Transport In Plants — Important Questions

The grapes will shrink as water moves out of them

Step 1: The grape cells contain cell sap at a certain concentration. The surrounding sugar solution is highly concentrated (has less water). Step 2: In osmosis, water moves from higher water concentration to lower water concentration through the semi-permeable membrane of grape cells. Step 3: The sugar solution outside has a LOWER water concentration than inside the grape cells. Step 4: Therefore, water will move OUT of the grape cells into the surrounding sugar solution — this is called exosmosis. Step 5: As water leaves the cells, the grapes shrink and become wrinkled. This is the opposite o

Ascent of sap

Step 1: 'Sap' refers to the solution of water and dissolved minerals that moves through the xylem. Step 2: The upward movement of this sap from roots through the stem to the leaves is specifically called the 'ascent of sap'. Step 3: Transpiration is the loss of water vapour from leaves — not the upward movement of water. Step 4: Translocation refers to the movement of food (sucrose) through the phloem — not water through xylem. Step 5: Active transport is the movement of molecules against their concentration gradient using energy — it is a mechanism, not the name of this overall upward water m

Nitrogen

Step 1: Nitrogen is a macronutrient, meaning it is needed in large amounts by plants. Step 2: Nitrogen is the major constituent of all proteins, which are essential for plant growth and development. Step 3: When a plant lacks nitrogen, it cannot make enough proteins, leading to poor growth. Step 4: The visible symptoms of nitrogen deficiency are yellowing of leaves (called chlorosis) and wrinkling of cereal grains. Step 5: Phosphorus deficiency causes purple/red spots on leaves. Potassium deficiency causes poor growth. Iron is a micronutrient (not macronutrient) and also causes yellowing but i

Unidirectional — only upward from roots to leaves

Step 1: Xylem transports water and mineral salts from the roots upward to all aerial parts of the plant. Step 2: This movement is unidirectional, meaning it goes in only ONE direction — upward. Step 3: The driving forces for this upward movement are root pressure, transpirational pull, and capillary action. Step 4: In contrast, phloem transport is bidirectional — food made in leaves can travel both upward (to growing tips) and downward (to roots and storage organs). Step 5: So xylem = upward only (unidirectional), while phloem = both directions (bidirectional). This is an important difference