Question

What type of response is shown by the radicle of the seed?
A. Positively geotropic
B. Negatively geotropic
C. Positively phototropic
D. Negatively gravitropic

Answer 1

Hint: Positive geotropism is the tendency when growth occurs downwards in direction of gravity, while negative geotropism is the tendency when growth occurs in the opposite direction of gravity.

Complete step by step answer: The radicle is referred to as the first part of a seedling to emerge from the seed during the process of germination. It is considered as the embryonic root of the plant and grows downward in the soil. The roots exhibit positive geotropism or grow with gravity as the growth occurs in a complementary manner with the gravity, while the stem exhibits negative geotropism or growth against gravity. All parts of a plant grow in opposite directions depending on their functions as each has a different function to perform. The roots elongate or grow into the ground as it provides stability to the plant, as well as help to access water and nutrients. The stem grows upward towards the sunlight in order to help the plant with the photosynthesis process.
i. Negatively geotropic is when the direction of growth is opposite to gravity. This will be used to describe the growth of stem that occurs upwards.
 ii. Positively phototropic is the growth of an organism in response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi. Cells of the plant that are farthest from the light, have a chemical called auxin, that reacts when phototropism occurs.
 iii. Gravitropism is the movement or growth of plants in response to gravity. The shoot of the plant is growing in the opposite direction of gravity so it is negative gravitropism.
Hence, the correct answer is option A.

Note: Geotropism helps the roots to grow downwards or in some cases horizontally. The horizontal movement occurs in shallow topsoil. It helps to build structural anchorage and integrity of the plant essentially when stems and leaves start to occur.