General Science/Everyday Science MCQs
Topic Notes: General Science/Everyday Science
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
111
The total amount of organic matter produced by autotrophs in an ecosystem is known as:
Answer:
Gross Primary Productivity (GPP)
GPP is the total rate at which solar energy is captured by photosynthesis. When the energy used by the producers for their own respiration is subtracted from GPP, the result is the Net Primary Productivity (NPP).
112
Which process in the nitrogen cycle converts atmospheric nitrogen ($N_2$) into a form plants can use?
Answer:
Nitrogen fixation
Atmospheric nitrogen is very stable and cannot be used directly by plants. Nitrogen-fixing bacteria, often found in the root nodules of legumes, convert $N_2$ gas into ammonia or nitrates.
113
What is 'carrying capacity' in an ecosystem?
Answer:
The maximum population size an environment can sustain indefinitely.
Carrying capacity (K) is determined by limiting factors such as food, water, and space. When a population exceeds this limit, resources become scarce, leading to increased mortality or decreased birth rates.
114
Primary succession would most likely occur in which of the following areas?
Answer:
A newly formed volcanic island
Primary succession occurs in virtually lifeless areas where soil has not yet formed, such as on bare rock or newly cooled lava. Pioneer species like lichens and mosses help break down rock to begin soil formation.
115
Which biome is characterized by permafrost and very low precipitation?
Answer:
Tundra
The tundra is a cold, treeless biome found in the Arctic and on high mountains. It features a layer of permanently frozen subsoil called permafrost, which limits root growth and prevents the drainage of water.
116
What is the term for a species that has a disproportionately large effect on its environment relative to its abundance?
Answer:
Keystone species
Keystone species, such as sea otters or wolves, play a crucial role in maintaining the structure of an ecological community. Their removal can lead to drastic changes or the collapse of the entire ecosystem.
117
In a symbiotic relationship, if one organism benefits and the other is neither helped nor harmed, it is called:
Answer:
Commensalism
Commensalism is a type of interaction where one species (the commensal) gains an advantage, such as food or shelter, while the host species is unaffected. An example is barnacles attaching to a whale.
118
Which biogeochemical cycle does not typically include a significant atmospheric phase?
Answer:
Phosphorus cycle
The phosphorus cycle is primarily sedimentary. Phosphorus is found in rocks and minerals and is released through weathering; unlike carbon or nitrogen, it does not have a gaseous form that circulates in the atmosphere.
119
The '10% Rule' in ecology suggests that:
Answer:
Only 10% of the energy at one trophic level is passed on to the next.
When energy flows from one trophic level to the next, approximately 90% is used for metabolic processes or lost as heat. Only about 10% is stored as biomass and available for the next consumer level.
120
What is the primary role of decomposers in an ecosystem?
Answer:
To recycle nutrients back into the soil
Decomposers, such as bacteria and fungi, break down dead organic matter. This process is essential for returning vital nutrients like nitrogen and phosphorus to the soil, where they can be reused by producers.