Sodium ion (Na+) is often a spectator ion in many electrochemical reactions.

Silver ions (Ag+) are commonly used in reference electrodes, particularly in silver/silver chloride electrodes.

Potassium ions (K+) are commonly used in salt bridges to maintain electrical neutrality.

Cu²⁺ ions are reduced to copper metal at the cathode during the electrolysis of copper(II) sulfate solution.

Cations of transition metals are primarily responsible for the color of their complexes.

A condom is a barrier method of contraception that physically prevents sperm from reaching the egg.

Bacteria play a crucial role in decomposing organic matter, which helps in nutrient cycling.

Microbes play a crucial role in decomposing organic matter, which helps in nutrient cycling in ecosystems.

GMOs can lead to increased crop yield, reduced pesticide use, and enhanced nutritional content.

Genetically modified crops are developed to enhance yield, resistance to pests, and tolerance to environmental stresses.

Bioremediation uses microorganisms to degrade environmental contaminants, making it a key application in environmental management.

Gene therapy is a direct application of biotechnology in medicine, aimed at treating genetic disorders.

Bioremediation is a biotechnological approach that uses microorganisms to clean up contaminated environments.

Bioremediation uses microorganisms to degrade environmental contaminants, making it a method for waste management.

Fermentation is a biotechnological method used to produce vaccines by cultivating microorganisms.

Plants are biotic components of an ecosystem, while soil, water, and air are abiotic components.

Biotic factors are the living components of an ecosystem, which include plants, animals, and microorganisms.

The ability to reproduce is a characteristic feature of all living organisms.

Echinoderms, such as starfish and sea urchins, are characterized by a water vascular system, which aids in movement and feeding.

Epithelial tissue is characterized by closely packed cells with minimal intercellular space, forming a protective layer.

Fungi have chitin in their cell walls, distinguishing them from plants.

All of the options listed are characteristic features of living organisms.

Phylum Arthropoda is characterized by a segmented body, jointed appendages, and an exoskeleton made of chitin.

Photosynthesis is a characteristic feature of the kingdom Plantae, as plants are autotrophic and produce their own food using sunlight.

Viruses have a protein coat (capsid) and lack cellular structure and metabolism, requiring a host to reproduce.

A diode allows current to flow in one direction only, making it a unidirectional device.

A good cloning vector should have a high copy number to ensure that multiple copies of the inserted gene are produced within the host cell.

A reversible cell can be recharged, allowing it to be used multiple times.

Semiconductors have zero conductivity at absolute zero and their conductivity increases with temperature.

High biodiversity is a characteristic of a stable ecosystem, as it enhances resilience and stability.