NEET > Structural Organization in Animals and Plant

Explore popular questions from Structural Organization in Animals and Plant for NEET. This collection covers Structural Organization in Animals and Plant previous year NEET questions hand picked by popular teachers.


Q 1.    

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Incorrect-1

The vascular cambium normally gives rise to

A

primary phloem

secondary xylem

C

periderm

D

phelloderm.

Explanation

Cells of vascular cambium divide periclinally both on the outer and inner sides to form secondary permanent tissues, {tex}i.e.,{/tex} secondary xylem and secondary phloem.

Q 2.    

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Incorrect-1

Root hair develop from the region of

A

elongation

B

root cap

C

meristematic activity

maturation.

Explanation

Root hair are lateral tubular outgrowths that develop from the outer cells of zone of maturation or root hair zone.

Q 3.    

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Incorrect-1

Which of the following is made up of dead cells?

A

Collenchyma

Phellem

C

Phloem

D

Xylem parenchyma

Explanation

The phellem or cork consists of dead and compactly arranged rectangular cells that possess suberised cell wall.

Q 4.    

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Incorrect-1

Identify the wrong statement in context of heartwood.

A

It is highly durable.

It conducts water and minerals efficiently.

C

It comprises dead elements with highly lignified walls.

D

Organic compounds are deposited in it.

Explanation

Heartwood is the non-functional part of secondary xylem, hence, it does not conduct water and minerals.

Q 5.    

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Incorrect-1

Cortex is the region found between

epidermis and stele

B

pericycle and endodermis

C

endodermis and pith

D

endodermis and vascular bundle.

Explanation

Q 6.    

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Incorrect-1

The balloon-shaped structures called tyloses

A

originate in the lumen of vessels

B

characterise the sapwood

are extensions of xylem parenchyma cells into vessels

D

are linked to the ascent of sap through xylem vessels.

Explanation

Tyloses are balloon-like extensions of parenchyma cells that protrudes into the lumen of a neighbouring xylem vessel or tracheid through a pit in the cell wall. Tyloses form most commonly in older woody tissue, possibly in response to injury, they may eventually block the vessels and thus help prevent the spread of fungi and other pathogens within the plant. Tyloses may become filled with tannins, gums,pigments, etc., giving heartwood its dark colour, and their walls can remain thin or become lignified.

Q 7.    

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Incorrect-1

Specialised epidermal cells surrounding the guard cells are called

A

bulliform cells

B

lenticels

C

complementary cells

subsidiary cells.

Explanation

The leaf and stem epidermis of plant is covered with pores called stomata. Each stomata is surrounded by a pair of specialised epidermal cells known as guard cells which are in some cases further surrounded by another category of less modified epidermal cells known as subsidiary cells which provide support to the guard cells.

Q 8.    

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Incorrect-1

Read the different components from (i) to (iv) in the list given below and tell the correct order of the components with reference to their arrangement from outer side to inner side in a woody dicot stem
(i) Secondary cortex (ii) Wood (iii) Secondary phloem (iv) Phellem.
The correct order is

(iv), (i), (iii), (ii)

B

(iv), (iii), (i), (ii)

C

(iii), (iv), (ii), (i)

D

(i), (ii), (iv), (iii)

Explanation

In a woody dicot stem, phellem (cork) forms the outermost layer followed by phellogen and then secondary cortex (phelloderm). Secondary phloem forms a narrow circle on the outer side of vascular cambium whereas secondary xylem occurs on the inner side of vascular cambium.

Q 9.    

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Incorrect-1

A major characteristic of monocot root is the presence of

vasculature without cambium

B

cambium sandwiched between phloem and xylem along the radius

C

open vascular bundles

D

scattered vascular bundles.

Explanation

In monocot root, a large number of vascular bundles are arranged in the form of a ring around the central pith. Vascular bundles are closed because there is no cambium present between the xylem and phloem.

Q 10.    

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Incorrect-1

Vascular bundles in monocotyledons are considered closed because

A

there are no vessels with perforations

B

xylem is surrounded all around by phloem

C

a bundle sheath surrounds each bundle

cambium is absent.

Explanation

Q 11.    

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Incorrect-1

You are given a fairly old piece of dicot stem and a dicot root. Which of the following anatomical structures will you use to distinguish between the two?

A

Secondary xylem

B

Secondary phloem

Protoxylem

D

Cortical cells

Explanation

In stems, the protoxylem lies towards the centre (pith) and the metaxylem lies towards the periphery. This type of primary xylem is called endarch. In root, the protoxylem lies towards periphery and metaxylem lies towards the centre, such arrangement is called exarch.

Q 12.    

Correct4

Incorrect-1

Tracheids differ from other tracheary elements in

A

having casparian strips

being imperforate

C

lacking nucleus

D

being lignified.

Explanation

Tracheids are elongated, dead cells with hard lignified walls, wide lumens and narrow walls with spiral, annular, reticulate, scalariform and pitted thickening but without perforated end walls of septa.That is, they have intact end walls unlike vessels. Vessels are long cylindrical tube like structures made of many cells, called vessel members, each with lignified walls and a large central cavity. Vessel members are interconnected through perforation in their common walls.

Q 13.    

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Incorrect-1

Lenticels are involved in

A

food transport

B

photosynthesis

C

transpiration

gaseous exchange.

Explanation

Lenticels are lens shaped openings formed in bark due to secondary growth. They permit gaseous exchange in woody trees. They also contribute to transpiration but in minute amounts because the suberised complementary cells present beneath the pore prevent excessive water loss.

Q 14.    

Correct4

Incorrect-1

Age of a tree can be estimated by

number of annual rings

B

diameter of its heartwood

C

its height and girth

D

biomass.

Explanation

Two bands of secondary xylem {tex} i . e . , {/tex} autumn wood and spring wood are produced in one year.These two bands make an annual ring. The age of plant can be determined by counting the annual rings.It is called dendrochronolgy.

Q 15.    

Correct4

Incorrect-1

Interfascicular cambium develops from the cells of

A

endodermis

B

pericycle

medullary rays

D

xylem parenchyma.

Explanation

In dicot stems, the cells of cambium present between primary xylem and primary phloem is the intrasfascicular cambium. The cells of medullary rays,adjoining these intrafascicular cambium become meristematic and form the interfascicular cambium.Thus, a continuous ring of cambium is formed.

Q 16.    

Correct4

Incorrect-1

Meristematic tissue responsible for increase in girth of tree trunk is

A

intercalary meristem

lateral meristem

C

phellogen

D

apical meristem.

Explanation

Lateral meristems are the meristems which are present along the lateral sides of stem and roots.They divide only in radial direction. Intrastelar or vascular cambium ring formed by intra-fascicular (also called fascicular) and inter-fascicular cambium; and cork cambium (phellogen) are examples of this type of meristem. These meristems are responsible for increase in girth of stem and roots.

Q 17.    

Correct4

Incorrect-1

Bundle sheath cells

A

are rich in PEP carboxylase

B

lack RuBisCO

C

lack both RuBisCO and PEP carboxylase

are rich in RuBisCO.

Explanation

{tex} \mathrm { C } _ { 4 } {/tex} plants show kranz type of anatomy. In kranz anatomy, the mesophyll is undifferentiated and its cells occur in concentric layers around vascular bundles. The vascular bundles are surrounded by large sized bundle sheath cells which are arranged in wreath like manner in one to several layers. In {tex} \mathrm { C } _ { 4 } {/tex} plants there are two carboxylation reactions, first in mesophyll chloroplast and second in bundle sheath chloroplast.RuBP is present in bundle sheath chloroplasts where {tex} \mathrm { C } _ { 3 } {/tex} cycle takes place.

Q 18.    

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Incorrect-1

Which of the following statements is not true for stomatal apparatus?

A

Guard cells invariably possess chloroplasts and mitochondria.

Guard cells are always surrounded by subsidiary cells.

C

Stomata are involved in gaseous exchange.

D

Inner wall of guard cells are thick.

Explanation

The epidermal surface of the leaf exhibits 1,000 to 60,000 minute openings called stomata. The stomata are bordered by two specialized epidermal cells - the guard cells which in some cases are accompanied by subsidiary cells. The walls of guard cells are unevenly thickened. Each guard cell has thick, inelastic inner wall and thin, elastic outer wall. Stomatal aperture is present in between the guard cells. Guard cells are not always surrounded by accessory cells or subsidiary cells.

Q 19.    

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Incorrect-1

Gymnosperms are also called soft wood spermatophytes because they lack

A

cambium

B

phloem fibres

C

thick-walled tracheids

xylem fibres.

Explanation

Q 20.    

Correct4

Incorrect-1

Water containing cavities in vascular bundles are found in

A

sunflower

maize

C

{tex}Cycas{/tex}

D

{tex}Pinus.{/tex}

Explanation

Q 21.    

Correct4

Incorrect-1

Closed vascular bundles lack

A

ground tissue

B

conjunctive tissue

cambium

D

pith.

Explanation

Vascular bundle consists of complex tissues,the phloem and xylem. In dicots, between xylem and phloem, cambium is present which helps in secondary growth. This type of vascular bundle is called open.While in monocots cambium is absent, so these are called closed vascular bundles.

Q 22.    

Correct4

Incorrect-1

Companion cells are closely associated with

sieve elements

B

vessel elements

C

trichomes

D

guard cells.

Explanation

Companion cell is a type of cell found within the phloem of flowering plants. Each companion cell is usually closely associated with a sieve element. They remain connected with sieve cells by plasmodesmata. They help in loading of phloem sieve cells with sugars through active transport.

Q 23.    

Correct4

Incorrect-1

The common bottle cork is a product of

A

dermatogen

phellogen

C

xylem

D

vascular cambium.

Explanation

Cork cambium or phellogen is a type of cambium arising within the outer layer of the stems of woody plants, usually as a complete ring surrounding the inner tissues. The cells of the cork cambium divide to produce an outer corky tissue (cork or phellem) and an inner secondary cortex(phelloderm). The common bottle cork produced from {tex}Quercus\ suber{/tex} is a product of phellogen.

Q 24.    

Correct4

Incorrect-1

As compared to a dicot root, a monocot root has

A

more abundant secondary xylem

many xylem bundles

C

inconspicuous annual rings

D

relatively thicker periderm.

Explanation

In monocot root, secondary growth is absent and vascular cylinder is in the form of several alternate and radial xylem and phloem bundles. The vascular bundles are arranged in the form of ring around central pith. Their number in maize ranges between 20 - 30 whereas in {tex}Pandanus{/tex} and palms, they may be upto 100. Because of the presence of numerous xylem bundles and exarch condition, xylem of monocot root is polyarch.On the other hand, in dicot root, xylem and phloem are equal in number (2 - 6) and alternately arranged i.e.,they lie on different radii hence called radial bundles.According to number of ray (equivalent to number of xylem or phloem bundles) the roots may be diarch,triarch, tetrarch, pentarch or hexarch.

Q 25.    

Correct4

Incorrect-1

The cork cambium, cork and secondary cortex are collectively called

A

phelloderm

B

phellogen

periderm

D

phellem.

Explanation

In hypodermis or outer cortical cells, a layer becomes meristematic which is known as cork cambium or phellogen. This phellogen also cuts off cells both on its outer side and inner side. The cells cut off on outer side are phellem or cork cells and cells cut off on inner side are phelloderm or secondary cortex. Phellem, phellogen and phelloderm collectively constitute periderm.

The function of periderm is protective (because at maturity epidermis ruptures and hence the function is performed by periderm).