Vascular bundles in monocotyledons are considered closed because:

1.	a bundle sheath surrounds each bundle
2.	cambium is absent
3.	there are no vessels with perforations
4.	xylem is surrounded all around by phloem

Age of a tree can be estimated by:

1. biomass

2. number of annual rings

3. diameter of its heartwood

4. its height and girth

Closed vascular bundles lack:

1. Ground tissue

2. Conjuctive tissue

3. Cambium

4. Pith

Which one of the following is not a lateral meristem?

1. Intrafascicular cambium

2. Interfascicular cambium

3. Phellogen

4. Intercalary meristem

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

Grass leaves curl inwards during very dry weather. Select the most appropriate reason from the following :

1. Tyloses in vessels

2. Closure of stomata 

3. Flaccidity of bulliform cells

4. Shrinkage of air spaces in spongy mesophyll

Phloem in gymnosperms lacks:

1. Both sieve tubes and companion cells 

2. Albuminous cells and sieve cells

3. Sieve tubes only

4. Companion cells only

Which of the statements given below is not true about the formation of Annual Rings in trees?
 

Mechanical support to the growing parts of the plant such as young stem and petiole of leaf is provided by a living tissue called