Science M.C.Q

(C) A is true but R is false.

(A) Broken down by biological processes

(C) CFCs; Ozone

From the above food web, we can infer that out of the options given above, a mouse is the primary consumer of grass.
If the population of grass decreases, the available energy will decrease for a mouse.

Organisms of a higher trophic level that feed on several types of organisms belonging to a number of lower trophic levels constitute a food web.

Energy always flows in one direction in an ecosystem, from a lower trophic level to a higher trophic level.

In an ecosystem, green plants are the producers. Herbivores are primary consumers. They feed on producers. Carnivores are secondary consumers. They feed on primary consumers. Decomposers aid in the decomposition of dead remains of producers and consumers.

Biomagnification refers to an increase in the concentration of toxic chemicals at successive trophic levels.
This happens because a toxic substance accumulated by an organism cannot be metabolized or excreted, and it is passed on to the next higher trophic level.
In an aquatic ecosystem, birds are at the highest trophic level.

Food chain is the sequence of organisms through which food and energy is passed in an ecosystem with the members of trophic level. Trophic level is the hierarchical levels in an ecosystem which consists organism.

Incineration, which means burning harmful wastes into ashes, is the best method to dispose of biological wastes from hospitals.

As mice are in the lowest trophic level, they will have the minimum concentration of pesticides in their body.

A food chain is defined as a linear network of links in a food web starting from producer organisms and ending at an apex predator species, or decomposer species.
Green plants are known as producers as they trap energy from the sun and then pass it to all the consumers occupying successive trophic levels.

This type of food chain starts from the living green plants goes to grazing herbivores, and on to carnivores. Ecosystems with such type of food chain are directly dependent on an influx of solar radiation.

A grasshopper eats grass; hence, the grasshopper is the primary consumer. A frog eats the grasshopper, so the frog becomes the secondary consumer. The energy transfer is from the primary consumer to the secondary consumer, i.e., from the grasshopper to the frog.

Grass is eaten by goats, and goats are eaten by humans.

Two basic kinds of processes must occur in the ecosystems : a cycling of chemical elements and a flow of energy.

Ozone is a deadly poison and if all the oxygen were to get converted to ozone, no life on the earth would survive.

If deer are removed from the given food chain, the population of tigers will decrease as they will not have deer for their food and will starve to death. The density of grass will increase as there is no organism to consume it as food.

A food chain is defined as the linear sequence of transfer of matter and energy in the form of food from one organism to another in an ecosystem.

Only one per cent of the sun's energy falling on the leaves of green plants is utilised by the plants in the process of photosynthesis and stored as the chemical energy of food.

The food chain is a series of organisms in which one organism is dependent on the other for food. In a typical food chain, green plants are the producers; they are eaten by herbivores, which are in turn eaten by carnivores.

Deers, giraffes, cows, goats, rabbits, horses, insects and snails, all consume the producers and hence are primary consumers.

Producers use solar energy to make carbohydrates from water and carbon dioxides. Water and carbon dioxide are inorganic compounds.

The autotrophs capture the energy present in sunlight through leaves and convert it into chemicalenergy. This energy supports all the activities of the living world. From autotrophs, the energy goes to the heterotrophs and decomposers.
Thus, the source of energy in an ecosystem is the sunlight received by the leaves.

As nitrogen is an essential element for plant growth and development; however, due to environmental pollution, high nitrate concentrations accumulate in the edible parts of these leafy vegetables, particularly if excessive nitrogen fertilizer has been applied. Consuming these crops can harm human health.

Deforestation means cutting down the trees to a large extent be it forests, any barren land or trees we see on our way to school every day. Natural forests are being destructed to use the land for cultivation, building houses, factories, logging, making space for cattle grazing, extraction of oil, mining, construction of dams or to obtain wood for making furniture and using it as fuel.

Larvae feed on algae for their nutrition, so they get the energy they require directly from the producers. Thus, they get the maximum energy among all the consumers.

Trophic levels are divisions or steps in the food chain defined by the way of obtaining food.
In a food chain, producers are the initial trophic level.
The first trophic level will be occupied by the bamboo plant, which is a producer.

Green plants are known as autotrophs. They prepare their own food in the presence of sunlight, with the help of a pigment called chlorophyll. The process, in which they take away carbon dioxide from air and water from the soil and give out oxygen to prepare food is called photosynthesis.
So we can say the process of photosynthesis is the initiator of food chain as the food and energy produced by plants is consumed further by consumers.

In ecological pyramid, number of organisms at higher tropic level is always less than number of organisms at lower trophic level. An organism at higher trophic level usually feeds on more than one type of organisms. For example, consumers are always less than producers.