Question

What are Complex tissues? Describe various types of complex tissues.

Answer 1

Complex tissues are made up of more than one type of cells and they work together as a unit. They transport water, salt and prepared food material to various parts of the plant body. Complex tissues are of two types. Xylem and Phloem are also called vascular tissue and together they constitute vascular bundles.

Answer 2

HLO MATE HERE IS UR ANSWER.

❤. COMPLEX TISSUES ❤

⭐. The complex tissues are made of more than one type of cells and these work together as a unit.

⭐. The comolex tissues in plany are of two types.

a) xylem b) phloem.

❤. xylem ❤

• Functions as conducting tissue for water and minerals from roots to the stem and leaves.
• It also provides mechanical strength to the plants parts.
• It is comoosed of four differeny kinds of elements , namely

⭐. Tracheids .

⭐. vessels.

⭐. Xylem fibres and

⭐.Xylem parenchyma.

❤. Tracheids ❤

• Tracheids are elongated or tube like cells with and lignified walls and tapering ends.
• These are dead and without protoplasm.
• The inner layerd of the cell walls have thickenings which vary in form.

✨.In flowering plants , tracheids and vessels are the main water transporting elements .

❤. vessels ❤

• vessel is a long cylindrical tube - like structure made up of many cells called vessel membranes.
• Each with lignified walls and a large central cavity.
• The vessel cells are also devoid of protoplasm.
• Vessel members are interconnected through perforations in their common walls.
• The presence of vessels is a characteristic feature of angiosperms.
• Gymosperms lack vessels in their xylem.

❤. xylem fibres ❤

• Xylem fibres have highly thickned walls and obliterated central lumens.
• These may either be septate or aspetate.
• They provide mechanical support.

❤. Xylem parenchyma ❤

• Xylem parenchyma cells are living and thin -walled , stores the materials in the form of starch or fat , and other substance like tanins.
• The radial conduction of water takes place by the rau parenchymatous cells.

❤. Primary xylem ❤

• primary xylem is of two types , protoxylem and metaxylem.
• The first formed primary xylem elements are called protoxylem and the later formed primary xylem is called metaxylem.
• In stems , the protoxylem lies towards the centre (pith) and the metaxylem towards the periphery.Such arrangements of primary xylem is called endarch.
• In roots , the protoxylem lies towards the centre such arrangements of primary xylem is called exarch.

❤.PHLOEM ❤

⭐. phloem transports food materials , usually from leaves to other parts of plant.

⭐. phloem in angiosperms is composed of.

✨. sieve tube elements.

✨. Companian cells.

✨. Pholem parenchyma and

✨. Pholem fibres.

❤. Gymosperms have albuminous cells and sieve cells. They lack sieve tubed and companian cells ❤

❤. Sieve tube elements ❤

• Sieve tube elements are also long , tube like stmc-tures, arranged longitudnally and are associated with the companian cells.
• Their end walls are perforated in a sieve - like plates.
• A mature sieve element possesses a peripheral cytoplasm and a large vacuoble but lacks a nucleus.
• The functions of sieve tubes are controlled by the nucleus of companion cells.

❤. Companion cells ❤

• companion cells are specialised parenchyma -v tous cells , which are closely associated with sieve M tube elements.
• The sieve tibe elements and companion cells are connected by put fields present between their common longitudnal walls.
• The companion cells helps in maintaining the pressure gradient in the sieve tubes.

❤. Phloem parenchyma ❤

• Pholen parenchyma is made up elongated , tapering cylindrical cells which have dense cytoplasm and nucleus.
• The cell wall is composed of cellulose and has pits through which plasmodesmatal connections exist between the cells.
• The phloem parenchyma stores food material and other substance lime resins , latex and mucilage.
• Phloem parenchyma is absent in most of the monocotyledons.

❤. Phloem fibres ( bast fibres)❤

• Phloem fibres are made up of sclernchyma -tous cells.
• These are generally absent in the primary pholem but are found in the secondary phloem.
• These are much elongated , unbranched and have pointed , needle like apices.
• The cell wall of phloem fibres is quote thick.
• At maturity , these fibres lose theri protoplasm and become dead.
• Pholem fibres of jute , flax and hemp are used commercially.
• The first formef primary phloem consists of narrow sieve tubes and is referred to as protophloem and the later formed phloem has bigger sieve tubes and is reffered to as metaphloem.