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RootVery Short Answer Questions

1. Give the scientific names of two plants which store food in their tap roots. Howdo they differ in their shapes?Ans: Raphanussativus – fusiform roots with broad middle region and taperingtowards tip and base. Daucuscarota – Conical roots that are broad at the base andgradually taper towards the tip.

2. What are fasciculated roots? Give two examples.Ans: It is a tuft of storage adventitious roots. Ex: Asparagus, Dahlia, Ruelliatuberosa

3. What is epiphytic habit? Which roots help it?Ans: It is growing of a plant on some other plant for shelter to expose its foliage to thesun to get proper amount of sunlight to perform photosynthesis. Velamen roots orEpiphytic roots help for such habit.

4. Define root crops. What would happen if the root crops are harvested at the endof second year?Ans: Plants grown by farmers for their roots are called as Root crops. These plants arebiennnials. They synthesize and store the excess food in their roots. In the second yearthey utilize the stored food for reproduction. If harvested at the end of second year,either less or no food materials are left out in the roots.

5. What are assimilatory roots? Give two examples.Ans: Modified adventitious roots that become green colored and performphotosynthesis are called as assimilatory roots. Ex: Taeniophyllum, Trapa,Tinosporacordifolia.

6. Compare photosynthetic roots of Tinospora with those of Trapa.Ans: In Tinospora, the photosynthetic roots are aerial and in Trapa they areunderwater.

7. What is complete root parasite? Give an example.Ans: Achlorophyllus, usually leafless or with scale leaved parasite which establisheshaustorial connection with both xylem and phloem of host root to absorb both mineralwater and organic food is called as complete root parasite. Ex: Rafflesia,Balanophora, Orobanche.

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Short answer Questions1. Mention the characteristics of a root system. Add a note on its functions.

Ans: Characters of a Root system1. Root with its appendages is called as root system. The roots are usually positively

geotropic (except pneumatophores).2. Root is not differentiated into nodes and internodes.3. Leaves and normal buds are absent.4. Root is non-chlorophyllous and brown colored.5. Lateral roots are formed endogenously in acropetal manner.6. Apices of roots are protected by Root cap. In free floating hydrophytes root

pockets are present.7. Roots have unicellular epidermal outgrowths called as root hairs. These are short

lived, exogenous and developed acropetally.Functions:1. Root anchors the plant at proper place in the soil.2. It absorbs water and minerals from the soil or substratum.3. It conducts the absorbed mineral water to the aerial system of the plant.

2. Define root. Write briefly on the types of root system.Ans: Root is underground axis of the plant usually developed from radicle of embryo.There are two types of root systems. They are Tap root system and adventitious rootsystem.1. Tap Root system: It is developed from radicle of embryo. It has a directly growing

tap root from which the endogenously developed lateral roots are arranged inacropetal manner and grow obliquely into the soil. It is commonly seen in Dicots.

2. Adventitious root system: This root system is developed from any part of the pantother than radicle. It is usually developed from base of the stem as fiber likestructures. Hence it is also called as fibrous root system. It is commonly found inMonocots.

3. Write short notes on Storage roots.Storage Roots: These are also known as tuberous roots. These modified roots becomeswollen due to accumulation of excessive food materials.

Storage Tap roots: If storage root is formed from tap root system, usually the taproot stores food attains a specific shape. It is conical in Daucus, fusiform inRaphanussativus, napiform in Beta vulgaris.

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Storage adventitious roots: Only one storage irregularly shaped root arises atevery node in Ipomoea batatus. A group of storage adventitious roots arise at thebase of stem known as fasciculated roots in monocot Asparagus and in dicots likeRuelliatuberosa and Dahlia tuberosa.

In most of the storage roots starch is stored. But in Beta vulgaris, it is Sugar and inDahlia it is inulin.Plants grown by farmers for their roots are called root crops. Root crops arebiennials. They store the synthesized food in their roots during first year andutilize it in the second year for flowering and seed setting. Hence the root cropsmust be harvested at the end of first year.

4. Write short notes on velamen roots.Ans: Epiphytic roots: Plants that grow on some other plant for shelter are calledas epiphytes. These plants usually belong to families Orchidaceae and Aroideae.These plants are commonly seen in tropical evergreen forests. They inhabit on topbraches of host tree to get proper amount of sunlight to perform photosynthesis.Modified aerial adventitious roots seen in such plants are called as epiphytic roots.Epiphytes have two types of roots. They are clinging roots and velamen roots.Clinging roots are relatively short, slender, branched and enter into the crevices ofhost branch to fix the plant on the host branch. They also absorb mineral watercollected in the crevices. Velamen roots are elongated, stout, branched withoutroot hairs and freely hang in the air. They have dead hygroscopic multipleepidermis known as velamen which helps in absorbing atmospheric moisture byimbibition. Ex: Vanda, Bulbophyllum

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5. What are respiratory roots? Explain their role in mangrove plants.Ans: Respiratory roots: These are usually seen in Mangroves like Avicennia andRhizophora which grow in water logged muddy soils of estuaries. Undergroundroots of such plants face oxygen deficient conditions. In these plants some of thelateral roots of underground roots become aerial, have minute lenticular openingscalled pneumathodes, through which the air enters into the root and afterrespiration the CO2 comes out through the same pores. In this way these help inrespiration. Hence these are called as Respiratory roots or Pneumatophores orBreathing roots. Adventitious breathing roots are seen in a free floatinghydrophyte called as Jussiaea whose roots are spongy and porate.

6. What are nodular roots? What is their significance?Nodular roots: These are modified roots of tap root system with swollenstructures called nodules. These are inhabited by a bacterium Rhizobium inleguminous plants. This bacterium fixes atmospheric nitrogen into ammonia andsupplies it to the plant and in return it takes organic food from host cortical cells.In this way these modified roots show symbiosis. Nodules have a pigment calledLeg.haemoglobin which helps in controlled supply of oxygen to the bacterium.Because of these root nodules, leguminous plants are used in crop rotation and asgreen manure. Ex: Arachis, Dolichos.

7. Write short notes on parasitic roots.Ans: Parasitic roots: Plants that obtain either only mineral water or both mineralwater and organic food from other plants are called as parasitic plants. Modified

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roots seen in such plants are called as parasitic roots or Haustorial roots. If theplant establishes haustorial connection with the root of host it is called as rootparasite and that one with the stem as stem parasite. If the parasite isphotosynthetic, establishes haustorial connection only with the xylem of the host,it is called as partial parasite. If it is achlorophyllous, without leaves or with scaleleaves, establishes haustorial connection with both xylem and phloem of the hostit is called as complete parasite. These parasites are as follows.1. Complete stem parasite. Ex: Cuscuta2. Complete root parasite. Ex: Orobanche, Rafflesia, Balanophora.3. Partial stem parasite. Ex: Viscum, Loranthus4. Partial root parasite. Ex: Santalum album, Striga

Long Answer Questions1. Describe various types of Root modifications

Ans: The permanent change in the root or its part to perform either only additionalfunctions or both additional and normal functions that suit for the survival of the plantin the new conditions is called as Root modification. The modified roots are asfollows.1. Storage Roots: These are also known as tuberous roots. These modified roots

become swollen due to accumulation of excessive food materials.Storage Tap roots: If storage root is formed from tap root system, usually the taproot stores food attains a specific shape. It is conical in Daucus, fusiform inRaphanussativus, napiform in Beta vulgaris.Storage adventitious roots: Only one storage irregularly shaped root arises atevery node in Ipomoea batatus. A group of storage adventitious roots arise at thebase of stem known as fasciculated roots in monocot Asparagus and in dicots likeRuelliatuberosa and Dahlia tuberosa.

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In most of the storage roots starch is stored. But in Beta vulgaris, it is Sugar and inDahlia it is inulin.Plants grown by farmers for their roots are called root crops. Root crops arebiennials. They store the synthesized food in their roots during first year andutilize it in the second year for flowering and seed setting. Hence the root cropsmust be harvested at the end of first year.

2. Epiphytic roots: Plants that grow on some other plant for shelter are called asepiphytes. These plants usually belong to families Orchidaceae and Aroideae.These plants are commonly seen in tropical evergreen forests. They inhabit on topbraches of host tree to get proper amount of sunlight to perform photosynthesis.Modified aerial adventitious roots seen in such plants are called as epiphytic roots.Epiphytes have two types of roots. They are clinging roots and velamen roots.Clinging roots are relatively short, slender, branched and enter into the crevices ofhost branch to fix the plant on the host branch. They also absorb mineral watercollected in the crevices. Velamen roots are elongated, stout, branched withoutroot hairs and freely hang in the air. They have dead hygroscopic multipleepidermis known as velamen which helps in absorbing atmospheric moisture byimbibition. Ex: Vanda, Bulbophyllum

3. Photosynthetic roots: Modified adventitious roots which become green coloredand perform photosynthesis are called as Photosynthetic roots or Assimilatoryroots. These are usually seen in epiphytes like Taeniophyllum in which the rootsare flat ribbon like green velamen roots. Assimilatory roots are also seen in aclimber called as Tinosporacordifolia. A hydrophyte called Trapa has underwaterphotosynthetic roots.

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4. Respiratory roots: These are usually seen in Mangroves like Avicennia andRhizophora which grow in water logged muddy soils of estuaries. Undergroundroots of such plants face oxygen deficient conditions. In these plants some of thelateral roots of underground roots become aerial, have minute lenticular openingscalled pneumathodes, through which the air enters into the root and afterrespiration the CO2 comes out through the same pores. In this way these help inrespiration. Hence these are called as Respiratory roots or Pneumatophores orBreathing roots. Adventitious breathing roots are seen in a free floatinghydrophyte called as Jussiaea whose roots are spongy and porate.

5. Nodular roots: These are modified roots of tap root system with swollenstructures called nodules. These are inhabited by a bacterium Rhizobium inleguminous plants. This bacterium fixes atmospheric nitrogen into ammonia andsupplies it to the plant and in return it takes organic food from host cortical cells.In this way these modified roots show symbiosis. Nodules have a pigment calledLeg.haemoglobin which helps in controlled supply of oxygen to the bacterium.Because of these root nodules, leguminous plants are used in crop rotation and asgreen manure. Ex: Arachis, Dolichos.

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6. Parasitic roots: Plants that obtain either only mineral water or both mineral waterand organic food from other plants are called as parasitic plants. Modified rootsseen in such plants are called as parasitic roots or Haustorial roots. If the plantestablishes haustorial connection with the root of host it is called as root parasiteand that one with the stem as stem parasite. If the parasite is photosynthetic,establishes haustorial connection only with the xylem of the host, it is called aspartial parasite. If it is achloro phyllous, without leaves or with scale leaves,establishes haustorial connection with both xylem and phloem of the host it iscalled as complete parasite. These parasites are as follows.5. Complete stem parasite. Ex: Cuscuta6. Complete root parasite. Ex: Orobanche, Rafflesia, Balanophora.7. Partial stem parasite. Ex: Viscum, Loranthus8. Partial root parasite. Ex: Santalum album, Striga