NEET Practice Questions (MCQs) with Answers & Solutions

Circumnutation is a type of movement observed in growing plant organs, such as tendrils, where they exhibit a helical or spiral movement. This movement is essential for the development of leaf tendrils as it helps them find and attach to supports, aiding in the plant's climbing mechanism.

Photoperiodism refers to the physiological reaction of organisms to the length of day or night. It is most commonly associated with the timing of flowering in plants, where the length of daylight affects the plant's ability to flower. Hence, the correct answer is 'Effect of length of day on flowering.'

Ciliary movement involves the movement of organisms or cells using hair-like structures called cilia. Chlamydomonas, a type of green algae, uses cilia for movement. Therefore, the correct answer is 'Chlamydomonas.'

Crocus is an example of thermonasty. Thermonasty is the movement of plant parts in response to temperature changes. In Crocus flowers, the petals open when the temperature is warm and close when it is cold, which helps protect the reproductive organs from low temperatures.

Demonstration of cytoplasmic movement, also known as cyclosis, can be observed in the leaf cells of Tradescantia. The movement of the cytoplasm within these cells helps in the distribution of nutrients, organelles, and other essential materials throughout the cell.

In the absence of light, plants often exhibit a phenomenon known as etiolation. During etiolation, plants typically have elongated stems and longer internodes as they search for light. This results in the length of internodes increasing, which contributes to the growth of the plant along its longitudinal axis.

The sensitivity of leaves in Mimosa (also known as the 'touch-me-not' plant) primarily depends on mechanical stimuli such as touch. When touched, the leaves fold and droop due to changes in turgor pressure within the plant cells, which is a defense mechanism against herbivores.

The movement of cilia in Drosera (a genus of carnivorous plants) depends on touch. When an insect or prey touches the glandular hairs (cilia) on the leaf surface, the cilia bend towards the prey to capture it, facilitating digestion.