NCTB Class 7 Science Chapter 3 “External Morphology of Plants” Solution

Bangladesh Board Class 7 Science Solution Chapter 3 “External Morphology of Plants” Solution  Exercises Question and Answer by Experienced Teacher.

NCTB Solution Class 7 Chapter 3 “External Morphology of Plants:”

Board	NCTB Bangladesh Board
Class	7
Subject	Science
Chapter	Three
Chapter Name	“External Morphology of Plants”

Fill in the blanks:-

(1) Sweet potato is a modified—-.

Ans:- Root (tubercular root)

(2) Turmeric is a modified——-.

Ans:- Stem (Rhizomes)

(3) Cactus is a modified—.

Ans:-  Stem (Phylloclade).

(4) Water is carried from roots to leaves by—.

Ans:- Stem.

(5) Main function of leaf is—-.

Ans:- Photosynthesis.

Short answered questions:

(1) Ans:- potato is not roots, it is a modified stem which grown beneath the soil surface due to strange of food, vegetative propagation.
(2) Ans:- Cactus is a stem. It is a example of phylloclade which is a aerial modified stem. Leaves of this stem are modified to spines and are used for self defence.

(3) Ans:- Leaves are modified because of leaf tendrils, storage of foods, fly traps, leaf spines, scale leaves.

(4) Ans:- The special functions of stem are – synthesis of food, vegetative reproduction, self defence, climbing.

(5) Ans:- The reasons of root modification are- climbing, reproduction, standing straight, floating in the water.

Multiple choice questions:-

(1) In which plant Moniliform roots are found?

Ans:- (d) Bitter gourd.

(2) Characteristics of Rhizome are-

 Ans:-  (b) (i) And (iii)

(3) Now follow the stem and answer question number 3 and 4 Functions of M marked structure-

Ans:- (b) (i) and (ii)

(4) From which parts of the stems seedlings grow?

Ans:- (c) O and P

Creative questions:-

(1) (a) Ans:- In some climbers, auxiliary buds do not develop as branches but store food and become rounded ball like structure which are called bulbils.

(1) (b) Ans:- In Bryophyllum plant buds grow from the margins of leaves. Gradually these duds develop roots and ultimately when detached from the leaf, become independent plants.

(1) (c) Ans:- The practical use of X is it can be used as medical substances to cure cold or flu.

(1) (d) Ans:- Y is a modified stem which is a underground stem. But Z is a modified root which takes part in reproduction.

(2) (a) Ans:- Inter notes of some aquatic plants are thick and short, so the stems looks dwarf. These are called offset.

(2) (b) Ans:- Pitcher plant is called insect trap because when insects enter inside the pitcher, the lid of the pitcher is closed and the plant absorb juice from the insects body.

(2) (c) Ans:- The necessity of the part M is it helps the plant in respiration.

(2) (d) Ans:- The plant R has climbing root which helps the plant to climb clinging with another plant.

The plant N is a example of bulbil which auxiliary duds do not develop as branches but store food and become rounded ball like striations.