Permanent Tissue Questions in English

(B) $Collenchyma$ is known as living mechanical tissue.
It provides mechanical support to the growing parts of the plant, such as young stems and petioles of leaves.
Unlike $Sclerenchyma$, which consists of dead cells at maturity, $Collenchyma$ cells are living and possess thick primary cell walls composed of cellulose, hemicellulose, and pectin.

(C) The cells are classified based on their viability at maturity:
$1$. Parenchyma: These are living cells with thin cell walls.
$2$. Sclerenchyma fibers: These are dead cells at maturity,providing mechanical support.
$3$. Sclereids: These are also dead cells at maturity,characterized by thick,lignified walls.
$4$. Collenchyma: These are living cells that provide mechanical support to young stems and petioles.
Therefore,Sclerenchyma fibers and Sclereids are dead cells,while Parenchyma and Collenchyma are living cells.
Total number of dead cells = $2$.

(B) $P$. Parenchyma cells have thin cell walls made of cellulose,so they show no significant thickening.
$Q$. Collenchyma cells are characterized by uneven thickening of the cell wall due to the deposition of pectin,cellulose,and hemicellulose.
$R$. Sclerenchyma cells have thick,lignified secondary cell walls,which provide structural support.
Therefore,the correct matching is $(P-I), (Q-II), (R-III)$.

(A) Collenchyma is a simple permanent tissue that provides mechanical support to the growing parts of the plant,such as young stems and the petioles of leaves.
It consists of cells that are thickened at the corners due to the deposition of cellulose,hemicellulose,and pectin.
Unlike sclerenchyma,which provides support to mature plant parts,collenchyma provides flexibility and support to young,growing organs.

(B) Xylem vessels and tracheids are the main conducting elements of the xylem tissue in plants.
These cells have thick,lignified secondary walls.
Lignin is a complex polymer that provides structural support and mechanical strength to the plant body,allowing it to withstand the negative pressure generated during water transport.
Therefore,the thickening of the walls of xylem vessels and tracheids is due to the deposition of lignin.

(A) In plants,the primary xylem is differentiated into two types based on the time of their development:
$1$. $Protoxylem$: The first formed primary xylem elements are called protoxylem.
$2$. $Metaxylem$: The later formed primary xylem elements are called metaxylem.
These are components of the primary xylem,which develops from the procambium during primary growth.

(A) Permanent tissues are composed of cells that have lost the ability to divide. These cells are derived from meristematic tissues and have attained a specific shape,size,and function through the process of differentiation. Therefore,cells of permanent tissue are differentiated.

(B) The phloem consists of four types of elements: sieve tube elements,companion cells,phloem parenchyma,and phloem fibers.
Phloem fibers (also known as bast fibers) are made of sclerenchymatous cells.
These cells are generally absent in primary phloem but are found in secondary phloem.
Due to their thick-walled,lignified nature,phloem fibers provide mechanical support to the plant body.

(A) Xylem parenchyma cells are the only living cells in the xylem tissue. They store food materials in the form of starch or fat,and other substances like tannins.
Phloem parenchyma cells are composed of elongated,tapering cylindrical cells which have dense cytoplasm and nucleus. They store food materials in the form of food reserves like starch or fat,and other substances like mucilage,resins,or latex.

(A) The provided figure shows the structure of phloem tissue.
$P$ points to the sieve pores located on the sieve plate,which allow for the transport of materials between sieve tube elements.
$Q$ points to the companion cell,which is a specialized parenchyma cell associated with the sieve tube element.
$R$ points to the phloem parenchyma,which is involved in the storage of food materials and other substances.
Therefore,the correct identification is $P-$Sieve pore,$Q-$Companion cell,$R-$Phloem parenchyma.

(A) In plants,the primary xylem is the first formed xylem tissue that differentiates from the procambium during primary growth.
It consists of two types of vessels based on the time of their development:
$1$. $Protoxylem$: The first-formed primary xylem elements,which are smaller in diameter.
$2$. $Metaxylem$: The later-formed primary xylem elements,which are larger in diameter.
Therefore,both $Protoxylem$ and $Metaxylem$ are components of the primary xylem.

(A) Companion cells are specialized parenchymatous cells that are closely associated with sieve tube elements.
They are derived from the same mother cell as the sieve tube elements.
Since sieve tube elements are specialized parenchyma,companion cells are also considered to be derived from parenchyma cells.

(B) Primary phloem is formed from the procambium during the early development of the plant.
In primary phloem,phloem fibers are generally absent or very rare.
Phloem fibers (bast fibers) are typically found in secondary phloem,which is formed later by the vascular cambium.
Therefore,the correct answer is $B$.

(D) The fruit wall of nuts,such as walnuts or almonds,is extremely hard and provides protection to the seed.
This hardness is due to the presence of $Sclerenchyma$ tissue,specifically a type of $Sclerenchyma$ cell known as $Sclereids$ (or stone cells).
$Sclereids$ are dead cells with highly thickened,lignified cell walls that provide mechanical support and rigidity to plant parts.
While $Sclereids$ are a type of $Sclerenchyma$,in the context of specific anatomical structures like fruit walls (endocarp) and seed coats,$Sclereids$ is the most precise answer.

(C) Statement $I$ is false because both parenchyma and collenchyma are living tissues. Collenchyma cells are living and possess protoplasm.
Statement $II$ is true because gymnosperms typically lack xylem vessels (tracheids are the main water-conducting elements),whereas the presence of xylem vessels is a defining characteristic of angiosperms.

(B) The correct answer is $B$.
Collenchyma is a living mechanical tissue found in plants.
The cell walls of collenchyma are unevenly thickened due to the deposition of cellulose,hemicellulose,and pectin.
Unlike sclerenchyma (fibers and sclereids) and xylem elements (tracheae/vessels),collenchyma cells do not contain lignin in their cell walls.