In land plants, the guard cells differ from other epidermal cells in having:-

1. mitochondria

2. endoplasmic reticulum

3. chloroplasts

4. cytoskeleton

The cork cambium, cork and secondary cortex are collectively called

1. phellogen

2. periderm

3. phellem   

4. phelloderm

The chief water conducting elements of xylem in gymnosperms are

1. vessels

2. fibres

3. transfusion tissue

4. tracheids

Heartwood differs from sapwood in 

1. presence of rays and fibres

2. absence of vessels and parenchyma

3. having dead and non-conducting elements

4. being susceptible to pests and pathogens

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

In barley stem, vascular bundles are

1. open and scattered

2. closed and scattered

3. open and in a ring

4. closed and radial

Guard cells help in ?

1. protection against grazing

2. transpiration

3. guttation

4. fighting against infection

Palisade parenchyma is absent in leaves of :-

1. Sorghum

2. mustard

3. soybean

4. gram

Reduction in vascular tissue, mechanical tissue and cuticle is characteristic of

1. xerophytes

2. mesophytes

3. epiphytes

4. hydrophytes

Vascular tissues in flowering plants develop from

(1) phellogen

(2) plerome

(3) periblem

(4) dermatogen