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

Which of the following is correct statement for intercalary meristems?
1. They lie at tip of root apex
2. They lie at base of stem always
3. They are short lived and consumed during primary growth
4. They are long lived and cause increase in length

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

Which one of the following is not a lateral meristem?

1. Intrafascicular cambium

2. Interfascicular cambium

3. Phellogen

4. Intercalary meristem

Closed vascular bundles lack:

1. Ground tissue

2. Conjuctive tissue

3. Cambium

4. Pith

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