Ecology

Step 1: Understand biogeographical barriers.
Kangaroos evolved in Australia and became geographically isolated due to ocean barriers. They cannot naturally disperse to other continents because they cannot cross large water bodies.
Step 2: Analyze options.
(A) Incorrect — abiotic factors do influence distributions, but this does not explain continent-level restriction.
(B) Correct — limited dispersal due to Australia's isolation explains their confinement.
(C) Incorrect — animals do not “choose” continents; physical barriers matter more.
(D) Incorrect — predators do not prevent natural distribution across continents.
Step 3: Conclusion.
Kangaroos remain restricted to Australia mainly due to geographic isolation and limited dispersal ability.

Step 1: Understand what ecosystem ecology covers.
Ecosystem ecology focuses on the interactions between living (biotic) and non-living (abiotic) components such as energy flow, nutrient cycling, and matter transfer.
Step 2: Eliminate incorrect options.
(A) Organism behavior relates to behavioral ecology, not ecosystem ecology.
(B) Interaction among individuals in a population is studied in population ecology.
(D) Community ecology studies interactions among different species.
Step 3: Conclusion.
Thus, ecosystem ecology emphasizes biotic–abiotic interactions, making option (C) correct.

Step 1: Understanding the method.
This problem involves the use of the Mark and Recapture method to estimate the population size of animals. The formula for this method is: Where:
- = number of dolphins initially tagged = 180
- = total estimated population size (what we are solving for)
- = number of tagged dolphins in the second sample = 7
- = total number of dolphins in the second sample = 42
Step 2: Substituting the known values into the equation.
We can rearrange the formula to solve for : Substituting the values: Final Answer:

Step 1: General knowledge of biomes.
Different terrestrial biomes vary in biodiversity depending on climate, productivity, and habitat complexity.
Step 2: Evaluate each option.
- Tropical forest: Known for being the most species-rich biome. They have warm temperatures, high rainfall, and layered vegetation, supporting maximum biodiversity including insects, birds, mammals, and reptiles.
- Savana: Grass-dominated biome with scattered trees. Animal diversity is lower than tropical forests.
- Chaparral: Found in Mediterranean climates, has shrubs and small mammals, not high in animal diversity.
- Tundra: Harsh cold environment with very limited diversity.
Step 3: Conclusion.
Tropical forests are the most biodiverse terrestrial biome.
Final Answer: