0

Defense mechanism in plants - class-IX

Description: defense mechanism in plants
Number of Questions: 56
Created by:
Tags: tissues: plant and animal tissues biology tissues, organs, organ system, organism tissues soldiers of defense multicellular structure: tissue
Attempted 0/56 Correct 0 Score 0
Epiblema of roots is equivalent to
  1. pericycle

  2. endodermis

  3. epidermis

  4. stele


Correct Option: C
Explanation:

 In a typical monocot root, Epiblema is single layered, consists of thin- walled cells. A few tubular root hair arise as unicellular elongation of epiblema cells.

In a typical dicot root, Epidermis is uniseriate consisting of thin- walled, living parenchymatous cells. A few cells elongate to form root hair.
Therefore, from this analysis, It shows epiblema in monocot root is equivalent to epidermis of dicot root.
So, the correct answer is 'Epidermis'.

Which of the following is not a function of epidermis?

  1. Protection of underlying cells

  2. Gaseous exchange

  3. Conduction of water

  4. Non conduction of water by root hairs


Correct Option: C
Explanation:

The epidermis is a single layer of cells found on outer layers in different parts of the plant. It forms a barrier between the underlying tissues in a plant with the surrounding environment. Therefore, it is protected from adverse environmental conditions.

The presence of stomata and guard cells in the epidermal tissue will help in the exchange of $O _{2}$ and $CO _{2}$.

Conduction of water and minerals in plants takes place in conducting vessels. It is located in the core, known as xylem. Thus conduction of water is not the function of the epidermis but, it is of xylem.

The correct option is C.

Choose the odd feature for epidermis

  1. Living

  2. Parenchymatous

  3. Always single layered

  4. May have cutin deposition


Correct Option: C
Explanation:

Epidermis usually consists of a single layer of cells and is the outermost layer present on leaves, stem and roots of plants. The epidermis consists of living parenchyma cells. On most plant stem and leaves, cutin, a fatty substance, is very often deposited on the outer surface of the epidermal cell wall to form cuticle over which wax may also be deposited. Generally epidermis is single layered, but in xerophytes it is multilayered'

So, the correct option is 'always single layered'.

The external protective tissues of plants are

  1. Epidermis

  2. Xylem

  3. Pericycle

  4. None of the above


Correct Option: A
Explanation:

The epidermis is a single-layered group of cells that covers plants leaves, flowers, roots and stems. It forms a boundary between the plant and the external environment. The epidermis serves several functions, it protects against water loss, regulates gas exchange, secretes metabolic compounds, and especially in roots absorbs water and mineral nutrients. 

So, the correct answer is option A.

Out of the following, find the odd one out. 

  1. Epiblema

  2. Muscle fibre

  3. Nerve fibre

  4. Skin


Correct Option: A
Explanation:

Muscle fibre, nerve fibre,and skin are present in the animal body. Epiblema is a special epidermal cells present in rootlets. They are specially adapted for absorbing liquids. Epiblema is present in plants. 

So, the correct answer is option A.

Bulliform cells are

  1. Water filled and highly vacuolated epidermal cell

  2. Prokaryotic cell

  3. Eukaryotic cell

  4. Ball like parenchymatous cells


Correct Option: A
Explanation:

Bulliform cells  are so called because of its peculiar bubble shape. It mainly occurs on the upper surface of the leaves present in grasses. Water present in these cells helps to maintain its shape but loss of turgor pressure during the stress allows the leaves to roll up. During drought, the loss of moisture through vacuoles induces bulliform cells to cause the leaves of many grass species to close as the two edges of the grass blade fold up toward each other. Once adequate water is available, these cells enlarge and the leaves open again. 

So, the correct answer is option A.

Bulliform cells are found in

  1. Seeds of sunflower

  2. Leaf of wheat

  3. Pod of pea

  4. Tuber of potato


Correct Option: B
Explanation:

Bulliform cells are the special cells known for its peculiar bubble like shape. It is found in the higher plants. The turgor pressure created due to the water present in the cells is lost during stress like transpiration or infection which allows the leaf to roll up. Once adequate water is available, these cells enlarge and the leaves open again. So, bulliform cells are found in the leaf of wheat (grasses) and not in seeds of sunflower, a pod of pea and tuber of potato. Thus, option B is correct.

Waxy coating on epidermis of young stem is called

  1. Suberin

  2. Periderm

  3. Phellem

  4. Cuticle


Correct Option: D
Explanation:

A cuticle is the waxy layer present on the epidermis of a young stem which generally curtails the water loss by transpiration.

Phellem (the cork) consists of cells that are dead at maturity and their primary walls become covered from the inside by the secondary wall which consists of parallel suberin lamellae alternating with wax layers.
The periderm is the secondary protective (dermal) tissue that replaces the epidermis during growth in thickness of stems and roots of gymnosperms and dicotyledons. Suberin is a waterproofing waxy substance found in higher plants. Suberin is a main constituent of cork and is named after the cork oak, Quercus suber. Its main function is as a barrier to movement of water and solutes. 
Thus, the correct answer is option D.

Fatty substance found in epidermal cell walls is

  1. Cutin

  2. Suberin

  3. Both B and C

  4. None of the above


Correct Option: A
Explanation:

The cuticle is the waxy layer present on the epidermis of the leaf which curtails the rate of water loss by transpiration in certain higher plants. 
Cutin is especially noticeable in many fruits, e.g., apple, nectarine, and cherry, which can be buffed to a high gloss. Carnauba wax is derived from the cuticles of the leaves of Copernicia cerifera, a Brazilian palm.
Suberin is the inert waxy substance which is present in the cell wall of cork tissue.

Thus, the correct answer is option A.

Passage cells occur in

  1. Epidermis

  2. Cortex

  3. Endodermis

  4. Pericycle


Correct Option: C
Explanation:

Passage cells are endodermal in origin. These are found in cells of older roots which have retained thin walls and casparian strips to allow some symplastic flow to the inside. These do not get suberized or thickened.
Experimental evidence suggests that passage cells function to allow transfer of solutes such as calcium and magnesium into the stele, in order to eventually reach the transpiration system. For the most part, however, old roots seal themselves off at the endodermis and only serve as a passageway for water and minerals taken up by younger roots downstream. So, passage cells occur in endodermis and not in pericycle, cortex or epidermis.
Thus, the correct answer is option C.

Which would do maximum harm to a tree?

  1. Loss of half of its leaves

  2. Loss of half of its branches

  3. Loss of all of its leaves

  4. Loss of all its bark


Correct Option: D
Explanation:
The loss of half of branches does not harm the tree much, as half of the branches are present to carry out photosynthesis and transpiration. This condition we can see in real day to day life also that if the half of the branches are cut down then also tree can be alive. 
Shedding of all leaves is carried out by the plant itself but it does not harm the tree. Soon after shedding, the new leaves can be observed on the tree. 
The bark is the outermost layer of the stems of the woody plants. All the tissues outside the vascular cambium are called as bark. It protects the tree from wear and tear, bacterial infection and water loss. If all of the bark of the tree is removed then water loss will dry out the tree and tree will also become vulnerable to infections. 
So, the correct answer is 'Loss of all its bark'

The cotton fibres are 

  1. Fibres taken out from stem

  2. Epidermal hairs of seed

  3. Epidermal hairs of fruits

  4. Fibres taken out from roots


Correct Option: B
Explanation:

Cotton, seed hair fibre of a variety of plants of the genus Gossypium, belonging to the hibiscus, or mallow family (Malvaceae) and native to most subtropical parts of the world. Cotton is a soft, fluffy staple fibre that grows in a boll or protective capsule, around the seeds of cotton plants of the genus Gossypium in the family of Malvaceae.
The fibre is almost pure cellulose. Under natural conditions, the cotton bolls will tend to increase the dispersion of the seeds. The epidermis cells is a single-layered group of cells that covers plants leaves, flowers, roots and stems. It forms a boundary between the plant and the external environment. Cotton fibres are collected from epidermal layer of seeds. So, cotton fibres are epidermal hairs of seed and not epidermal hairs of fruits, fibres taken out from roots or fibres taken out from the stem. 
Thus, the correct answer is option B.

Endodermis is a part of

  1. Vascular tissue system

  2. Extrastelar tissue system

  3. Epidermal tissue system

  4. Intrastelar tissue system


Correct Option: B
Explanation:

The epidermal tissues system forms the outer protective covering of primary plant body in form of epidermis and of secondary plant organs in form of periderm. 

During secondary growth, rupturing of epidermal cell and outer cortex by secondary tissues induces formation of new protective layer, periderm which in turn divides to form cork cambium /phellogen. 
Vascular tissues system consists of stele, which is the central region having vascular bundle, pericycle, pith and medullary rays. 
The tissues present outside the stele forms extrasteler tissues system. Stele is surrounded by endodermis and cortex, these two together make extra steler system. 
Intrasteler tissues system refers to the tissues present in a stele i.e., vascular bundle, pericycle, pith and medullary rays.

Periblem gives rise to 

  1. Epidermis

  2. Cortex

  3. Pericycle

  4. Pith


Correct Option: B
Explanation:

The apical meristematic tissue is continuously dividing tissue which mainly helps forms different specialized cells. Periblem is the histogen in plants that gives rise to the cortex. It does not give rise to the epidermis, pericycle, and the pith. It is the multilayered zone that lies beneath the dermatogen. The periblem cells divide into anticlinal and periclinal planes and give rise to cortex and endodermis. Pleurome gives rise to pericycle, vascular tissues, pith and medullary rays. Dermatogen gives rise to an epidermal layer of plant organs. 
Thus, the correct answer is option B.

Scaly bark occurs in

  1. Eucalyptus

  2. Betula

  3. Psidium

  4. None of the above


Correct Option: C
Explanation:

The bark is composed of periderm and stem's secondary phloem, the cork cambium, phelloderm and cork cells together make up the periderm. Formation of new periderm layer renders the previous layer dead due to stoppage of water and nutrient supply and differentiates the bark into two regions, namely outer and inner bark. The cork, secondary cortex and phloem present just outside the innermost phellogen constitute outer bark while rest of the tissues present in the outer bark make inner bark. Formation of subsequent periderm layers as overlapping scales gives scaly bark as is present in Psidium. When the bark is peeled off as large sheets, it is termed as intermediate bark as is found in Eucalyptus and Betula.
Thus, the correct answer is option C.

Multiple epidermis occurs in

  1. Gossypium

  2. Cucurbita

  3. Nerium

  4. All of the above


Correct Option: C
Explanation:

The epidermis cells are the cells which form the outer layer and plays an important role in protection. It helps to prevent the water loss by transpiration. Nerium, is a xerophyte which has layers of epidermal tissue to curtail the rate of transpiration. It is a type of xerophytic adaptation.
Thus, the correct answer is option D.

Protosteles are found in

  1. Bryophyta

  2. Gymnosperms

  3. Pteridophyta

  4. Angiosperms


Correct Option: C
Explanation:

Prostele is a primitive and simple type of stele. It consists of a solid mass of xylem surrounded by phloem, pericycle, and endodermis. It is permanently present in adult stems of many living pteridophytes, e.g. Lygodium, Lycopodium, Hymemophyllus, and Selaginella. It is present in vascular plants. Protostele is of four types as haplostele, actinostele, plectostele and mixed protostele. Thus, option C is correct.

In which of the following plant part, laticiferous glands are found?

  1. Cortex

  2. Epidermis

  3. Endodermis

  4. Vascular bundle


Correct Option: A
Explanation:

Laticiferous vessels are the specialized thin walled parenchymatous cells that secrete latex and are found in the cortex. They lack pits and are composed of cellulose and hemicelluloses and serve to secrete latex. Epidermis is the outermost covering of the primary plant body and is mostly represented by a single layer of compactly arranged, barrel-shaped parenchyma cells.
The innermost layer of cortex forms endodermis which has compactly arranged barrel shaped cells. The primary thin walled endodermis shows suberin deposition in form of bands or strips that run around the radial and end walls of the cells and forms casparian strips. Vascular bundle consists of xylem, phloem and cambium (in dicot only) which are derived from procambium and serve in translocation of food and sap.
Thus, the correct answer is option A.

The function of hypodermis is

  1. Protection

  2. Hardness

  3. Support

  4. Storage


Correct Option: C
Explanation:

Hypodermis lies below the epidermis. These cells are sometimes modified to give additional structural support or to store food materials or water. Since its cell walls are heavily suberized and impermeable to water its apparent function is to keep the water and nutrients from leaking out through the cortex. The hypodermis is especially well developed in plants of arid regions and in those with shallow root systems. It also deters the entrance of soil microorganisms. So, the function of hypodermis is support and not storage, hardness or protection. Thus, option C is correct.

Innermost layer of cortex is

  1. Endodermis

  2. Epidermis

  3. Exodermis

  4. Hypodermis


Correct Option: A
Explanation:

Epidermis is the outermost covering of the primary plant body and is mostly represented by a single layer of compactly arranged, barrel-shaped parenchyma cells that delimit cotex on outer side.  

The inner most layer of cortex forms endodermis, which has compactly arranged barrel shaped cells. 
The outer suberized sub-epidermal layer of cortex is exodermis, it has unthickened passage cells and is mostly present in roots. 
Hypodermis refers to 5-7 layers of cortical cells present just beneath the epidermis. It is present in leaves not in roots.
So, the correct answer is option A.

Scaly bark occurs in

  1. Eucalyptus

  2. Betula

  3. Psidium

  4. None of the above


Correct Option: A
Explanation:

Scaly bark refers to the type of bark of trees where the stem has discontinuous, overlapping successive periderms and patches of the bark are shed. This is generally found in Eucalyptus squamosa growing in and around Sydney.

So, the correct answer is option A.

Epidermal cells are

  1. Guard cells

  2. Root hairs

  3. Trichomes

  4. All of the above


Correct Option: D
Explanation:

Epidermal cells make the outermost covering of primary plant body. They are compactly arranged, barrel-shaped parenchyma cells with no or little intercellular spaces. 

Each stomatal pore is surrounded by two guard cells that assist in stomatal opening driven by turgidity of guard cells. The guard cells are the only epidermal cells with unevenly thickened walls and chloroplasts.  
A root hair cell is a tubular unicellular extension of epiblema, the epidermis of root. It has a nucleus and large vacuole with lots of mitochondria in the cytoplasm and serves to absorb water and mineral salts by osmosis and active transport respectively. 
Trichomes are the hairy outgrowth of epidermis that may be unicellular or multicellular, live or dead and are mostly present on leaf surfaces.

Cell wall is impermeable to water and deposition of suberin occurs in

  1. Bark

  2. Cork

  3. Bast

  4. Xylem


Correct Option: B
Explanation:

Suberin is a waterproofing waxy layer. Its main function is to serve as a barrier to movement of water and solutes. A mature cork cell is nonliving and has cell walls that are composed of a waxy substance that is highly impermeable to gasses and water, called as suberin. Thus, option B is correct. 

The outermost primary meristem gives rise to

  1. Epidermis

  2. Procambium

  3. Ground meristem

  4. All of the above


Correct Option: A
Explanation:

The apical meristem has upper promeristem and lower primary meristem. Primary meristem differentiates into three distinct meristematic regions, the outermost protoderm, middle ground meristem, and innermost procambium. The protoderm gives rise to epidermal tissue system, ground meristem forms cortex/ground tissue system and procambium forms vascular tissue system (xylem, phloem, and cambium). 

So, the correct answer is option is A.

Which of the following plant shows multiple epidermis?

  1. Palm

  2. Ficus

  3. Croton

  4. Cucurbita


Correct Option: B
Explanation:

Epidermis is the outermost protective layer which minimizes the loss of water by transpiration. Some plants, like Ficus elastica and Peperomia, which have periclinal cellular division within the protoderm of the leaves, have an epidermis with multiple cell layers.

So, the correct answer is option B.

The cells are chlorophyllous, fewer in number, unique in shape and inner walls thick. The description fits into

  1. Guard cells

  2. Subsidiary cells

  3. Passage cells

  4. Bulliform cells


Correct Option: A
Explanation:

Each stomatal pore is surrounded by two guard cells that assist in stomatal opening driven by turgidity of guard cells. The only epidermal cells with unevenly thickened walls and chloroplasts are the guard cells, they are kidney shaped in dicots and dumbell shaped in monocots.

Cuticle is secreted by

  1. Epidermis

  2. Endodermis

  3. Both A and B

  4. Hypodermis


Correct Option: A
Explanation:

Epidermis is the part of epidermal tissue system and forms the outer protective covering of primary plant body. The epidermal cells secrete cutin, which is a hydrophobic substance and prevents water loss and desiccation. The cutin forms a covering outside the epidermal cells in all plants parts except root.

The innermost layer of cortex forms endodermis, which has compactly arranged barrel shaped cells. The primary thin walled endodermis shows suberin deposition in form of bands or strips that run around the radial and end walls of the cells and forms Casparian strips. 
Hypodermis refers to 5-7 layers of cortical cells present just beneath the epidermis.

The wall of cork cells are thickened by the deposition of________________

  1. Cutin

  2. Suberin

  3. Lignin

  4. Pectin


Correct Option: B
Explanation:

  • Cork cells are dead and have cell walls composed of a waxy substance "suberin", which is highly impermeable to gases and water. This substance prevents water loss from stem. Therefore, option B is correct.

Identify the incorrect statements out of the following and select the correct option.
(i)  Epidermal tissue system forms the outermost covering of various plant organs.
(ii)  Ground tissue synthesizes organic compounds and controls photosynthesis with the help of collenchyma cells.
(iii)  Epidermal tissue of leaves is called mesophyll which is made up of two types of cells. palisade and spongy.
(iv)  Ground tissue system forms interior of plant organs with exclusion of dermal and vascular systems.

  1. (i) and (ii)

  2. (ii) and (iii)

  3. (i) and (iv)

  4. (i), (ii) and (iv)


Correct Option: A
Explanation:

The ground tissue system synthesizes organic compounds, supports the plant and provides storage for the plant. It is mostly made up of parenchyma cells. Parenchyma cells synthesize and store organic products in a plant. Parenchyma cells in leaves control photosynthesis. Collenchyma cells have a support function in plants, particularly in young plants. Mesophyll tissue is the photosynthetic parenchyma cells that lie between the upper and lower epidermis layers of a leaf. In dicotyledonous leaves, there are two types of mesophyll cells; palisade mesophyll and spongy mesophyll.

So, the correct answer is option A.

In desert plants, the epidermis has a thick waterproof coating of____________

  1. Cutin

  2. Suberin

  3. Elastin

  4. Chondrin


Correct Option: A
Explanation:

  • In deserts, water is scarce and saving water is a major step which plants of this region have to undertake. So in many of the desert plants like Yucca, creosote, cactus, etc, the epidermis has a thick waxy coating of cutin. 
  • This restricts the loss of water through transpiration. In desert plants, the epidermis has a thick waterproof coating that is not made of suberin, elastin or chondrin. 

Therefore, the correct answer is option A.

External protective tissues of plants are_____________

  1. Cortex and epidermis

  2. Pericycle and cortex

  3. Epidermis and cork

  4. Pericycle and cork


Correct Option: C
Explanation:

The epidermis cells is a single layer of cells that covers the leaves, flowers, roots and stems of plants. It forms a boundary between the plant and the external environment. Cork cambium is a tissue found in many vascular plants as part of the periderm. The cork cambium is a lateral meristem and is responsible for secondary growth that replaces the epidermis in roots and stems. The pericycle is a cylinder of parenchyma or sclerenchyma cells that lies just inside the endodermis and is the outer most part of the stele of plants. Cortex, in plants, the tissue of unspecialized cells lying between the epidermis (surface cells) and the vascular, or conducting, tissues of stems and roots. 

Therefore, the correct answer is option C

Cork cells are generally impervious to water and gases because of the presence of_______________

  1. Cellulose

  2. Suberin

  3. Pectin

  4. Lignin


Correct Option: B
Explanation:

  • Cork cells are formed as a part of the bark. The waterproof waxy layer present on the cork cell is the suberin., Quercus suber. Its main function is as a barrier to the movement of water and solutes. Suberin is highly hydrophobic and a somewhat 'rubbery' material. In roots, suberin is deposited in the radial and transverse cell walls of the endodermal cells. 
  • This structure, known as the Casparian strip or Casparian band, functions to prevent water and nutrients taken up by the root from entering the stele through the apoplast. Pectin, lignin, and cellulose are not hydrophobic materials. 

Therefore, the correct answer is option B.

Find the incorrect statements from the following.
A. Roots hairs are multicellulars elongation of the epidermal cells.
B. Trichomes are unicellular epidermal hairs of the stem.
C. Guard cells are specialized cells regulating opening and closing of stomata.
D. Cuticle, collenchyma and stomata are absent in roots.

  1. A, C and D are incorrect

  2. B, C and D are incorrect

  3. A and B are incorrect

  4. B and D are incorrect


Correct Option: C
Explanation:

A root hair is the minute structures generally, present on the stem and the roots. It is a tubular outgrowth of a trichoblast, a hair-forming cell on the epidermis of a plant root.

The trichomes often cover the plant body are the result of divisions of epidermal cells. Trichomes may be either unicellular or multicellular and are either glandular, consisting of a stalk terminating in a glandular head, or nonglandular, consisting of elongated tapering structures.
Guard cells are specialized cells regulating opening and closing of stomata. Cuticle, collenchyma, and stomata are absent in roots. 
Therefore, the correct answer is option C.

Which of the following is not a feature or function of epidermis?

  1. Thick walled cells

  2. Protection from mechanical injury

  3. Gaseous exchange through stomatal pores

  4. Trichomes and glandular hairs


Correct Option: A
Explanation:

  • The epidermis is the outermost covering and acts as a protective layer. it is formed initially by protoderm. 
  • These are thin-walled as they are generally made up of parenchymatous cells. 
  • The epidermis serves several functions, it protects against water loss, regulates gas exchange, secretes metabolic compounds, and (especially in roots) absorbs water and mineral nutrients. 
  • The epidermal tissue includes several differentiated cell types of epidermal cells, guard cells, subsidiary cells, and epidermal hairs (trichomes). They have thin-walled cells. 

Therefore, the correct answer is option A.

The cell of epidermal tissues does not have intercellular space because 

  1. They are square shaped.

  2. They have a protective fluid.

  3. They have a dense cytoplasm.

  4. Their side walls stick together due to the wax secretion.


Correct Option: D
Explanation:

The epidermis is the outermost cellular layer which covers the whole plant structure, i.e., it covers roots, stem, leaves, flowers and fruit. It is composed of a single layer of living cells, although there are exceptions. Epidermis is usually closely packed, without intercellular spaces or chloroplasts. The outer walls, which are exposed to the atmosphere and usually thickened and may be covered by a waxy, waterproof cuticle which are made up of cutin. So, their side walls stick together due to the wax secretion. 

Therefore, the correct answer is option D.

Epidermis protects the plant against loss of

  1. Food

  2. Minerals

  3. Strength

  4. Water


Correct Option: D
Explanation:

The epidermis is the outermost cellular layer which covers the whole plant structure, i.e., it covers roots, stem, leaves, flowers and fruit. It is composed of a single layer of living cells, although there are exceptions.

Function:
1) The epidermal cells protect the underlying cells.
2) The waxy cuticle prevents the loss of moisture from the leaves and stems.
3) The transparent epidermal cells allow sunlight (for photosynthesis) to pass through to the chloroplasts in the mesophyll tissue.
4) The stomata of leaves and stems allow gaseous exchange to take place which is necessary for photosynthesis and respiration.
5) Water vapour may be given off through the stomata during transpiration.
6) The root hairs absorb water and dissolved ions from the soil.

Endodermis is a part of

  1. Cortex

  2. Pericycle

  3. Medulla

  4. Epidermis


Correct Option: A
Explanation:

A conspicuous part of the primary structure of many roots is the endodermis, the innermost layer of the cortex, the walls of which often become conspicuously thickened, plus strips of suberized tissue on the radial walls called as 'Casparian strips.'

Which of the following cells cover the entire plant body?

  1. Parenchyma

  2. Collenchyma

  3. Epidermal

  4. Xylem


Correct Option: C
Explanation:

The epidermis is a single layer of cells that covers the leaves, flowers, roots and stems of plants. It forms a boundary between the plant and the external environment. Its main function is protection. It has small opening known as stomata.

So, the correct answer is option C.

Small pores on the epidermis of leaf are

  1. Stomata

  2. Nodes

  3. Tubes

  4. None of the above


Correct Option: A
Explanation:

The epidermis is the outermost covering of the cell and it is composed of living cells. Epidermis is usually closely packed, without intercellular spaces or chloroplasts. The outer walls, which are exposed to the atmosphere and usually thickened, and may be covered by a waxy, waterproof cuticle which is made up of cutin. Apart from the normal epidermal cells, there are also stomata in the epidermis of leaves and stem. A stoma is an opening (pore) which is bounded by two bean-shaped cells called as guard cells.

Which of the following contiguous cells lack middle lamella?

  1. All epidermal cells

  2. Guard and subsidiary cells

  3. Subsidiary cells

  4. Guard cells


Correct Option: A

Why is epidermis important for the plants?

  1. It gives protection

  2. It helps in gaseous exchange

  3. It checks water loss

  4. All of the above


Correct Option: D
Explanation:

  • Epidermis is the outermost layer of the plant body. It carries out functions as follows:
1. It covers the body from outside and protects from pathogen attack and atmosphere changes.  
2. It shows the presence of stomata (minute pore-like structure) on leaves. Stomata are involved in gaseous exchange (oxygen, carbon dioxide) with the atmosphere. It also shows the presence of lenticels on the woody stem for gaseous exchange. 
3. The stomata present on leaves are also involved in transpiration (water evaporation from plant body). Stomata are guarded by guard cells, which close and open the stomata as per requirement. Therefore, epidermis bearing stomata also check for water loss from the plant body. 
4. The epidermis is protected by cuticle at some parts of the tree and it helps to stop water loss by evaporation.

Cork cells posses ...................... on their walls that makes it impervious to gases and water.

  1. Suberin

  2. Lignin

  3. Pectin

  4. Hemicellulose


Correct Option: A
Explanation:

  • Lignin is a substance, which is impermeable to water. It is absent in cork cells.
  • Pectin is not present in cork cells. 
  • Hemicellulose is permeable to water and gases.
  • Cork cells are dead and have cell walls composed of a waxy substance "suberin", which is highly impermeable to gases and water. This substance prevents water loss from the stem. 

So, the correct answer is option A. 

Motor cells help in

  1. Inward rolling of leaves

  2. Transpiration

  3. Guttation

  4. All of the above


Correct Option: A
Explanation:

Bulliform cells or motor cells are large, bubble-shaped epidermal cells that occur in groups on the upper surface of the leaves of many grasses. Loss of turgor pressure in these cells causes leaves to roll up during water stress. During drought, the loss of moisture through vacuoles induces bulliform cells to cause the leaves of many grass species to close as the two edges of the grass blade fold up toward each other. Once adequate water is available, these cells enlarge and the leaves open again. Folded leaves offer less exposure to sunlight, so they are heated less thus, reducing evaporation and conserving the remaining water in the plant and occur on the leaves of many monocotyledons but are probably best known in grasses. They are thought to play a role in the unfolding of developing leaves and in the rolling and unrolling of mature leaves in response to alternating wet and dry periods. So, motor cells helps in inward rolling of leaves and not in transpiration or guttation. 
Thus, the correct answer is option A.

The term periderm is used to include

  1. Cortex 

  2. Secondary cortex

  3. Both of the above

  4. None of the above


Correct Option: C
Explanation:

The periderm is the secondary protective dermal tissue that replaces the epidermis during growth in thickness of stems and roots of gymnosperms and dicotyledons i.e., secondary growth. 

Unlike typical epidermis, the periderm is a multilayered tissue system, the bulk of which usually constitutes the cork or phellem. It has cortex, secondary cortex.

Which of the following sclereids are the characteristic of intercellular spaces of Nymphaea?

  1. Osteosclereids

  2. Brachysclereids

  3. Macrosclereids

  4. Astrosclerieds


Correct Option: D
Explanation:

Astrosclerieds is a sclereid having its cell wall drawn out into lobes or arms to form a more or less stellate body. It is found in certain xerophytes. Nymphaea contains large intercellular spaces, which occur in the petiole. These airspaces are surrounded by long columns of parenchyma cells. The columnar cells contain chloroplasts and are presumably photosynthetic. Part of a large astroscleried can be seen cutting across one of the parenchymatous fingers. These sclereids add some mechanical strength to fragile structure. 

In grasses, certain adaxial epidermal cells along the veins modify themselves into large empty, colourless cells, called as

  1. Bulliform cells

  2. Companion cells

  3. Guard cells

  4. Subsidiary cells

  5. Albuminous cells


Correct Option: A
Explanation:

Bulliform cells  are so called because of its peculiar bubble shape. It mainly occurs on the upper surface of the leaves present in grasses. Water present in these cells helps to maintain its shape but loss of turgor pressure during the stress allows the leaves to roll up. During drought, the loss of moisture through vacuoles induces bulliform cells to cause the leaves of many grass species to close as the two edges of the grass blade fold up toward each other. Once adequate water is available, these cells enlarge and the leaves open again. 

Companion cells are specialized parenchyma cell, located in the phloem of flowering plants and closely associated with development and function with a sieve-tube element. 
Guard cells are cells surrounding each stoma. They help to regulate the rate of transpiration by opening and closing the stomata. 
The stoma is protected by subsidiary cells that have papillae that arch across the stoma, creating a mini-depression. This will tend to retain escaped water, giving it time to diffuse back into the stoma instead of being immediately blown away by a breeze. 
Albuminous cells have a similar role to companion cells, but are associated with sieve cells only and are therefore found only in seedless vascular plants and gymnosperms. 
So, the correct answer is option A.

How many tissue systems are suggested by Sachs?

  1. Two

  2. Three

  3. Four

  4. Five


Correct Option: B
Explanation:

Two or more tissues together constitutes the tissue system. The activities of the constituent tissues are responsible for the major function, although they are different in structure and origin. All the different type of tissues in a plant that perform the similar basic function, irrespective of their location is known as tissue system. 

Sachs (1875), recognized three types of tissue system in plants: 
1. Epidermal or Dermal Tissue System 
2. Cortical or Fundamental or Ground Tissue System. 
3. Vascular Tissue System. 
So, the correct answer is 'Three'

In respect of many grasses, the presence of motor cells in the upper epidermis of leaves is to

  1. Increase the surface area of the leaf

  2. Store large amount of water

  3. Check transpiration by reducing the surface area of the leaf

  4. Bear unicellular trichomes


Correct Option: C
Explanation:
Bulliform cells or motor cells are large, bubble-shaped epidermal cells that occur in groups on the upper surface of the leaves of many grasses. Loss of turgor pressure in these cells causes leaves to roll up during water stress. During drought, the loss of moisture through vacuoles induces bulliform cells to cause the leaves of many grass species to close as the two edges of the grass blade fold up toward each other. Once adequate water is available, these cells enlarge and the leaves open again. Folded leaves offer less exposure to sunlight, so they are heated less thus, reducing evaporation and conserving the remaining water in the plant and occur on the leaves of many monocotyledons but are probably best known in grasses
So, the correct answer is 'Check transpiration by reducing the surface area of the leaf'

The stems and leaves of grasses are rough due to

  1. Calcium carbonates

  2. Resins

  3. Silica

  4. Calcium oxalate


Correct Option: C
Explanation:

The grass leaves are linear in shape and sessile and are rough in texture due to the presence of cork cells in the epidermis and deposition of silica material. The process of deposition of silica material over the epidermis is known as silicification. It checks the transpiration rate and prevents the entry of pathogens and gives stiffness to the lamina.

So, the correct answer is option C.

Periblem form

  1. Endodermis

  2. Cortex

  3. Both A and B

  4. Epidermis


Correct Option: C
Explanation:

Histogen theory (By Hanstein 1870) concludes that shoot apical meristem consists three distinct zones. 

Dermatogen (external layer), which forms the outer covering of all organ of the plant. 
Periblem (middle layer) gives rise to the cortex and endodermis. 
Plerome (central layer) forms pith and primary vascular bundle. 
Thus, option C is correct.

If all the lenticels of stem are blocked, the first to die will be

  1. Leaves

  2. Shoot tips

  3. Roots

  4. None of the above


Correct Option: C
Explanation:

A lenticel is mainly the opening present on the periderm of the secondarily thickened organs and the bark of woody stems and roots of dicotyledonous flowering plants. It is a porous tissue consisting of cells with large intercellular spaces. It helps in the direct exchange of gasses between the internal tissues and atmosphere through the bark, which is otherwise impermeable to gasses. Lenticels are found in most of the woody trees but absent is  woody climbers. If lenticels are blocked then root will die first due to lack of gaseous exchange. Thus, option C is correct.

In the leaf, vascular bundles are found in

  1. Veins

  2. Palisade tissue

  3. Upper epidermis

  4. Lower epidermis


Correct Option: A
Explanation:

A vascular bundle is a part of the transport system in vascular plants. The transport itself happens in vascular tissue, which exists in two forms: xylem and phloem. These are generally present in the veins of the leaf where the xylem channelizes the water and phloem conducts the prepared food from the source to the sink.

Thus, the correct answer is option A.

Bulliform cells that help in the folding down of lamina in drought are present in the epidermis of

  1. Monocotyledonous grass leaf

  2. Dicotyledonous leaf

  3. Both A and B

  4. None of the above


Correct Option: A
Explanation:

Bulliform cells  are so called because of its peculiar bubble shape. It mainly occurs on the upper surface of the leaves present in grasses. Water present in these cells helps to maintain its shape but loss of turgor pressure during the stress allows the leaves to roll up. During drought, the loss of moisture through vacuoles induces bulliform cells to cause the leaves of many grass species to close as the two edges of the grass blade fold up toward each other. Once adequate water is available, these cells enlarge and the leaves open again. Bulliform cells are present in only monocot leaf and absent in dicot leaf. 
Thus, the correct answer is option A.

In which plant part, laticiferous gland are found?

  1. Cortex

  2. Epidermis

  3. Endodermis

  4. Vascular bundle


Correct Option: A
Explanation:

Laticiferous vessels are the specialized thin walled parenchymatous cells that secrete latex and are found in the cortex. They lack pits and are composed of cellulose and hemicelluloses and serve to secrete latex. 

Epidermis is the outermost covering of the primary plant body and is mostly represented by a single layer of compactly arranged, barrel-shaped parenchyma cells. 
The innermost layer of cortex forms endodermis, which has compactly arranged barrel shaped cells. The primary thin walled endodermis shows suberin deposition in form of bands or strips that run around the radial and end walls of the cells and forms Casparian strips. 
Vascular bundle consists of xylem, phloem, and cambium (in dicot only), which are derived from procambium and serve in translocation of food and sap.
So, the correct answer is option A.

Vascular layers of plant body shows

  1. Protective tissue

  2. Epithelial tissue

  3. Meristematic tissue

  4. None of the above


Correct Option: A
Explanation:

Vascular bundles of the plant show vascular cambium or cork cambium. Cork cambium is involved in making cork. Cork is a nonliving, water resistant tissue formed in many plants to prevent water loss. Cork cells are dead and have cell walls composed of a waxy substance "suberin" which is highly impermeable to gasses and water. This substance prevents the water loss from the stem. Cork also protects the plant from wear and tear. Hence, it is a protective type of tissue. Therefore, option A is correct.  

Which of following tissues do you expect to be the most important during droughts and why?

  1. Vascular tissue because phloem regulates water supply to the plant

  2. Ground tissue because water can be stored in sclerenchyma for use during drought

  3. Epidermal tissue because it is covered with a waxy cuticle and also bears drought responsive stomata

  4. All of the above


Correct Option: C
Explanation:

The epidermis is the outermost cellular layer which covers the whole plant structure, i.e. it covers roots, stem, leaves, flowers, and fruit. It is composed of a single layer of living cells. The outer walls, which are exposed to the atmosphere and usually thickened, are covered by a waxy, waterproof cuticle which is made up of cutin. The waxy cuticle prevents the loss of moisture from the leaves and stems. During drought, the plant hormone abscisic acid (ABA) triggers stomatal closure, thus reducing water loss.

So, the correct answer is option C.

- Hide questions