- Xylem contains tracheids, vessels, xylem parenchyma and xylem fibre.
- Tracheids: They are elongated, tubular dead cells with tapering end walls.
- Vessels: These are also known as trachea. They are elongated, tubular dead cells. They are joined to each other by end to end forming a continuous pipe. The cells are thick and lignified.
- Xylem parenchyma: They are also called wood parenchyma. This is the only living tissue of xylem.
- Xylem fibre: They are dead cells with thick walled fibre.
- Phloem consists of sieve tubes, companion cells, phloem parenchyma and phloem fibres.
- Sieve tubes: These are elongated, tubular living cells arranged in a row, with their perforated end walls forming a sieve. They are non-nucleated. Their protoplasm are inter-connected through sieve plates. They possess vacuoles.
- Companion cell: They are elongated, lens-shaped cells containing dense cytoplasm and prominent nuclei. These cells maintain connection with sieve cells through pits.
- Phloem parenchyma: They are living thin walled parenchyma cells.
- Phloem fibre: They are also known as bast fibre. They are elongated fibre like sclerenchymatous dead cells with thick walls containing pits and interlocked ends. Phloem fibre are the only dead cells in phloem.
Hope you could get an idea from here.
Doubt clarification - use comment section.
The correct answers are a, c, d.
There are three types of capillaries: continuous, sinusoidal (or discontinuous) and fenestrated. Continuous capillaries are the most common type and they form tight junctions. Sinusoidal capillaries form an incomplete lining with several gaps, which allow red and white blood cells and some serum proteins to pass. These capillaries are mainly found in the bone marrow, lymph nodes and adrenal glands. Finally, fenestrated capillaries facilitate the movement of smaller molecules and plasma proteins and are mainly found in the small intestine. The majority of the fluid transport happens through the fenestrated capillaries.
Answer:
The statement is false.
Explanation:
Passive transport moves molecules from one side of the membrane to the other with the energy of the chemical gradient (or concentration gradient). Otherwise, active transport uses the hydrolyzation of ATP to gain energy in order to move molecules across the membrane without taking into account the gradient.
