NEET Practice Questions (MCQs) with Answers & Solutions

The cytoskeleton is a complex network of protein filaments and tubules that extends throughout the cytoplasm of eukaryotic cells. It is primarily made up of microfilaments (actin filaments), intermediate filaments, and microtubules, all of which are proteinaceous in nature.

In higher plants, the cell wall is primarily composed of cellulose. Cellulose is a polysaccharide consisting of a linear chain of glucose molecules. It provides structural support to the plant cells and is the most abundant organic polymer on Earth.

Rudolf Virchow, a German physician, and pathologist, proposed that new cells arise from preexisting cells through cell division. This concept is encapsulated in his famous dictum 'Omnis cellula e cellula,' which means 'every cell from a cell.' This idea is fundamental to the cell theory.

The fluid mosaic model of the cell membrane was proposed by Singer and Nicolson in 1972. According to this model, the cell membrane is a fluid combination of phospholipids, cholesterol, and proteins. The proteins float in or on the fluid lipid bilayer like boats on a pond.

The flagella of eukaryotic cells exhibit a 9+2 arrangement of microtubules. This means that there are nine doublets of microtubules arranged in a circle around two central microtubules. This structure is crucial for the movement of the flagella.

Microtubules are made up of tubulin proteins. Tubulin is a globular protein that polymerizes to form the hollow tubes that make up the microtubules. These structures are essential for various cellular processes, including cell division and intracellular transport.

Bacteria possess 70S ribosomes, which are smaller than the 80S ribosomes found in eukaryotic cells. The 'S' stands for Svedberg units, which measure the rate of sedimentation during centrifugation, indicating the size and density of the ribosome.

FACT

The Golgi apparatus is the site for the synthesis of glycolipids and glycoproteins. It modifies proteins and lipids that have been built in the endoplasmic reticulum and prepares them for export to different destinations inside or outside the cell.

Mitochondria are known as the powerhouses of the cell because they are the site of ATP (adenosine triphosphate) production. ATP is the primary energy carrier in cells, and its production is crucial for cellular activities.