Most living organisms cannot survive at temperature above 45°C°. How are some microbes able to live in habitats with temperatures exceeding 100°C?
Solution and Explanation
Top Questions on Organisms and Populations
As a pait of his tescarch, Arun conducted a study on the number of locusts in a forest, He compiled his findings in the form of the following dala.
- ICSE Class XII - 2026
- Biology
- Organisms and Populations
- Identify and explain the type of ecological interaction where Paramecium caudatum got eliminated when grown with Paramecium aurelia based on Gause’s principle.
- ICSE Class XII - 2026
- Biology
- Organisms and Populations
- Roselin had an aquarium at her home with 10 fish in it. In a year, a fish gave birth to 7 fish. During this period, 3 adult fish had died. Roselin's father purchased 2 more pairs of fish from market for the aquarium. Later, Roselin gifted 4 fish from the aquarium to her friend. Find out the growth rate of fish in Roselin's aquarium.
- ICSE Class XII - 2026
- Biology
- Organisms and Populations
- There were 770 frogs in a pond. 70 of them died within a month. Calculate the death rate of the population of frogs in the pond.
- ICSE Class XII - 2026
- Biology
- Organisms and Populations
- Read the following passage and answer the questions that follow:
In nature, we rarely find isolated, single individuals of any species; majority of them live in groups in a well-defined geographical area, share or compete for similar resources, potentially interbreed and thus constitute a population. The population has certain attributes whereas, an individual organism does not. A population at a given time is composed of individuals of different ages. The size of the population tells us a lot about its status in the habitat. Whatever ecological processes we wish to investigate in a population, be it the outcome of competition with another species, the impact of the predator or the effect of pesticide application, we always evaluate in terms of any change in the population size. The size, in nature, could be low or go into millions. Population size, technically called population density (N) need not necessarily be measured in numbers only. The size of a population for any species is not a static parameter. It keeps on changing with time depending on various factors including food availability, predation pressure and adverse weather. (a) The Monarch butterfly is highly distasteful to its predator because of a special chemical present in its body. How does the butterfly acquire this chemical?
(b) If population density at a time t + 1 is 800, Emigration = 100, Immigration = 200, Natality = 200 and Mortality = 150, calculate the population density at time t and comment upon the type of age pyramid that will be formed in this case.
Student to attempt either sub-part (c) or (d):
(c) What is the difference in a method of measuring population density in an area if there are 200 carrot grass plants to only single huge banyan tree?
\begin{center} OR \end{center} (d) Name two methods to measure the population density of tigers.- CBSE CLASS XII - 2025
- Biology
- Organisms and Populations
Questions Asked in CBSE CLASS XII exam
- The rate for the following reaction is given by: \[ A + B \rightarrow C, \quad \text{Rate} = k[A][B]^2 \] How is the rate affected if we double the concentration of B?
- CBSE CLASS XII - 2026
- Chemical Kinetics
- Find the general solution of the differential equation \[ y\log y\,\frac{dx}{dy}+x=\frac{2}{y}. \]
- CBSE CLASS XII - 2026
- Differential Equations
- A square loop of side 0.50 m is placed in a uniform magnetic field of 0.4 T perpendicular to the plane of the loop. The loop is rotated through an angle of 60° in 0.2 s. The value of emf induced in the loop will be:
- CBSE CLASS XII - 2026
- Electromagnetic induction
A racing track is built around an elliptical ground whose equation is given by \[ 9x^2 + 16y^2 = 144 \] The width of the track is \(3\) m as shown. Based on the given information answer the following:
(i) Express \(y\) as a function of \(x\) from the given equation of ellipse.
(ii) Integrate the function obtained in (i) with respect to \(x\).
(iii)(a) Find the area of the region enclosed within the elliptical ground excluding the track using integration.
OR
(iii)(b) Write the coordinates of the points \(P\) and \(Q\) where the outer edge of the track cuts \(x\)-axis and \(y\)-axis in first quadrant and find the area of triangle formed by points \(P,O,Q\).
- CBSE CLASS XII - 2026
- Integration
- Consider a cylindrical conductor of length \( l \) and area of cross-section \( A \). Current \( I \) is maintained in the conductor and electrons drift with velocity \( \vec{v}_d \, (|\vec{v}_d| = \frac{eE}{m} \tau) \), where symbols have their usual meanings. Show that the conductivity of the material of the conductor is given by \[ \sigma = \frac{n e^2 \tau}{m}. \]
- CBSE CLASS XII - 2026
- Current Density
Concepts Used:
Organisms and their Environments
Ecology is the branch of biology that involves the study of the interactions that takes place between an organism and its environment. Any biological organization consists of 4 levels, namely, Organisms, Populations, Biomes, and Communities.
Organisms:
An Organism is an attached living system that lives in an environment. They are able to retain specific behaviours and structure such as bacteria, fungi, plants, animals, and humans. A population is formed by the collection of all these organisms. The collection of population forms a community that helps in the operation of ecosystems.
Environment:
The study of the interaction of organisms in an area with the surrounding environment is Ecology. This interaction constitutes an overall adaptation of the organisms to their environment that also includes the continuity of species.
The environment comprises of both biotic (living things) and abiotic components (non-living things)
Food Chain:
Food Chain is the transfer of food energy from the plant source through a series of organisms that consume and are consumed.
Grass(Producer) → Deer(Herbivore) → Tiger(Carnivore), Grass(Producers) → Insect(Herbivores) → Frog(Carnivores) → Snake(Secondary Carnivore).
Food Web:
Food web is the interlocking pattern of multiple food chains in the ecosystem. In this, many food chains are interconnected and there are increased possibilities of eating and getting eaten by different organisms of various species.