Insights Static Quiz -26, 2018

Solution: d)

A keystone species is a species that has a disproportionately large effect on its environment relative to its abundance.[1] Such species are described as playing a critical role in maintaining the structure of an ecological community, affecting many other organisms in an ecosystem and helping to determine the types and numbers of various other species in the community. A keystone species is a plant or animal that plays a unique and crucial role in the way an ecosystem functions. Without keystone species, the ecosystem would be dramatically different or cease to exist altogether.

For examples: https://en.wikipedia.org/wiki/Keystone_species

Solution: b)

Urban ecosystems are often warmer than other ecosystems that surround them, have less infiltration of rainwater into the local soil, and show higher rates and amounts of surface runoff after rain and storms. Heavy metals, calcium dust, particulates, and human-made organic compounds (e.g., fertilizers, pesticides, and contaminants from pharmaceutical and personal care products) are also concentrated in cities.

Urban animal communities tend to be dominated by medium-size generalists, such as raccoons, coyotes, opossums, skunks, foxes, and other animals capable of surviving across a wide range of environmental conditions. In contrast, nonurban ecosystems tend to contain specialist species and animals that vary across a broader range of sizes. Urban habitats tend to be dominated by introduced plant and animal species that have a long history of association with humans and that show adaptations to urban conditions.

Solution: b)

All are INCORRECT (Question is asking which statements are incorrect)

All biological communities have a basic structure of interaction that forms a trophic pyramid. The trophic pyramid is made up of trophic levels, and food energy is passed from one level to the next along the food chain (see below Food chains and food webs). The base of the pyramid is composed of species called autotrophs, the primary producers of the ecosystem. They do not obtain energy and nutrients by eating other organisms. Instead, they harness solar energy by photosynthesis (photoautotrophs) or, more rarely, chemical energy by oxidation (chemoautotrophs) to make organic substances from inorganic ones. All other organisms in the ecosystem are consumers called heterotrophs, which either directly or indirectly depend on the producers for food energy.

Within all biological communities, energy at each trophic level is lost in the form of heat (as much as 80 to 90 percent), as organisms expend energy for metabolic processes such as staying warm and digesting food (see biosphere: The flow of energy). The higher the organism is on the trophic pyramid, the less energy is available to it; herbivores and detritivores (primary consumers) have less available energy than plants, and the carnivores that feed on herbivores and detritivores (secondary consumers) and those that eat other carnivores (tertiary consumers) have the least amount of available energy.

Solution: d)

The cells of all organisms are made up primarily of six major elements that occur in similar proportions in all life-forms. These elements—hydrogen, oxygen, carbon, nitrogen, phosphorus, and sulfur—form the core protoplasm of organisms, and the first four of these elements make up about 99 percent of the mass of most cells.

Comes under Nutrient Cycling, under ecology

Solution: a)

Krill are considered an important trophic level connection – near the bottom of the food chain – because they feed on phytoplankton and (to a lesser extent) zooplankton, converting these into a form suitable for many larger animals for which krill make up the largest part of their diets. In the Southern Ocean, one species, the Antarctic krill, Euphausia superba, makes up an estimated biomass of around 379,000,000 tonnes,[2] making it among the species with the largest total biomass. Of this, over half is eaten by whales, seals, penguins, squid, and fish each year, and is replaced by growth and reproduction. Most krill species display large daily vertical migrations, thus providing food for predators near the surface at night and in deeper waters during the day.