Question 1

Q1: List the attributes that populations possess but not individuals.

Accepted Answer

An individual organism is born and dies, but a population has attributes that individuals do not. These attributes are: 1.  Birth Rate and Death Rate: These are per capita rates of births and deaths in the population over a given time. An individual has a birth and a death, but not a birth rate or d...

Question 2

Q10: List any three important characteristics of a population and explain.

Accepted Answer

Three important characteristics (or attributes) of a population are: 1.  Population Density: This is the size of a population in relation to a unit of space, expressed as the number of individuals per unit area or volume. For example, 200 carrot grass plants per square meter. It is a fundamental pro...

Question 3

Q2: If a population growing exponentially double in size in 3 years, what is the intrinsic rate of increase ( r ) of the population?

Accepted Answer

Given: - The population is growing exponentially. - Time taken to double, $t = 3$ years. - Let the initial population density be $N_0$.  - The final population density after 3 years is $N_t = 2N_0$. To Find: The intrinsic rate of increase, $r$. Formula: The integral form of the exponential growth eq...

Question 4

Q3: Name important defence mechanisms in plants against herbivory.

Accepted Answer

Plants have evolved various defense mechanisms against herbivores because, unlike animals, they cannot run away from their predators. The important defense mechanisms are: 1.  Morphological Defenses: These are physical structures that deter herbivores. The most common example is the presence of thor...

Question 5

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?

Accepted Answer

The interaction between an orchid plant growing on the branch of a mango tree is an example of Commensalism. In this type of interaction, one species benefits while the other is neither harmed nor benefited.  - The Orchid (Beneficiary): As an epiphyte, the orchid benefits by getting a surface to gro...

Question 6

Q5: What is the ecological principle behind the biological control method of managing with pest insects?

Accepted Answer

The ecological principle behind the biological control method of managing pest insects is the predator-prey relationship. In any ecosystem, predators play an important role in regulating the population of their prey. When a prey species (like a pest insect) has no natural predators, its population c...

Question 7

Q6: Define population and community.

Accepted Answer

Population: A population is defined as a group of individuals of the same species that live in a well-defined geographical area, share or compete for similar resources, and can potentially interbreed. For example, all the teakwood trees in a forest tract or all the lotus plants in a pond constitute...

Question 8

Q7: Define the following terms and give one example for each: (a) Commensalism (b) Parasitism (c) Camouflage (d) Mutualism (e) Interspecific competition

Accepted Answer

(a) Commensalism: This is an interspecific interaction where one species benefits and the other is neither harmed nor benefited (+/0).         Example: An orchid growing as an epiphyte on a mango tree. The orchid gets support and sunlight, while the mango tree is unaffected. (b) Parasitism: This is...

Question 9

Q8: With the help of suitable diagram describe the logistic population growth curve.

Accepted Answer

The logistic population growth curve describes the growth of a population in a habitat with limited resources. This model is considered more realistic than exponential growth. The plot of population density (N) in relation to time (t) results in a sigmoid or S-shaped curve (as shown in Figure 11.3b...

Question 10

Q9: Select the statement which explains best parasitism. (a) One organism is benefited. (b) Both the organisms are benefited. (c) One organism is benefite...

Accepted Answer

The correct statement that best explains parasitism is: (d) One organism is benefited, other is affected. Explanation: Parasitism is a type of interspecific interaction where one organism, the parasite, lives in or on another organism, the host, and derives benefits (like nutrition and shelter) from...

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