sana Archive


Primary growth takes place by the activity of apical meristematic cells of stem. Primary growth  passes through following phases. ---------------------------- ----------------------------  Phase of Cell division: The numbers of cells are increased by mitosis during this phase. It occurs at the tip of root and

Structure of Stem (Parts of Stem)

The internal structure of the stem is more complex. Stem is differentiated into nodes and internodes. The leaves are inserted on the nodes. The arrangement of leaves on the ‘nodes has made the stem more complicated. Stem has three fundamental systems. These tissues systems

Secondary Growth of Root

The roots increase in thickness by the formation of secondary vascular tissues. The secondary vascular tissues are produced by the activity of the vascular cambium. It produces the secondary xylem towards the inner side and secondaryphloem towards the outer side. Secondary growth is common

Structure of Root

The root is underground part of the plant. It anchors the plant in the soil. It is also used to absorb Water and minerals from the soil. .1–he root structure is almost uniform throughout its length. It is without nodes and internodes. There are


  Multiple Choice Questions (MCQs) Average rain fall in Pakistan is less than (a) 400mm                  (b) 250mm     (c) 340mm      (d) 450inm The percentage of earth covered with water is: (a) 50%                        (b) 25%          (c) 75%            (d) 23% The percentage of water in the form


There are following application of ecology in different environmental managements: Land management The operation by which land is prepared for crops plantation, harvesting is called land management. Good land management increases efficiency. Poor land management cause soil erosion, salinity and water logging. It changes


Spreading of deserts to the green areas is called desertification. Desertification occurs due to human activities. Desertification occurs in grasslands and forests. Earlier, vegetation was present there. But over exploitation of these natural resources changes them deserts. These are not natural deserts. But they


The wearing away of the soil by wind, water, snow or gravity is called soil erosion. Climatic, topographic. biotic, edaphic, and geologic factors cause the soil erosion. Climatic factors: Wind and rainfall are climatic factors. Topographic factors: Length of slope is a topographic factor.