Tag: types of transport

• Negative hydrostatic pressure develops at the time of water loss, it occurs when the water is lost through transpiration and creates tension in the cell.
• Transpiration is the process in which water is lost through the upper or aerial plant parts in the form of water. 
• Imbibition is the swelling of cells that occurs due to the absorption of water. 
• Positive pressure is the force in the xylem which exudates drops of liquids through the stoma to the outside and also requires hydathodes which help in the process of guttation (exudation of water droplets mostly from the leaves margins). 
  

Food from the leaves is conducted downwards through the phloem in the stem.conduction of water through the xylem occurs generally upwards.

Xylem transports and stores water and water-soluble nutrients in vascular plants. Phloem is responsible for transporting sugars, proteins, and other organic molecules in plants.

Water and salt travel upwards mainly in the xylem and food substances travel up and down in the phloem.

Leaf has epidermis on both of its surfaces. The photosynthetic tissue of a leaf is sandwiched between its upper and lower epidermis and is well supplied by the vascular system. In a leaf, xylem always faces the upper epidermis i.e. the adaxial side while phloem faces both upper as well as lower epidermis.

Photosynthesis is the process by which green plants make their own food from carbon dioxide and water in the presence of sunlight. The prepared food is glucose. To prepare one molecule of glucose, by the process of photosynthesis six molecules of carbon dioxide and six molecules of water is required. Six oxygen molecule is released as a waste product. This oxygen is produced due to splitting of water by the process of photolysis during light reaction. So, the correct answer is option 'Oxygen'.

In physiology, respiration is defined as the movement of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction. The physiological definition of respiration should not be confused with the biochemical definition of respiration, which refers to cellular respiration. The metabolic process by which an organism obtains energy by reacting oxygen with glucose to give water, carbon dioxide and 38 ATP (energy). Although, physiologic respiration is necessary to sustain cellular respiration and thus life in animals, the processes are distinct: cellular respiration takes place in individual cells of the organism, while physiologic respiration concerns the bulk flow and transport of metabolites between the organism and the external environment. 

Lenticels are involved in gaseous exchange between internal tissues and atmosphere. These are porous tissues present in periderm that are developed during secondary growth.

The highest rate of respiration are found in the actively growing root and stem tips, cambium and embryos of germinating seeds and lowest rates in dormant seeds or spores. As, the growing tips are generally rich in meristematic tissues the rate of respiration is also high.