SL Pre-class: B4.1.3— Abiotic variables affecting species ...

Which scenario best illustrates the Law of Tolerance in practice?

• A cactus that grows best in dry deserts but dies when exposed to high rainfall over extended periods.

• A polar bear that survives in icy regions but thrives equally well when relocated to hot tropical rainforests.

• A lavender plant that grows equally well in acidic, alkaline, and nutrient-poor soils across different regions.

• A salmon species that spawns successfully in any type of freshwater, regardless of pH or oxygen conditions.

How do abiotic factors act as environmental filters shaping ecosystems?

• They provide uniform opportunities for all species to survive equally, regardless of adaptations or physiology.

• They primarily influence species through competition and predation rather than through physical constraints.

• They primarily influence species through competition and predation rather than through physical constraints.

• They allow only species with specific adaptations to survive, excluding those unable to tolerate given conditions.

Why are shade-tolerant plants in rainforests considered adapted to their abiotic environment?

• They thrive in the canopy layer by growing taller than competing species to capture strong sunlight.

• They rely only on biotic factors such as symbiosis rather than adjusting to light intensity levels.

• They develop large, thin leaves with high chlorophyll content to maximize photosynthesis in low light.

• They require direct, high-intensity light to survive, which limits their growth on shaded forest floors.

Which statement best explains the vulnerability of the Brazil nut tree to climate change?

• It can survive equally well in a wide range of rainfall, soil, and temperature conditions outside the Amazon.

• Its survival depends on overlapping conditions of high rainfall, acidic soils, and stable tropical temperatures.

• Its distribution is determined mostly by seed dispersal by animals rather than abiotic environmental factors.

• It is unaffected by abiotic conditions because of its strong tolerance to soil, climate, and rainfall variation.

What would happen to a salmon population if freshwater pH dropped below 5.5?

• The population would continue to reproduce normally because fish adapt instantly to new pH conditions.

• Survival would increase as stress zones improve growth in acidic conditions beyond the tolerance curve.

• Spawning would fail because the species cannot reproduce outside its optimal pH tolerance range.

• Spawning success would remain unaffected since pH is not a critical abiotic factor for aquatic organisms.

Which example shows how adaptations arise in response to abiotic stress zones?

• Banana trees develop thicker waxy leaves to resist frost damage in alpine habitats at high elevation.

• Elephants use small ears to conserve heat in cold polar regions with low ambient temperatures.

• Owls evolve to tolerate high-intensity sunlight in desert conditions by hunting actively at midday.

• Ranunculus glacialis develops antifreeze compounds to cope with cold, high-altitude environments.

What conclusion can be drawn from observing kangaroo rats producing highly concentrated urine?

• They are unaffected by desert conditions because they can freely access abundant surface water sources.

• They have evolved a water-conserving adaptation to survive in deserts where water is extremely limited.

• They are poorly adapted to dry habitats and survive mainly through assistance from other desert animals.

• They reproduce only in aquatic environments since desert abiotic factors prevent their survival long-term.

How does soil pH act as a limiting factor for plant distribution?

• Plants grow equally well in any soil pH, but nutrient competition with animals determines distribution.

• Soil pH affects only the physical structure of roots and has no effect on reproduction or survival.

• Certain plants thrive only in acidic soils, while others grow only in alkaline soils, restricting their ranges.

• Plant species distribution depends only on rainfall and temperature, not on soil conditions or chemistry.

Which description best matches Shelford’s concept of the optimal zone in species survival?

• It is the range where conditions allow maximal growth and reproduction, producing peak population success.

• It is the range where survival is possible but reproduction becomes significantly reduced and unreliable.

• It is the range where conditions are extreme, making it impossible for individuals to persist in the habitat.

• It is the range where environmental filters eliminate adaptations, preventing long-term evolutionary change.

How does climate change create new challenges for species distributions?

• Ecosystem stability is maintained because abiotic variables are fixed and unaffected by global climate change.

• Only biotic factors such as competition or predation change, while abiotic conditions remain constant globally.

• Shifts in abiotic conditions may force species to adapt, migrate, or face extinction if tolerance limits are exceeded.

• Adaptations remain permanently effective, so species distribution is unaffected by long-term environmental change.