Ecology Ecosystems

Explanation

Lichens and mosses are most likely to be found surviving on a surface without soil. Lichens are a symbiotic association between a fungus and an alga or cyanobacterium, allowing them to grow on bare rock, walls, and tree bark. Mosses, being non-vascular plants, can absorb water and nutrients directly through their leaves, enabling them to thrive in environments without soil.

Explanation

Cyanobacteria and diatoms are primary producers in the food chains of oceans. Cyanobacteria are photosynthetic bacteria that can convert sunlight into energy, while diatoms are a type of algae that also photosynthesize. These organisms form the base of marine food chains by producing organic matter through photosynthesis.

Explanation

Detritivores are organisms that feed on dead and decaying organic matter. Earthworms, millipedes, and woodlice are examples of detritivores as they play a crucial role in breaking down organic material into simpler forms, aiding in the decomposition process and nutrient recycling within ecosystems.

Explanation

Cnidarians, fungi, and protozoa are organisms that can establish symbiotic relationships with other organisms. Cnidarians like corals have symbiotic relationships with algae, fungi form mycorrhizal associations with plant roots, and certain protozoa can engage in mutualistic relationships with other organisms.

Explanation

The correct sequence of ecosystems in the order of decreasing productivity is: Mangroves, grasslands, lakes, oceans. This means that mangroves have the highest productivity, followed by grasslands, then lakes, and finally oceans.

Explanation

An ecosystem refers to a community of organisms that coexist and interact with each other in a particular environment. This interaction involves both living organisms such as plants and animals, as well as non-living elements like weather, soil, and climate.

Explanation

Lichens are a mutualistic relationship between algae and fungi. They are able to start ecological succession on a bare rock.

Explanation

In a food chain, diatoms are the primary producers that make their own food. Crustaceans come next, as herbivores that consume diatoms. Finally, herrings, the carnivores, feed on crustaceans. Therefore, the correct sequence of the food chain is Diatoms-Crustaceans-Herrings, as shown in option (a).

Explanation

Volcanic activity, respiration, and the decomposition of organic matter all contribute carbon dioxide to the carbon cycle on Earth. Meanwhile, photosynthesis utilizes carbon dioxide to create food. The correct answer is option (c) - 1, 2, and 4 only.

Explanation

Lichens are organisms that can start the process of ecological succession on bare rocks. They are a symbiotic partnership between algae and fungi. The fungus provides the algae with shelter, water, and minerals, while the algae produces food through photosynthesis for both partners.

Explanation

In an ecosystem, a food chain shows the sequence of organisms feeding on each other for sustenance. It depicts the hierarchy of consumption within a biological community.

Explanation

Ecological niche is the term used to describe both the physical space inhabited by an organism and its functional role within a community of organisms. It encompasses the unique way of life of a species, detailing how it interacts with available resources and competitors in its environment.

Explanation

In grasslands, trees do not take over from grasses in the ecological succession due to constraints such as scarcity of water and the presence of fire.

Explanation

In terms of decreasing productivity, the correct sequence of ecosystems is Mangroves, grasslands, lakes, oceans. Mangroves have the highest productivity, followed by grasslands, then lakes, and finally oceans.

Explanation

In ecosystems, decomposer organisms are crucial for breaking down organic matter. Bacteria and Fungi are both examples of decomposers. Bacteria are particularly effective at decomposing various types of organic material, while Fungi play a primary role in decomposition.

Explanation

The Millennium Ecosystem Assessment identifies five main types of ecosystem services: provisioning, supporting, regulating, preserving, and cultural. Supporting services are essential for the functioning of other ecosystem services, such as soil formation, nutrient cycling, and photosynthesis. Nutrient cycling and crop pollination fall under the category of supporting services.

Explanation

If all phytoplankton in an ocean were to be completely destroyed, it would have negative impacts on the ocean ecosystem. The ocean's ability to absorb carbon dioxide as a carbon sink would be compromised, and the food chains within the ocean would also suffer, as many marine species rely on phytoplankton as a food source. This would result in disruptions to the marine food web. The density of ocean water would not be drastically affected by the destruction of phytoplankton. Therefore, the correct answer is option (a), which states that both the carbon sink function and the food chains in the ocean would be adversely affected.

Explanation

In the context of ecosystem productivity, marine upwelling zones play a crucial role in increasing marine productivity by bringing nutrients from deeper waters to the surface. This process does not involve decomposer microorganisms but rather helps in providing essential nutrients for phytoplankton growth. Marine upwelling zones do not bring bottom-dwelling organisms to the surface. Therefore, the correct statement is that marine upwelling zones bring nutrients to the surface, which corresponds to option (b) - 2 only.

Explanation

In the carbon cycle on Earth, carbon dioxide is added by respiration, decay of organic matter, and volcanic action. Respiration releases CO2 into the atmosphere, while volcanic eruptions and metamorphism also release gases, including CO2. On the other hand, photosynthesis works to remove CO2 from the atmosphere.

Explanation

When a chlorinated hydrocarbon pesticide is sprayed on a food crop, it can accumulate in the food chain as it moves from the food crop to the rat, snake, and finally the hawk. The process of increasing concentration of a compound in the tissues of organisms as it moves up the food chain is known as biomagnification. In this case, since the hawk is at the top of the food chain, it will have the highest concentration of the pesticide.

Explanation

As a chlorinated hydrocarbon pesticide is sprayed on a food crop, it gets passed along the food chain from the food crop to the rat, then to the snake, and finally to the hawk. In this scenario, the highest concentration of the pesticide would be found in the hawk. This is because of biomagnification, where the pesticide accumulates more as it moves up the food chain, with the hawk being at the top trophic level.