Test: Transportation In Plants - 2 - Class 10 MCQ

In plants, water transport mineral salts through special tubes called xylem. Plants have root hairs on their primary and secondary roots. Plants absorb water and mineral salts from the soil with the help of root hairs. They absorb water by the process of osmosis. Osmosis is the movement of water molecules (solutes) from a lower concentration solution to a higher concentration solution through a semi permeable membrane. So when concentration of solutes in the cell sap is high, water is absorbed by root hair. 

The principal pathways by which water is translocated in angiosperms:
The translocation of water in angiosperms mainly occurs through the xylem vessel system. Here are the key points explaining the process:
1. Xylem vessel system:
- The xylem vessels are specialized cells that form a continuous network throughout the plant.
- They are responsible for transporting water and minerals from the roots to the rest of the plant.
- Water moves through the xylem vessels in a unidirectional manner, driven by transpiration and the cohesive properties of water molecules.
2. Xylem and phloem:
- While the xylem vessels primarily transport water, the phloem is responsible for the translocation of organic compounds, such as sugars.
- The xylem and phloem are adjacent tissues within the plant's vascular system.
- However, water movement primarily occurs through the xylem vessels, while the phloem transports sugars and other organic molecules.
3. Sieve tube members of phloem:
- The phloem consists of specialized cells called sieve tube members.
- These cells are arranged end to end, forming sieve tubes that facilitate the translocation of sugars and other organic compounds.
- The movement of water through the phloem is limited and occurs through the apoplast pathway.
4. Sieve cells of phloem:
- Sieve cells are present in some gymnosperms and lower vascular plants but are not found in angiosperms.
- These cells are involved in the translocation of organic compounds in plants where they are present.
In conclusion, the principal pathway for water translocation in angiosperms is the xylem vessel system. While the phloem also plays a role in the transport of organic compounds, water movement primarily occurs through the xylem.

Water molecules have high cohesion and adhesion forces acting between them thus, a continuous column of water is formed in the xylem. Transpiration i.e., evaporation of water molecules from the cells of the leaf creates a suction force (transpiration pull) which pulls water from xylem cells. To maintain the continuous water column due to cohesion forces water is absorbed from the soil.

Transpiration is the loss of water from leaves in the form of vapour. There are some factors that affect the transpiration such as temperature, concentration of carbon dioxide, humidity, and atmospheric pressure. The reduction of atmospheric pressure reduces the density of the external atmosphere. This allows more rapid diffusion of water. The plants growing on hills show the higher rate of transpiration because of low atmospheric pressure and thus they develop xerophytes characters. Thus, option A is correct and other options are wrong.

Transpiration is loss of water in vapour form through stomata. Rate of transpiration depends on a number of factors, like carbon dioxide concentration, temperature, light, humidity etc. The most important factor which governs rate of transpiration is the vapour pressure gradient, which exists between leaf mesophyll and atmosphere. Thus, more the humidity lesser the rate of transpiration and vice versa.

Two equal pieces of cobalt chloride paper are dried and placed one on the upper surface and the other on the lower surface of dorsiventral leaves. They are firmly held in place by pieces of cellotapes or glass slides. After a few minutes the cohalt chloride paper shows change in colour from blue to pink. The time taken for the cobalt chloride paper on the upper surface of the leaf to turn pink is much longer than for the under surface. Thus, it proves that the rate of transpiration is greater from the under surface of dorsiventral leaves.

Transpiration is the process of water loss from leaves in the form of vapour. It is necessary for transporting minerals from the soil to the plant parts, cooling the plant, moving sugars and maintaining turgor pressure. Excretion of minerals does not occur through transpiration.

Rate of transpiration slows down when the non-rigid parts of the plant loses its rigidity and is called wilting of plant.

Transpiration occurs through the stomatal openings present on the leaves of plants. About 80% to 90% of water is lost through transpiration. Maximum transpiration occurs in mesophyte. In mesophytic plants, stomata are present on both surface of leaves. In hydrophytic plants, stomata are present only on the upper surface. Thus, the correct answer is option A.

Stomata are pores in the leaf that allow gas exchange where water vapor leaves the plant and carbon dioxide enters. Special cells called guard cells control each pore's opening or closing. When stomata are open, transpiration rates increase; when they are closed, transpiration rates decrease.

Stomatal transpiration occurs during the day time as the stomata remain open during the day time. Lenticular transpiration is the type of transpiration is the type of transpiration which occurs through the small pores present in the bark. 
Cuticular transpiration, cuticle is an impermeable covering present on the leaves and stem. 

The big banyan tree leaves transpire. It loses a lot of water during summer by transpiration. The transpired water vapour stays around the tree. This makes the area cooler. This makes us feel cool near a banyan tree during summer.

It happened so because there is a frequent lossof water from the leaves by transpiration due to which a transpirational pull is developed in the leaves which pull the water against the force of gravity.

A potometer sometimes known as a transpirometer, is a device used for measuring the rate of water uptake of a leafy shoot.

Transpiration is the process of evaporation of water through aerial parts of the plant. The rate is high when the soil is wet and the air is dry. 

Transpiration plays a vital role in the body of the plants, some of them are : It helps it to transport water and minerals towards the leaves from the roots in the upward direction against the gravitational pull It cools down the plant during summers It removes excess water Also when water is eliminated from the plant it urges the roots to pull more water and along with them minerals are also absorbed with is beneficial for the plant.