CUET UG Biology Booster Test 3-Life Histories and Interactions

This matching exercise aligns standard population ecology variables with their definitions. Carrying capacity (K) is defined by environmental limits; r (intrinsic rate) is the parameter for growth impact; Darwinian fitness is the evolutionary success (high r); and N represents the density of individuals at a specific point in time.

Option B is false because life history strategies are diverse. While many organisms are iteroparous (breed multiple times), others are semelparous (breed once), such as Bamboo and Pacific salmon. Evolution does not force a single "breed many times" strategy on all species; it selects for the most efficient strategy for the specific habitat.

This order follows the specific life history traits described in the NCERT: Bamboo is the exemplar for breeding once; Oysters are the exemplar for high-fecundity/low-investment (many small offspring); Birds are the exemplar for low-fecundity/high-investment (few large offspring).

Statement I correctly identifies birds and mammals as multi-breeders. Statement II is false because it incorrectly implies a necessary trade-off (many/small) for all multi-breeders. Mammals and birds breed many times but produce a small number of large, high-investment offspring.

This strategy is an adaptation to high environmental pressure. In an unstable or high-predation pelagic habitat, producing many small offspring increases the statistical probability that at least a few will survive to reproductive age, thus maximizing fitness despite the high loss rate.

This aligns the strategies with the classic NCERT examples: Pacific Salmon are the example for once-only breeding; Birds are the example for multi-breeding; Oysters represent the r-strategy (many small); Mammals/Birds represent the K-strategy (few large).

Commensalism is defined by a (+, 0) interaction. Neither participant suffers a "detrimental" impact. In contrast, predation, parasitism, and competition all involve a negative outcome for at least one species (the prey, host, or competitor).

This ordering is based on the number of "plus" signs: Mutualism has two, Commensalism has one, and Competition has zero. This logical sequence organizes interactions by the magnitude of positive outcome per species interaction.

Option D is false because the role of predation (including herbivory) is precisely to facilitate the flow of energy to secondary and tertiary consumers. The ecosystem relies on this flow; preventing it would be the exact opposite of the predator's ecological function.

These statements summarize the core role of predators in ecosystem regulation. Exotic invasions are fueled by the lack of top-down control (I), and ecosystem stability is maintained through the control of prey densities (II), preventing habitat degradation from overgrazing or overpopulation.

The passage explicitly states: "Biological control methods adopted in agricultural pest control are based on the ability of the predator to regulate prey population." Option B captures this core principle, explaining that predators are essential tools for suppressing pests to a manageable, stable density.

Correct Answer Explanation The passage clearly attributes the rapid spread to the absence of the species' natural enemy. When a species is introduced to a new range, it often escapes the "top-down" control of its home environment, allowing it to colonize effectively.

Ecological stability requires a balance. If a predator is too efficient (imprudent), it destroys its own foundation (the prey). The inevitable result is the starvation and subsequent extinction of the predator population, reinforcing why natural selection favors moderate, prudent behavior.

Monarchs use a dietary chemical acquired from milkweed plants. Claiming it is synthesized "entirely from its own genome" is a scientifically incorrect interpretation, making it the "NOT" answer.

Evolutionary pressure (natural selection) acts on traits that improve survival. Since plants are stationary, those that mutated to grow thorns were less likely to be eaten. These individuals survived to produce more offspring, effectively "selecting" for the development of physical defenses.

Chemical defenses work by creating a "negative feedback loop" for the herbivore. If the herbivore consumes the plant and experiences sickness or death, it (or its population) learns to avoid the plant, providing a powerful evolutionary defense for the plant species.

The "arms race" describes the constant co-evolution between plant defenses and herbivore adaptations. As insects evolve ways to eat plants, plants evolve new ways to stop them, resulting in the massive biological diversity of defensive chemicals and physical structures we observe today.

This question connects the "human" application to the "ecological" reality. Commercial plant extracts are almost always secondary metabolites that function as chemical defenses in nature. Humans use them because they are biologically potent (toxic/active), which is exactly what makes them effective herbivore deterrents.

This is the principle of competitive exclusion prevention. In the absence of a predator, the strongest prey species can monopolize resources and drive others to extinction. Predators hold these dominant populations down, facilitating the "co-existence" of many species.

This result is the empirical validation of the "Competitive Exclusion Principle" being held in check by predation. When the predator (Pisaster) was gone, the "exclusion" occurred naturally among the prey, resulting in lower diversity.