Botany MCQs for NEET — Practice Questions with Answers

Photosynthetically fixed carbon is evntually degraded by micro-organisms and two major forms of carbon result methane(${\mathrm{CH}}_4$) and carbon dioxide(${\mathrm{CO}}_2$). The micro-organisms breakdown the complex compunds of dead protoplasm of producers and consumers absorb some of the decomposition products and release simple substances. The slow rate of decomposition of fallen logs in nature is due to their low moisture content. 

The cellulose is in high amount in fallen logs. The environment around the fallen logs in aerobic, ie, ${\mathrm{o}}_2$ is present

Temperate deciduous forests grow in continental climates with summer rainfall and severe winters. They are dominated by broad leaved deciduous trees like Quercus virginiana, magnolias, boys and hallies as well as such tropical species as Ficus aurea, Lysiloma.

Tropical rain forests occupy low altitude zones near the equator where annual rainfall exceeds 80^" to 90^" distributed over the year. Trees generally form three storeys scattered very tall emergent trees, canopy layer and understorey stratum.

Tropical scrub forests develop in areas where moisture relations are intermediate between desert and savanna on one hand and rainforest on other.

Prodcutivity of tropical rainforest is highes. The tropical rain forest covering 300,000 km² area. They contain more than 50% of total flora and fauna of the world.

Ecological pyramids are the graphical representation of the trophic structure and function at successive trophic lveles. Ecological pyramids are of three general types, listed as here under:
(i) Pyramids of numbers, showing the number of organisms at each level.

(ii) Pyramid of biomass, showing the total dry weight flow/productivity at successive trophic levels.
Thus, fresh weight is not used for the construction of ecological pyramids.

(c) : Benthic zone is the bottom part of a water body. Light is not available here so it is dark. Micro-organisms and other benthic organisms are found in this region.

(c) : Benthic region or zone is the bottom of the quatic body which is made of sediments above. In deep lakes and sea, the benithic region is in perpetual darkness. Therefore, only consumers occur over here. They are either carnivorous or detrivorous. The common benthic organisms are snails, some specialised fishes and microorganisms.

(a) Prosopis are tree found in scrub. Saccharum is grass which is cultivated. Shorea robusta (Sal) is tree found in moist tropical forest. Acacia catechu is tree found in dry deciduous forests.

(b) : Light is the visible part of electromagnetic radiations. Sunlight or solar radiations reaching the earth have wavelength between 300 nm to 2600 nm. Part of the spectrum used in photosynthesis  has a wavelength between 400-700 nm. It is called photosynthetically active radiation (PAR).

(d) : Bacteria attacking the dead animals represent the end of the food chain and are decomposers. These are the organisms that obtain energy from chemical breakdown of organisms. They secrete enzymes onto dead matter and then absorb the breakdown products. Bacteria are specialised to breakdown organic materials that are difficult for other organism to digest. They also fulfil a vital role in the ecosystem, returning the constituents of organic matter to the enviroment in inorganic forms so that they can again be assimilated by producers.