Questions: Ecosystem

Q1. Describe the components of an ecosystem.

Answer (English): An ecosystem has abiotic and biotic components. The abiotic part includes air, water, soil, dissolved substances, sunlight, temperature and day length. The biotic part has producers, which fix solar energy; consumers, which feed on producers or on other consumers; and decomposers, mainly fungi and bacteria, which break down dead matter and release inorganic nutrients.

Hinglish: Ecosystem ke do components hain: abiotic aur biotic. Abiotic mein air, water, soil, dissolved substances, sunlight, temperature aur day length aate hain. Biotic mein producers (jo solar energy fix karte hain), consumers (jo producers ya doosre consumers ko khaate hain) aur decomposers (fungi aur bacteria jo dead matter todkar nutrients release karte hain) aate hain.

Q2. Define ecological pyramids and describe the pyramids of number and biomass with examples.

Answer (English): An ecological pyramid shows the feeding relationship between trophic levels in terms of number, biomass or energy, with producers at the base and top consumers at the apex. The pyramid of number counts individuals at each level; a grassland shows a broad base of many grass plants and few top carnivores, so it is upright, while a single tree with many insects and birds gives an inverted pyramid of numbers. The pyramid of biomass uses the mass of living material at each level; it is usually upright on land, but in a sea it is inverted because a small standing crop of fast-growing phytoplankton supports a much larger biomass of zooplankton and fish.

Hinglish: Ecological pyramid trophic levels ke beech feeding relationship ko number, biomass ya energy ke terms mein dikhata hai; base par producers aur apex par top consumers hote hain. Pyramid of number har level ke individuals ginata hai; grassland mein bahut ghaas aur kam top carnivores hote hain, isliye upright hota hai, jabki ek bade ped par bahut insects aur birds inverted pyramid dete hain. Pyramid of biomass har level ki living mass leta hai; zameen par yeh aksar upright hota hai, lekin samundar mein inverted hota hai kyunki tezi se badhne wala chhota phytoplankton standing crop bade zooplankton aur fish biomass ko support karta hai.

Q3. What is primary productivity, and which factors affect it?

Answer (English): Primary productivity is the rate at which plants produce biomass or organic matter per unit area over a period of time during photosynthesis, and it is expressed per unit area per year. It is divided into gross primary productivity, which is total production, and net primary productivity, which is what remains after the plants' respiration is subtracted. It depends on the plant species present, on environmental factors, on nutrient availability and on the photosynthetic capacity of the plants.

Hinglish: Primary productivity wo rate hai jis par plants photosynthesis mein per unit area per time biomass ya organic matter banate hain, aur ise per unit area per year mein likhte hain. Iske do hisse hain: GPP total production, aur NPP jo respiration ke baad bachta hai. Ye plant species, environmental factors, nutrient availability aur plants ki photosynthetic capacity par depend karta hai.

Q4. Define decomposition and describe its processes and products.

Answer (English): Decomposition is the breakdown of complex organic matter in detritus into carbon dioxide, water and inorganic nutrients. It has five named steps. Fragmentation breaks detritus into smaller pieces. Leaching carries water-soluble inorganic nutrients into the soil, where they precipitate. Catabolism uses bacterial and fungal enzymes to degrade detritus into simpler inorganic substances. Humification produces humus, a dark resistant colloid that stores nutrients. Mineralisation breaks humus further and releases inorganic nutrients.

Hinglish: Decomposition mein detritus ka complex organic matter carbon dioxide, water aur inorganic nutrients mein tootta hai. Iske paanch steps hain: fragmentation mein detritus chhote tukdon mein tootta hai, leaching mein water-soluble inorganic nutrients soil mein neeche jaate hain, catabolism mein bacterial aur fungal enzymes detritus ko simple inorganic padarthon mein todte hain, humification se humus banta hai jo nutrients ka store hai, aur mineralisation mein humus aur tootta hai aur inorganic nutrients release hote hain.

Q5. Distinguish between grazing and detritus food chains.

Answer (English): A grazing food chain begins with a producer and passes to herbivores and then carnivores, for example grass, goat and man. A detritus food chain begins with dead organic matter and is run by decomposers, mainly fungi and bacteria, which break the detritus down and absorb the products. In aquatic ecosystems the grazing chain is the main route for energy flow; in terrestrial ecosystems a much larger share of energy moves through the detritus chain.

Hinglish: Grazing food chain producer se shuru hoti hai aur herbivores phir carnivores tak jaati hai, jaise ghaas, bakri aur insaan. Detritus food chain dead organic matter se shuru hoti hai aur ise decomposers chalate hain, mainly fungi aur bacteria, jo detritus ko todkar products absorb karte hain. Aquatic ecosystems mein grazing chain main route hai; terrestrial ecosystems mein energy ka bada hissa detritus chain se flow karta hai.

Q6. Distinguish between primary and secondary productivity.

Answer (English): Primary productivity is the rate at which producers capture solar energy and build organic matter during photosynthesis. Secondary productivity is the rate at which consumers form new organic matter from the food they eat. Primary productivity supplies the energy for the whole ecosystem; secondary productivity is limited by the energy that reaches consumers after the ten per cent law has acted.

Hinglish: Primary productivity wo rate hai jis par producers photosynthesis mein solar energy capture karke organic matter banate hain. Secondary productivity wo rate hai jis par consumers khane se naya organic matter banate hain. Primary productivity poore ecosystem ko energy deti hai, jabki secondary productivity us energy tak seemit hoti hai jo ten per cent law ke baad consumers tak pahunchti hai.

Q7. What fraction of the incident solar radiation is photosynthetically active, and how much of it can plants capture?

Answer (English): Less than 50 per cent of the incident solar radiation is photosynthetically active radiation, the part that plants can use in photosynthesis. Plants capture only about 2 to 10 per cent of that PAR, and this small fraction supports the entire living world.

Hinglish: Incident solar radiation ka 50 percent se kam hissa PAR hota hai, yaani woh part jo plants photosynthesis mein use kar sakte hain. Plants us PAR ka sirf 2 se 10 percent capture karte hain, aur yahi chhota hissa poore living world ko support karta hai.

Q8. Describe how energy moves through an ecosystem.

Answer (English): Energy enters from the sun, and less than half of the incoming radiation is PAR, of which plants capture 2 to 10 per cent. From producers the energy moves to primary consumers, then to secondary and tertiary consumers, and some reaches decomposers when organisms die. The flow is unidirectional, because energy is not returned to the sun. About 90 per cent of the energy at each level is lost, mostly as heat, so only 10 per cent reaches the next level. This is why food chains are short and why the pyramid of energy can never be inverted.

Hinglish: Energy sun se aati hai; incoming radiation ka 50 percent se kam PAR hota hai, jismein plants 2 se 10 percent capture karte hain. Producers se energy primary consumers, phir secondary aur tertiary consumers tak jaati hai, aur organisms marne par kuch decomposers tak pahunchti hai. Flow unidirectional hota hai kyunki energy wapas sun tak nahi jaati. Har level par lagbhag 90 percent energy heat ke roop mein loss hoti hai, isliye sirf 10 percent next level tak pahunchti hai; isi wajah se food chains chhoti hoti hain aur energy pyramid kabhi inverted nahi hota.

Q9. In a lake, which group occupies the second trophic level?

Answer (English): The second trophic level is occupied by the primary consumers, which in a lake are the zooplankton. Phytoplankton are producers and sit at the first trophic level, while benthos and fishes occupy higher levels. So among the usual options, zooplankton is the correct answer for the second trophic level in a lake.

Hinglish: Doosra trophic level primary consumers ka hota hai, aur lake mein yeh zooplankton hote hain. Phytoplankton producers hain aur first trophic level par hain, jabki benthos aur fishes upar ke levels par aate hain. Isliye lake ke second trophic level ke liye zooplankton sahi answer hai.

Q10. What are the limitations of ecological pyramids?

Answer (English): Ecological pyramids do not allow for a species that occupies two or more trophic levels at the same time. They assume a simple food chain, although a food web is what exists in nature, and they do not accommodate saprophytes even though these play a vital role in the ecosystem. They also say nothing about the amount of energy lost as heat at each step.

Hinglish: Ecological pyramids ki limitations: ek species ek saath do ya zyada trophic levels par ho sakti hai, jo pyramid nahi dikhata; yeh simple food chain maan lete hain jabki nature mein food web hota hai; aur saprophytes ko koi jagah nahi dete, haalaanki unka role bahut zaroori hai. Ye heat ke roop mein hone wale energy loss ko bhi nahi dikhate.

To check how much of this stuck, take the five-question quiz below. Each answer explains the reasoning, so read the explanation even when you get it right.

Quiz: the five question check for this chapter is set from the same topics. Attempt it after the questions above, then revisit any topic page where you lost a mark.