General knowledge

DYK?
The human nose can detect about 1 trillion smells.

DYK?
Your fingernails don’t actually grow after you’re dead.

Bodyfacts
It’s possible to brush your teeth too aggressively. Doing so can wear down enamel and make teeth sensitive to hot and cold foods.

Taj Mahal (Agra, India)















A mausoleum commissioned for the wife of Mughal Emperor Shah Jahan, the Taj Mahal was built between 1632 and 1648. Considered the most perfect specimen of Muslim art in India, the white marble structure actually represents a number of architectural styles, including Persian, Islamic, Turkish and Indian.
The Taj Mahal also encompasses formal gardens of raised pathways, sunken flower beds and a linear reflecting pool.

Great Wall of China (China)





Built between the 5th century B.C. and the 16th century, the Great Wall of China is a stone-and-earth fortification created to protect the borders of the Chinese Empire from invading Mongols. The Great Wall is actually a succession of multiple walls spanning approximately 4,000 miles, making it the world’s longest man-made structure.

DYK??
Left handed people can recover from strokes faster.

Female Reproductive System
The female germ-cells or eggs are produced in the ovaries.

The egg is transported from the o***y to the womb through a thin oviduct known as fallopian tube.

The two oviducts unite and form an elastic bag-like structure known as the uterus, which opens into the va**na through the cervix.

During the sexual in*******se, most likely, the egg and the s***m (zygote) get fertilized and implanted in the lining of the uterus.

The thickened lining (of the uterus) and richly supplied blood nourish the growing embryo (in the uterus).

The embryo receives nutrition from the mother’s blood with the help of a special tissue known as placenta.

Likewise, the development of a child inside the mother’s body, takes about nine months.

Source:science basic app biology

Biology - The Fundamental Unit of Life
Introduction
The fundamental unit of life is cell.

Cell was first discovered by Robert Hooke in 1665 in a simple microscope.

Animal Cell Structure

In 1674, Leeuwenhoek, with the help of developed microscope, discovered the free living cells in pond water.

In 1831, Robert Brown had discovered the nucleus in the cell.

In 1839, Purkinje used the term ‘protoplasm’ for the fluid substance found in the cell.

The cell theory was proposed by Schleiden (1838) and Schwann (1839).

According to the cell theory, all the plants and animals are composed of cells and that the cell is the basic unit of life.

In 1855, Virchow further expanded the cell theory and suggested that all cells arise from pre-existing cells.

In 1940, the discovery of electron microscope made possible to observe and understand the complex structure of the cell.

Unicellular Organisms
The single cellular organisms, such as Amoeba, Chlamydomonas, Paramoecium, and bacteria, are known as unicellular organisms.

Multicellular Organisms
The organisms consisting of many cells are known as multicellular organisms. E.g. human being, animals, birds, etc.

Significant Characteristics of Cells
Each living cell has the aptitude to perform certain basic functions that are characteristic of all living forms.

Each such cell has certain specific components within it known as cell organelles.

Different types of cells have different function and each cell organelle performs a special function.

These organelles collectively constitute the basic unit of life known as cell.

All cells are found to have the same organelles, irrespective of their different functions and the organism they found in.

Structural Organization of Cell
Following are the three basic features that every cell possesses −

Plasma Membrane/Cell Membrane

Nucleus

Cytoplasm

Basic Features of Cell

Let’s discuss each one of them in brief −

Plasma Membrane/Cell Membrane
Plasma membrane is the outermost covering layer of the cell (as shown in the image given above).

Plasma membrane allows certain materials to enter inside the cell and come out from the cell; therefore, it is known as selectively permeable membrane.

The movement of water molecules through the selectively permeable membrane is known as osmosis.

Cell Wall

Plant cells have an addition protecting cover known as cell wall (absent in animal cell).

The cell wall lies outside the plasma membrane; likewise, it also covers plasma membrane.

The cell wall is essentially composed of cellulose.

Nucleus
Nucleus or nuculeus is a Latin term and its meaning is kernel or seed.

The nucleus has a double layered covering, which is known as nuclear membrane (see the image given above).

The nuclear membrane has some pores, which allow certain materials come inside (in nucleus) and go outside (in the cytoplasm).

The most significant feature of nucleus is – it contains chromosomes.

Chromosomes are rod-shaped structures and it is visible only when the cell is about to divide.

Chromosomes are composed of DNA and protein.

DNA (Deoxyribo Nucleic Acid) molecules contain inheritance features from parents to next generation.

DNA molecules also contain the information essential for constructing and organizing cells.

Functional segments of DNA are known as genes.

DNA is present as the part of chromatin material.

Chromatin material is visible as entangled mass of thread like structures (as shown in the image given below).

Human DNA

Whenever the cell is about to divide, the chromatin material gets organized into chromosomes.

The nucleus plays a central and significant role in cellular reproduction.

The cell, which has no nuclear membrane, is known as prokaryotes (i.e. Pro = primitive or primary; karyote ≈ karyon = nucleus). See the image given below:

Eukaryote Prokaryote

The cell, which has a nuclear membrane, is known as eukaryotes.

Prokaryotic cell does not have many other cytoplasmic organelles those are present in eukaryotic cells (see the image given above).

Cytoplasm
Cells consist of cytoplasm inside the cell membrane, which contains many biomolecules including proteins and nucleic acids.

There are many structures found in the cytoplasm known as cell organelles.

Cell Organelles
Following are the major cell organelles that play a major role in the functioning of cell −

Nucleus

Endoplasmic Reticulum

Ribosome

Golgi apparatus

Lysosomes

Mitochondria

Plastids

Vacuoles

Cell Organelles

Let’s discuss each one in brief −

Nucleus is discussed above.

Endoplasmic Reticulum
The endoplasmic reticulum (or simply ER) is a large network of membrane-bound tubes and sheets (see the image given above).

Based on visual structure, ER is categorized as rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER).

When the ribosome attached on the surface of ER, it is known as Rough Endoplasmic Reticulum and without ribosome, it is known as Smooth Endoplasmic Reticulum.

The SER helps in the manufacturing of fat molecules, or lipids, which is important for cell functioning.

One of the significant functions of ER is to serve as channels for the transportation of materials (especially proteins) in various regions of the cytoplasm and also between the cytoplasm and the nucleus.

Ribosome
The ribosomes, normally, present in all active cells.

Ribosome are the sites of protein manufacturing.

Golgi Apparatus
The Golgi Apparatus is named after the name of its discover Camillo Golgi.

Golgi Apparatus consists of a system of membrane-bound vesicles arranged roughly parallel to each other in stacks known as cisterns (see the image given above).

The significant functions of Golgi Apparatus are the storage, modification, and packaging of products in vesicles.

The Golgi apparatus also helps in the formation of lysosomes.

Lysosomes
Lysosomes are a sort of waste disposal system of the cell.

Lysosomes help in keeping the cell clean by digesting the foreign material as well as worn-out cell organelles.

Lysosomes contain powerful digestive enzymes capable of breaking down all sorts of organic materials.

Lysosome has a typical feature i.e. when the cell gets damaged lysosome most likely bursts and the released enzymes digest their own cell. Because of this reason, lysosome is also known as the ‘suicide bags’ of a cell.

Mitochondria
Mitochondria, commonly, are known as the powerhouses of the cell.

Mitochondria release the energy required for various chemical activities (essential for the life).

Mitochondria release energy in the form of ATP (Adenosine Triphopshate) molecules.

ATP is popular as the energy currency of the cell.

Mitochondria have their own DNA and ribosomes; hence, they are capable to make some of their own proteins.

Plastids
Plastids are present only in the plant cells (see image given below).

Cell Organelles Plant

Plastid is categorized as – Chromoplasts (it is colored plastids) and Leucoplasts (It is either white or colorless plastids).

Plastids contain chlorophyll pigment, which are known as Chloroplasts.

Chloroplasts play important role in the photosynthesis in plants.

Chloroplasts also contain various types of yellow or orange pigments.

Leucoplasts are the organelles in which some important materials such as starch, oils, and protein granules get stored.

Plastids look like mitochondria (in terms of external structure).

Like the mitochondria, plastids also possess their own DNA and ribosomes.

Vacuoles
Vacuoles are commonly the storage sacs that contain solid or liquid materials.

In animal cell, vacuoles are small; whereas in plant cell, vacuoles are of large size.

Plant cells vacuoles are filled with cell sap and provide turgidity and rigidity to the cell.

Source:science basics app biology

Biology - Structure and Functions
Introduction
The basic structural unit of an organ is known as the cell.

In 1665, Robert Hooke discovered the cell.

A cell is a living organism.

A human body has trillions of cells, which vary in shapes and sizes.

The organism, which is made up of more than one cell, is known as multicellular organism.

The single-celled organisms are known as unicellular organism. E.g. Amoeba.

Amoeba

A single-celled organism performs all the essential functions that a multicellular organism performs.

Unlike other organisms, Amoeba has no definite shape; so, it keeps on changing its shape.

Amoeba has pseudopodia, which means – pseudo means false and podia means feet.

Amoeba is a full-fledged organism capable of independent existence.

Shape of the cells are normally round, spherical, or elongated.

Protoplasm is known as the living substance of the cell.

The cells having nuclear substances without nuclear membrane are known as prokaryotic cells. E.g. bacteria and blue green algae.

The cells having well organized nucleus with a nuclear membrane are designated as eukaryotic cells. All multicellular organisms are eukaryotic cells.

Cell Structure and Function
The basic parts of a cell are cell membrane, cytoplasm, and nucleus.

Human Cell

Cell membrane is also known as the plasma membrane.

The plasma membrane is porous and allows certain substances or materials move both inward and outward.

The central dense round structure in the center is known as nucleus.

The jelly-like substance between the nucleus and the cell membrane (as shown in the above image) is known as cytoplasm.

Different organelles of cells are also present in the cytoplasm such as Mitochondria, Golgi bodies, Ribosomes, etc.

Located in central part, nucleus is almost in spherical shape.

Nucleus is separated from the cytoplasm by a porous membrane known as the nuclear membrane.

The smaller and spherical structure, found inside the nucleus, is known as nucleolus.

Nucleus contains thread-like structures known as chromosomes.

Chromosomes carry genes and help in inheriting the characteristics of the parents to the offspring.

Gene is a fundamental unit of inheritance in living organisms.

The entire constituents of a living cell are known as protoplasm, which include nucleus and cytoplasm.

Plant Cell
The cell membrane provides shape to the cells of plants and animals.

In plant cell, cell wall is an additional covering over the cell membrane.

Cell Structure

An animal cell does not have cell wall.

Cell wall gives shape and rigidity to plant cells.

Cell wall gives protection, plant cells need protection against varying temperature, high wind speed, atmospheric moisture, etc.

Bacterial cell also has a cell wall.

Usually, most of the cells are microscopic in size and are not visible to the naked eye.

The size of smallest cell is 0.1 to 0.5 micrometer found in bacteria.

The size of largest cell is 170 mm × 130 mm, found in the egg of an ostrich.

The size of the cells however has no relation with the size of the body of the animal or plant.

Some small colored bodies in the cytoplasm of the cells of Tradescantia leaf are known as plastids.

Plastids are found in different colors.

Some plastids have green pigment and known as chlorophyll.

Green colored plastids are known as chloroplasts.

Chloroplasts give green color to the leaves.

Chlorophyll is essential for the photosynthesis.
Source:by science basics app biology 🧫

Science facts
Question: In human body ‘Vitamin K’ is necessary for what ?
Ans: Formation of Prothrombin

Science facts
Question: What is the best source of Protein ?
Ans: Soybean

Science facts
Question: To measure the Humidity in air, what instrument used ?
Ans: Hygrograph