Class 12 Biology – Organisms and Populations

1. Which of the following correctly represents a population attribute?

A) Photosynthesis B) Natality C) Respiration D) Excretion

2. A population growing in an environment with unlimited resources shows:

A) Logistic growth B) Exponential growth C) Declining growth D) Zero population growth

3. The equation dN/dt = rN represents:

A) Logistic growth B) Population interaction C) Exponential growth D) Carrying capacity

4. Carrying capacity refers to:

A) Maximum birth rate B) Maximum population supported by environment C) Number of predators in ecosystem D) Total immigration rate

5. In logistic growth curve, population growth slows down due to:

A) Unlimited food B) High natality C) Environmental resistance D) Absence of predators

6. Which of the following population interactions benefits both species?

A) Competition B) Predation C) Mutualism D) Amensalism

7. The association between cattle egret and grazing cattle is an example of:

A) Mutualism B) Commensalism C) Predation D) Competition

8. A parasite generally:

A) Kills host immediately B) Benefits host C) Derives nourishment from host D) Competes equally with host

9. Which of the following is an example of amensalism?

A) Orchid on mango tree B) Tiger eating deer C) Penicillium inhibiting bacteria D) Lichen association

10. Population density can be measured by:

A) Number only B) Biomass only C) Percentage cover only D) All of these

11. Which factor does NOT directly decrease population density?

A) Mortality B) Emigration C) Natality D) Predation

12. Age pyramid with broad base indicates:

A) Declining population B) Stable population C) Expanding population D) Zero growth population

13. Which organism is correctly matched with its adaptation?

A) Kangaroo rat – excretes dilute urine B) Desert plants – sunken stomata C) Polar bear – less body fat D) Frogs – uricotelic

14. Gause’s Competitive Exclusion Principle states that:

A) Two species can indefinitely occupy same niche B) Predators eliminate all prey C) Competition has no ecological role D) Two closely related species competing for same resources cannot coexist permanently

15. The sigmoid growth curve is represented by:

A) J-shaped curve B) S-shaped curve C) Circular curve D) Straight line