QCAA Biology Functioning ecosystems and succession

ATP and NADPH (not NADH) are produced during the light-dependent stage in the thylakoid membranes, and they are transported to the stroma for the light-independent stage.

Photosynthesis utilizes NADPH, not NADH. Furthermore, the light-dependent stage produces ATP and NADPH, rather than ADP.

The Krebs cycle is a stage of cellular respiration that occurs in the mitochondria, not a part of photosynthesis.

Zooplankton are heterotrophs (consumers) that feed on phytoplankton; they do not perform photosynthesis, which is the role of the autotrophic phytoplankton.

Phytoplankton are primary producers, not predators, and the relationship in question involves the transfer of energy from the first trophic level to the second, not competition within the first.

If carnivores increased their consumption of zooplankton, the biomass of zooplankton would decrease, making it less likely to exceed the biomass of phytoplankton.

Nitrite ($NO_2^-$) is an intermediate formed during the reduction of nitrate; it is generally toxic to plants in high concentrations and is not the primary source absorbed for protein synthesis.

While nitrogen is incorporated into organic molecules as ammonium ($NH_4^+$), free ammonia ($NH_3$) is toxic to plant cells, and nitrate is the predominant form of nitrogen available in and absorbed from the soil.

Plants cannot directly utilize atmospheric nitrogen ($N_2$) because they lack the enzyme nitrogenase required to break the strong triple bond between nitrogen atoms; they rely on nitrogen-fixing bacteria or soil nutrients.

Direct contact transmission requires physical contact between an infected person and a susceptible person, not an intermediate organism like a mosquito.

Droplet transmission occurs when respiratory droplets from coughing or sneezing carry pathogens directly to a susceptible person, which does not involve a mosquito.

Airborne transmission involves pathogens traveling through the air over time and distance, rather than being delivered by a biting insect.

An ecoregion is a large geographic area defined by distinct natural communities and environmental conditions, not the specific role of an individual organism.

The environment refers to the general surroundings and conditions (biotic and abiotic) in which an organism lives, rather than its specific function or "job" within that setting.

A microhabitat is a small, specialized physical space within a larger habitat, but the term does not encompass the organism's functional role or interactions.

Different species can coexist in the same habitat by utilizing different resources or occupying different microhabitats, a concept known as resource partitioning.

Many species share the same general environment; exclusion only occurs when their specific functional roles and resource requirements (niches) overlap completely.

Species can occupy the same trophic level (e.g., different herbivores) and coexist if they feed on different plants or are active at different times.

Carrying capacity refers to the maximum population size of a specific species, not the total biomass of producers, although producer biomass does influence the resources available.

Carrying capacity applies to populations at any trophic level, not exclusively to top predators.

Carrying capacity is a concept applied to a specific population of a single species, not the aggregate sum of individuals across multiple different species.

A harvested crop field retains its soil; therefore, the ecological recovery that follows is an example of secondary succession.

While fire destroys vegetation, the underlying soil remains intact, allowing for secondary succession to occur rather than primary succession.

A cyclone damages existing vegetation but leaves the soil layer present, resulting in secondary succession.

While nitrogen fixation is beneficial in nutrient-poor soil, pioneer species typically require rapid germination to quickly colonize and populate open areas.

This species lacks both key adaptations required for pioneer species: it cannot establish itself quickly (slow germination) nor can it generate its own nutrients in poor soil.

Although rapid germination is a trait of pioneer species, the lack of nitrogen-fixing bacteria makes this species less likely to thrive in the nutrient-depleted soils typical of early succession compared to Option C.

This is incorrect because specimens should not be exposed to decomposers (II). Decomposers break down organic matter, which prevents fossilisation.

This is incorrect because both exposure to decomposers (II) and disturbance (V) would destroy the specimen before it has a chance to fossilise.

This is incorrect because exposure to decomposers (II) and physical disturbance (V) actively destroy remains, making fossilisation impossible.

Incorrect. Frogs are vertebrates with hard, bony skeletons, which are much more likely to be preserved in the fossil record than soft tissues.

Incorrect. Beetles have hard exoskeletons made of chitin, which can fossilize or be perfectly preserved in tree resin (amber).

Incorrect. Pine trees contain hard, woody tissues that fossilize very well, often resulting in petrified wood or fossilized resin.