Plant Transport and Physiology

Senescence refers to a number of controlled processes which finally culminate in death of the plant part. Senescence is a controlled process and is generally responsible for conservation of precious part nutrients like nitrogen and phosphorous. The senescing plant part is separated from plant due to formation of an abscission layer which finally separated the plant part.

Certain fruits ripen with sudden rise in cellular respiration and ethylene production. Such fruits are called 'climacteric fruits'. Climacteric is considered final stage in fruit ripening process during which the fruit is maximum ripened with best taste for consumption. After that period, it starts to gradually deteriorate and the respiration returns to normal rate.

Stress hormone is a hormone produced during adverse environmental conditions. Abscisic acid (ABA) is called as stress hormone. Due to this hormone, plants respond to stresses conditions like cold, drought. Stomatal closure under stress condition is due to this hormone. It also promotes seed dormancy under adverse condition.

ABA inhibits seed germination. ABA stimulates the closure of stomata in the epidermis and increases the tolerance of plants to various kinds of stresses.

Acid deposition primarily damages the waxy cuticle of leaves, which leads to increased water loss and susceptibility to pathogens. While it can affect soil chemistry and roots indirectly, the direct primary damage is to the foliage.

A plant cell is characterised by a single large sap vacuole. They enclose sap or water with dissolved inorganic and organic substances. It is surrounded by a membrane called as tonoplast. Plant cell vacuole maintains osmotic pressure for turgidity and osmosis. They also store useful as well as waste substances. The growth in terms of increase in size depends on the elongation of the cell. For elongation of the cell, the protoplasm needs to push against cell wall from inside. The generation of pushing force depends on the osmotic pressure created by substances stored in central vacuole. Thus, the correct answer is option D.

Gymnosperms and angiosperms (like maize) are seed plants that use pollen tubes for fertilization, meaning they do not require external water for the sperm to reach the egg.

Gymnosperms do not have vessels in their xylem. Water conducting tissues present in them are tracheids.

Sphagnum do  not decay readily because of the phenolic compounds embedded in the moss's cell walls. Peat moss can also acidify its surroundings by taking up cations, such as calcium and magnesium and releasing hydrogen ions. Due to presence of hyaline cells, they have the large water-holding capacity.

• Moss peat is decayed dried sphagnum moss. It is hygroscopic, i.e. it has the ability to hold water either by absorption or adsorption. Its use as packing material for sending flowers and live plants to distant places helps to keep flowers and plants fresh.
• Hence Moss peat is used as a packing material and for sending flowers and live plants to distant places because it is hygroscopic.
• So, the correct answer is 'Hygroscopic'.

Sporophyte of moss differentiates into foot, seta and capsule. The foot embedded in the female receptacle and absorbs inorganic nutrients. Seta is a long stalk with a pear-shaped capsule by its tip. Capsule has 3 parts-basal apophysis, central theca and terminal operculum.

Vascular tissues, specifically xylem and phloem, run vertically through the stem to transport water, minerals, and sugars between the roots and the leaves.

The root system is responsible for anchoring the plant securely in the ground and absorbing water and essential minerals from the soil.

Turgor pressure is the force exerted by the cell contents against the cell wall in plants, which helps maintain structural rigidity. Osmotic pressure drives the water movement that creates this force.