Secondary growth and annual rings — practice questions

Question 1 · difficulty L3 · understanding

Consider the following tissues in the stelar region of a stem showing secondary growth. (A) Primary xylem (B) Secondary xylem (C) Primary phloem (D) Secondary phloem Arrange these in the correct sequence of their position from pith towards corts.

• A. (A), (B), (D), (C)
• B. (B), (A), (C), (D)
• C. (A), (B), (C), (D)
• D. (B), (A), (D), (C)

Question 2 · difficulty L3 · understanding

Consider the following plant tissues : (A) Axillary buds (B) Fascicular vascular cambium (C) Interfascicular cambium (D) Cork cambium (E) Intercalary meristem Identify the lateral meristems among the above.

• A. (A), (C) and (D) only
• B. (B), (C) and (D) only
• C. (A), (B), (C) and (E) only
• D. (A), (B), (D) and (E) only

Question 3 · difficulty L3 · understanding

Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R : Assertion A : Late wood has fewer xylary elements with narrow vessels. Reason R : Cambium is less active in winters. In the light of the above statements, choose the correct answer from the options given below :

• A. Both A and R are true but R is NOT the correct explanation of A
• B. A is true but R is false
• C. A is false but R is true
• D. Both A and R are true and R is the correct explanation of A

Question 4 · difficulty L3 · understanding

Initiation of lateral roots and vascular cambium during secondary growth takes place in cells of

• A. Pericycle
• B. Epiblema
• C. Cortex
• D. Endodermis

Question 5 · difficulty L3 · understanding

In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to : (a) secretion of secondary metabolities and their deposition in the lumen of vessels. (b) deposition of organic compounds like tannins and resins in the central layers of stem. (c) deposition of suberin and aromatic substances in the outer layer of stem. (d) deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem. (e) presence of parenchyma cells, functionally active xylem elements and essential oils. Choose the correct answer from the options given below :

• A. (a) and (b) only
• B. (c) and (d) only
• C. (d) and (e) only
• D. (b) and (d) only

Question 6 · difficulty L3 · understanding

Match List-I with List-II. List-I List-II (a) Lenticels (i) Phellogen (b) Cork cambium (ii) Suberin deposition (c) Secondary cortex (iii) Exchange of gases (d) Cork (iv) Phelloderm Choose the correct answer from the options given below.

• A. (a) (b) (c) (d) (iv) (ii) (i) (iii)
• B. (a) (b) (c) (d) (iv) (i) (iii) (ii)
• C. (a) (b) (c) (d) (iii) (i) (iv) (ii)
• D. (a) (b) (c) (d) (ii) (iii) (iv) (i)

Question 7 · difficulty L3 · application

A woody stem shows a broad band of spring wood followed by a denser band of autumn wood produced during the same growing season. Together, these two bands represent what?

• A. One annual ring
• B. Two annual rings
• C. One vascular bundle
• D. The periderm only