Root System : 12th Class Biology Question Answer Lesson 6 – NIOS

Root System : 12th Class Biology Question Answer Lesson 6 – NIOS

INTEXT QUESTIONS 6.1

1. Name the plant organ which grows towards gravity and water but away from light – Root
   
2. From which part of the germinating seed does the root develop? Plants and animals – Radicle
   
3. Which root system gives better anchorage and why?
   Ans. Tap root system gives better anchorage because it is very deep seated,and branches profusely which ramify through large areas in soil.
   
4. Give two examples each of plants having fibrous and tap root system?
   Ans. Fibrous root system in maize, sugarcane and tap root system in sunflower, mango.
   
5. Mention three characters by which you can say that carrot which you eat is a root.
   Ans. Absence of nodes and internodes, buds and leaves.

INTEXT QUESTIONS 6.2

1. Name the structure which protects the root apical meristem.
   Ans. Root cap
   
2. Give in a sequence, the various regions of root from its tip towards its base.
   Ans. Root cap region, region of meristematic cells, region of elongation, regionof maturation.
   
3. Into which tissues do dermatogen and plerome differentiate?
   Ans. Dermatogen differentiates into epiblema and cap, whereas plerome
   differentiates into stele.
   
4. Which region of root absorbs water and mineral salts?
   Ans. Root hair or piliferous region / Region of maturation.

INTEXT QUESTIONS 6.3

1. Are carrot, radish and turnip roots? Justify. Why have they become fleshy?
   Ans. Yes, they are roots since they do not have nodes and internodes, buds orleaves; they become fleshy for storage of food.
   
2. Name the type of root modification found in plants growing in marshy areas. What is their function?
   Ans. Pneumatophore, respiration
   
3. What is the tissue in aerial roots of epiphytes known as which helps in absorption of moisture from the atmosphere?
   Ans. Velamen
   
4. What are the two main functions of roots?
   Ans. Anchorage and absorption of water and mineral salts
   
5. Match the items of column A with those in column B
   A B
   (a) Prop roots (i) Storage
   (b) Haustorium (ii) Jussiaea
   (c) Sweet potato (iii) Banyan
   (d) Floating roots (iv) Cuscuta
   Ans. (a) – (iii); (b) – (iv); (c) – (i); (d) – (ii)

INTEXT QUESTIONS 6.4

1. Name the condition where protoxylem lies towards the periphery and metaxylem towards centre.
   Ans. Exarch
   
2. Why is it difficult to pluck lateral roots from carrot?
   Ans. Because these arise from the inner layer i.e.pericycle / endogenous origin
   
3. What is the seat of origin of lateral roots and cambium?
   Ans. Pericycle
   
4. Name the endodermal cells which do not possess casparian strips and help in the movement of water?
   Ans. Passage cells
   
5. Give two major differences between a dicot and monocot root.
   Ans. In dicot root 2-6 vascular bundles and cambium is present but in monocotroot many vascular bundles are present while cambium is absent.
   
6. If the number of xylem bundles is 4 (tetrarch), how many lateral roots will be formed in that area?
   Ans. Four

INTEXT QUESTIONS 6.5

1. Name the lateral meristems found in old dicot roots? What is their function?
   Ans. Vascular cambium and cork cambium; Vascular cambium forms secondaryvascular tissue while cork cambium forms cork and secondary cortex.
   
2. From which layer does the vascular cambium originate?
   Ans. Pericycle and conjunctive tissue.
   
3. What is the conjunctive tissue?
   Ans. Conjunctive tissue is the parenchyma tissue lying between xylem andphloem patches that are arranged radially in roots.
   
4. Define periderm. What role does it play in a root?
   Ans. Periderm is a tissue which is formed during secondary growth and consistsof phellem, phellogen and phelloderm; protection.
   
5. Do primary roots of dicot plant possess cambium?
   Ans. No, cambium is absent in the primary dicot root.

TERMINAL EXERCISES

1. Describe any four adventitious root modifications.
2. Give one point of difference between:
   (i) Tap root and adventitious root
   (ii) Prop and stilt roots
   (iii) Protoxylem and metaxylem
   (iv) Phelloderm and periderm
   (v) Vascular cambium and cork cambium
3. Describe the various types of edible roots which you have studied.
4. What are pneumatophores? Where are they found and what is their function?
5. Describe secondary growth in dicot roots.
6. Why is it difficult to break the lateral roots from the main root?
7. What is periderm ? How is it formed?
8. Give four characteristics by which you can identify a root.
9. What is the function of region of maturation?
10. Give one example each of plants having pneumatophores, climbing roots,
    floating roots and haustoria.
11. A cross section of plant organ when seen under the microscope shows—radial
    vascular bundles, exarch xylem, single layered pericycle and unicellular hair.
    What organ is it?
12. Name the meristematic tissues which help the dicot roots to grow in length
    and girth.
13. Name the modification of root which supports tree branches.
14. If a transverse section of root shows polyarch condition of vascular bundles,
    large pith and no cambium, which type of root will it be?
15. Differentiate between stele of dicot and monocot root.

NIOS 12th class biology Q Ans

• Origin and Evolution of Life & Classification : 12th Class Biology Notes – NIOS
• The Kingdoms Monera, Protista & Fungi : 12th Class Biology Notes – NIOS
• Kingdoms Plantae & Animalia : 12th Class Biology Question Answer Lesson 3 – NIOS
• Cell Structure & Function : 12th Class Biology Question Answer Lesson 4 – NIOS
• Tissues & Others Level of Organization : 12th Class Biology Question Answer Lesson 5 – NIOS

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