Answers and bookmarks are saved in this browser, across visits. They do not sync to your account.
100 questions in this collection · Page 7 of 10
Question 61 of 100
📘 CLASS XII
Organisms And Populations
Consider the following statements regarding the extinction of the Abingdon tortoise:
I. The Abingdon tortoise became extinct on the Galapagos Islands within a decade after goats were introduced. II. The primary cause of extinction was direct predation on tortoise hatchlings by the goats. III. Goats outcompeted the tortoises due to their significantly greater browsing efficiency. IV. This event represents a classic real-world example of competitive exclusion in nature.
Which of the statements given above are correct?
Statements I, III, and IV are correct. The Abingdon tortoise disappeared because introduced goats were much more efficient browsers and depleted available vegetation. Statement II is incorrect because goats are herbivores and did not prey upon tortoise hatchlings.
Question 62 of 100
📘 CLASS XII
Organisms And Populations
Read the following statements regarding Gause's Competitive Exclusion Principle:
I. It states that two closely related species competing for the identical resources cannot co-exist indefinitely. II. The principle assumes that the competitively inferior species will eventually be eliminated unless it adapts. III. More recent ecological findings support the idea that species in nature almost always undergo competitive exclusion rather than co-existence. IV. Gause's principle is highly accurate when resources are unlimited, but fails when resources are limiting.
Which of the statements given above are correct?
Statements I and II are correct. Recent ecological studies emphasize mechanisms such as resource partitioning that promote coexistence, making statement III incorrect. Statement IV is also incorrect because Gause's principle applies under conditions of limiting resources, not unlimited resources.
Question 63 of 100
📘 CLASS XII
Organisms And Populations
Consider the following statements regarding the behavior of the cuckoo (koel) and the crow:
I. Brood parasitism in these birds occurs during the breeding season from spring to summer. II. The parasitic koel builds a temporary nest next to the crow's nest to monitor the eggs. III. The eggs of the parasitic bird have evolved to mimic the host's eggs in size and color to reduce the chances of detection. IV. The host crow incubates and raises the koel's chicks alongside or in place of its own.
Which of the statements given above are correct?
Statements I, III, and IV are correct. Brood parasitism between the koel and crow occurs during the breeding season, and the koel lays mimetic eggs directly in the crow's nest. Statement II is incorrect because the koel does not construct any nest of its own.
Question 64 of 100
📘 CLASS XII
Organisms And Populations
Read the following statements regarding the parasitic plant Cuscuta:
I. Cuscuta is an ectoparasitic plant commonly found growing on hedge plants. II. It has completely lost its leaves and chlorophyll during the course of evolution. III. It derives its nutrition from the host plant by developing specialized roots called haustoria that tap into host tissues. IV. Since it is a plant, it produces its own organic food via photosynthesis but relies on the host strictly for water and minerals.
Which of the statements given above are correct?
Statements I, II, and III are correct. Cuscuta is a non-photosynthetic ectoparasitic plant that has lost chlorophyll and leaves and obtains water, minerals, and food through haustoria. Statement IV is incorrect because it cannot photosynthesize.
Question 65 of 100
📘 CLASS XII
Organisms And Populations
Consider the following statements regarding the human liver fluke:
I. The human liver fluke is a trematode parasite. II. It has an extremely simple life cycle that is completed entirely within the human host without any vector. III. It depends on two intermediate hosts, a snail and a fish, to complete its life cycle. IV. The intermediate hosts serve to facilitate the transmission of the parasite to its primary human host.
Which of the statements given above are correct?
Statements I, III, and IV are correct. The human liver fluke is a trematode with a complex life cycle involving a snail and a fish before reaching humans. Statement II is incorrect because its life cycle is not simple and is not completed entirely within humans.
Question 66 of 100
📘 CLASS XII
Organisms And Populations
Refer to the following matrix of interspecific interactions:
I. Competition is represented as (-, -) because both species suffer. II. Amensalism is represented as (-, 0) because one species is harmed while the other is unaffected. III. Commensalism is represented as (+, 0) because one species benefits and the other is unaffected. IV. Parasitism and Predation are both represented as (+, -) because one species benefits at the expense of the other.
Which of the statements given above are correct?
All four statements are correct. Competition (-,-), amensalism (-,0), commensalism (+,0), and parasitism/predation (+,-) represent the standard ecological interaction categories.
Question 67 of 100
📘 CLASS XII
Organisms And Populations
Read the following statements regarding the association between clown fish and sea anemones:
I. The clown fish lives among the stinging tentacles of the sea anemone. II. The stinging tentacles protect the clown fish from its predators, which avoid the anemone. III. The sea anemone derives substantial metabolic sugars from the clown fish, making this a mutualistic relationship. IV. This interaction is classified as commensalism because the fish benefits, while the anemone is neither benefited nor harmed.
Which of the statements given above are correct?
Statements I, II, and IV are correct. The clown fish gains protection from predators among the anemone's tentacles. Statement III is incorrect because the anemone receives no apparent benefit, making the interaction commensalism rather than mutualism.
Question 68 of 100
📘 CLASS XII
Organisms And Populations
Consider the following statements regarding human population age pyramids:
I. The age pyramid displays the percentage of males and females across pre-reproductive, reproductive, and post-reproductive age groups. II. A pyramid with a very narrow pre-reproductive base and a broad reproductive middle represents a rapidly growing population. III. A stable population shows a bell-shaped distribution where the pre-reproductive and reproductive age groups are almost equal. IV. A declining population features an urn-shaped pyramid with fewer pre-reproductive individuals than reproductive individuals.
Which of the statements given above are correct?
Statements I, III, and IV are correct. A rapidly growing population has a broad pre-reproductive base. Statement II is incorrect because a narrow base indicates a declining population.
Question 69 of 100
📘 CLASS XII
Organisms And Populations
Read the following statements regarding carrying capacity (K):
I. The carrying capacity (K) is the absolute maximum number of individuals of a species that a given habitat can support indefinitely. II. Carrying capacity is a fixed, unchanging value for a habitat and does not vary even if environmental resources change. III. When a population exceeds its carrying capacity (N > K), the growth rate dN/dt becomes negative, driving the population size back down. IV. Resource limitation is the fundamental biological cause of the carrying capacity.
Which of the statements given above are correct?
Statements I, III, and IV are correct. Carrying capacity depends on available resources and may change with environmental conditions. Statement II is incorrect because K is not a permanently fixed value.
Question 70 of 100
📘 CLASS XII
Organisms And Populations
Consider the following statements regarding exponential growth:
I. Under unlimited resource conditions, the population growth rate is directly proportional to the population size (dN/dt = rN). II. Any species growing exponentially can reach enormous population densities in a short time in the absence of limiting factors. III. Darwin showed that even a slow-growing animal like the elephant could reach enormous numbers if it grew exponentially without check. IV. Real-world populations can maintain exponential growth indefinitely as long as they have a high intrinsic rate of natural increase (r).
Which of the statements given above are correct?
Statements I, II, and III are correct. Unlimited resources permit exponential growth, and Darwin used the elephant as an illustration. Statement IV is incorrect because unlimited exponential growth cannot continue indefinitely under natural conditions due to resource limitation.