Yes, the stem of a plant can be compared with a street with two-way traffic because of the following reasons :
(i) It carries water and minerals from the roots to other parts in upward direction.
(ii) It carries food from the leaves to other parts of the plant.

No, it will not turn blue-black because the stored starch would have been used up by the plant when kept in a dark room for a few days. Starch would not be synthesized due to absence of sunlight.

Three types of plants are :
1.Herbs 2. Shrubs 3. 'frees

Plants are characterised into three types on the basis of several features. One of the features is "Type of stem" :
Trees: They are tall, have hard, thick and woody stems.
Shrubs: They are of medium height, have hard and woody stems.
Herbs: They are short and have tender, green and short stems.

Roots absorb minerals and water from the soil. These are needed for the manufacture of food by plant leaves. So, roots are necessary to keep the plant healthy and alive.

In grass, fibrous root system is present. In such type of roots, there is no main root, instead many roots arise from one region. These grow horizontally in soil and make a bushy/clustered appearance.

The type of leaf venation and root in plants are related in an interesting way. The plant having leaves with reticulate venation has tap roots, e.g. sunflower plant.

Paheli is watering the plants correctly. She is sprinkling water on the roots, from where it can travel to all other parts of the plant.

Yes, the stem of a plant can be compared with a street with two ways traffic because
(i) It carries water and minerals from the roots to the leaves and other parts of plant in upward direction.
(ii) It takes the prepared food by the leaves to other parts of the plant.

No, a leaf from a potted plant kept in dark will not turn blue-black when tested for the presence of starch. This is because all the stored starch would have been used up by the plant. No fresh starch would be synthesised due to non availability of sunlight.

Flowers with joined sepals - Hibiscus, datura, cotton, tomato (anyone).
Flowers with separate sepals - mustard, lotus, lily, jasmine, rose (anyone).

Yes, it is possible to find whether a plant has tap root or fibrous root by looking at the impression of its leaf on paper. If the leaf has parallel venation, the roots of the plant will be fibrous root and if the leaf has reticulate venation, the root would be tap root. It is an interesting fact that the leaf venation and the type of roots in a plants are always related to each other.

If a plant has leaves with reticulate venation, then the plant is likely to have tap root system.

Yes, we can find a plant in our house as well as in our neighbourhood, which has a long but weak stem. Its name is money plant. It is classified as a climber. It readily climbs up by taking support of the neighbouring structures such as a tree or a rod, etc.

a)
 
b)

c)