Biology for NEET and other Competitive Exams Botany and Zoology

Mastering Plant Physiology

Q: What is Plant Physiology?

A: It's the study of the functional processes occurring within plants, encompassing how they grow, develop, respond to their environment, and convert energy.

Why do leaves turn yellow and fall in autumn?

This is due to a decrease in daylight hours, influencing plant hormones that trigger pigments like chlorophyll to break down, revealing the yellow pigments like carotenoids naturally present in leaves.

Q: What are the essential processes in Plant Physiology?

A:

Photosynthesis: The process by which plants capture sunlight energy to convert carbon dioxide and water into carbohydrates (glucose) for food, releasing oxygen as a byproduct.

Respiration: Plants break down organic molecules (glucose) to release energy for various cellular functions, utilizing oxygen and releasing carbon dioxide (opposite of photosynthesis).

Mineral Nutrition: Plants require essential mineral elements from the soil for growth and development. These are absorbed through their roots.

Transport: Plants transport water, minerals, and manufactured food (glucose) throughout their body using specialized tissues like xylem and phloem.

Plant Growth and Development: This includes understanding the role of plant hormones (auxins, gibberellins, cytokinins) in regulating various growth processes.

Xylem transports water and minerals upwards from the roots, while phloem transports dissolved organic solutes like glucose throughout the plant.

Understanding Plant Reproduction

Q: What are the different modes of plant reproduction?

A: Plants can reproduce through both sexual and asexual reproduction:

Sexual Reproduction: Requires the fusion of male and female gametes (sperm and egg) to form a zygote, which develops into a new plant.

Pollen grains (male gametes) from a flower are transferred to the stigma (female) of another flower, leading to fertilization and seed development.

Asexual Reproduction: Does not involve the fusion of gametes. Offspring are genetically identical to the parent plant.

Reproduction through runners (stolons) in strawberries or tubers (potatoes) that give rise to new plants.

Q: What are the floral structures involved in sexual reproduction of flowering plants?

A: The flower is the reproductive unit of an angiosperm (flowering plant). Key structures include:

Stamen: Male reproductive organ that produces pollen grains containing sperm cells.

Pistil: Female reproductive organ consisting of stigma (receives pollen), style (connects stigma to ovary), and ovary (contains ovules that develop into seeds).

Q: What are the different types of asexual reproduction in plants?

A: Several methods exist, including:

Vegetative propagation: Using vegetative parts like stems, leaves, or roots to grow new plants (e.g., stem cuttings in roses).

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