Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Bio Botany Guide Pdf Chapter 10 Secondary Growth Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Bio Botany Solutions Chapter 10 Secondary Growth

11th Bio Botany Guide Secondary Growth Text Book Back Questions and Answers

PART -I

I. Consider the following statements

Question 1.
In spring vascular cambium
i) is less active
ii) Produces a large number of xylary elements
iii) forms vessels with wide cavities of these,
a) (i) is correct but (ii) and (iii) are not correct
b) (i) is not correct but (ii) and (iii) are correct
c) (i) and (ii) are correct but (iii) is not correct
d) (i) and (ii) are not correct but (iii) is correct
Answer:
b) (i) is not correct but (ii) and (iii) are correct

Question 2.
Usually, the monocotyledons do not increase their girth, because
a) They possess actively dividing cambium
b) They do not possess actively dividing cambium
c) Ceases activity of cambium
d) All are correct
Answer:
b) They do not possess actively dividing cambium

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 3.
In the diagram of lenticel identify the parts marked as A, B, C, D
Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth 1
a) A. phellem, B. Complementary tissue, C. Phelloderm, D. Phellogen.
b) A. Complementary tissue, B.Phellem, C. Phellogcn,
c) A. Phellogen, B.Phellem, C. Phelloderm, D. Complementary tissue
d) A. Phelloderm, B. Phellem, C. Complementary tissue, D. Phellogen
Answer:
a) A. phellem, B. Complementary tissue, C. Phelloderm, D. Phellogen.

Question 4.
The common bottle cork is a product of
a) Dermatogen
b) Phellogen
c) Xylem
d) Vascular cambium
Answer:
b) Phellogen

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 5.
What is the fate of primary xylem in a dicot root showing extensive secondary growth?
a) It is retained in the center of the axis
b) It gets crushed
c) May or may not get crushed
d) It gets surrounded by primary phloem
Answer:
b) It gets crushed

Question 6.
In a forest, if the bark of a tree is damaged by the horn of a deer, How will the plant overcome the damage?
Answer:
(Bark include all tissues outerto cambium)
1. The innate wound healing mechanism get activated.
2. In the wounded site, there is rapid cell division, in the cambium to seal the wound to prevent any microbial infection.
3. A reaction zone is created, which alters the chemistry of the wood, in the wound site to avoid microbial infection.
4. Barrier zone or callus sep;  other, it over grow the wound and seal it, thereby new wood grow beneath to complete the healing.

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 7.
In which season the vessels of angiosperms are larger in size, why?
Ans:
1. Spring is a season with favourable climatic conditions, such as Optimum temperature, light intensity, good soil water source, which facilitate growth.
2. So to optimize photosynthesis and in tum growth, cambium is very active, producing large number of xylary elements such as vessels and tracheids with wide lumen – (springwood) thus increases uptake
of water and minerals to large scale.

Question 8.
Continuous state of dividing tissue is called meristem. In connection to this, what is the role is lateral meristem?
Answer:
The secondary growth in dicots and gymnosperms is brought about by two lateral meristems.

  1. Vascular cambium and
  2. Cork cambium

1. Vascular cambium:
The vascular cambium is the lateral meristem that produces the secondary vascular tissues, i.e.. secondary xylem and secondary phloem.
Origin and Formation of Vascular Cambium:

  • A strip of vascular cambium originate from the procambium is present between xylem and pholem of the vascular bundle. This cambial strip is known as intrafascicular or fascicular cambium.
  • In between the vascular bundles, a few parenchymatous cells of the medullary rays that are in line with the fascicular cambium become meristematic and form strips of vascular cambium. It is called interfascicular cambium.

A. Organization of Vascular cambium:

  • The active vascular cambium possesses cells with large central vacuole (or vacuoles) surrounded by a thin, layers of dense cytoplasm.
  • The most important character of the vascular cambium is the presence of two kinds of initials, namely fusiform initials and ray initials.

Fusiform Initials:

  • These are vertically elongated cells. They give rise to the longitudinal or axial system of the secondary xylem (tracheary elements, fibres, and Axia? parenchyma) and pholem (sieve, elements, fibres, and axial parenchyma).
  • Based on the arrangement of the fusiform initials two types of vascular cambium are recognized.

Stoned (Stratified cambium) and Non – storied (Non – stratified cambium)

  • If the fusiform initials are arranged in horizontal tiers, with the end of the cells of one tier appearing at approximately the same level, as seen in tangential longitudinal section (TLS) it is called storied (stratified) cambium. It is the characteristic of the plants with short fùsiform initials.
  • In plants with long fusiform initials, they strongly overlap at the ends, and this type of cambium is called non – storied (non stratified) cambium.

Ray Initials:
These are horizontally elongated cells. They give rise to the ray cells and form the elements of the radial system of secondary xylem and pholem.

Activity of Vascular Cambium:

  • The vascular cambial ring, when active, cuts off new cells both towards the inner and outer side. The cells which are produced outward form secondary phloem and inward secondary xylem.
  • Due to the continued formation of secondary xylem and phloem through vascular cambial activity, both the primary xylem and phloem get gradullay crushed.

B. Phellogen (Cork Cambium)

  • It is a secondary lateral meristem. It comprises homogenous meristematic cells unlike vascular cambium. It arises from epidermis, cortex, pholem or pericycle (extrastelar in origin). Its cells divide periclinally and produce radially arranged files of cells.
  • The cells towards the outer side differentiate into phellem (cork) and those towards the inside as phelloderm (secondary cortex).

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 9.
A timer merchant bought 2 logs of wood from, a forest & named them A & B, The log A was 50 year old & B was 20 years old. Which log of wood will last longer for the merchant? Why?
Answer:

  • In wood, the older it is, the stronger it becomes.
  • Log A – Which was 50 years old is stronger and it will last longer.
  • In a tree the central part of the wood will be darker in colour, dead in nature known as Heart wood or Duramen, and the outer sad wood is lighter in colour, living and conducting water.
  • In the central Heart wood the conduction is blocked by the formation of tyloses from the nearby
    parenchyma cells, and dead.
  • In the fully developed tyloses, starch crystals, resings, gums, oils tannins and coloured substances are
    found and it become very hard and durable.
  • It is more resistant to the attack of microbes and insects like termites.
  • Older woods have more heart wood than sap wood.
  • Here log ‘A’ is older, has more heart wood and it is stronger and will last longer.

Question 10.
A transverse section of the trunk of a tree shows concentric rings which are known as growth rings. How are these rings formed? What are the significance of these rings?
Answer:

Growth (or) Annual Rings:

  • In spring season cambium is very active and produces large number of xylary elements called Earlywood or Springwood.
    In Winter season – cambium is less active and form few xylary elements – Latewood or Autumn Wood.
  • The springwood is lighter in colour and has a lower density whereas the autumn wood is darker and has a higher density. The annual ring denotes the combination of earlywood and latewood and the ring becomes evident to our eye due to the high density of latewood. Sometimes annual rings are called growth rings
  • Pseudo – Annual Rings :
    Additional growth rings are developed within a year due to adverse natural calamities like drought, frost defoliation, flood, mechanical, injury and biotic factors. Such rings arc called pseudo – or false – annual rings
  • Dendrochronology:
    Each annual ring corresponds to one year’s growth and on the basis of these rings, the age of a particular plant can easily be calculated. The determination of the age of a tree by counting the annual rings is called dendrochronology.

Part – II.

11th Bio Botany Guide Secondary Growth Additional Important Questions and Answers

I. Choose the Correct answer.

Question 1.
Growth in Girth is also known as
a) Primary growth or longitudinal growth
b) Secondary growth or lattitudinal growth
c) Secondary growth or vertical growth
d) Primary growth or lattitudinal growth
Answer:
b. Secondary or lattitudinal growth

Question 2.
The Gymnosperm in which vessel is present
a) Pinus
b) Cýcas
c) Ginkgo
d) Gnetum
Answer:
d. Gnetum

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 3.
Secondary growth occur in
a) Grass
b) Paddy
c) Wheat
d) Yucca
Answer:
d. Yucca

Question 4.
In a dicotyledonous stem, the sequence of tissues from the outside to the inside of
a) Phellem, Pericycle, Endodermis, phloem
b) Phellem phloem, Endodermis, Pericycle
c) Phellem, Endodermis, Pericycle, phloem
d) Pericycle, Phellem, Endodermis, Phloem
Answer:
c. Phellem, Endodermis, Pericycle, Phloem

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 5.
For a critical study of secondary growth in plants which one of the following pairs is suitable?
a) Sugarcane and sunflower
b) Teak and pine
c) Bamboo and Fem
d) Wheat and Fem
Answer:
b. Teak and pine

Question 6.
Why do we consider cambium as Lateral mer- istem?
a) Because it gives rise to lateral branches
b) Because it causes growth in girth
c) Because it increases height and diameter of a plant
d) Because it adds bulk to a plant
Answer:
b. Because it causes growth in girth

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 7.
Tissues considered in an annual ring is/are
a) Secondary xylem and phloem
b) Primary xylem and phloem
c) Secondary xylem only
d) Primary phloem and secondary xylem
Answer:
c. Secondary xylem only

Question 8.
Amount of secondary xylem is more than secondary phloem because
a) Cambium is more active on the outer side
b) Cambium is more active on inner side
c) Cambium has no role
d) Cambium is active equally on both sides but xylem is required more ti t m phloem
Answer:
b. Cambium is more active on inner side

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 9.
Inter fascicular cambium is a
a) Primary meristemate tissue
b) Primordial meristem
c) Type of protoderm
d) Secondary meristematic tissue
Answer:
d. Secondary meristematic tissue

Question 10.
Inter fascicular cambium develops from the cells of
a) Xylem parenchyma
b) endodermis
c) Pericycle
d) Medullary rays
Answer:
d. Medullary rays

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 11.
Duramen is present in
a) Inner regions of secondary wood.
b) Part of sap wood
c) Outer region of secondary wood
d) Region of pericycle
Answer:
a. Inner region of secondary wood

Question 12.
At maturity, the sieve plates become impregnated with
a) Cellulose
b) Pectin
c) Suberin
d) Callose
Answer:
d. Callose

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 13.
You are given a fairly old piece of dicot stem and a dicot root, which of the following anatomical structures will you to distinguish between the two?
a) Secondary xylem
b) Secondary phloem
c) Protoxylem
d) Cortical cells
Answer:
c. Protoxylem

Question 14.
When one wood is lighter in colour with a lower density, the other wood is darker with a higher density. They are
a) Springwood and autumn wood
b) Heartwood and latewood
c) Springwood and earlywood
d) Sapwood and springwood
Answer:
a. Springwood and Autumn wood

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 15.
Which one of the following is dead and work efficiently?
a) Sieve tube
b) Companian cells
c) Vessels
d) Both (b) and (c)
Answer:
c. Vessels

Question 16.
Which one of the following pairs is an example for meristematic tissue
a) Phellogen and phelloderm
b) Phellogen and Fascicular cambium
c) Procambium and phelloderm
d) Inter fascicular cambium and phellem
Answer:
b. Phellogen and Fascicular cambium

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 17.
A vesselless piece of stem possessing prominent sieve tubes would belong to
a) Pinus
b) Eucalyptos
c) Grass
d) Trochodendron
Answer:
d. Trochodendron

Question 18.
Which wood is also known as Non porous
a) Soft wood
b) Heart wood
c) Hard wood
d) Sap wood
Answer:
a. Soft wood

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 19.
The meristem responsible for extra stelar secondary growth in shoot stem is
a) Fascicular cambium
b) Interfascicular cambium
c) Inter calary meristem
d) Cork cambium
Answer:
d. Cork cambium

Question 20.
Removal of a ring of wood tissue outside the vascular cambium from the tree trunk kills it because
a) Water cannot move up
b) Food does not travel down and root become starved
c) Shoot apex become starved
d) Annuval rings are not produced
Answer:
food does not travel down root become starved

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 21.
The trees growing in desert will
a) Show alternate rings of xylem and sclerenchyma
b) Have only conjuctive tissue and phloem formed by the activity of cambium
c) do show distinct annual rings
d) do not show distinct annual rings
Answer:
d. do not show distinct annual rings.

Question 22.
Which one of the tissue is formed in a stem from cells cut off by the cambium on its innerside?
a) Wood fibres
b) bast fibres
c) Sieve tubes
d) Camparian cells
Answer:
a. Wood fibres

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 23.
Choose the living cells from the given
I) Phellem
II) Phloem
III) Phellogen
IV) Xylem parenchyma
a) (I) (II) & (III)
b) (II) (III) & (IV)
c) (I) (III) & (IV)
d) (I) (II) & (IV)
Answer:
b) (II) (III) & (IV)

Question 24.
When we peel the skin of a potato tuber we remove
a) Periderm
b) Epidermis
c) Cuticle
d) Sapwood
Answer:
a) Periderm

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 25.
How many shoot apical meristems are likely to be present in a twig of a plant possessing 4 branches and 26 leaves
a) 26
b) 1
c) 5
d) 30
Answer:
c) 5

Question 26.
The waxy substances associated with cell walls of cork cells are impervious to water because of the presence of ………………. which gets deposited on the cork cells
a) Cutin
b) Suberin
c) Eignin
d) Hemicellulose
Answer:
b) Suberin

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 27.
External protective tissues of dicot stem are
a) Cork and pericycle
b) Cortex and epidem.
c) Pericycle and cortex
d) Epidermis and cork
Answer:
d) Epidermis and Cork

Question 28.
Annual rings are distinct in plants growing in
a) Tropical regions
b) Arctic regions
c) Grasslands
d) Temperate region
Answer:
d) Temperate region

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 29.
Bark does include which three except one from the options.
I) Cortex
II) Periderm
III) Pith
IV) Secondary phloem
a) (I) (II) & (Ill)
b) (II) (III) & (IV)
c) (I) (III) & (IV)
d) (I) (II) & (IV)
Answer:
d) (I) (II) & (IV)

Question 30.
The wood formed early occur during
a) Autumn season
b) Spring season
c) Winter season
d) Summer season
Answer:
b) Spring season

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 31.
Wood actually means
a) Primary xylem
b) Secondary xylem
c) Primary phloem
d) Secondary phloem
Answer:
b) Secondary xylem

Question 32.
When a plant is wounded, the wound is healed by the formation of new cells, by the cavity of
a) Primary meristem
b) Apical meristem
c) Secondary meristem
d) Intercalary meristem
Answer:
c) Secondary meristem

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 33.
Commercial cork is obtained from
a) Oak
b) Silver oak
c) Pine
d) Ficus
Answer:
a) Oak

II. Match correctly and choose the right answer

Question 1.
I) Spicy bark – A Turpentine
II) Ornamental Antique – B Quinine
III) Active drug – C Cinnamon
IV) Thinner and solvent – D Amber
Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth 2
Answer:
d) C-D- B-A

Question 2.
I) Phellogen – A. Cork
II) Phelloderm – B. Cork cambium
III) Phellem – C. Lack suberin
IV) Phelloids – D. Secondary cortex
Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth 3
Answer:
a) B-D- A-C

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 3.
I) D Sap wood – A. Softwood
II) Heart wood – B. Hard wood
III) Porous wood – C. Albumum.
IV) Non porous wood – D. Duramen
Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth 4
Answer:
c) C-D-B-A

III Identify True or false and from the given option choose the right answer:

Question 1.
A) In pinus wood is Non porous
B) In Morns wood is porous
C) In Quercus the wood is Diffuse porous
D) In Acer the wood is Ring porous
a) A&DTrue B&C False
b) A & B True C & D False
c) A & C True B & D False
d) A&BFalseC &DTrue
Answer:
b) A & B True C & D False

Question 2.
Arrange the given plants in an order from more distinct Annual rings to least distinct Annual rings.
a) Seashore plants, Desert plants, Tropical plants & Temperature plants
b) Temperature plants, Tropical plants, Desert plants, Sea shore plants
c) Tropical plants, Desert plants, Temperature plants, Sea shore plants
d) Temperature plants, Sea shore plants, Tropical plants, Desert plants
Answer:
b) Temperature plants, Tropical plants, Desert plants, Sea shore plants.

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 3.
In a wood the Annual rings become clearly evident to our eyes due to
a) The high density and dark coloured late wood or Autumn wood
b) The low density and light coloured early wood or spring wood
c) The high density and dark coloured early wood or spring wood
d) The low density and light coloured late wood or Autumn wood
Answer:
a) The high density and dark coloured of late wood or Autumn wood

Question 4.
Column I and Column II – Match them correctly and Find out the right option.

Column I

Column II

A. Spring wood or early wood
B. Autumn wood or Late wood
1. Lighter in colour
2. Density high
3. Density low
4. Darker in colour
5. Larger number of xylem elements
6. Vessels with wider cavity
7. Lesser number of xylem elements
8. Vessels with small cavity

Which of the following combination is correct?
a) A – 2, 4, 7, 8 B- 1,3, 5,6
b) A- 1,2, 7,8 B-3,4, 5, 6
c) A – 1,3, 5,6 B – 2,4, 7, 8
d) A- 1,3,7, 8 B – 2, 4, 5, 6
Answer:
b) A – 1, 2, 7,8 B-3,4,5, 6

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

IV. Assertion and Reason

Question 1.
ASSERTION: – A All tissues lying inside the Vascular Cambium are called as Bark
REASON -R: Bark is made up of Phellogen. Phellem and Phelloderm Cortex, primary and secondary phloem
a) Both A and R are true and R is the correct explanation of A
b) Both A and R are true, but R is not the correct explanation of A
c) A is true but ‘R’ is false d) A is false and ‘R’ is true
d) Both A and ‘R’ are false
Answer:
d) ‘A’ is false and ‘R’ is true

Question 2.
ASSERTION: -A In angiosperms, the conduction of water is more efficient because their xylem has vessels
REASON – R: Conduction of water by vessel element is an active process in which energy is supplied by xylem parenchyma with large number of Mitochondria
Answer:
a) Both A and R – are true and ‘R’ is the correct explanation of A

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 3.
ASSERTION: -A. All the endoderma.l cells of the root do not contain casparian thickenings on their radial and transverse walls.
REASON-R: Passage cells are found in the root endodermis, which conduct water in to the xylem
Answer:
a) Both A and R are true and ‘R’ is the correct explanation of A

Question 4.
ASSERTION:-A Cambium is a lateral meristem and causes growth in width
REASON-R Cambium is made up of fusiform and ray initials in stem
Answer:
b) Both A and R are true, but R is not the correct explanation of A

Question 5.
ASSERTION: – A The lenticel is meant for gaseous exchange.
REASON-R Lenticel checks excessive evaporation of water.
Answer:
b) Both A and R are true but R is not the correct explanation of A

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 6.
ASSERTION:-A Heart wood is more durable
REASON – R Heart wood contains organic compounds like tannins, resins, oil, gums, aromatic substances and essential oils help to resist microbial and termites attack.
Answer:
a) Both A and R are true and R is correct explanation of A

V.

2 Mark Questions

Question 1.
Distinguish between Primary and Secondary growth
Answer:

Primary growth

Secondary growth

1. The roots and stem grow in length with the help of Apical meristem 1. The roots and stem show increase in thickness or width with the help of Lateral meristem
2. It is known as longitudinal growth 2. It is also known as latitudinal growth or growth in girth
3. Eg. Angiosperms & Gymnosperms 3. Eg. Most Angiosperms, including some Monocots and Gymnosperms

Question 2.
Name the tissues that bring out secondary growth in dicots.
Answer:

  • It is the lateral Meristem – that brings out secondary growth.
  • It is divided into Vascular cambium, Cork cambium
  • Vascular cambium gives rise to secondary xylem and secondary phloem
  • Cork cambium gives rise to secondary cortex. and phellem.

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 3.
Differentiate between Cork and Rubber
Answer:

Cork

Rubber

1. It is a part of bark 1. It is derived as stem latex
2. It is non living tissue 2. It is a secondary metabolite
3. Used in making bottle stoppers 3. 80-85% of world’s Rubber products like tyre are produced from this plant
Eg. Querces suber Eg. Hevea brasiliensis

Question 4.
Fill in the blanks
Answer:

Botanical name of plant

Common name of the product

Use

1. Abies balsamea Canada balsam ………………………………..
2.  Acacia Senegal (meska) ………………………………………… Natural gum used as a bind. to ‘ water colour painting
3. ………………………………… Cork Hydrophobic, impermeable, used as bottle stopper.
4. ……………………………………………… Haematoxylin Dye from the heart wood to stain plant materials view under microscope

Answer:
1) Resin used as mounting medium for microscopic slide preparation.
2) Gum Arabic 3) Quercus suber 4) Haematoxylon campechianum

Question 5.
Distinguish between stratified cambium and Non stratified cambium.
Answer:

Stratified cambium

Non stratified cambium

1. Plants with short fusiform initials, produced, storied, cambium in horizontal tiers known as
stratified cambium
1. Plants with long fusiform initials produced non storied cambium, strongly overlap at the ends, known as Non stratified cambium

Question 6.
Why do porous wood is harder than non porous wood?
Answer:

  • Porous wood is a wood with xylem vessels which appear as pore in cross section.
  • When a tree stem become old, most of its vessels are blocked by tyloses with deposition of gum, resin, tannin, oils etc. (Heart wood)
  • So porous wood is harder and commercially important.

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 7.
What is the source of turpentine? and What is its use?
Answer:

  • Turpentine – is a resin obtained from the bark of conifers Eg. pinus
  • It is also used as a thinner for oil based paints.
  • It is also used as an organic solvent.
  • It is also used as a balm to relieve muscular plain.

Question 8.
Distinguish between Periderm and Polyderm
Answer:

Periderm

Polyderm

1. The secondary growth replaces the epidermis and primary cortex and form the Periderm 1. It is a special type of protective tissue consisting of uniserable suberized layer, alternating with multiseriate non suberized cells in periderm
2. It consists of
Phellem
Phellogen
Phelloderm
Eg. Dicot stem & roots
Eg. Roots and under ground stems of Rosaceae plants

Question 9.
What is Amber? What is it’s use?
Answer:

  • Amber is a fossilized tree resin got from wood.
  • It is appreciated for its colour and natural beauty since Neolithic times.
  • Value as a gemstone – variety of decorative objects made out of it.
  • Used in jewellery making.
  • Used as a healing agent in folk medicine.

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 10.
What is the use of Canada balsam.
Answer:
From the resin ducts, Abies balsamea plant produces an organic gum like substance, used as a permanent mounting medium for microscopic slide preparation.
Eg. A slide of 60 years old holotype specimen of a flat worm is permanently mounted in Canada balsam.

VI.

3 Mark Questions

Question 1.
Define the following:
Answer:
A-Phelloids, B – Xylotomy, C – Tylosoids
Phelloids: Phellem (cork) like cells, which lack suberin in their walls are known as phelloids.
Xylotomy: The study of wood by preparing sections for microscopic observation is known as xylotomy.
Tylosoids: These are tylose like in growth from neighbouring parenchyma cells blocking the lumen of the parts, such as Resinduct – sievetubes etc.
Eg. Resin ducts – Eg. Pinus (Gymnosperm), Sieve tube – Eg. Bombox (Angiosperm)

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 2.
Notes on Lenticels.
Answer:

  • The aerating pores seen as raised opening on the surface of bark as scars on old stems and roots.
  • It is fonned during secondary growth in stems.
  • In this portion phellogen activity is more than else where, a filling tissue known as complementary tissue (loosely arranged parenchyma) is formed.
  • Lenticel is helpful in exchange of gases and also facilitate little amount of transpiration

Question 3.
Distinguish between Ring barks and scale barks
Answer:

Ring barks

Scale barks

1. When Phellogen form a complete cylinder around the stem, it is ring bark 1. Bark is formed by over lapping scale like layers
2. It won’t peel off
Eg. Quercus
2. It often peel off
Eg. Guava

Question 4.
Differences between Diffuse porous wood and Ring porous wood
Answer:

 Diffuse porous wood

Ring porous wood

1.This type of wood is formed where the climatic conditions are uniform 1. This type of wood is formed where the climatic conditions are not uniform
2. The vessels are more or less equal in diameter in any annual ring 2. The vessels are wide and narrow within any annual ring
3. The vessels are uniformly distributed throughout the wood 3. The vessels are not uniformly distributed throughout the wood

Question 5.
Differences between Porous Wood and Non – porous wood
Answer:

Porous wood or Hard wood, Ex: Morus

Non porous wood or soft wood Ex : Pinus

1. Common in Angiosperms 1. Common in Gymnosperms
2. Porous because it contains vessels 2. Non – porous because it does not contain vessels

Question 6.
Differences between Sap wood (alburnum) and Heart Wood (duramen)
Answer:

Sap wood (Alburnum)

Heart wood (Duramen)

1. Living part of the wood 1. Dead part of the wood
2. It is situated on the outer side of wood 2. It is situated in the centre part of wood
3. It is lighter in colour 3. It is dark coloured
4. Very soft in nature 4. Hard in nature
5. Tyloses are absent 5. Tyloses are present
6. It is not durable and not resistant to microorganisms 6. It is more durable and resists microorganisms
insects and termites

Question 7.
Differences Between Phellem and Phelloderm
Answer:

Phellem (Cork)

Phelloderm (secondary cortex)

1. It is formed on the outer side of phellogen 1. It is formed on the inner side of phellogen
2. Cells are compactly arranged in regular tires and rows without intercellular spaces. 2. Cells are loosely arranged with intercellular spaces.
3. Protective in function. 3. As it contains chloroplasts,, it synthesises and stores food
4. Consists of non living cells with suberized walls 4. Consists of living cells, parenchymatous in nature and does not have suberin
5. Lenticels are present 5. Lenticels are absent

Question 8.
Differences between Vascular Cambium and Cork cambium
Answer:

Vascular cambium

Cork cambium

1. Also called Cambium 1. Also called Phellogen
2. In stenvarises from Pro cambium & Inter fascicular parenchyma
In roots – arises from conjunctive parenchyma
2. In stem – arises from epidermis, cortex & phloem
In roots – arises from pericycle
3. It comprises long fusiform and short and initials. 3. It comprises of homogenous cells.
4. It produces secondary phloem towards the outer side the secondary xylem towards inner side 4. It produces phellem (cork) towards outer side and phelloderm (secondary cortex) towards inner side.

Question 9.
Differentiate between Dicot stem and Dicot root with reference to secondary growth meristems.
Answer:

Dicot stem

Dicot root

1. Vascular cambium, partially primary and
partially secondary in origin
1.Vascular cambium is purely secondary in origin
2. Phellogen formed from outer Cortical cells 2. Phellogen formed from Pericycle
 3. Vascular cambium formed from interstelar cells and phellogen from extra stellar cells 3. Both vascular cambium and phellogen from
intra stelar cells

Question 10.
Annual rings are not clear and distinct in desert trees and seashore plants – Justify.
Answer:

  • In desert, as well sea shore regions the climatic condition remain same through out the year.
  • Secondary growth in plants are influenced by seasonal changes, since in these areas seasonal changes is not significant enough to bring in distinct Annual rings with early and late wood formation alternatively.

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 11.
A plant dies if the sap wood is damaged, but not with that of Heart wood – Give factual justification.
Answer:

  • Sap wood is living part of wood, perform water conduction, thats why it is known as Sap wood.
  • Heart wood is dead part of wood, do not perform water conduction so if destroyed, no vital function of plant is affected
  • If sap wood is damaged, or exposed conduction of water will be blocked, water loss is rapid leading decay and decomposition of tissues, and leads to death of the plant.

Question 12.
What is Dendrochronology. Add a note on the significance of studying the growth rings.
Answer:

  • Annual ring of a tree corresponds to one year’s growth.
  • If we count the rings we can determine the very age of the plant
  • This method of calculating the age of a tree by counting the annual ring is known as dendrochronology.

Significance of studying growth rings :
I) Age of wood – calculated
II) Age verified by Radio active carbon dating
III) Provides evidence in Forensic investigation.

Question 13.
If  ‘A’ is vascular cambium, then label other parts with reference to cambial activity.
Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth 5

Answer:
A- Vascular cambium
B – First formed phloem – (Primary phloem)
C – First formed xylem – (Primary xylem)
D – Second formed phloem – (Secondary phloem)
E – Second formed xylem – (Secondary xylem)

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 14.
Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth 6
Answer:
Cross section of wood showing Annual rings.
A-Bark
B-Sapwood ,
C – heart wood
D -Annual rings

Question 15.
Identify the diagram & Label the parts.
Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth 7
Answer:
Structure of Tyloses A – Parenchyma cell
B – Tyloses
C – Vessel wall
D – Vessel Lumen

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

Question 16.
In the given diagram, the parts labelled are A, B, C, D identify the part correctly with respect to its function.
Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth 8
a) A – Periderm for gaseous exchange
b) C – Secondary cortex for protection
c) B – Complementary tissues for gaseous exchange
d) D – Phellogen for xylem and phloem formation
Answer:
c. B – Complementary tissues for gaseous exchange

Question 17.
Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth 9
Answer:
Different stages of secondary growth in Dicot root
A – Cambial ring
B – Primary’ xylem
C – Secondary xylem
D – Primary phloem
E – Secondary phloem

VII.

5 Mark Questions

Question 1.
Differentiate between Secondary xylem and Secondary phloem
Answer:

Secondary xylem

Secondary phloem

1. It is known as wood – ………………….
2, It is formed towards the inside of vascular cambium It is formed towards the outside of vascular cambium
3. From Fusiform initials, axial system is developed consists of tracheary elements, fibres and parenchyma From fusiform initials, axial system is developed consists of sieve elements phloem fibres and phloem parenchyma
From ray initials, the radial system consists of rows of parenchyma cells From ray initials, the radial system consists of phloem rays.
4. Wood is of 2 types porous wood (Hard) & Non Porous wood – …………..
5. Varies – very greatly from species to species no much variation
6, Life span – long Life span comparatively shorter than sec. xylem
7. It is dead – conduction does not occur It is living tissue, help in transport of organic solutes from leaves to other parts
8. Commercially important Commercially bast fibres are used

Question 2.
Distinguish the significance of Cork and Bark
Answer:

Cork

Bark

1. It includes only phellem layer of bark 1. It includes all tissues outside vascular cambium (Periderm, Cortex, Primary and secondary phloem)
2. It is composed of suberin a hydrophobic substance
3. It has impermeable buoyant, elastic and fibre retartant properties 3. It has insect repellent, decay proof, fire proof properties.
4. Used in making bottle stoppers Eg. Bark of Quercus suber 4. Used as Drugs or spices.
Eg. Bark of Chichona – (AntimalariaJ drug)
Bark of Cinnamomum (Used as spice)

Question 3.
Differentiate between, the vascular cambial components Fusiform initials and Ray initials.
Answer:

Fusiform initials

Ray initials

1. Vertically elongated cells 1. Horizontally elongated cells
2. Give rise to axial system of secondary tissues, xylem and phloem 2. Give rise to radial system of secondary xylem and phloem
3. Secondary xylem includes tracheary elements, fibres and axial parenchyma 3. Radial system consists of rows of
parenchymatous cells oriented at right angles to the longitudinal axis of xylem elements
4. Secondary phloem includes sieve elements 4. Secondary phloem include phloem rays
fibres and axial parenchyma
5. Based on arrangement of fusiform initials
2 types of vascular cambium recognised
a – stratified cambium
b – Non stratified cambium

Question 4.
Give an account of Primary & Secondary structure of Dicto Stern. (Flow chart)
Answer:
Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth 10

Question 5.
Give an account of Any 5 Commercial barks their, properties and uses
Answer:
Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth 11

Samacheer Kalvi 11th Bio Botany Guide Chapter 10 Secondary Growth

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