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. 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.

Study the diagrams given below and answer the following question. How do the structures X and Y differ from each other?

X is a stem tendril while Y is leaf tendril. Characteristics Stem tendril Leaf tendril Definition (i) It is a modified stem. (i) It is a modified leaf. Characteristics Stem tendril Leaf tendril Position (ii) It is developed in the position of the stem, bud or flower. (ii) It is developed in the position of the leaf or its parts. Example (iii) Passiflora (iii) Pea

Study the diagrams given below and answer the following question. Give examples of the plants which show the said phenomenon.

Thigmotropism is the phenomenon shown by the tendrils of the soft plants. Tendrils give support to the plants. Here in the figure, X is the stem tendril and Y is the leaf tendril. An example of stem tendril is Passiflora and an example of leaf tendril is Pea plant. Both types of tendrils have the same function but do not show structural similarities. These are called analogous parts of the plant.

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Concise Biology Part-II Class 10>Plant Physiology>Chapter 7 - Chemical Coordination in Plants>Review Questions

Review Questions

Author:H S Vishnoi

H S Vishnoi Biology Solutions for Exercise - Review Questions

Simple step-by-step solutions to Review Questions questions of Chemical Coordination in Plants from Concise Biology Part-II Class 10. Also get 3D topic explainers, cheat sheets, and unlimited doubts solving on EMBIBE.