NEET Biology Anatomy of Flowering Plants MCQs Set 15

Answer: (b) manoxylic wood

Explanation:
1. Cycas stem has manoxylic wood, that is, soft wood with broad parenchymatous rays and abundant parenchyma.
2. Pycnoxylic wood is the compact wood of conifers.
3. Hence option (b) is correct: manoxylic wood

Teacher's Note:
1. Cycas stem shows monoxylic wood with broad parenchymatous rays and often contain abundant resinous cells and resin canals.
2. Towards the periphery of the stem, cycads produce a 'leaf armour' consisting of the tightly packed, helically arranged leaf bases.

Answer: (a) parenchyma

Explanation:
1. Aerenchyma is the modification of parenchyma tissue in which cells are arranged in such a way that - large air filled spaces are formed.
2. Aerenchyma is found in aquatic plants to produce buoyancy.
3. Hence option (a) is correct: parenchyma

Teacher's Note:
1. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.
2. Remember the contrasts between monocot and dicot, and between primary and secondary growth.

Answer: (c) Cambium

Explanation:
1. Monocot vascular Dicot vascular bundle bundle Phloem Phloem Cambium Xylem Xylem No secondary growth, secondary growth, cambium absent V.B. is open. i.e.
2. V.B. is closed.
3. Hence option (c) is correct: Cambium

Teacher's Note:
1. Remember the contrasts between monocot and dicot, and between primary and secondary growth.
2. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.

Answer: (a) lateral meristem

Explanation:
1. Cork cambium (phellogen) is a secondary lateral meristem which develops from permanent tissues in the region of epidermis, hypodermis, cortex and even in outer layers of phloem.
2. Hence option (a) is correct: lateral meristem

Teacher's Note:
1. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.
2. Remember the contrasts between monocot and dicot, and between primary and secondary growth.

Answer: (a) cortex

Explanation:
1. Endodermis is the inner most layer of cortex.
2. The cells are characterized by the presence of casparian strips.
3. Hence option (a) is correct: cortex

Teacher's Note:
1. Remember the contrasts between monocot and dicot, and between primary and secondary growth.
2. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.

Answer: (b) pericycle

Explanation:
1. The lateral roots arise from the cell of pericycle and hence, the root branches are said to be endogenous in origin (arising from a layer inner to endodermis).
2. The lateral roots help in absorption of water and mineral salts from the soil.
3. Hence option (b) is correct: pericycle

Teacher's Note:
1. The meristematic cells of the lateral root push through the endodermis and cortex and then pierce through the epidermis to come out to form the lateral root.
2. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.

Answer: (d) Sieve tube cell

Explanation:
1. Sieve tube cell is enucleate at maturity due to the degeneration of its nucleus during its developmental process.
2. The companion cell-that develops from the same initial as the sieve tube cell, possesses the nucleus throughout its life.
3. Hence option (d) is correct: Sieve tube cell

Teacher's Note:
1. The companion cell carries out the function of the sieve tube cell in the event of its degeneration.
2. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.

Answer: (a) vessels

Explanation:
1. Porous wood contains vessels, with sieve cells, which contains passages for movement of substances.
2. Hence option (a) is correct: vessels

Teacher's Note:
1. Remember the contrasts between monocot and dicot, and between primary and secondary growth.
2. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.

Answer: (a) endodermis

Explanation:
1. Passage cells are found in endodermis which allow a limited transfer of materials between the cortex and the vascular cylinder.
2. Hence option (a) is correct: endodermis

Teacher's Note:
1. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.
2. Remember the contrasts between monocot and dicot, and between primary and secondary growth.

Answer: (b) dicot stem

Explanation:
1. In dicot stem, fascicular cambium and interfascicular cambium join to form a complete ring which helps in secondary growth.
2. Hence option (b) is correct: dicot stem

Teacher's Note:
1. Remember the contrasts between monocot and dicot, and between primary and secondary growth.
2. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.

Answer: (c) dorsiventral leaf

Explanation:
1. In a dorsiventral leaf, mesophyll is differentiated into two layers i.e. palisade parenchyma and spongy parenchyma.
2. Hence option (c) is correct: dorsiventral leaf

Teacher's Note:
1. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.
2. Remember the contrasts between monocot and dicot, and between primary and secondary growth.

Answer: (c) phellem-endodermis-pericycle-phloem

Explanation:
1. In a dicotyledonous stem, the sequence of tissues from outside to the inside is phellem-endodermis-pericycle-phloem.
2. Hence option (c) is correct: phellem-endodermis-pericycle-phloem

Teacher's Note:
1. Remember the contrasts between monocot and dicot, and between primary and secondary growth.
2. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.

Answer: (c) reserve for replenishment of damaged cells of the meristem.

Explanation:
1. The concept of Quiescent Centre was proposed by Clowes in 1961.
2. On the basis of autoradiographic studies of DNA synthesis in the root tip of zea, he found a reservoir of cells having low DNA, RNA and protein concentration.
3. Hence option (c) is correct: reserve for replenishment of damaged cells of the meristem.

Teacher's Note:
1. He called it as Quiescent Centre.
2. They may or may not divide.

Answer: (c) sieve elements

Explanation:
1. Companion cells are long elongated living cells, that lie on the sides of the sieve tubes in phloem.
2. Companion cells control the activities of the sieve tube through plasmodesmata.
3. Hence option (c) is correct: sieve elements

Teacher's Note:
1. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.
2. Remember the contrasts between monocot and dicot, and between primary and secondary growth.

Answer: (b) suberin

Explanation:
1. Phellogen produces cork or phellem on the outer side.
2. It consists of dead and compactly arranged rectangular cells that possess suberised cell walls.
3. Hence option (b) is correct: suberin

Teacher's Note:
1. Lenticels Cork cells (suberized) Phellogen Secondary cortex.
2. Remember the contrasts between monocot and dicot, and between primary and secondary growth.

Answer: (d) endarch condition of stem and exarch condition of root

Explanation:
1. The cross sections of stem and root appear simple, when viewed by naked eye but under microscope they can be differentiated as endarch condition in stem and exarch condition in root.
2. In endarch, protoxylem is present towards the center of stem while metaxylem towards the pericycle.
3. Hence option (d) is correct: endarch condition of stem and exarch condition of root

Teacher's Note:
1. In the exarch condition, protoxylem is present towards pericycle and metaxylem towards the center of the root.
2. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.

Answer: (a) Root dies first

Explanation:
1. If a stem is girdled, root dies first, as the food synthesized by leaves is not able to reach to the roots.
2. Hence option (a) is correct: Root dies first

Teacher's Note:
1. Remember the contrasts between monocot and dicot, and between primary and secondary growth.
2. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.

Answer: (d) dead, without

Explanation:
1. Sclerenchyma consists of long, narrow cells with thick and lignified cell walls having a few or numerous pits.
2. They are usually dead and without protoplasts.
3. Hence option (d) is correct: dead, without

Teacher's Note:
1. Remember the contrasts between monocot and dicot, and between primary and secondary growth.
2. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.

Answer: (d) Sealing mechanism on wounding.

Explanation:
1. P-proteins (phloem proteins) occur in sieve elements.
2. When a sieve tube is injured they plug the sieve plate pores and act as a sealing mechanism against loss of sap.
3. Callose is a polysaccharide, so it is not deposited by P-proteins.
4. Hence option (d) is correct: Sealing mechanism on wounding.

Teacher's Note:
1. P-protein is also called slime protein.
2. Callose seals sieve plates in old or injured phloem, but it is not a protein.

Answer: (d) B, C and E only

Explanation:
1. Statement A is wrong: uneven thickening is a feature of collenchyma.
2. B is right: periblem forms the cortex.
3. C is right: tracheids are the chief water conducting elements of gymnosperms.
4. D is wrong: a companion cell has a nucleus.
5. E is right: commercial cork comes from Quercus suber, so B, C and E only are correct.
6. Hence option (d) is correct: B, C and E only

Teacher's Note:
1. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.
2. Remember the contrasts between monocot and dicot, and between primary and secondary growth.

Answer: (a) centre (pith), periphery

Explanation:
1. The first formed primary xylem is protoxylem and the later formed one is metaxylem.
2. In stems the protoxylem lies towards the pith and the metaxylem towards the periphery.
3. This arrangement is called endarch.
4. Hence option (a) is correct: centre (pith), periphery

Teacher's Note:
1. The first formed primary xylem elements are called protoxylem and the later formed primary xylem is called metaxylem.
2. In stems, the protoxylem lies towards the centre (pith) and the metaxylem lies towards the periphery of the organ.

Answer: (b) Both Assertion and Reason are true but the Reason is not a correct explanation of the Assertion.

Explanation:
1. Fusiform initials are vertically elongated cells that produce xylem and phloem elements.
2. Ray initials are isodiametric and produce parenchymatous rays in secondary xylem and phloem.
3. Hence option (b) is correct: Both Assertion and Reason are true but the Reason is not a correct explanation of the Assertion.

Teacher's Note:
1. Remember the contrasts between monocot and dicot, and between primary and secondary growth.
2. Anatomy questions are tissue-location based: note where each tissue or cell type lies in root, stem and leaf.

Answer: (a) Both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.

Explanation:
1. The root apex and shoot apex are meristematic in nature.
2. These meristematic tissues are embryonic in origin.
3. Hence option (a) is correct: Both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.

Teacher's Note:
1. They are primary in origin because it develops from embryonic tissues and primary in function Anatomy of Flowering Plants because they form the primary structure of the plant cell, the root apex and shoot apex, that live till the death of the whole plant.
2. Hence, plants have the feature of indefinite growth.

Answer: (d) Both Assertion and Reason are false.

Explanation:
1. In a collateral bundle the xylem lies towards the inner side and the phloem towards the outer side, so the Assertion is false.
2. The monocot stem has no cambium (closed bundles), so the Reason is also false.
3. Hence option (d) is correct: Both Assertion and Reason are false.

Teacher's Note:
1. Collateral vascular bundles have the xylem pointing towards the inner side of the phloem.
2. In the same way in monocots, cambium is absent.

Answer: (c) Assertion is true but the Reason is false.

Explanation:
1. Vessels make water conduction in angiosperms more efficient, so the Assertion is true.
2. But water movement through vessel elements is passive.
3. They are dead cells, so no energy is supplied by xylem parenchyma and the Reason is false.
4. Hence option (c) is correct: Assertion is true but the Reason is false.

Teacher's Note:
1. Xylem is the water conducting tissue.
2. It consists of living cells like parenchyma and dead cells like tracheary elements.

Answer: (a) Both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.

Explanation:
1. In woody trees, the central portion of stem is dark in colour.
2. It is hard and tough due to deposition of resins, tannins, gums and formation of tyloses.
3. Hence option (a) is correct: Both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.

Teacher's Note:
1. This central hard portion is called heart wood.
2. It is formed by secondary growth.

Answer: (b) Both Assertion and Reason are true but the Reason is not a correct explanation of the Assertion.

Explanation:
1. Vessels are more efficient for water conduction as compared to tracheids.
2. Vessels resemble tracheids very much in structure and function.
3. Hence option (b) is correct: Both Assertion and Reason are true but the Reason is not a correct explanation of the Assertion.

Teacher's Note:
1. But unlike tracheids these are like long tubes arranged in vertical row formed of cylindrical cells arranged to end with their end walls completely dissolved.
2. These are also dead and lignified.