Plant Transport and Physiology

It is the pipeline that carries water and nutrients from roots to leaves.

Sliced leaves reduce wind resistance.

Parenchyma is a versatile living tissue involved in storage, photosynthesis, and providing basic structural support. Flexibility, which allows plant parts to bend without breaking, is specifically provided by collenchyma tissue. Collenchyma cells have characteristic wall thickenings that parenchyma cells lack.

Phloem is the vascular tissue responsible for transporting organic nutrients, primarily sucrose, from the leaves to other parts of the plant. Sieve tubes are the main conducting elements within the phloem that facilitate this transport. Xylem components like vessels and tracheids are instead responsible for water and mineral transport.

Transpiration is the process where plants lose water in the form of vapor. This primarily occurs through small pores called stomata located on the surface of leaves. Phloem and sclerenchyma are structural or transport tissues not directly responsible for gas exchange or vapor loss.

Desert plants, or xerophytes, must conserve water in arid environments. A thick epidermis, often covered by a heavy waxy cuticle, helps reduce water loss through evaporation. Other adaptations like sunken stomata or fleshy stems also contribute to water conservation.

Xylem is responsible for the upward conduction of water and minerals from the roots to the rest of the plant. Its thick, lignified cell walls also provide significant mechanical strength and structural support to the plant body.

High humidity restricts the transpiration because humid air is almost saturated with water vapour and cannot absorb much more by transpiration.

Iron is essential for the synthesis of chlorophyll. Because iron is immobile within the plant, its deficiency first appears as interveinal chlorosis (yellowing between the veins) on young, developing leaves.

Exanthema is a physiological disorder in citrus plants caused by a deficiency of copper. It is characterized by the formation of gum pockets under the bark and the dying back of young twigs.

Necrosis refers to the localized death of plant tissue, often appearing as brown or black spots on leaves. Deficiencies in mobile macronutrients like Potassium (K) and Magnesium (Mg), as well as Calcium (Ca), frequently manifest as necrotic areas.

By utilizing capillary action and the inherent surface tension of water, transpiration pull and cohesion force transport the water by xylem in tall trees.

Sir J.C. Bose (1923) advocated pulsation theory to explain ascent of sap. He proved that the living cells of innermost layer of cortex lying just outside the endodermis were in a state of rhythmic pulsations.

Guttation is the secretion of water, during conditions of high humidity, on to the surface of leaves through specialized pores, or hydathodes. 

Transpiration primarily occurs through the stomata, which are located in the epidermis of the leaves. The epidermis is a type of dermal tissue, making it the site of maximum water loss.