Types of wood - class-VI

In certain plants like Strychnos, anomalous secondary growth occurs where the cambium produces phloem islands within the xylem, a phenomenon known as interxylary phloem.

Urtica is a well-known example of a plant that exhibits anomalous secondary growth, specifically the presence of phloem or parenchyma islands within the wood.

Ochroma, commonly known as Balsa wood, is famous for having an extremely low density and specific gravity, often well below 0.2.

Fibre is a narrow, elongated cell with thick lignified wall and narrow lumen tapering to a wedge-shape at both ends. Sometimes the deposition of lignin is so thick as to obliterate the central lumen. The fibres appear more or less angular in cross-sectional view with little intercellular spaces. The cell wall is pitted and may show slight indentation (ex. Zingiber).

• Dalbergia is also known as African Blackwood.
• It is a flowering plant belonging to the family Fabaceae which are native to seasonally dry regions of Africa.
  
• It produces dense, lustrous wood which is reddish to pure black in colour.
• So, the correct answer is 'Dalbergia'.

Springwood is formed due to the rapid activity of the vascular cambium. The vessels are wider in lumen. It is light and has low density. Heartwood is the wood that has non-functional vessels due to deposition of lignin by tyloses. It appears dark and has more density. So, the correct answer is springwood is lighter in colour and has a lower density as compared to heartwood.

A. Springwood is the soft and porous portion of an annual ring of wood developed during the early growing season or spring season and is known as earlywood.

• Heartwood is also known as duramen.
• It is the central dead part wood of trees. 
• The cells in this region contain tannins or resins that give it a dark colour.
• It is inactive and does not conduct water.
  
• So, the correct answer is '(i) and (iv)'.

• The outer, new living layers of a secondary wood of a tree where transport of water and minerals to the crown of the tree take place are called alburnum. 
  
• Alburnum is also known as sapwood.
• It contains high moisture content than a heartwood.
• So, the correct answer is 'Sapwood'.

Heartwood is the dead, inner part of the wood that no longer conducts water. Its primary function is to provide structural support and mechanical strength to the tree.

Wood is the common name for secondary xylem, which is produced by the vascular cambium during secondary growth in dicot stems and roots.

In most of the gymnosperms such as conifers and cycads. Vessels are not present and the wood is made entirely of tracheids. These woods are known as nonporous. In angiosperms, the wood consists of both tracheids and vessels. The wide vessels are appearing with pores between. Such wood is called porous. 

In these porous woods, if vessels have essentially equal diameters the wood is known as diffuse-porous. It is the characteristic of plants growing in tropical regions.

So, the correct option is D.

The older woody trees show two characteristic types of wood namely heartwood and sapwood. The heartwood is made up of dead xylem vessels that have been filled with tyloses and are rich in deposits of resins and tannins. These are non-functional and appear darker. 

The sapwood contains the newly formed vessels that are functional and appear lighter. The hardwood provides resistance from the pest attack and increases the durability of the wood.

Hence, the correct answer will be having dead and non-conducting elements.

The correct option is B.

In the dicotyledonous trees growing temperate regions, during secondary growth, vascular cambium is less active in autumn season because of the existence of unfavourable conditions.

So, the correct option is ‘Less active’.

In the dicotyledonous trees growing temperate regions, during favorable conditions, large amount of secondary xylem is formed. It is called Spring wood or early wood. It consists of large, thin walled broad tracheary elements. In the unfavorable conditions, less amount of secondary xylem is formed. It is called autumn wood or late wood. It consists of small, thick walled narrow tracheary elements.

So, the correct option is ‘Narrow tracheary elements’.

The inner or central dark coloured non-functional wood or secondary xylem formed during secondary growth in dicot stem is called Heartwood or duramen.

So, the correct option is ‘Inner part of secondary xylem’.

Heartwood or duramen is a source for the manufacture of different varieties of furniture items. So heart wood is the wood of commerce.

So, the correct option is ‘Heartwood(duramen)'.

A.Collenchyma – cells are living present in the younger parts of the plant body.

B.Chlorenchyma – cells are living, possess more number of chloroplast.

C.Periderm – a multilayered tissues composed with both living and non living or dead cells

D.Endodermis – cells are living, vertically elongated, appear barrel shape.

So, the correct option is 'Periderm'.

Secondary xylem, light in density and porous are called lightest wood. It is obtained from the tree Ochroma lagopus, a member of Malvaceae.

Tectona grandis - Hard wood is present.

The large sized, slightly raised sports or aerating pores present in the cork tissue or are called Lenticels. These are the patches on the surface of the bark. These are found in old dicotyledonous stems. These are formed in the place of stomata. They have outer raised margins and internally, loosely arranged colourless parenchyma cells are present, called as complementary cells, These are meant for gaseous exchange.

Secondary xylem without vessels is called non-porous wood. It is found in the wood of gymnosperms. 

In dicotyledonous stems, during intra stellar secondary growth, a ring of cambium called vascular cambium is formed.  In the plants growing temperate regions, the activity of vascular cambium is influenced by the existence of maximum seasonal variations. In the spring or early summer, due to the existence of favourable conditions, a large amount of secondary xylem is formed. it is called Springwood or early wood. It is lighter in colour with low density. In the autumn season, due to the presence of unfavourable conditions, less amount of wood is formed. it is called autumn wood or latewood. It is darker in colour with higher density.

So the correct option is ‘Spring wood and autumn wood’.

In Quercus and Pinus, during secondary growth, secondary xylem show vessels without pores, also non porous vessels. It is loose and soft. So it is not considered as heart wood. So, heart wood is absent in Quercus and Pinus.

So,
the correct option is ‘Quercus and Pinus’.

A.Salix  - wood is used in making boxes, brooms, cricket bats, Hockey bats,cradle boards, chairmans and other furniture, dolls, flutes, poles, sweat lodges, toys, turnery, tool handles, veneer, wands and whistles.

B.Morus – wood is used in making Fence posts, furniture, and turned objects

C.Picea – wood is used in buildings

d.Phytelephas – wood is used in making ivory.

So,
the correct option is ‘ Salix’.    

In Dalbergia, during secondary growth, hart wood is formed. It consists of vessels, trachieds and parenchyma in equal proportions.

So,
the correct option is ‘Vessels, trachieds, and parenchyma in equal proportions’.

In the trunk and older branches of the large trees, only the outer secondary xylem i.e. sapwood serves in water conduction. Whereas the inner part i.e. heartwood,  is composed of dead but structurally strong primary xylem. Thus the youngest layer of secondary xylem is located just inner to sapwood and not in the centre of the stem.

The correct answer is option C.

• Wood specific gravity is the measurement of the amount of dry cell-wall material per unit volume of the wood. 
• It is in such a way that probably the single most important predictor of the properties of wood. 
• It is among the species as woods range in specific gravity from less than 0.05 for Aeschynomene hispida Wild.
• Thus, the correct answer is option D.

• The hardness of a cell refers to the sturdiness of the cell wall because of the presence of lignin and cellulose present in them.
  
• Lignin is a naturally occurring complex organic cross-linked phenolic polymer that forms an important structural material of the plant cell wall (secondary cell wall).
• They are mainly found regions of wood and bark as they provide rigidity and prevents deterioration.
  
• It also provides support to tissues of vascular plants and few algae.
• So, the correct answer is 'Lignin'.

They are generally propagated by vegetative to produce offsprings which are practically clones of their parent plants. If a plant has favourable traits, it can continue to pass down its helpful genetic information to its family. This is especially economically advantageous as it allows commercial growers to clone a particular plant to ensure consistency throughout their crops.

Thus, the correct answer is C.

Cellulosic materials are comprised of lignin, hemicellulose as well as cellulose. So, these are called as lignocellulosic materials. One main function of lignin is to provide structural support for the plant. Cellulose molecules are consisting of long chains of glucose molecules. This is for that the starch molecules to have a different structural configuration. So, the preparation of pure cellulose by removing lignin is an important step in the manufacture of pulp. It is for the paper industry from the woody tissues of plants to make a better quality paper.

Removal of water from the wood by prolonged heating at approximately $50^{0} C$. The other options are not relevant.

Thus, the correct answer is option D.

Secondary xylem consists of large-sized vessels and tracheas. Their cell walls are thickened by lignin deposition and it provides excellent mechanical support to the plant. This thicken deposition is the wood of the plant and it is used for making timber.

Catch is obtained from the heartwood of Acacia species, especially from Senegalia catechu or Acacia catechu. 

Secondary growth is characterized by an increase in thickness or girth of the plant, and is caused by cell division in the lateral meristem, which are lacking in herbaceous plants. Lateral meristems include the vascular cambium and, in woody plants, the cork cambium.

Heartwood is non -functional as it does not conduct water and minerals. It may have ingrowths of tylosis, deposition of resins, tannins and other secondary metabolites of the plant. It is hard and is also called duramen.

A.Central wood - The hard fibrous material that forms the main substance of the trunk or branches of a tree or shrub, used for fuel or timber.

B.Heart wood -  The inner or central dark colored non-functional resin clogged wood or secondary xylem formed during secondary growth in dicot stem is called Heart wood or duramen.

C.Alburnum– The outer light coloured functional wood which contains living cells formed during secondary growth in dicot stem is called Alburnum or sap wood.

D.Hardwood – secondary xylem or wood present in broad leaved tropical and temperate forests.

So, the correct option is ‘Heart wood’.

A.Duramen – also called heart wood.

B.Alburnum – also called sap wood.

C.Primary xylem – also called hydromel.

D.Spring wood – also called early wood.

So, correct option is ‘duramen’.

A ring of wood or secondary xylem formed by the association of spring wood and autumn wood is called annual ring. In every year one annual ring formation occurs in dicot stems.

So, the correct option is ‘autumn wood and springwood’.

In dicotyledonous stems, during intra stellar secondary growth, a ring of cambium called vascular cambium is formed.  In the plants growing temperate regions, the activity of vascular cambium is influenced by the existence of maximum seasonal variations. In the spring or early summer, due to the existence of favourable conditions, a large amount of secondary xylem is formed. it is called Springwood or early wood. In the autumn season, due to the presence of unfavourable conditions, less amount of wood is formed. it is called autumn wood or latewood.  Every ring of spring wood and autumn wood together form into an annual ring. In the 26 rings, 13 rings constitute spring wood and 13 rings constitute autumn wood. So total 13 annual rings are present.

A.False – Secondary xylem formed during spring season, during the secondary growth of dicotyledonous stem is called Spring wood or early wood. It is light coloured and high density.

B.False - Secondary xylem formed during spring season, during the secondary growth of dicotyledonous stem is called Spring wood or early wood. It is light coloured and high density.

C.False – Secondary xylem formed during autumn season, during secondary growth of dicotyledonous stem is called autumn wood or late wood. It is dark coloured and high density.

D.True - Secondary xylem formed during autumn season, during secondary growth of dicotyledonous stem is called autumn wood or late wood. It is dark coloured and high density.

So,
the correct option is ‘Autumn wood- dark colour, high density’.

In winter, when the cambium is less active and forms fewer xylary elements that have narrow vessels then this wood is called autumn wood or late wood. While, in spring season, cambium is very active and produces a large number of xylary elements having vessels with wider cavities, this wood is called springwood or early wood.

In dicotyledonous stems, during intra stellar secondary growth, a ring of cambium called vascular cambium is formed.  In the plants growing temperate regions, the activity of vascular cambium is influenced by the existence of maximum seasonal variations. In the spring or early summer, due to the existence of favourable conditions, a large amount of secondary xylem is formed. it is called Springwood or early wood. In the autumn season, due to the presence of unfavourable conditions, less amount of wood is formed. it is called autumn wood or latewood.  A spring wood and autumn wood together form into an annual ring. Every annual ring becomes sapwood, it is light coloured, peripheral functional wood and every sap wood gradually transform into heat wood, it is inner or central dark coloured non-functional wood contains resin clogged structures called tyloses. 

So, the correct answer is 'Duramen and alburnum'.

In coniferous gymnosperms, secondary growth takes place by the formation of vascular cambium. it produces secondary xylem or wood towards its innerside and secondary phloem or bast towards outerside. Secondary xylem, shows more number of vessels without pores. So these are called non-porous vessesl. So the wood is called soft wood or non-porous wood.

In dicotyledonous stems, during intra stelar secondary growth, a ring of cambium called vascular cambium is formed.  Vascular cambium produces more amount of secondary xylem towards its innerside, and less amount of secondary phloem towards innerside. In the plants growing temperate regions, the activity of vascular cambium is influenced by existence of maximum seasonal variations. In the spring or early summer, due to the existence of favorable conditions, large amount of secondary xylem is formed. it is called Springwood or early wood. It is lighter in colour with low density. In the autumn season, due to the presence of unfavorable conditions, less amount of wood is formed. it is called autumn wood or late wood. It is darker in colour with higher density.

So, the correct answer is 'Depends on season and region where the plant grows'.

Secondary xylem is of different types is called heteroxylous wood. In this, the formation of sapwood and heartwood takes place. It is mostly found in dicotyledons.

So, the correct option is ‘Angiosperms’.

Cambium activity is influenced by the climatic changes The cambium is more active during the spring that forms plenty of xylem vessels with wider cavities also called as earlywood or the spring wood. Springwood constitutes a major part of the annual ring and occurs at the beginning of an annual ring. It contains larger and wider elements and wood is lighter in color.

Cambium activity is influenced by the climatic changes The cambium is more active during the spring that forms plenty of xylem vessels with wider cavities also called as early wood. In winter this activity slows down and gives rise to narrower xylem elements. This is the late wood or autumn wood. 

Some of the dividing pericycle cells are committed to the asymmetric, formative divisions that give rise to lateral root primordia and lateral root formation. The endodermis is the central, innermost layer of cortex in some land plants. It is made of compact living cells surrounded by an outer ring of endodermal cells with hydrophobic substances (Casparian Strip) to restrict the apoplastic flow of water to the inside. Sapwood is the soft outer layers of recently formed wood between the heartwood and the bark, containing the functioning vascular tissue and not central, dark colored, non-conducting part of secondary xylem.

• In the spring season, cambium is very active and produces a large number of xylary elements having vessels with wider cavities and form spring or earlywood and has light colour with lower density while late or autumn wood is formed in winter and vessels are less in number with a narrow lumen which is dark in color with high density.