Cattle Egret $(+)$ and Grazing Cattle $(0)$ |
The cattle egrets forage in close proximity to grazing cattle. As the cattle move through the vegetation, their heavy hooves stir up and flush out resting insects. The egrets easily catch these insects, thus drastically improving their foraging efficiency $(+)$. The cattle derive no benefit from the birds eating the insects, nor are they hindered by the birds' presence $(0)$. |
| Botanical | Epiphytic Orchid $(+)$ and Mango Tree $(0)$ |
An orchid growing as an epiphyte on the branch of a large mango tree gains physical support and elevation, affording it better access to sunlight and atmospheric moisture $(+)$. Because the orchid does not tap into the vascular tissue of the mango tree (unlike a parasite), the mango tree loses no nutrients and remains totally unaffected $(0)$. |
Final Solution: Commensalism is defined as an interspecific population interaction where one species benefits (the commensal) while the other species is neither benefited nor harmed (the host), mathematically represented as a $(+, 0)$ interaction. A classic example is the relationship between the Cattle Egret and grazing cattle, where the egret benefits by feeding on insects flushed out by the moving cattle, while the cattle remain completely unaffected.
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 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.
- 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
Super Tutor
Nerul, Mumbai
10 yrs of
Exp
16 students
684 hrs of classes completed
900
per hour
Online Classes
I'm a ex-faculty member of Allen, FIITJEE & Unacademy, and I taught in DAV for 2 years. Now I'm working as a freelancer. I have more than 10 years of experience.. So overall I've all kinds of experience to meet with academic & JEE aspirants as well.. Join me to learn mathematics from basic to advanced..
Good tutor, teaches different concepts of class 12 very well. Easily able to understand methods and problem solving skills. Good communication.
Top Tutor
Jahangirpura, Surat
15 yrs of
Exp
6 students
3652 hrs of classes completed
250
per hour
Online Classes
I have 15 years of teaching Maths to students of clasd 11,12 Science. I have taught NCERT and RD Sharma.
Top Tutor
Anna Nagar Mullai Nagar, Chennai
9 yrs of
Exp
9 students
410 hrs of classes completed
600
per hour
Online Classes
Hi, I'm Kalaiselvi, an M.Sc. Mathematics graduate with 9 years of experience in one-on-one online Maths tutoring. I specialize in teaching Classes 10, 11, and 12 for CBSE and Tamil Nadu State Board. My classes are conducted in both English and Tamil (bilingual), making concepts easy to understand. I focus on concept clarity, problem-solving, regular practice, and exam preparation, with personalized attention for every student.
Math class was interesting at times, especially when the topics were explained with real-life examples.The mix of learning and problem-solving made the experience enjoyable and not just about memorizing formulas.This made math feel more flexible and creative rather than just following one method.
Top Tutor
Krishnarajapura, Bangalore
10 yrs of
Exp
5 students
397 hrs of classes completed
500
per hour
Online Classes
Tutor's home
I am an IITian. Passed out from IIT Delhi. Teaching is my passion. I have seven years of teaching experience teach chemistry, Biology ,Biochemistry, Biotechnology for class 11 and 12 from different boards.I teach chemistry for entrance exams like NEET, JEE.
Anasuya mam teaches each topic in detail and giving excellent support in JEE chemistry preparations.
Top Tutor
KR Puram, Bangalore
8 yrs of
Exp
2 students
31 hrs of classes completed
500
per hour
Online Classes
I am a physics teacher handling X,XI,XII grades, having 8 years experience as Science HOD in a cbse School. I have a degree in BE ( electronics and telecommunications).With my best efforts, support, patience ,commitment I unlock my students potential.Concepts are presented in a clear, simple and direct manner. Consistently my class result is 100% with good subject average. Expanding pupils horizons is my accomplishment.
