" A jaw less marine organism,but migrate for spawning to fresh water,after that dies within few days.It belongs to "

Both Fresh water and marine water organisms are found in

Fill in the blanks : Fishes showing migrations from sea water to fresh water for spawning are termed ………., fishes while those migrating form fresh water to sea water are called ………, fishes .

An organism X having breathing organs A lives on land. When organism X goes under water, it cannot survive for a long time unless carrying an oxygen cylinder. On the other hand, the organism Y having breathing organs B always lives in water and if taken out of water, it dies after a short while. A third organism Z having breathing orgains C and D which lives on the banks of ponds, lakes and rivers can survive on land as well as in water equally well. (a) What could organism X be? Name the breathing organs A. (b) What could organism Y be? Name the breathing orgains B. (c) What could organism Z be ? Name the breathing organs C and D (d) Out of X, Y and Z, which organism is (i) amphibian, (ii) aquatic, and (iii) terrestrial ?

Read the following statements and find out the incorrect statement. (a) Water is essential for all physiological activities of the plant and plays a very important role in all living organisms. (b) A mature corn plant absorbs almost five litres of water in a day. (c) A mature plant absorbs water equal to its own weight in about 3 hours. (d) Water is often the limiting factor for plant growth and productivity in both agricultural and natural environments. (e) A watermelon has over 92 percent water, most herbaceous plants have only about 10 to 20 percnet of its fresh weigth as dry matter.

Statement (S). Marine lampreys migrate to rivers for spawning Reason (R). Marine lampreys return to sea water after spawning

A lake near a village suffered heavy mortality of fishes within a few days. Which of the following statements could be the correct explanation for this ? (i) Lots of urea and phosphate fertillisers were used in the crops in the nearby fields. (ii) The croplands of the village were fertillised fields rich in nitrate and phosphate. (iii) The lake water turned green and stinky. (iv) Phytoplankton populations in the lake declined initially thereby greatly reducing photosynthesis.