▶️ Answer/Explanation
To find the number of consumers, we trace the energy flow from the producers (kelp, algae, diatom). Secondary consumers eat the primary consumers (herbivores). In this web, the secondary consumers are the sea otter (eats urchin, mussel, clam), seal (eats prawn), sea lion (eats prawn), and orca whale (when it eats the prawn directly). This gives a total of $4$.
Tertiary consumers occupy the next level by eating secondary consumers. Here, the orca whale acts as the tertiary consumer when it eats the sea otter, seal, or sea lion. Since the orca whale is the only organism at this specific level in these chains, there is $1$ tertiary consumer.
✅ Answer: (B)
▶️ Answer/Explanation
Xerophytes are plants adapted to survive in arid environments where water is scarce. To conserve water, they possess a thick waxy cuticle on their stems or leaves, which acts as a waterproof barrier to stop (minimize) water evaporation. Additionally, they often develop extensive root systems that spread wide or deep into the soil to maximise water uptake from infrequent rainfall or deep underground tables. Options B and C are incorrect because increasing evaporation would be detrimental, and options C and D are incorrect because restricted roots would limit the plant’s ability to find water in a dry climate.
✅ Answer: (A)
✅ Answer: (A)
▶️ Answer/Explanation
An adaptive feature is an inherited functional characteristic that increases an organism’s fitness. Statement $1$ is correct because adaptation directly improves the chances of survival and successful reproduction. Statement $3$ is also correct because for a trait to be an evolutionary adaptation, it must be genetically determined and passed to offspring. Statement $2$ is incorrect because adaptations can be discrete (discontinuous), such as blood type or specific defensive structures, and are not limited to continuous variation.
✅ Answer: (C)
✅ Answer: (C)