Cellular Reaction to Its Environments - SS1 Biology Past Questions and Answers - page 1

Tropic response

Nyctinasty

Tactic response

Nastic response

Tropic responses are growth-related, while nastic responses are movement-related.

Cilia and flagella are both short, hair-like structures involved in cell movement.

 Flagellum

It involves the fusion of gametes from two parents.

Budding

Nastic, tactic, and tropic responses are different types of responses exhibited by organisms in relation to stimuli.

Nastic responses refer to non-directional and often rapid movements in response to external stimuli, such as changes in temperature or humidity. These movements are not dependent on the direction of the stimulus but are rather triggered by the intensity of the stimulus.

Tactic responses, on the other hand, involve directional movements in response to stimuli. Organisms may move towards or away from a stimulus, such as light or chemicals, depending on their specific sensitivities.

Tropic responses are directional growth or movement responses exhibited by organisms in relation to a stimulus. These responses can be positive, where the organism moves towards the stimulus, or negative, where the organism moves away from the stimulus.

Tropic responses are typically slower compared to nastic or tactic responses and are often observed in plants, such as the growth of roots towards gravity (positive gravitropism) or the bending of plants towards light (positive phototropism).