Untitled Quiz

Botany (Plant Physiology)

• Course: 1st Level
• Instructor: Dr. Awatef Saad

Introduction

• Plant physiology is a core component of botany.
• Plants, being immobile, face diverse and ever-changing environmental challenges.
• Physiological adaptations are as crucial to plant survival as their morphological features.
• Plant physiology explores the functions of living organisms, from molecules to entire organisms.
• The intimate relationship between structure and function is a central concept.
• Life's essence lies in biochemical reactions controlled by enzymes within the protoplasm.
• Protoplasm's components are typically in water solutions and associate with water molecules.
• Colloidal state is a key feature of protoplasm.

Water and Cell

• Water is indispensable for plant life.
• Plant cells contain a large water-filled vacuole, with cytoplasm comprising a small portion.
• Growing plant tissues are primarily composed of water.
• Water's properties include being an excellent solvent, directly participating in cellular reactions, and forming the medium for intracellular molecule movement.
• Plants continuously absorb and lose water, with transpiration being a significant water loss.
• Water uptake is crucial for mineral absorption.
• Understanding water uptake and loss is important for agricultural productivity and ecosystem dynamics.

Water Potential

• Water potential represents the free energy status of water.
• Water moves from high to low water potential.
• Major factors influencing water potential in plants include concentration, pressure, and gravity.
• Factors that impact water potential include solute concentration (osmotic potential), pressure potential (turgor pressure), and gravity potential.
• Pure water at ambient pressure and temperature has a water potential of zero, whereas solutions have lower values.
• Dissolved solutes negatively impact water potential.
• Pressure (turgor pressure) can increase water potential.

Permeability

• Permeability determines how readily materials pass through membranes.
• Membranes can be permeable, impermeable, semi-permeable, or selectively permeable.
• Selective permeability is crucial for regulating substance movement into and out of cells.
• Factors affecting membrane permeability include temperature, light, alkalinity, acidity, and anaesthetics.

Diffusion

• Diffusion is the net movement of a substance from regions of high concentration to low concentration.
• Relevant factors include temperature (increased temperature increases diffusion rate), pressure (higher pressure gradients force higher diffusion rates), presence of solutes (lowering water potential encourages diffusion).

Size and Mass of Diffusing Particles

• Smaller particles diffuse faster than larger particles.
• Heavier particles diffuse more slowly compared to lighter ones.

Osmosis

• Osmosis is the specific diffusion of water across a selectively permeable membrane.
• It's driven by differences in water potential.
• An osmometer is a device demonstrating and studying osmosis.
• Key terms include osmotic pressure, turgor pressure, and wall pressure.
• Plant cell type responses differ based on relative water potential concentrations inside and outside the cells.

Plasmolysis

• Plasmolysis is the process where plant cells lose water to a hypertonic solution, leading to shrinking of the protoplasm.
• The protoplasm detaches from the cell wall.
• Reversal of plasmolysis (deplasmolysis) is possible when placed in an hypotonic solution.

Metabolism

• Metabolism encompasses all the chemical reactions within a plant.
• It involves two main processes: anabolism and catabolism.

Enzymes

• Enzymes are biological catalysts that speed up biochemical reactions without being consumed.
• Enzymes are highly specific and function within specific conditions of temperature and pH.
• Enzyme activity can be affected by factors like temperature, substrate concentration, and the presence of inhibitors.
• Enzyme inhibitors either block the active site or change the enzyme's shape.

Photosynthesis

• Photosynthesis is the process by which green plants convert light energy into chemical energy.
• Key stages include light-dependent and light-independent reactions.
• Chlorophyll is the key pigment in this process, absorbing light energy.
• The process releases oxygen.

Respiration

• Respiration is the release of chemical energy through the oxidation of organic compounds.
• It occurs in two major types including anaerobic and aerobic respiration.
• Both processes produce ATP (adenosine triphosphate), the primary energy currency of the cell.