Cell Biology and Structure

 Nerve cells are the biggest cells of the body. The smallest cell is bacteria. The smallest cell in the human body is the red blood cell.

The protruding projection,  which helps in movement and feeding of ameoba is called pseudopedia.

Polyester is a category of polymers which contain the ester functional group in their main chain. Polyesters include naturally-occurring chemicals, such as in the cutin of plant cuticles, as well as synthetics through step-growth polymerization such as polycarbonate and polybutyrate.

Nitric oxide has been implicated in initiating and inhibiting apoptosis through its possible action as a signal molecule of subsequent pathways that activates apoptosis

Nucleus is a site for transcription in which messenger RNA (mRNA) are produced for protein synthesis.

It is the flattened membrane, which is mainly used to store the substances made by the cell. This membrane also helps in preserving and transporting materials within the cell. Hence, it is also called as the post office of a cell.

Cytoplasmic streaming is indeed the movement of the cytoplasm within a cell. This internal circulation helps distribute nutrients, organelles, and other materials throughout the cell.

Muscle cells require continuous energy (ATP) for contraction and relaxation. Mitochondria are the powerhouses of the cell producing ATP through cellular respiration, so cells with high energy demands like muscle cells contain the most mitochondria.

The cell membrane (also called plasma membrane) surrounds all organelles as well as the entire cell. It is selectively permeable and regulates the movement of substances in and out. The nuclear membrane specifically surrounds only the nucleus.

A hen's egg is a single cell (the yolk is the actual cell) large enough to be visible to the naked eye. Most neurons are microscopic, and while giant squid neurons are exceptionally long, they are still too thin to be clearly visible without magnification.

Human egg cells (oocytes) contain centrioles which help organize the spindle apparatus during cell division. Option A is wrong because animal cells lack cell walls. Option C is wrong because tonoplast is found in plant cells. Option D is wrong because mature human eggs have minimal vacuoles.

Cell theory states that the cell is the basic structural and functional unit of all living organisms. Option A is wrong because many cells (like animal cells) lack cell walls. Option B is wrong because cells arise only from pre-existing cells (omnis cellula e cellula). Option D is wrong because red blood cells lack nuclei.

Amoeba exhibits cellular level of organization because it is a unicellular organism - all life functions (nutrition, respiration, reproduction) occur within a single cell. Tissue, organ, and organ system levels require multicellular organisms with specialized cell groups.

Nerve cells (neurons) are post-mitotic, meaning they lose their ability to divide after reaching maturity. This is why brain damage from injury or stroke is often permanent. Blood cells, muscle cells, and bone cells retain regenerative capacity through stem cells.

Cell sap refers to the fluid inside plant cell vacuoles, which is a solution of water containing dissolved salts, sugars, and other substances. This solution helps maintain turgor pressure and stores nutrients and waste products.