Which element is responsible for causing soil salinity? At what concentration does the soil become saline?
Soil salinity is the salt content in soil, which is caused by improper irrigation. The process of increasing salt content is termed as salinisation.
Causes of Soil Salinity The high salt concentration of soil is caused by improper irrigation method from a salt laden water table. When salt concentration in soil is increased, than it get accumulated due to evaporation.
Human activities like fertilising crop is also responsible for salinity of soil. As fertiliser contain potassium, which can form a naturally occuring salt-sylvite. Salinity of soil degrades soil and vegetation. Normally the pH value of soil comprises between 2.2-9.7, while above which the soil is degrading by salt content.
Does light factor affect the distribution of organisms? Write a brief note giving suitable examples of either plants or animals.
Plants require sunlight for photosynthesis. Therefore, light is an important factor that affects the distribution of plants. e.g.,
(i) Many species of small plants (herbs and shrubs) growing in forests are adapted to photosynthesise optimally under very low light conditions so they will be seen distributed in shady areas under tall, canopied trees.
(ii) Many plants in the shade will grow vertically to gain access to light. These plants will appear to have smaller leafs and smaller than others of the same species of the same age found in conditions with better sunlight.
(iii) Large sized trees will be present in areas that get abundant sunlight.
(iv) Plants dependent on sunlight to meet their photoperiodic requirements for flowering, will try to be distributed in area, where this requirement is being met for their reproductive success.
Give one example for each of the following
I. Eurythermal plant species..............
II. A hot water spring organism ..............
III. An organism seen in deep ocean trenches ..............
IV. An organism seen in compost pit ..............
V. A parasitic angiosperm ..............
VI. A stenothermal plant species..............
VII. Soil organism ..............
VIII. A benthic animal ..............
IX. Antifreeze compound seen in antarctic fish $\qquad$
X. An organism which can conform $\qquad$
I. Mango, Acacia
II. Archaebacteria
III. Jelly fishes
IV. Earthworm
V. Cuscuta
VI. Cocos nucifera
VII. Bacteria
VIII. Octopus
IX. Salt content (osmotic regulation)
X. All plant and fish like large mouth bass (temperature conformer)