All questions of Organisms and Populations for NEET Exam

Answer is c) logistic

Commensalism is a type of symbiotic relationship where one species benefits from the association, while the other is neither harmed nor helped. In this type of association, one species derives benefits from the other without causing any harm to the host.

Explanation:

In the given scenario, the small fish gets stuck near the bottom of a shark and derives its nutrition from it. The small fish is not harming the shark, nor is it providing any benefits to the shark. Therefore, this is an example of commensalism.

The small fish is using the shark as a shelter and also gets access to food particles that are present near the shark's mouth. The shark is not affected by the presence of the small fish, and it does not derive any benefit from it either.

In summary, commensalism is a type of symbiotic relationship where one species benefits from the association, while the other is neither harmed nor helped. The small fish getting stuck near the bottom of a shark and deriving its nutrition from it is an example of commensalism.

Logarithmic or Exponential phase : It is characterized by rapid growth in population which continues till enough food is available. But with the increase in reindeer population, there is corresponding decrease in the availability of food and space, which finally become exhausted, which leads to mass starvation and mortality. This sudden increase in mortality is called population crash. Lemming of Tundra, some insect, algal blooms and annual plants also show J-shaped curves. The population growth curve is S- shaped in most of the organisms, Human population also shows S-shaped curve.

Understanding Population Growth Dynamics
Population dynamics is a crucial field of study in ecology, focusing on how populations change over time. Let's evaluate the given statements:
1. Exponential Growth and Resource Limitations
- Incorrect Statement: Exponential growth occurs when resources are abundant, allowing populations to grow rapidly without constraints. It does not occur only when resources are limited.
2. Logistic Growth and Carrying Capacity
- Correct Statement: Logistic growth is characterized by a sigmoid curve, which illustrates how a population grows rapidly at first, then slows as it approaches the carrying capacity of the environment. This model effectively integrates the concept of environmental limitations.
3. Factors Influencing Population Size
- Correct Statement: Natality (birth rate), mortality (death rate), immigration (movement into a population), and emigration (movement out of a population) are indeed the primary factors that influence population size, making this statement accurate.
4. Intrinsic Rate of Natural Increase (r)
- Incorrect Statement: The intrinsic rate of natural increase (r) is not constant; it can vary based on environmental conditions, resource availability, and other ecological factors.
Conclusion
Based on the evaluation:
- Statements 2 and 3 are correct, while statements 1 and 4 are incorrect. Thus, the correct answer is option B: "Statements 2 and 3 are correct."
Understanding these principles is essential for grasping how populations grow and interact with their environments, which is a key aspect of ecological studies in NEET.

No,It would be amensalism only when one population is being harmed by other population unconditionally means there is no intention of the population to harm the other population but it occurs due to release of some toxic substances by the population which harms the other population unintentionally and the population releasing toxic substances remains unharmed. but Accord to your question ans can also be predation and parasitism.

Understanding Carnivore Population Dynamics
The growth of a carnivore population is closely linked to the availability of their prey, primarily herbivores. Here’s a detailed explanation of why the correct answer is option 'D'—the increase in the population of herbivores.
Relationship Between Carnivores and Herbivores
- Carnivores are animals that primarily consume other animals (herbivores or other carnivores).
- The population of carnivores is dependent on the availability of herbivores as a food source.
Impact of Herbivore Population on Carnivores
- An increase in herbivore population means more food availability for carnivores.
- With sufficient food sources, carnivores can reproduce more successfully and increase their population size.
Ecological Balance
- Herbivores play a crucial role in maintaining the balance of ecosystems.
- When herbivore populations thrive, it can lead to an increase in carnivore numbers, as they have ample resources to sustain themselves.
Other Options Explained
- a) Decrease in Grass Availability: This would negatively impact herbivores, leading to a decline in their population, which would, in turn, affect carnivores negatively.
- b) Increase in Omnivores: While omnivores may compete with carnivores for food, their population growth does not directly enhance carnivore numbers.
- c) Increase in Scavengers: Scavengers primarily feed on dead animals and do not significantly impact the population dynamics of living carnivores.
In conclusion, the growth of a carnivore population is intricately linked to the availability of herbivores, making option 'D' the correct answer.

Mortality no. of death in the population and emigration means no. of individuals left the habitat and gone at another place. so both will decrease no. of individuals in population hence decreasing population density

Exponential Growth Phase

When the number of immigration and births is more than emigration and deaths, the growth curve of the population will show an exponential phase. This means that the population will experience rapid and continuous growth over time.

Key Points:
- Immigration refers to the movement of individuals from one country to another for the purpose of permanently residing there.
- Births refer to the number of individuals being born within a population.
- Emigration refers to the movement of individuals out of a country to permanently reside in another.
- Deaths refer to the number of individuals dying within a population.

Explanation:
When the number of immigration and births exceeds the number of emigration and deaths, the population experiences a positive net migration rate and a positive natural increase rate. This leads to an increase in the total population size, which is reflected in an exponential growth phase on the population growth curve.

During the exponential phase, the population grows at an accelerating rate. This occurs because the number of individuals being added to the population through immigration and births is greater than the number of individuals being lost through emigration and deaths. As a result, the population size increases rapidly, leading to a steep upward curve on the growth graph.

The exponential growth phase is characterized by a doubling of the population size within a relatively short period of time. This is due to the compounding effect of population growth, where the larger the population becomes, the more individuals are available for reproduction and immigration, leading to even faster growth rates.

This phase can continue until certain limiting factors, such as resource availability or environmental constraints, begin to exert pressure on the population. At this point, the growth may start to slow down and eventually reach a steady phase or enter a declining phase if the limiting factors become severe enough.

In summary, when immigration and births outnumber emigration and deaths, the population undergoes exponential growth, leading to a rapid increase in population size over time.