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:
Show Hint
- 80
- 70
- 10
- 90
The Correct Option is B
Solution and Explanation
= (280 + 40) − (200 + 50)
= 320 − 250
= 70
Top Questions on 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
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- 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
- (a) Draw a graph for a population whose population density has reached the carrying capacity.
(b) Out of the two population growth curves, which one is considered a more realistic for most populations? Why?
(c) Draw a growth curve where resources are not limiting for the growth of a population and give its equation.
- CBSE CLASS XII - 2025
- Biology
- Organisms and Populations
(a) (i) Describe the population growth curve applicable in a population of any species in nature that has limited resources at its disposal.
(ii) Give the equation of this growth curve.
(iii) Name the growth curve and depict a graphical plot for this type of population growth.OR
(b) (i) Explain the Species-Area relationship within a natural forest and also predict the nature of the graph when species richness is plotted against the area for a wide variety of taxa.
(ii) Depict the graphical relationship between species richness and area.
(iii) Give the equation of the Species-Area relationship for a wide variety of taxa on a logarithmic scale.- CBSE CLASS XII - 2025
- Biology
- Organisms and Populations
Questions Asked in CBSE CLASS XII exam
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