Correct Answer: Option 3 hide from predators.

Stick insects have chromatic adaptations to hide from insectivorous animals like moles and robins. In this way, they have less probability of being seen by these predators.

Option 1 is incorrect because stick insects are not competing with all birds. Stick insects are herbivores, while birds are herbivores or carnivores. They only compete with herbivorous birds but not with the birds with different mode of nutrition.

Option 2 is incorrect because stick insects are not plants, they just look like plants in order to adapt to their environment. This is called chromatic adaptation wherein pigment granules migrate in their epidermis. Since stick insects are not plants, they cannot make their own food.

Option 4 is incorrect. Molecular adaptation is the common way used by insects to avoid toxic waste materials (e.g. leaf beetles).

CORRECT ANSWER: Option 2 The energy content of level A depends on energy provided from an abiotic source.

A food web like this shows the complex energy transformations in an ecosystem. The organisms in level A are called producers or autotrophs. They are able to make their own food through photosynthesis. Level B contains the primary consumers, they eat products of photosynthesis in order to survive. Level C contains the secondary consumers. Energy transfers within food webs are governed by the first and second laws of thermodynamics. The first law states that energy can be transformed from one form to another, but it cannot be created or destroyed. This law suggests that all energy transfers, gains, and losses within a food web can be accounted for in an energy budget.

The energy is transferred from the first level (producers) to the next level that consumes it. Therefore, option 1 is incorrect because level B depends on level A. Option 4 is also incorrect because energy from level B is transferred to the next level which is level C.

The second law relates to the quality of energy. This law states that whenever energy is transformed, some must be degraded into a less useful form. The second law explains why energy transfers are never 100% efficient. In fact, ecological efficiency, which is the amount of energy transferred from one trophic level to the next, ranges from 5-30%. On average, ecological efficiency is only about 10%. Because ecological efficiency is so low, each trophic level has a successively smaller energy pool from which it can withdraw energy. This is why food webs have no more than four to five trophic levels. Beyond that, there is not enough energy to sustain higher-order predators. Hence, there is less energy in level C than the first level (level A). For that reason, option 3 is false.

Correct Answer: Option 1 They act as limiting factors.

If any of these factors become limited, the production of an ecosystem will be greatly affected. For instance, if water becomes scarce, most organisms would suffer because of its dependence on this important resource.

Though these resources can be converted to become nutrients, option 2 is not the best choice. They also aid in decomposition yet not directly the best answer.

Option 4 is not the best answer. Environmental temperature is most of the time affected by the solar energy coming from the sun.

Correct answer: Option 2 Destroyed environments can recover as a result of the process of ecological succession.

Secondary succession occurred in the island.  Secondary succession refers to the sequence of community changes that takes place after a community is disrupted by natural disasters (e.g. volcanic eruption) or human actions. During succession, the community of organisms inhabiting an area gradually changes. Secondary succession, however, occurs in areas that previously contained life, and on land that contains soil. Therefore, the pioneer species involved in secondary succession are different from those in primary succession, but the same climax community will be reached in areas with similar climate. So in the case of the island mentioned in the question, the climax community was reached that is why it looks like it was before the eruption.

Correct Answer: Option 4 D

The carrying capacity of a biological species in an environment is the population size of the species that the environment can sustain in the long term, given the food, habitat, water and other necessities available in the environment. In the given diagram, B is incorrect because the time in that given population is 0. Point A is also incorrect because the population is at 0.

Point C is incorrect because it is the lowest population size over time. After point C, the population rose due to the high amount of available resources not consumed by the population during the time of point C. Below carrying capacity, populations typically increase, while above, they typically decrease. A factor that keeps population size at equilibrium is known as a regulating factor. Population size decreases above carrying capacity due to a range of factors depending on the species concerned, but can include insufficient space, food supply, or sunlight. The carrying capacity of an environment may vary for different species and may change over time due to a variety of factors, including: food availability, water supply, environmental conditions and living space.

Correct Answer: Option 1 biodiversity

Biodiversity is the variety of life: the different plants, animals and micro-organisms, their genes and the ecosystems of which they are a part. Since there would be less variety of organisms left for propagation, the biodiversity in that area will not flourish. Plus, there would be fewer habitats left for survival so some of the organisms might migrate to places with more resources and better habitat.

Due to scarcity of resources brought about by the destruction of habitats, the organisms would tend to compete more on the few remaining food source. This would lead to more interaction between species. Thus, options 2 and 3 are incorrect.

As for option 4, sun could penetrate more through a clearing than densely covered area of habitat. Therefore, more solar radiation would reach the area.

Correct Answer: Option 1 decomposer

Food chain is the transfer of energy from one trophic level to another. Decomposer is the fifth and last level in the food chain. All the other levels (producers/autotrophs, primary consumers/herbivores, secondary and tertiary consumers/predators) interact with the decomposers. Decomposers (or saprotrophs) are organisms that consume dead or decaying organisms (from either levels of the food chain), and, in doing so, carry out the natural process of decomposition. Like herbivores and predators, decomposers are heterotrophic, meaning that they use organic substrates to get their energy, carbon and nutrients for growth and development. Decomposers use deceased organisms and non-living organic compounds as their food source. The primary decomposers are bacteria and fungi.

Correct Answer: Option 1 An increase in the number of carnivore species.

There will be an increase in competition of the herbivores. This would lead to scarcity of food resources. Some herbivores will change their nutrition mode into carnivore in order to survive.

A predator is an organism that lives by preying on other organisms.

Option 2 is incorrect. Since there will be an increase in the number of prey (due to removal of nearly all the predators, there will also be an increase in new predators migrating into that ecosystem.

Option 3 is incorrect. The number of decomposers will increase because the preys might die of natural death instead of being eaten by predators.

Option 4 is incorrect. The number of herbivores will decrease because there will be higher competition the herbivores that will survive are only the fittest ones.

Correct Answer: Option 4 Sugar maples can grow anywhere black oats can grow.

Option 1 is incorrect. The diagram shows that there is an increase the number of trees when the moisture content is low for Red oak and Black oak. When the moisture in high, American elm and Black willow thrive. On the other hand, sugar maple flourishes when the moisture content is moderate. Therefore, these five species have different habitat preferences.

Option 2 is incorrect. American elm prefers to live in wet environments.

Option 3 is incorrect. Red oaks prefer dry environments, while black willows favor wet.

Correct Answer: Option 1 source of energy

Autotrophs make organic molecules from inorganic raw materials obtained from the environment. After photosynthesis, they form glucose which is the storage form of energy for the plants.

Glucose cannot function as hormone, vitamin or biotic resource.