NEET 2020 NEWS
NATIONAL LEVEL OFFLINE TEST
An ecosystem is a complex collection of relationships between a given area's living resources, habitats, and residents. It encompasses animals, plants, trees, birds, fish, water, soil, micro-organisms, and humans. An ecosystem can be enormous, as it may consist of various plants and animals, or small in particularly harsh places around the world.
The syllabus contains other more important topics than Ecosystem and students are required to pay greater attention to them. Ecosystem, however, is perhaps the most simple chapter in the NEET 2020 Biology Syllabus.With thorough preparation, you can get a good score in this chapter and boost your overall score in NEET.
A.G Tansley coined the word 'ecosystem' in 1935. Two components form the structure of any ecosystem. These are:
An ecosystem's abiotic factors include surrounding non-living substances. Examples would be water, soil, air, light, minerals, climate, and pressure, to name a few. The ecosystem's biotic factors rely for their survival on the abiotic factors.
The biotic factors include surrounding living organisms. Examples are plants, bacteria, and viruses. An ecosystem's biotic factors are classified into three principal groups, which are as follows:
Question: Which among the following ecosystems has the maximum biomass?
(a) Grassland ecosystem
(b) Pond ecosystem
(c) Lake ecosystem
(d) Forest ecosystem
Question: What is the rate at which food energy is integrated to the consumer trophic level called?
(a) Gross primary productivity
(b) Net primary productivity
(c) Secondary productivity
(d) None of the above
There are three kinds of ecological pyramids as given below.
At the trophic level, the number of individuals declines from producer level to consumer level. This means that the number of producers in an ecosystem is very high. The number of herbivores is less than the number of producers. Likewise, carnivores are smaller in number than herbivores.
Crop -> Grasshopper -> Frogs -> Snakes -> Hawks
A grassland ecosystem: The grasses are in large numbers in grasslands. In the given order, the consumers decrease in number.
Grass -> Grasshopper -> Lizard -> Hawk
Grass -> Rabbit -> Fox -> Lion
Phytoplankton -> Zooplankton -> Fishes -> Snakes
The biomass corresponds to the total weight per unit area of living matter. In an ecosystem, the biomass reduces from level of the producer to level of the consumer.
In an ecosystem, energy flows from the level of the producer to the level of the consumer. 80 to 90 percent of energy is lost at each trophic level. Therefore, the amount of energy is reduced from the level of the producer to that of the consumer. It can be reflected at the consumer level in an energy-level pyramid.
Question: All these claims contain drawbacks of ecological pyramids, with the exception of:
(a) They take into consideration a simple food chain and not food webs
(b) Saprotrophs are not given any place in the ecological pyramids
(c) They do not consider the same species which belong to two or more trophic levels
(d) They do not reflect relationships at different trophic levels between organisms;
Succession occurs in two ways:
Life forms: Raunkiaer (1934) differentiated plants by size, shape, branching, crown, life span, and perenniality into five forms.
Question: In the process of ecological succession:
(a) the animal types and numbers remain constant
(b) the creation of a new biotic community is rapid in its primary stages
(c) predictable and gradual variations in the composition of species occur in a particular region
(d) changes result in a community that is in close balance with the environment and is referred to as a pioneering community
Carbon flow into the biotic system: Carbon flows through the biotic system in two ways:
Carbon comes in from photosynthesis into the biotic system. Green plants use CO2 in photosynthesis, which convert CO2 carbon into glucose. Glucose gets used for synthesis of carbohydrates, proteins, and lipids of certain forms. These carbon-containing compounds are preserved in the tissues of plants. When herbivores chew up plants, the carbon flows through the food chain into the body of herbivorous animals. When carnivores eat herbivores, the carbon reaches the carnivorous animals' bodies.
6CO2 + 6H2O ® C6H12O6 + 6O2
ii) Shell formation
Marine animals, such as protozoans, corals, molluscs, and algae use the CO2 dissolved in seawater for shell construction. In these animals, CO2 gets converted into calcium carbonate ( CaCO3) that is used for shell construction.
CO2 + H2O -> H2CO3 (Carbonic acid)
H2CO3 -> H+ + HCO3 (Bicarbonate)
HCO3 + Ca+ -> H+ + CaCO3 (Calcium carbonate)
Carbon into the abiotic system: The biotic system's carbon flow into the abiotic system happens in five ways:
By respiration, plants and animals emit CO2 (biological oxidation).
As plants and animals perish, decomposers such as bacteria, algae, and so on decompose the dead bodies into CO2.
After the demise of marine organisms, CaCO3 retained in the shells is either stored as sedimentary rocks or dispersed in water to release CO2 by the reversal of the reactions described above.
Any part of plant carbon is stored as coal. Coal carbon returns to air through combustion and weathering, in the form of CO2.
v) Forest fire
In the forest wood, combustion absorbs carbon from plants in the form of CO2.
Question: Which among the following factors contributes to the carbon cycle?
(a) fossil fuel combustion
(d) all of these
Question: Which of the following describes phosphorus cycle the best?
(a) Gaseous cycle
(b) Perfect cycle
(c) Imperfect cycle
(d) Partly gaseous and partly sedimentary
Under Ecosystems, certain subtopics bear more weightage than others. Even though it is advised that a student studies all the subtopics, the more important topics given below may be allocated more time.
Question 1: Which of the following entities in an ecosystem occupies more than one trophic level?
Question 2: Which among the following will be the first to colonize a bare rock?
(a) Herbs and shrubs
(b) Annual plants
(d) Perennial plants
Question 3: The deep-sea hydrothermal vent ecosystem's primary producers are ___.
(a) blue-green algae
(b) coral reefs
(c) chemosynthetic bacteria
(d) green algae
Question: Which among the following is a characteristic feature of the cropland ecosystem?
(a) Absence of weeds
(b) Ecological succession
(c) least genetic diversity
(d) absence of soil entities
Question: When 20J of energy is trapped at the producer level, how much energy will be available in the subsequent chain to a peacock as food?
Plant -> Mice -> Snake -> Peacock
(a) 0.2 J
(b) 0.02 J
(c) 0.002 J
(d) 0.0002 J
When confronted with answering questions, candidates are often faced with a lot of irrelevant details. Many of the specifics given are meaningless for the solution. In these situations, candidates must mentally take note of the aspects of the question related to problem-solving to prevent silly mistakes. Aspirants must pay special attention to words like 'all', 'some', etc.
Even when the question is new to the aspirant, it is possible to realize through the elimination process that about 50 percent of the 4 probable answers are not valid. Afterward, all candidates have to evaluate and understand which of the 2 possible responses is the correct choice.
If you do not know the answer, and are sure you will not remember it, do not even attempt it. This is to guarantee that you do not get any negative markings. Considering your total score, getting a zero is better than getting a negative marking in NEET 2020.
Especially when it comes to studying for NEET Biology, keeping the whole syllabus in perspective for a successful preparation plan goes a long way. The available time for the syllabus of NEET and each of its subjects must be allocated according to the weightage of the topic. It is also important that one complies with the study plan and implements modifications as one progresses. Since Ecosystems in Biology is considered an easy-to-score section, follow the indicators below to design an efficient plan for the topic and the subject.