Assertion (A): A person goes to high altitude and experiences 'altitude sickness' with symptoms like breathing difficulty and heart palpitations. Reason (R): Due to low atmospheric pressure at high altitude, the body does not get sufficient oxygen.
In the light of the above statements, choose the
correct answer from the options given below.
(I)Symbiotic association of fungi with plant roots
(B)Parasite
(II)Decomposition of dead organic materials
(C)Lichens
(III)Living on living plants or animals
(D)Mycorrhiza
(IV)Symbiotic association of algae and fungi
Choose the correct answer from the options given
below:
Explanation:
Correct match: A-Saprophyte ↔ II-Decomposition of dead organic materials; B-Parasite ↔ III-Living on living plants or animals; C-Lichens ↔ IV-Symbiotic association of algae and fungi; D-Mycorrhiza ↔ I-Symbiotic association of fungi with plant roots. So the pairings are (A)-(II), (B)-(III), (C)-(IV), (D)-(I), i.e., option 4. This follows NCERT definitions: saprophytes decompose dead matter; parasites live on hosts; lichens are a fungus-alga mutualism; mycorrhiza is a fungus-plant root symbiosis.
🧠 Did You Know?
Mycorrhiza improves water and nutrient uptake for plants, while lichens can survive in harsh environments due to their composite organism.
💡 NCERT Memory Line:
Saprophytes decompose dead organic materials; Mycorrhiza is a fungus–plant root symbiosis; Parasites live on living hosts; Lichens are a fungus–alga mutualism.
Consider a population of 10 million cells. Given the per-capita birth rate of 0.002 (per unit time) and the per-capita death rate of 0.002 (per unit time), the expected number of cells after 10 generations is
Since the per-capita birth rate equals the per-capita death rate, the population growth rate is zero. Therefore, the population size remains unchanged.
B. One species is harmed and the other is benefited
II. Mutualism
C. Both species are benefited
III. Competition
D. One is benefited while the other has no effect
IV. Commensalism
Competition harms both species. Predation benefits one and harms the other. Mutualism benefits both species. Commensalism benefits one species while the other is unaffected.
