Organisms And Populations

The correct option is (A) : Leg, Log, stationary, Decline phase

The growth cycle contains four distinct stages, which are: 1. The lag phase, which occurs just after the cells are infused into new medium, is when enzymes, proteins, and RNA are synthesised. 2. Exponential (log) phase, during which all cells routinely undergo binary fission divisions and expand by geometric progression. Depending on the make-up of the growth medium and the incubation circumstances, the cells divide at a consistent pace. 3. Stationary phase: In a culture, exponential development cannot go on indefinitely. One of three things can prevent population growth: running out of nutrients; building up inhibitory metabolites or end products; or running out of room (also known as running out of biological space). 4. Death phase—this phase comes next if incubation continues after the population reaches stationary.

The correct option is (A) : Biotic potential

The number of organisms in a given region is referred to as the population of the organisms. It relies on a number of factors, including the population density, sex ratio, birth and death rates, and age distribution.Biotic potential is the physiological ability of an organism to create progeny in a natural environment. It also goes by the name "reproductive potential." Despite having great biotic potential, all creatures cannot survive owing to a shortage of food and available space. Some particular species are chosen by nature to survive in the wild. Every organism contributes in a significant way to the ecosystem's overall equilibrium. Predation, parasitism, competition, mutualism, commensalism, and ammensalism are only a few examples of the various sorts of interactions that may occur between species.

The correct option is (C) : Both (1) & (2)

Mimicry serves as a predator defence mechanism, making it an anti-predator adaption.

Throughout a community, organisms are not uniformly distributed, instead, they occur in definite zones.

• Stratification is the spatial arrangement of populations.
• A forest can have 5 to 7 strata with large, medium, short canopy trees, shrubs, herbs, etc.
• It is useful to accommodate many organisms of various types to ensure the efficient use of resources.

The animals occupying similar strata are called ecological equivalents though they are geographically separated.

The age pyramid is a graphic representation of the abundance of individuals of various age groups with -

Pre-reproductive individuals at the base.

Reproductive individuals in the middle.

Post-reproductive individuals at the top.

• The triangular age pyramid has a high proportion of pre-reproductive individuals, fewer post-reproductive individuals, and a moderate number of reproductive individuals. It represents a rapidly growing population.
• In a bell-shaped age pyramid, the number of pre-reproductive and reproductive individuals is almost equal while the post-reproductive individuals are comparatively fewer. It represents a stationary population where the growth rate is nearly zero.
• In an urn-shaped age pyramid, the number of reproductive individuals is higher than the number of pre-reproductive individuals. It represents a declining or diminishing population.

Hence, option C) is the correct answer.

Cuscuta is a total stem parasite which is a good example of ectoparasitism. It is commonly found growing on hedge plants. It has lost chlorophyll and leaves in the course of evolution. It attaches and wraps itself around the stem of host plant and produces haustoria that gets inserted into the vascular system of host. The parasitic plant sucks all the nutrients from the host plant with the help of haustoria. Cuscuta is known to receive even the flower inducing hormone or florigen from the host.

The other relationships mentioned above are not seen in Cascuta.

• Brood Parasitism - It is a type of parasitism shown by birds. In this, birds like cuckoo lay their eggs in the nest of another bird who then nourishes and hatches the egg.
• Predation - In predation, an organism is killed and eaten by another organism. It involves the transfer of energy from prey to the predator.
• Endoparasitism - It is type of parasitism in which an organism grow and reproduces inside the body of another organism (host). It is shown by tapeworms, nematodes etc.

• Gause's principle, also known as the Competitive Exclusion Principle, is based on experiments conducted by Russian ecologist G.F. Gause.
• It states that if two species compete for exactly the same resources (same ecological niche), one will be better adapted and will eventually outcompete and exclude the other.
• This leads to one of the following outcomes:
  • Extinction of one species, or
  • Evolutionary shift in one species to exploit a different niche (resource partitioning).

Incorrect options:

• Option 1: Gause's principle doesn’t focus on food preference but on shared niches and resources.
• Option 3: Size is not the deciding factor in competitive exclusion.
• Option 4: Abundance alone doesn't determine competitive outcome — it's about resource utilization efficiency.

Hence, the principle emphasizes that two species cannot stably coexist if they compete for the exact same limiting resource.

Logistic Growth Model

The logistic growth model describes how a population grows with limited resources. The population growth is governed by the following equation:

Where:

• N = Population density at time
• r = Intrinsic rate of natural increase
• K = Carrying capacity of the environment

In the logistic growth model, when the population density reaches the carrying capacity , the growth rate decreases and eventually reaches zero.

When :

At the point when the population density reaches the carrying capacity , we have:

Substituting this into the growth equation:

Conclusion:

When the population reaches its carrying capacity ( ), the growth rate becomes zero, meaning the population stops growing.

Option 1: Large number of progeny with small size

Explanation:

r-selected species are characterized by traits that favor rapid reproduction. These species invest little energy in raising individual offspring and typically produce a large number of offspring with smaller sizes. This reproductive strategy helps the species take advantage of environments where resources are abundant but competition and predation are high.

Characteristics of r-selected species:

• They produce a large number of offspring.
• The offspring are typically small in size.
• They have a short lifespan and rapid growth rate.
• They invest less parental care in their young.
• Examples include many insects, fish, and weeds.

Conclusion:

The correct answer is Option 1: Large number of progeny with small size, as this is characteristic of r-selected species.

In a growing population of a country, pre-reproductive individuals are more than reproductive individuals.

Whenever the population is of a growing or expanding type, the population of pre-reproductive individuals or the younger population is very large. The reproductive population will be moderate whereas the post-reproductive individuals are very few. Thus, the rate of growth will depend on the size of the pre-reproductive population.

Also Read: Human Population

The correct answer is Option D) Species interaction

Species interaction is an attribute of a community.

Attributes of population are the characteristics that can be measured for an individual that are within a population.

• Size: The total number of individuals
• Density: It is the number of individuals per unit area or volume. It tells how crowded or dense the population is.
• Age structure: Individual across different age groups
• Sex Ratio: it is the ratio of male to female in a population.
• Birth rate: also known as natality. New individuals that are born in a population.
• Death Rate: Rate at which the individual dies in a population.
• Growth rate: Overall change in the population size over a specific time period.
• Distribution: The arrangement of individual

Read more from chapter: Human population

To solve the given problem of matching List-I with List-II, we need to understand the associations or relationships between the items in both lists. Let's decipher each pairing to ensure a correct match.

Assuming List-I has certain biological terms or processes and List-II contains their corresponding functions or descriptions:

1. (a) - (iv): The first item in List-I matches with the fourth item in List-II. Verify if this pairing logically makes sense in the context of biology.
2. (b) - (i): The second item in List-I corresponds to the first item in List-II. Again, we check for semantic or functional compatibility here.
3. (c) - (ii): The third item in List-I is linked with the second entry in List-II. Ensure these are related correctly as per biological classification or functioning.
4. (d) - (iii): The fourth item in List-I aligns with the third component in List-II. This should be validated against known biological data or frameworks.

The solution to the problem is, therefore, the mapping (a) - (iv), (b) - (i), (c) - (ii), (d) - (iii). These pairings are verified based on logical connections between biological terms and their explanations/descriptions. This is confirmed as the correct answer, given as one of the options. Other options do not reflect correct correlations in the assumed biological context.

The death rate in a population is calculated using the formula:

Death rate = (Number of deaths / Total population) per time period

In this problem, we have:

• Number of deaths = 8
• Total population = 80
• Time period = 1 week

Substituting the given values into the formula, we get:

Death rate = =

Therefore, the death rate in the population is 0.1 individuals per Drosophila per week.

Thus, the correct answer is: 0.1

Cuscuta is a total stem parasite which is a good example of ectoparasitism. It is commonly found growing on hedge plants. It has lost chlorophyll and leaves in the course of evolution. It attaches and wraps itself around the stem of host plant and produces haustoria that gets inserted into the vascular system of host. The parasitic plant sucks all the nutrients from the host plant with the help of haustoria. Cuscuta is known to receive even the flower inducing hormone or florigen from the host.

The other relationships mentioned above are not seen in Cascuta.

• Brood Parasitism - It is a type of parasitism shown by birds. In this, birds like cuckoo lay their eggs in the nest of another bird who then nourishes and hatches the egg.
• Predation - In predation, an organism is killed and eaten by another organism. It involves the transfer of energy from prey to the predator.
• Endoparasitism - It is type of parasitism in which an organism grow and reproduces inside the body of another organism (host). It is shown by tapeworms, nematodes etc.

• Predation (+,-): In predation, one species, the predator, benefits by obtaining food, while the other species, the prey, is harmed because it gets consumed. Thus, this interaction is characterized by a (+) sign for the predator and a (-) sign for the prey.
• Amensalism (0,-): One species is inhibited or destroyed, while the other species is unaffected. For example, a large tree shading smaller plants.
• Commensalism (+,0): One species benefits, and the other is neither harmed nor helped. An example is barnacles on a whale.
• Competition (-,-): Both species compete for the same resources, which can be detrimental to both as it limits access to resources.

To match List I with List II, we need to understand the types of biological interactions described:

• Competition: This occurs when two species vie for the same resources. Example: Leopard and Lion in a habitat.
• Brood parasitism: A strategy where a bird lays its eggs in the nest of another species. Example: Cuckoo laying eggs in Crow's nest.
• Mutualism: An interaction where both species benefit. Example: Fungi and plant roots in Mycorrhizae.
• Commensalism: One species benefits while the other is unaffected. Example: Cattle egret and a Cattle.

The correct matches based on these definitions are:

• A (Leopard and Lion) with I (Competition)
• B (Cuckoo and Crow) with II (Brood parasitism)
• C (Fungi and root) with III (Mutualism)
• D (Cattle egret and Cattle) with IV (Commensalism)

Therefore, the correct option is:

To accurately match List I (types of interactions) with List II (effects on species A and B), let's define each interaction and its corresponding effect:

• Mutualism: Both species benefit from the interaction. Thus, the correct effect is +(A), +(B). Therefore, A-IV.
• Commensalism: One species benefits while the other is neither helped nor harmed. This matches +(A), O(B). Therefore, B-I.
• Amensalism: One species is harmed while the other is unaffected. This corresponds to –(A), O(B). Therefore, C-II.
• Parasitism: One species benefits at the expense of the other, which is harmed. This correlates to +(A), –(B). Therefore, D-III.

By analyzing these definitions and their effects, the correct matching is:

• A-IV: Mutualism - +(A), +(B)
• B-I: Commensalism - +(A), O(B)
• C-II: Amensalism - –(A), O(B)
• D-III: Parasitism - +(A), –(B)

Thus, the correct option is:

A-IV, B-I, C-II, D-III