The common bottle cork is a product of:

1. dermatogen

2. phellogen

3. xylem

4. vascular cambium

Companion cells are closely associated with:

1. Sieve elements

2. Vessel elements

3. Trichomes

4. Guard cells

Closed vascular bundles lack:

1. Ground tissue

2. Conjuctive tissue

3. Cambium

4. Pith

Water containing cavities in vascular bundles are found in:

1. Sunflower

2. Maize

3. Cycas

4. Pinus

Gymnosperms are also called softwood spermatophytes because they lack:

1. Cambium

2. Phloem fibres

3. Thick-walled tracheids

4. Xylem fibres

The chief water conducting elements of xylem in gymnosperms are:

1. vessels

2. fibres

3. transfusion tissue

4. tracheids

The annular and spirally thickened conducting elements generally develop in the protoxylem when the root or stem is:

1. maturing

2. elongating

3. widening

4. differentiating