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Test: Secondary Growth - ACT MCQ


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30 Questions MCQ Test - Test: Secondary Growth

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Test: Secondary Growth - Question 1

Spring wood (early wood) differs with autumn wood (late wood) in -

Detailed Solution for Test: Secondary Growth - Question 1

The growth ring closer to the centre of the tree, and formed early in the growing season (when the growth is rapid) is usually composed of wider elements. It is usually light in color as compared to the outer ring and is called springwood (earlywood). The outer ring is called winterwood (latewood).

Test: Secondary Growth - Question 2

Most conspicuous annual rings form in -

Detailed Solution for Test: Secondary Growth - Question 2

More distinct annual rings are formed in that regions, where climatic variations are sharp. More distinct annual rings are formed in temperate plants. Distinct annual rings are not formed in tropical plants. Distinct annual rings are not formed in India except Himalayan regions. Least distinct annual rings are formed in seashore regions, because the climate remains same throughout the year. 
More clear annual rings are formed in deciduous plants as compared to evergreen plants in temperate regions. In deserts annual rings are less distinct. Annual rings are bands of secondary xylem and xylem rays
So, the correct answer is 'Temperate deciduous plants'

Test: Secondary Growth - Question 3

Formation of vascular rays occurs in which order

Detailed Solution for Test: Secondary Growth - Question 3

The vascular cambium that gives rise to secondary xylem consists of fusiform and ray initials. The ray initials of the vascular bundle divide tangentially and produce cells on both sides, which differentiate as parenchymatous vascular rays. 
These rays traverse from pith to cortex through secondary xylem and phloem. Growth pattern that moves towards the centre is called as 'centripetal', while those moving outwards away from centre is called as 'centrifugal'. Since the tangential, division is followed, the rays are produced in both directions. 
Whereas acropetal order refers to development in succession from base to apex; it is normally used to refer the developmental pattern in leaves and flower.

Test: Secondary Growth - Question 4

Which of the following provide maximum mechanical strength to a tree trunk.

Detailed Solution for Test: Secondary Growth - Question 4
Solution
Heartwood, also called as duramen, dead, central wood of trees. Its cells usually contain tannins or other substances that make it dark in colour and sometimes aromatic. Heartwood is mechanically strong, resistant to decay, and less easily penetrated by wood preservative chemicals than other types of wood. One or more layers of living and functional sapwood cells are periodically converted to heartwood. Heart wood provide maximum mechanical strength to a tree trunk than sapwood, cork or late wood (autumn wood). 
Test: Secondary Growth - Question 5

Youngest layer of secondary xylem is located

Detailed Solution for Test: Secondary Growth - Question 5
Position of youngest layer of secondary phloem is just outside the vascular cambium. Position of oldest layer of secondary phloem is just inside the primary phloem. Position of youngest layer of secondary xylem is just inside the vascular cambium.
Test: Secondary Growth - Question 6

Diffuse porous woods are characteristic of plants growing in

Detailed Solution for Test: Secondary Growth - Question 6
Tropics. In most of the gymnosperms, like conifers and cycads, vessels are absent and the timber is made totally of tracheids. Such wood is known as nonporous.
Test: Secondary Growth - Question 7

Bottle cork is obtained from

Detailed Solution for Test: Secondary Growth - Question 7
Cork is an impermeable buoyant material, the phellem layer of bark tissue that is harvested for commercial use primarily from Quercus suber (the cork oak), which is endemic to southwest Europe and northwest Africa.
Test: Secondary Growth - Question 8

Inner bark composed of

Detailed Solution for Test: Secondary Growth - Question 8
The inner soft bark, or bast, is produced by the vascular cambium; it consists of secondary phloem tissue whose innermost layer conveys food from the leaves to the rest of the plant. The outer bark, which is mostly dead tissue, is the product of the cork cambium (phellogen).
Test: Secondary Growth - Question 9

Living tissue in lenticel is called

Detailed Solution for Test: Secondary Growth - Question 9

A lenticel is a porous tissue consisting of cells with large intercellular spaces in the periderm of the secondarily thickened organs and the bark of woody stems and roots of dicotyledonous flowering plants. It functions as a pore, providing a pathway for the direct exchange of gases between the internal tissues and atmosphere through the bark, which is otherwise impermeable to gases. 
As the lenticels formation starts, the parenchyma cells found near substomatal cavity lose their chlorophyll content and irregularly divide in different plants giving rise to a mass of colourless, rounded, thin walled, loosely arranged cells, called as complementary cells. Sometimes, complementary cells produced by phellogen towards outside instead of producing cork cells. Complementary cells are living cells in lenticles. Conjunctive tissue, connective tissue and phelloderm are not the living tissue in lenticel

Test: Secondary Growth - Question 10

Stem of date palm increases in girth due to activity of

Detailed Solution for Test: Secondary Growth - Question 10

Most monocots either have no secondary growth or else anomalous secondary growth of some type. For example, palm trees increase their trunk diameter due to division and enlargement of parenchyma cells, which is termed as 'diffuse secondary growth'. In some other monocot stems with anomalous secondary growth, a cambium forms but it produces vascular bundles and parenchyma internally and just parenchyma externally. Some monocot stems increase in diameter due to the activity of a primary thickening meristem, which is derived from the apical meristem. Stem of date palm increases in girth due to activity of apical meristem and not because of intercalary meristem and lateral meristem (involves in normal secondary growth of dicots). 

Test: Secondary Growth - Question 11

Normal secondary growth takes place in

Detailed Solution for Test: Secondary Growth - Question 11
Normal secondary growth takes place only in dicots and gymnosperms because they have cambium which possess the ability to form secondary xylem and phloen.
Test: Secondary Growth - Question 12

Select true statements :-
(a) Lenticels are absent in woody climbers
(b) Lenticels occur in most woody trees
(c) The spring wood is lighter in colour and has a lower density
(d) The sap wood also called as duramen

Detailed Solution for Test: Secondary Growth - Question 12

A lenticel is a porous tissue consisting of cells with large intercellular spaces in the periderm of the secondarily thickened organs and the bark of woody stems and roots of dicotyledonous flowering plants. It functions as a pore, providing a pathway for the direct exchange of gases between the internal tissues and atmosphere through the bark, which is otherwise impermeable to gases. Lenticels are absent in woody climbers.
Heart wood is also called as 'duramen'. The spring wood is lighter in colour and has a lower density.

Test: Secondary Growth - Question 13

Formation of secondary xylem and phloem respectively

Detailed Solution for Test: Secondary Growth - Question 13
Solution
The cambial zone forming a ring of thin-walled, non lignified cells, which run through the middle of each vascular bundle and across the interfascicular parenchyma. The cambial zone consists of the true vascular cambium and on either side of it, the cambial derivatives, which are almost indistinguishable from it. The derivatives formed centrifugally are destined to differentiate into secondary phloem and the derivatives formed centripetally are destined to differentiate into secondary xylem. Note that the cells of the cambium are arranged in regular radial rows, that they are flattened tangentially, that the tangential walls are thinner than the radial walls and that the cells contain cytoplasm and nuclei. If seen in longitudinal section, you would notice that the cambial cells are elongated, with chisel-shaped ends. 
Therefore, the correct answer is option B.
Test: Secondary Growth - Question 14

Secondary growth is absent in -

Detailed Solution for Test: Secondary Growth - Question 14
  • Cambium ring is present between xylem and phloem.
  • In monocots stem vascular cambium is absent. 
  • The vascular cambium is responsible for secondary growth. 

Therefore in monocots' secondary growth is absent. 

Test: Secondary Growth - Question 15

In dicot root which tissue becomes dead due to activity of phellogen

Detailed Solution for Test: Secondary Growth - Question 15

Pericycle is the outer most covering of stele, lying just beneath the endodermis. During secondary growth, the cells of pericycle present against protoxylem divide and form multiple layers of cells which are joined by cambial cells derived from conjunctive tissues and together they make a complete cambium ring. Cambial activity produces secondary tissues that push and rupture epidermal cell and outer cortex; a new protective layer, periderm is formed. Periderm divides to form cork cambium or phellogen. The cork cambium exhibit meristematic activity and produces cork or phellem towards the periphery and phelloderm on inside, i.e., extrastellar growth. These secondary tissues cause pressure and rupture the cells layers present outside the pericycle (endodermis and cortex)
A dicot root has tissues layers in following order: epidermis, cortex, endodermis, pericycle and vascular tissues, cork cambium activity rupture the cells layers present outside the pericycle. Hypodermis is the thickest layer of epidermis but is present in leaves not in roots
So, the correct answer is 'Tissue outside pericycle'

Test: Secondary Growth - Question 16

In dicot root, vascular cambium originates from

Detailed Solution for Test: Secondary Growth - Question 16

Dicot roots have little or no pith and thus pith rays are not the source of interfascicular cambium. The parenchyma cells present between xylem and phloem elements in the vascular bundles constitute conjunctive tissue. The parenchymatous cells present beneath phloem take on meristematic activity and form cambial strands. Similarly, the cells of pericycle present against protoxylem divide and form multiple layers of cells, which are joined by cambial cells derived from conjunctive tissues and together they make a complete cambium ring. Thus, the correct answer is option D.

Test: Secondary Growth - Question 17

In a hollow stem, what is most affected

Detailed Solution for Test: Secondary Growth - Question 17

Hollow stem is characterized by the disintegration of pith leaving the central space empty which is otherwise occupied by pith. The disintegration of pith is caused by rapid elongation and radial expansion of growing stem. Translocation of organic nutrient and water is the function of phloem and xylem respectively and hence, the disintegration of pith does not affect these functions. Pith serves to store and transport the nutrient while the hollow stem contains water, storage of food is most affected in hollow stem. 
Thus, the correct answer is option C.

Test: Secondary Growth - Question 18

Formation of which tissue is example of dedifferentiation

Detailed Solution for Test: Secondary Growth - Question 18
In plants characterized by a residual meristem, fascicular cambium develops from provascular tissue (which has developed from residual meristem) and interfascicular cambium develops from any intervening residual meristem; or if intervening residual meristem differentiates into interfascicular parenchyma.
Test: Secondary Growth - Question 19

In which stem, lateral meristem is absent

Detailed Solution for Test: Secondary Growth - Question 19
Palm, Inc. was an American company that specialized in manufacturing personal digital assistants and various other electronics.This is usually seen in monocotyledonous plants. Lateral Meristems – The lateral meristems are present on the lateral side of the stem and root of a plant. These meristems help in increasing the thickness of the plants. The vascular cambium and the cork cambium are good examples of a lateral meristematic tissue.
Test: Secondary Growth - Question 20

In dicot roots, the initiation of the lateral roots and the vascular cambium during the secondary growth takes place in:

Detailed Solution for Test: Secondary Growth - Question 20

Pericycle cells are thick-walled parenchymatous cells that lie next to the endodermis. Initiation of lateral roots and vascular cambium take place from these cells.

Test: Secondary Growth - Question 21

In dicot stem cork cambium first derived from

Detailed Solution for Test: Secondary Growth - Question 21
Cork cambium is secondary in origin but it itself is firstly derived from cells of cortex.
Test: Secondary Growth - Question 22

What happens to primary phloem in stem after sec growth

Detailed Solution for Test: Secondary Growth - Question 22
Phloem is located on the outer side of intrafascicular cambium and when the cambium generates new cells to form secondary phloem to the outer side then the primary phloem gets compressed to the outer side due to pressure of the new cells generated from inside of primary phloem.
Test: Secondary Growth - Question 23

Which tissue remains more active during autumn

Detailed Solution for Test: Secondary Growth - Question 23

The highest activity of cork cambium is in winter (Autumn) season. Ring of cork cambium remains living only for one year. Each year, a new cambium is formed below the previous cambium. This new cambium is derived from the secondary cortex or phelloderm.

Test: Secondary Growth - Question 24

Water conduction in stem of tree takes place by

Detailed Solution for Test: Secondary Growth - Question 24

Sapwood is the younger, outermost wood in the growing tree. It is living wood and its principal functions are to conduct water from the roots to the leaves and to store up and give back according to the season the reserves prepared in the leaves. However, by the time they become competent to conduct water, all xylem tracheids and vessels have lost their cytoplasm and the cells are therefore functionally dead. All wood in a tree is first formed as sapwood. The more leaves a tree bears and the more vigorous its growth, the larger the volume of sapwood required.

Test: Secondary Growth - Question 25

Closed vascular bundles lack

Detailed Solution for Test: Secondary Growth - Question 25
  • Closed vascular bundles lack a layer of tissue that produces partially undifferentiated cells and helps in secondary growth.
  • Closed type vascular bundles are commonly found in monocot plants. 
Test: Secondary Growth - Question 26

In a woody dicotyledonous tree, which of the following parts will mainly consist of primary tissues?

Detailed Solution for Test: Secondary Growth - Question 26

In a woody dicotyledonous tree, the meristems which occur at tips of roots and shoots produce primary tissues and are called apical meristems.

So, the correct answer is 'Shoot tips and Root tips'.

Test: Secondary Growth - Question 27

Study of wood is called

Detailed Solution for Test: Secondary Growth - Question 27
Xylotomy is the preparation of small slivers of wood for examination under a microscope, often using a microtome. It is useful for providing forensic evidence in some criminal cases where finding a fragment of wood on an individual and matching it to a weapon used in a crime would be helpful.
Test: Secondary Growth - Question 28

How many types of cells are present in vascular cambium

Detailed Solution for Test: Secondary Growth - Question 28

The vascular cambium is located between the xylem and the phloem in the stem and root of a vascular plant and is the source of both the secondary xylem growth inwards, towards the pith and the secondary phloem growth outwards. It is a cylinder of unspecialized meristem cells that divide to give new cells, which then specialize to form secondary vascular tissues. The vascular cambium usually consists of two types of cells - fusiform initials and ray initials. The fusiform initial cells are tall cells and axially oriented. The ray initials are small and round. Sometimes, they are angular in shape.

Test: Secondary Growth - Question 29

Annual ring involves

Detailed Solution for Test: Secondary Growth - Question 29
The cambium produces numerous large cells with thin walls that form the springwood (earlywood). If you look at a cross section of a tree, this is the light-coloured ring.
Then, towards the end of the summer, growth slows down. The cells manufactured at this time of year are small, with thick walls. They form the summerwood (latewood) which appears as a darker ring on the tree cross section.
Test: Secondary Growth - Question 30

Bark includes all the tissues

Detailed Solution for Test: Secondary Growth - Question 30

Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a non-technical term. It overlays the wood and consists of the inner bark and the outer bark. The inner bark, which in older stems is living tissue, includes the innermost area of the periderm.
The outer bark in older stems includes the dead tissue on the surface of the stems, along with parts of the innermost periderm and all the tissues on the outer side of the periderm. The outer bark on trees which lies external to the last formed periderm is also called as the rhytidome. So, bark includes the tissue lying outside the vascular cambium and not of formed by vascular cambium, formed by phellogen and phellem and phelloderm. 
Thus, the correct answer is option A.

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