The figure given below shows the stages of ripening in a banana. Answer the question that follow: Mention two characteristic features of ethylene hormone.

Ethylene is one of the plant hormones which is responsible for fruit ripening. It also induces flowering. Ethylene causes two processes in plants- reduction in stem elongation and acceleration of senescence. Features of this hormone:- (i) It is a colourless, flammable gas having a sweet taste and odour. (ii) Due to its gaseous form, its site of synthesis and action are the same.

The diagram given alongside shows a type of tropism. Study the same and answer the question that follow: Name two effective stimulants that help in the growth of part (2).

Pollen grain when attaches to the stigma, pollen tube is formed through style to the ovary, where egg cell is present. In the pollen tube, male gametes are present which when fuses with the egg cell, the zygote is formed. The growth of pollen tube in plants is an example of chemotropism as its movement is towards the sugar and peptones secreted by the cells of the style. So, the effective stimulant for the growth of the pollen tube is sugar and peptones .

The diagram given alongside shows a type of tropism. Study the diagram and answer the question given below: Name two groups of plants where part (2) grows towards gametophyte with the help of the stimulants sugar and peptones.

Pollination is the process of transfer of pollen grains from the anther to the stigma. The pollen tube is formed when pollen grain lands on the stigma in flowering plants and on ovules in non-flowering plants. Its growth is attracted to the sugar and peptones secreted from the neck canal cells of the female gametophyte. This is an example of chemotropism. Angiosperms and Gymnosperms are two plant categories in which the pollen tube grows towards the gametophyte with the help of stimulants.

Study the diagrams given below and answer the following question. Name the structures shown as X and Y in the figures (A) and (B), respectively.

Thigmotropism is the growing movement of plant parts in response to a touch stimulus. It can be seen in sweet peas, Cuscuta, and vines which have tendrils that coil around support in response to one-sided contact or touch. Tips of the tendril receive the stimulus which is transmitted to basal parts. After receiving the stimulus, the tendril starts twining around the support. This happens due to the hormone auxin. This hormone moves on the opposite side of the touch and helps the cells to grow there which results in curling around the support. In the shown figure in the given question, X and Y are stem tendrils and leaf tendrils respectively. The tendrils provide a well-known example of thigmotropism.

Study the diagrams given below and answer the following question. Write the functions performed by the structures X and Y.

In the shown figure in the given question, X and Y are stem tendril and leaf tendril respectively. The tendrils provide a well-known example of thigmotropism. This tendril gives support to the whole plant. Here tendril is showing the example of thigmotropism. Tendril is a specialised leaf or stem which is a thread-like structure used to curl around any other structure to give support to the weak stem of the plant. As it is green in colour it can photosynthesise too, i.e it can prepare food for the plant.

Study the diagrams given below and answer the following questions. Name the phenomenon depicted and define it.

Thigmotropism is the phenomenon depicted here. It refers to the growing movement of plant parts in response to the touch stimulus. The plant part which is opposite to the touch area of the support grows more due to the presence of auxin. Due to which it curls around the support. Plants such as sweet peas, Cuscuta, and vines show such a phenomenon. Tendrils present in these plants curl around other structures. It can be a stem tendril or leaf tendril.