Review Question Solving, Class IX-Biology 2012
Review Question Solving (Class IX-Biology)
Dawa Tshering (BE091909)
B.Ed. IV S Sci ‘A’
Samtse College of Education
Samtse
BGY 410
Ecology
Mr. Kinzang Dorji
15th, October 2012
(DawaTshering, BE 091909)
Page 1
Review Question Solving, Class IX-Biology 2012
Chapter: Internal Structure of Root and Leaf
In text self-check questions (ONE)
1. Mention if the following statements are true (T) or false (F)
i.
Tap root system is a characteristic of monocots -F
ii.
Primary root is formed from the radicle of the germinating seed-T
iii.
In monocots the radicle (main root) dies off soon- T
2. List the three primary functions of primary roots.
Ans:
i.
Anchorage (fixation)
ii.
Absorption of water and dissolved mineral salts from the soil
iii.
Transport of the absorbed water and mineral salts
In text self –check questions (TWO)
1. Rearrange the following regions of the root tips starting from the one found at the
extreme end of the root
Zone of elongation, root cap, growing zone, zone of maturation
Ans: Root cap, growing zone, zone of elongation, zone of maturation
2. Choose the correct alternatives in the following statement s about dicot root structure.
i.
Root cap is formed of several layers of mostly (dead/alive) cells.
-dead
ii.
Root hairs are (solid/tubular) outgrowths of epidermal cells
-Tubular
iii.
Rapidly multiplying cells lie just next to (root cap/zone of maturation)
-
iv.
The last layer of cortex is differentiated as (pericycle/endodermis)
-
v.
root cap
endodermis
The vascular bundles are (scattered/radially arranged)
-
radially arranged
(DawaTshering, BE 091909)
Page 2
Review Question Solving, Class IX-Biology 2012
vi.
Xylem bundles are (exarch/endarch)
-
vii.
exarch
In exarch xylem bundles the immature xylem called (protoxylem/metaxylem) is
the outer part.
-
viii.
protoxylem
The vascular bundles in monocot root are (less/more) numerous than in dicot root.
-
more
In text self-check questions (THREE)
Mention if the following statements about monocot leaf are true (T) or false (F)
i.
The stomata are more numerous on upper surface than on the lower one- F
ii.
The mesophyll cells are undifferentiated into palisade and spongy cells- T
iii.
Vascular bundles are much similar to those in the dorsiventral leaf - T
iv.
Stomata are present on only one surface-F
Review Questions
1. List the three regions of the young dicot root. Describe the characteristic features of
each region.
Ans:
a) Outermost epidermis:
 It is the outermost single layer of cells.
 Has root hair which is outgrowths from a single cell.
b) Cortex:
 It is multilayered and parenchymatous.
 It consists of thin walled cells, round/polygonal in shape with intercellular spaces.
 Helps in radial conduction of water from root hairs to the xylem of the vascular
bundle of the stele.
 Last layer is differentiated as endodermis.
(DawaTshering, BE 091909)
Page 3
Review Question Solving, Class IX-Biology 2012
c) Stele
 Occupies center of the root
 It consists of (i) pericycle, which gives rise to lateral roots, and (ii) Vascular
bundles, which are few in numbers at the center of root.
 Vascular tissue occurs in separate strands of phloem and xylem.
2. Suppose you are examining a transverse section of young dicot root. Name the
cellular layers/regions in sequence starting from the outermost layer up to the
center.
Ans:
 Epidermis (piliferous layer), cortex, endodermis, pericycle, protoxylem,
metaxylem, phloem, pith.
3. Differentiate between exarch and endarch xylem bundle. Which kind of these is
found in (i) dicot root and (ii) monocot root?
Ans:
Exarch
Endarch xylem bundle
-Xylem starts maturing from the outside
- Xylem starts maturing form the
towards center
inside towards the outside
- Outer part is protoxylem and inner part
-Inner part is protoxylem and
is metaxylem
outer part is metaxylem
i)
Dicot root- has exarch xylem bundle
ii)
Monocot root-has endarch xylem bundle
(DawaTshering, BE 091909)
Page 4
Review Question Solving, Class IX-Biology 2012
4. Describe the structure of the cortex of dicot root. Add a note on its function.
Ans:
Structure of cortex:
 It is multilayered and parenchymatous.
 It consists of thin-walled cells, round or polygonal in shape with intercellular space.
 Last layer of cortex is differentiated into endodermis.
Function
 It helps to conduct radially water absorbed by the root hairs to xylem of the vascular
bundles of the stele
 Endodermis diverts water absorbed by the root hairs directly into the xylem bundles of
the vascular tissue in the stele.
5. Given below is the diagram of the transverse section of young root.
i.
Name the parts numbered 1-9
ii.
Is this section of a dicot root or monocot root? Give two reasons in support
of your answer.
Answer (i):
1. Root hair
2. Epidermis
3. Cortex
4. Endodermis
5. Pericycle
6. Protoxylem
7. Metaxylem
8. Pith
9. Phloem
Source: http://textbook.s-anand.net/ncert/class-11/biology/6-anatomy-of-flowering-plants
(DawaTshering, BE 091909)
Page 5
Review Question Solving, Class IX-Biology 2012
Ans (ii):
It is dicot root because:
1. Pericycle is single layered whereas in monocot root it is often multilayered
2. Cortex is comparatively narrow and pith is not well developed in dicot root
6. Describe the similarity in dicot and monocot root pertaining to:
i.
Nature of cortex
ii.
Arrangement of vascular bundles
iii.
Pattern of xylem bundles
Ans:
(i)
 Cortex multilayered
 Parenchymatous in nature
(ii)
Both, monocot and dicot has numerous vascular bundles and are arranged in single
ring
(iii)
Xylem bundles exarch –outer part is protoxylem and inner part is metaxylem
7. Describe two major differences between the dicot and monocot root easy to make
out in their transverse section.
Ans:
Dicot root
Monocot root
Xylem bundles
Fewer
More numerous
Pith
Absent
Present
(metaxylem of the bundles
(consists of parenchymatous cells)
meet in the center)
(DawaTshering, BE 091909)
Page 6
Review Question Solving, Class IX-Biology 2012
8. What is the basis of classifying the leaves into dorsiventral and isobilateral leaves.
Ans: The basis of classifying is the arrangement of the leaves towards sun;
 Dorsiventral leaf-leaf arrangement such that only one surface is exposed to sun,
 Isobilateral leaf-arrangement of leaf such that both the side of leaf is exposed towards
sun.
9. Differentiate between the dorsiventral and isobilateral leaves pertaining to the
nature of
i.
Epidermis on the two sides.
ii.
Mesophyll cells.
iii.
Distribution of stomata.
iv.
Shape of guard cells.
Ans:
(i)
Dorsiventral
Isobilateral leaf
- Upper epidermis is single layer with
-epidermis on both sides is uniformly
thick cuticle, it does not contains
thickened.
chloroplasts, stomata are also absent.
- Stomata present on both the surface
-Lower epidermis is also single layer but
almost equal in number.
with a thin cuticle. It bears many stomata,
two guard cells of which contain some
chloroplast.
(ii)
Dorsiventral
Isobilateral leaf
-mesophyll cell is differentiated into
- is not differentiated into palisade and
palisade and spongy mesophyll.
spongy mesophyll.
(DawaTshering, BE 091909)
Page 7
Review Question Solving, Class IX-Biology 2012
(iii)
Dorsiventral
-
Isobilateral leaf
Upper epidermis is absent of
-stomata are present on both the side of
stomata whereas lower epidermis
the epidermis almost equal in numbers.
has numerous stomata.
(iv)
Dorsiventral

Has sausage-shaped guard cells
Isobilateral leaf

Has specialized kidney shaped
cells
10. List the parts in sequence in the section of an isobilateral leaf of a monocot plant
staring from the outer epidermis of the one surface up to that of the other.
Ans: Upper epidermis, Sclerenchyma cells, Mesophyll cells (xylem, Phloem, Respiratory
cavity), sclerenchyma cells, stomata, lower epidermis.
11. Why the palisade and the spongy cells of mesophyll are named so? What is the
functional advantage of their different nature to the plant?
Ans:
Palisade mesophyll-it was named because it has column of closely packed long cylindrical cells
with their long axes at right angle to the epidermis.
Function- contains chloroplast and enables to carry out photosynthesis.
Spongy mesophyll- it was so named because it contains irregularly shaped cells loosely
arranged leaving large intercellular spaces.
Function- helps in gaseous exchange
(DawaTshering, BE 091909)
Page 8
Review Question Solving, Class IX-Biology 2012
References
Vishnoi, S. (2008).Concise Biology, I.C.S.E. (Class IX Biology textbook).New Dehli, Daryaganj:
Selina Publishers.
Anatomy of Flowering Plants, (n.d). Dicot root image. Retrieved 14, October 2012 from
http://textbook.s-anand.net/ncert/class-11/biology/6-anatomy-of-flowering-plants
(DawaTshering, BE 091909)
Page 9