Railway Science (Biology – Cell : Basic Unit of Life)

Contractile Vacuole - Regulate the osmotic pressure by pumping water out of the cell. Amoeba are the simplest form of life. They are single-celled organisms that can reproduce by simple division. The cell of amoeba consists of the following parts - Cell Membrane, Nucleus, Vacuoles, Cytoplasm and Pseudopods. Food Vacuole - Contain food ingested by the Amoeba.

ATP (Adenosine triphosphate) is the source of energy for use and storage at the cellular level. The structure of ATP is a nucleoside triphosphate, consisting of a nitrogenous base (adenine), a ribose sugar, and three serially bonded phosphate groups.
Glucose (C₆H₁₂O₆) is a simple type of sugar in the blood and is the major source of energy for the body's cells. Adenosine diphosphate (ADP) is an important biological molecule in metabolism and it is essential to the flow of energy in living cells.
Pyruvic acid (C₃H₄O₃) is an organic acid that mostly occurs in all living cells. It ionises to give a hydrogen ion and an anion, termed pyruvate. Biochemists use the terms pyruvate and pyruvic acid almost interchangeably.

It is a Plasmolysis process, which takes place when a cell is placed in a hypertonic (sugar) solution. When water is drawn out of the cell through diffusion into the extracellular (outside cell) fluid causes the protoplast to shrink away from the walls.

The covering or protective tissues in the animal body are epithelial tissues. The skin, the lining of the mouth, the lining of blood vessels, lung alveoli and kidney tubules are all made of epithelial tissue. Types - Simple epithelium and compound epithelium. Fig A - Simple, Fig B - Cuboidal, Fig C - Columnar, Fig D - Stratified.

A prokaryotic ribosome (70S) is made up of two subunits 50S and 30S while an eukaryotic ribosome (80S) is made up of two subunits 60S and 40S. Prokaryotic cells are cells without a nucleus. Eukaryotic cells are cells that contain a nucleus.

Human cheek cells are animal cells while the onion peel cells are the plant cells. The major difference between the plant cells and animal cells are the presence of the chloroplast and cell wall in the plant cells. The animal cells are devoid of these two cell organelles.
The presence of cell membranes, mitochondria, endoplasmic reticulum, and the nucleus is common in both plant cells and animal cells. The cellular functions are similar in both.

Prokaryotic cells are single-celled microorganisms, having no nucleus, reproduce by binary fission (a form of asexual reproduction). Examples - Archaea, bacteria, and cyanobacteria. Eukaryotic cells are multi celled microorganisms having definite nucleus, Membrane bound cell organelles such as Mitochondria, Golgi apparatus, Chloroplasts are present, reproduce by Both asexual and sexual reproduction. Examples - Protists, Fungi, Plants, and Animals.

Ribosomes synthesize the proteins by gathering and assembling amino acids into protein chains called Translation. Ribosomes are tiny, oval-shaped organelles of the cell present both in prokaryotic and eukaryotic organisms. Chloroplasts, the organelles responsible for photosynthesis, are in many respects similar to mitochondria.
Mitochondria are membrane-bound cell organelles that generate the chemical energy needed to power the cell's biochemical reactions.
The Golgi apparatus (Golgi complex) functions as a factory in which proteins received from the ER (endoplasmic reticulum) are further processed and sorted for transport to their eventual destinations: lysosomes, the plasma membrane, or secretion.

Paramecium is a slipper -shaped, unicellular organism found in pond water. Unicellular organisms are made up of only one cell. In a unicellular organism, all the important life processes such as respiration, digestion, excretion, and reproduction take place within a single cell. Examples - Bacteria, Protists, and yeast.

Osmosis:- It is the process that causes living cells to expand in size and shape when placed in a hypotonic solution. Transpiration is a process that involves loss of water vapour through the stomata of plants.
Diffusion is defined as the movement of individual molecules of a substance through a semipermeable barrier from an area of higher concentration to an area of lower concentration.
Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar.