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100 questions in this collection · Page 5 of 10
Question 41 of 100
📘 CLASS XII
Organisms And Populations
Read the following statements about Gause's Competitive Exclusion Principle:
I. It states that two closely related species competing for the same resources cannot co-exist indefinitely, and the competitively inferior one will be eliminated eventually. II. This principle holds true in nature whether resources are limiting or completely unlimited. III. More recent ecological studies do not support gross generalizations about competitive exclusion. IV. Species facing competition may evolve mechanisms that promote co-existence rather than exclusion.
Which of the statements given above are correct?
Statements I, III, and IV are correct. Statement II is incorrect because Gause's Competitive Exclusion Principle applies only when resources are limiting.
Question 42 of 100
📘 CLASS XII
Organisms And Populations
Consider the following statements regarding mechanisms of species co-existence:
I. Species facing competition can avoid exclusion by evolving mechanisms that promote co-existence. II. Resource partitioning allows competing species to avoid competition by choosing different feeding times or different foraging patterns. III. MacArthur showed that five closely related species of warblers were able to co-exist on the same tree. IV. The co-existence of the five warbler species was due to behavioral differences in their foraging activities.
Which of the statements given above are correct?
All statements are correct. MacArthur's classic study demonstrated that behavioral differences in foraging enabled closely related warbler species to partition resources and coexist.
Question 43 of 100
📘 CLASS XII
Organisms And Populations
Read the following statements regarding the evolutionary adaptations of parasites:
I. Parasitism has evolved in a vast array of taxonomic groups, spanning from plants to higher vertebrates. II. Many parasites are host-specific, meaning they can parasitize only a single species of host. III. Both host and parasite tend to co-evolve, with hosts developing resistance mechanisms and parasites developing counter-mechanisms to bypass them. IV. Adaptations in parasites commonly include the loss of unnecessary sense organs, presence of adhesive organs or suckers, loss of digestive system, and high reproductive capacity.
Which of the statements given above are correct?
All four statements are correct and accurately describe the distribution, host specificity, co-evolution, and structural and physiological adaptations of parasites.
Question 44 of 100
📘 CLASS XII
Organisms And Populations
Consider the following statements regarding parasite life cycles and vectors:
I. Parasites have evolved to have highly advanced, complex internal digestive systems to cope with host tissue digestion. II. The life cycles of parasites are often complex, involving one or two intermediate hosts or vectors to facilitate transmission to the primary host. III. The human liver fluke (a trematode parasite) depends on two intermediate hosts—a snail and a fish—to complete its life cycle. IV. The malarial parasite requires a vector (mosquito) to spread to other hosts.
Which of the statements given above are correct?
Statements II, III, and IV are correct. Statement I is incorrect because parasites have undergone loss of the digestive system as they absorb pre-digested nutrients directly from the host.
Question 45 of 100
📘 CLASS XII
Organisms And Populations
Read the following statements regarding host-parasite dynamics:
I. The majority of parasites harm their host by reducing the host's survival, growth, and reproduction. II. Parasites can lead to a significant reduction in host population density. III. Parasites can render the host more vulnerable to predation by making it physically weak. IV. Natural selection has successfully driven the evolution of totally harmless parasites that absorb nutrients without putting any stress on the host.
Which of the statements given above are correct?
Statements I, II, and III are correct. Statement IV is incorrect because parasites invariably impose some cost on their hosts by reducing survival, growth, or reproductive fitness.
Question 46 of 100
📘 CLASS XII
Organisms And Populations
Consider the following statements regarding ectoparasites:
I. Ectoparasites are parasites that feed on the external surface of the host organism. II. Ticks on dogs and lice on humans are classic examples of ectoparasites. III. Many marine fish are infested with ectoparasitic copepods. IV. Cuscuta is an ectoparasitic plant commonly found growing on hedge plants, having lost its chlorophyll and leaves during evolution.
Which of the statements given above are correct?
All statements are correct. Ectoparasites live on the external surface of the host. Examples include lice, ticks, marine copepods, and the parasitic plant Cuscuta.
Question 47 of 100
📘 CLASS XII
Organisms And Populations
Read the following statements regarding parasitic classification:
I. The female mosquito is considered a parasite because it feeds on human blood to nourish its developing eggs. II. Endoparasites live inside the host's body at sites like the liver, kidney, lungs, or red blood cells. III. The life cycles of endoparasites are more complex because of their extreme specialization. IV. Morphological and anatomical features of endoparasites are greatly simplified while emphasizing their reproductive potential.
Which of the statements given above are correct?
Statements II, III, and IV are correct. Statement I is incorrect because the female mosquito is not regarded as a parasite despite requiring a blood meal for egg development.
Question 48 of 100
📘 CLASS XII
Organisms And Populations
Consider the following statements regarding brood parasitism in birds:
I. Brood parasitism is an interaction where a parasitic bird lays its eggs in the host's nest and lets the host incubate them. II. The cuckoo (koel) and the crow exhibit brood parasitism during their breeding season. III. During evolution, the eggs of parasitic birds have evolved to resemble the host's eggs in size and color. IV. This evolutionary resemblance reduces the chances of the host bird detecting the foreign eggs and ejecting them from the nest.
Which of the statements given above are correct?
All statements are correct. Brood parasites such as the koel lay eggs in crow nests, and their eggs mimic the host's eggs to reduce rejection.
Question 49 of 100
📘 CLASS XII
Organisms And Populations
Read the following statements regarding commensal interactions (+, 0):
I. Commensalism is an interaction in which one species benefits and the other is neither harmed nor benefited. II. An orchid growing as an epiphyte on a mango branch is a commensal relationship. III. Barnacles growing on the back of a whale benefit from movement and feeding opportunities, while the whale is unaffected. IV. The mango tree branch and the whale derive significant metabolic nutrients from their commensal partners.
Which of the statements given above are correct?
Statements I, II, and III are correct. Statement IV is incorrect because the host in commensalism neither benefits nor is harmed.
Question 50 of 100
📘 CLASS XII
Organisms And Populations
Consider the following statements regarding further examples of commensalism:
I. Cattle egrets forage close to grazing cattle because the cattle flush out insects from the vegetation that are otherwise hard to find. II. This association between egrets and cattle is a classic example of commensalism. III. The association between sea anemone (with stinging tentacles) and clown fish protects the fish from predators, while the anemone is unaffected. IV. The clown fish provides metabolic sugars directly to the sea anemone, making this interaction a tight mutualistic relationship.
Which of the statements given above are correct?
Statements I, II, and III are correct. Statement IV is incorrect because the sea anemone derives no apparent benefit from the clown fish; therefore the interaction is commensalism, not mutualism.