Distinguish between the following:
(a) Hibernation and Aestivation.
(b) Ectotherms and Endotherms
Distinguish between the following:
(a) Hibernation and Aestivation.
(b) Ectotherms and Endotherms
Solution and Explanation
(a) Hibernation and Aestivation
| Hibernation | Aestivation | ||
| 1. | Hibernation is a state of reduced activity in some organisms to escape cold winter conditions. | 1. | Aestivation is a state of reduced activity in some organisms to escape desiccation due to heat in summers. |
| 2. | Bears and squirrels inhabiting cold regions are examples of animals that hibernate during winters. | 2. | Fishes and snails are examples of organisms aestivating during summers. |
(b) Ectotherms and Endotherms
| Ectotherms | Endotherms | ||
| 1. | Ectotherms are cold blooded animals. Their temperature varies with their surroundings. | 1. | Endotherms are warm blooded animals. They maintain a constant body temperature. |
| 2. | Fishes amphibians and reptiles are ectothermal animals. | 2. | Birds and mammals are endothermal animals. |
Top Questions on 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
- A biologist studied the population of rats in a granary. He found the average natality was 280, average mortality was 200, immigration was 40 and emigration was 50. The net increase in population is:
- CBSE CLASS XII - 2025
- Biology
- Organisms and Populations
Answer the following questions:
- [(i)] Describe the population growth curve applicable in a population of any species in nature that has unlimited resources at its disposal.
- [(ii)] Explain the equation of this growth curve.
- [(iii)] Name the growth curve and depict a graphical plot for this type of population growth.
- [(i)] Explain the conclusion drawn by Alexander von Humboldt during his extensive explorations in the wilderness of South American jungles.
- [(ii)] Give the equation of the Species-Area relationship.
- [(iii)] Draw a graphical representation of the relation between species richness and area for a wide variety of taxa such as birds, bats, etc.
- CBSE CLASS XII - 2025
- Biology
- Organisms and Populations
Student to attempt either option (A) or (B):
(A) Explain how the interaction between a fig tree and its tight one-to-one relationship with the pollinator species of wasp is one of the best examples of mutualism.
OR
(B) Correctly depict (also indicate the trophic level) and describe the ecological pyramid of number with 32 birds dependent on 20 insects feeding on one banyan tree.- CBSE CLASS XII - 2025
- Biology
- Organisms and Populations
Student to attempt either option (A) or (B):
(A) How is the interaction between Ophrys and its specific bee pollinator one of the best examples of co-evolution? Explain.
OR
(B) Arrange the given important steps of decomposition in their correct order of occurrence in the breakdown of complex organic matter and explain the fourth step in the process.- CBSE CLASS XII - 2025
- Biology
- Organisms and Populations
Questions Asked in CBSE CLASS XII exam
- Analyse the role of Gandhiji after independence of India.
- CBSE CLASS XII - 2025
- Mahatma Gandhi and the Nationalist Movement
A current-carrying coil is placed in an external uniform magnetic field. The coil is free to turn in the magnetic field. What is the net force acting on the coil? Obtain the orientation of the coil in stable equilibrium. Show that in this orientation the flux of the total field (field produced by the loop + external field) through the coil is maximum.
- CBSE CLASS XII - 2025
- Magnetism and matter
- Sudha, Sudama and Sulochna were partners in a firm sharing profits equally. On 31st March, 2020, Sudha retired. On the date of retirement ₹ 2,40,000 became due to her. Sudama and Sulochana agreed to pay Sudha in four equal yearly instalments plus interest @ 10% p.a. on the unpaid balance starting from 31st March, 2021. The firm closes its books on 31st March every year.
Prepare Sudha’s loan account till it is fully paid.- CBSE CLASS XII - 2025
- Retirement and Death of a Partner
- Using integration, find the area of the region bounded by the line \[ y = 5x + 2, \] the \( x \)-axis, and the ordinates \( x = -2 \) and \( x = 2 \).
- CBSE CLASS XII - 2025
- Evaluation of Definite Integrals by Substitution
- Centurian Ltd. invited applications for issuing 2,00,000 equity shares of ₹ 10 each at a premium of ₹ 20 per share. The amount was payable as follows: On Application and Allotment – ₹ 20 per share (including premium ₹ 17 per share)
On First and Final call – ₹ 10 per share (including premium ₹ 3 per share)
Applications were received for 3,00,000 equity shares and allotment was made to the applicants as follows: (i) Applicants for 2,00,000 shares were allotted 1,50,000 shares.
(ii) Applicants for 1,00,000 shares were allotted 50,000 shares.
Excess money received on application and allotment was adjusted towards sums due on first and final call. Deepali, who had applied for 2,000 shares, failed to pay the first and final call money. Her shares were subsequently forfeited. Deepali belonged to Category (i).
Pass necessary journal entries for the above transactions in the Books of Centurian Ltd.
Open Calls-in-Arrears and Calls-in-Advance account, wherever necessary.- CBSE CLASS XII - 2025
- Accounting for Share Capital
Concepts Used:
Population Interactions
Population interaction is generally between two different species populations.“Population interaction is the interaction between different populations. It refers to the effects that the organisms in a community have on one another.”
An ecosystem is a geographic area wherein plants, animals, and many other organisms, alongwith weather and landscape, work together to form a bubble of life.
Types of Population Interactions:
Interactions can be beneficial or neutral or detrimental. Accordingly, there are six types of population interaction.
The different ways populations interact with each other can be summarized under the following headings.
- Competition
- Predation
- Herbivory
- Mutualism
- Commensalism
- Parasitism
- Competition