Organism and Population Class 12 NEET MCQs

1. Which term describes the role and position of an organism in its ecosystem?

a) Habitat
b) Niche
c) Community
d) Population

Answer:

b) Niche

Explanation:

A niche refers to the role and position an organism has in its environment.

2. Which of the following best defines “population density”?

a) Total number of individuals of a species in an area
b) Number of species in a given area
c) Number of individuals of a species per unit area or volume
d) Total number of species in an ecosystem

Answer:

c) Number of individuals of a species per unit area or volume

Explanation:

Population density gives a measure of the number of organisms in a specified space.

3. In which type of population dispersion do individuals maintain a certain distance from each other?

a) Random dispersion
b) Clumped dispersion
c) Uniform dispersion
d) Clustered dispersion

Answer:

c) Uniform dispersion

Explanation:

In uniform dispersion, individuals are evenly distributed and maintain a certain distance from each other.

4. Which type of interaction is beneficial for both species involved?

a) Commensalism
b) Mutualism
c) Parasitism
d) Competition

Answer:

b) Mutualism

Explanation:

In mutualism, both species involved derive benefits from the interaction.

5. Which of the following factors affects the life history variation in organisms?

a) Predation
b) Competition
c) Disturbance
d) All of the above

Answer:

d) All of the above

Explanation:

Life history traits of an organism can be influenced by various ecological factors, including predation, competition, and disturbance.

6. What is the primary factor for an organism’s ecological success in an aquatic environment?

a) Reproduction rate
b) Longevity
c) Buoyancy
d) Speed

Answer:

c) Buoyancy

Explanation:

In aquatic environments, buoyancy determines the ability of an organism to remain suspended in water.

7. What term describes a group of individuals of the same species living in a particular geographic area?

a) Community
b) Ecosystem
c) Population
d) Habitat

Answer:

c) Population

Explanation:

A population comprises individuals of the same species living in a specific area.

8. Which pattern of population growth is represented by the equation

a) Exponential growth
b) Logistic growth
c) Oscillatory growth
d) Deceleration growth

Answer:

a) Exponential growth

Explanation:

The equation represents a population’s exponential growth, where N is population size, r is intrinsic growth rate, and

9. Which factor is NOT density-dependent in population regulation?

a) Disease
b) Food
c) Weather conditions
d) Predation

Answer:

c) Weather conditions

Explanation:

Weather conditions are density-independent factors, meaning they affect population size regardless of the population’s density.

10. Which organism shows a K-strategy of reproduction?

a) Bacteria
b) Algae
c) Humans
d) Insects

Answer:

c) Humans

Explanation:

K-strategists like humans have fewer offspring, provide parental care, and have longer life spans.

11. Which of the following is NOT an abiotic component of the habitat?

a) Soil
b) Temperature
c) Light
d) Bacteria

Answer:

d) Bacteria

Explanation:

Bacteria are biotic components as they are living organisms.

12. Which curve represents the growth of a population when resources are unlimited?

a) J-shaped curve
b) S-shaped curve
c) Zigzag curve
d) U-shaped curve

Answer:

a) J-shaped curve

Explanation:

A J-shaped curve represents exponential growth, which occurs when resources are unlimited.

13. Which term describes the maximum number of individuals that an environment can support indefinitely?

a) Carrying capacity
b) Biotic potential
c) Ecological footprint
d) Niche

Answer:

a) Carrying capacity

Explanation:

Carrying capacity refers to the maximum population size that an environment can support over time without degradation.

14. Which of the following is a density-independent factor affecting population size?

a) Competition
b) Food availability
c) Natural disasters
d) Disease

Answer:

c) Natural disasters

Explanation:

Natural disasters affect populations regardless of their density and are thus density-independent.

15. Which animal is capable of obtaining water by oxidation of lipid?

a) Rat
b) Earthworm
c) Mole
d) Kangaroo rat

Answer:

d) Kangaroo rat

Explanation:

The Kangaroo rat is adapted to desert life and can obtain water through the oxidation of fats present in the seeds it consumes.

16. Which is the example of intraspecific competition for food?

a) Barnacle on rocks of the submerged water
b) Two female dogs and two male dogs
c) Various types of lichens
d) Paramaecium caudatuns and P. aurelia in the laboratory.

Answer:

b) Two female dogs and two male dogs

Explanation:

Intraspecific competition refers to competition among members of the same species. Here, two female dogs and two male dogs represent individuals of the same species competing for the same resource.

17. Name the animals with freshwater habit in which:

a) Freshwater fishes
b) Ophiocephalus
c) Crustacean Astacus
d) None of these

Answer:

c) Crustacean Astacus

Explanation:

Crustaceans like Astacus (crayfish) have green glands that function in excretion and osmoregulation, removing excess water in the form of dilute urine.

18. In snakes, realized (actual) natality is less than potential natality because…

a) All the eggs are not incubated.
b) Environmental boomrang (resistance).
c) Though eggs are incubated they do not reach up to the adult stage.
d) All of these.

Answer:

d) All of these.

Explanation:

Realized natality refers to the number of offspring that actually survive and reach reproductive age. For snakes, various factors like non-incubation of eggs, environmental resistances, and high mortality rates among juveniles contribute to the difference between potential and realized natality.

19. From the given option which is the appropriate for ecto parasite animal Ascaris, Tapeworm, Plasmodium, mites?

a) Phytoplanktons
b) Mesofauna
c) Macrofauna
d) Phytoplanktons and mesofauna.

Answer:

b) Mesofauna

Explanation:

Mesofauna refers to small animals, including arthropods and nematodes, which live in the soil. Among the given options, mites would fit the category of mesofauna and are ectoparasites.

20. Which living organism is seen in the hot water spring having temperature more than 100°C?

a) Methanogens
b) Thermoacidophils
c) Helophytes
d) Spirokit

Answer:

b) Thermoacidophils

Explanation:

Thermoacidophils are extremophiles that thrive in extremely hot, acidic environments such as hot springs with temperatures exceeding 100°C.

21. What is the vital index, if Birth rate is 0 and Death rate = 5?

a) 0
b) 100
c) 1
d) None of these

Answer:

a) 0

Explanation:

The Vital Index is calculated as (Birth rate/Death rate) x 100. If the birth rate is 0, the Vital Index will be 0, regardless of the death rate.

22. If the Birth rate is 10 and death rate is 0 then what is VITAL INDEX?

a) 0
b) 100
c) Infinite
d) 1

Answer:

c) Infinite

Explanation:

The Vital Index is calculated as (Birth rate/Death rate) x 100. If the death rate is 0, the Vital Index becomes infinite because division by zero is undefined in mathematics.

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