Human fertilization is the union of a human egg and sperm, usually occurring in the ampulla of the fallopian tube. The result of this union is the production of a zygote cell, or fertilized egg, initiating prenatal development.

The shape of our galaxy milky way is barred spiral galaxy in which the central elliptical buldge of closely packed starts lying in the direction of Sagittarius.

Mainly there are two types of cells which are Eukaryotic and Prokaryotic. 

The Prokaryotic cells do not have a well defined nuclear membrane. Eg blue green algae and bacteria. 

The Eukaryotic cells have a well defined nuclear membrane. Example human beings. 

On the basis of shape we have round cells,  elongated cells and branched cells. 

For example nerve cell is the longest and branched cell in a human body so that it can transmit the messages rapidly. 

Cells are classified into two categories,

1) prokaryotic cells

2)Eukaryotic cells

Eutrophication is enrichment of ecosystem with chemical nutrients mostly by compounds of Nitrogen and Phosphorus is called Eutrophication.It results in growth of algae in water and deteriorates the water quality.

Hydrophobic- hydro+phobic 

Hydro means water and phobic means hating or repelling

So it is the property of molecule which is water repelling in nature.They are non polar in nature and do not mix with water.for example oil,greese etc 

Aeroplane flys at much higher altitude than the helicopter. Therefore the decrese in air pressure in case of aeroplne is much more than helicopter at which they fly. Now we all know that inside the aeroplane we need to maintain the atmospheric pressure to keep all our biological systems properly. so an equillibrium of pressure is maintained there. if the doors and windows are opened that equillibrium will be disturbed and hence the situation can be fatal.

Since Helicopter can rise only upto a certain level where the air density is lower but not fatal for us so no air pressure equillibrium is maintained. Therefore the doors and windows can be open

Moreover drag caused by the air is much more in case of aeroplane than helicopter because the former runs in much faster speed than latter. This drag also hamper the functioning of the system of an aeroplane. so the windows are closed. Since the drag in case of helicopter is not much so it doesnot affect the working of a helicopter.

An embryo is multicellular diploid eukaryote in it earliest stage of development.At the end of 8 weeks in humans, the embryonic stage is over and the fetel stage begins.

Foetus is the last stage of baby's development while embryo is the first stage.

Foetus is fully developed and clearly identical as a baby while embryo is just the division's start of a baby and not clearly identical.

Foetus occurs after embryo and embryo before foetus.

Embryo is the combination of just two cells while foetus is almost a complete baby.

A microorganism is an organism that is so small to be seen by nakrd eye and are visible by an instrument called microscope.They can be unicellular or multicellular organisms.

A microorganism or microbe is an organism which is too small to be seen by the unaided human eye. They are microscopic.

The study of microorganisms is called microbiology.

Microorganisms include bacteria, fungi, archaea or protists and viruses.

When a light ray enters into a denser medium from a rarer medium it bends away from the normal at the interface of the two medium because of the decrease in the velocity. Light rays with longer wavelenth bends the least and with sorter wavelength bends the most. Now we all know the white light has seven component light rays of different colours. All of them vary with respective to their wavelength. Red has the longest wavelenth whereas the violet has the shortest. Therefore when a white light enters into the prism all the component light rays bends away from the normal inversely proportional to their wavelength.e.g. red light bends the least and violet bends the most. Therefore we get a spectrum of seven different colours.  

its simple because every colour of light have diffrent velocity and wavelength.So,when a white light enters the prism the light with large wavelength(red) bends the least and colour light with smallest wavelength(violet) bends the the most and similarly it happens for all the colour of light.and we can see all the diffreny colour of white light.

The molecule N2 is called nitrogen molecule.

Common name for the formula N₂ is Nitrogen molecule.

Dolly sheep was the first mammal clone. It was created by a process called nuclear transfer from a somatic cell (body cell). In this process from the body of a healthy individual some somatic cells are collected. In case of Dolly the nucleus was collected from the mammary gland of a feamale sheep. Then this nucleus is placed inside an unfertilized oocyte whose nucleus ia already removed. After this hybridization completed successfully this hybrid cell is stimulated for cell division (by giving an electric shock) and once it has attain the blastocyst phase it is implanted in the surrogate mother sheep. In case of Dolly she had three mothers. One has given the genetic material (the nucleus), second on has given the oocyte and third one is the surrogate mother.

• The Asiatic lion is endangered largely because of hunting by humans after firearms became widespread.  Its numbers are slowly recovering, having risen from merely 100 animals to about 200 today, according to Bristol Zoo Gardens.
• Tigers are endangered because of climate change, loss of habitat and poaching. Most of the reasons tigers are on the endangered species list are tied to human interference. The overall combined population of all five tiger species is between 3,000 and 5,000, according to National Geographic.                                                                             due to population loss and several inhuman activities they are endangered
• hope its helpful:)

Red List:

• The IUCN (International union for conservation of nature) Red list is the most authentic study of the global conservation status for the threatened biological species.
• The IUCN Red List is set upon criteria to evaluate the risk of being extinct of thousands of species and subspecies. These criteria are relevant to all species and all regions of the world.

Red Data Book:

• The Red data bool is the state document maintained for documenting the details rare and endengered species of plant animal fungi upto the level of sub species exist within the area of the state or country.
• This provides information about studies and monitoring programmes on rare and endengered species and their habitat. 

Extinct means the one which does not exist presently but they existed in the past.For example, Diana sores are extinct species.

anything which existed in a particular environment but now is not found or available.

Cultivation of crops involves several activities undertaken by a farmer over a period of time which are referred to as agricultural pratices. They are sequentially as follows:

1. Preparation of soil
2. Sowing
3. Adding manure and fertilisers
4. Irrigation
5. Protecting from weeds
6. Harvesting
7. Storage

Cultivation is the process of production of plants giving them proper nutrients, environment, water etc and taking their care .

The atmospheric pressure is the pressure that an area experiences due to the force exerted by the atmosphere.

Vacuum is ideally an area which is devoid of any matter that means in vacuum the atmospheric pressure is zero. 

vacuum pressure is measured as the difference between atmospheric pressure and absolute pressure. (Absolute pressuer : actual pressure at given position)

Vaccuum is the region where pressure is zero and even the sound cannot propagate in vaccuum .The atmospheric pressure is the pressure exerted by the air at sea level and it is taken as 1 atm as standard value.

Vacuum, is a region without any matter, or a region of zero pressure (perfect vacuum). It is practically impossible to create perfect vacuum. So real vacuum should actually be defined as a region <i>almost </i>devoid of matter, or of very low pressure.


Vaccum is a non-existent word. It is just a spelling mistake of the former. Other common spelling mistakes made in writing vacuum are <i>vacume, vacum, vaacum, vaccuum</i>

Absolute pressure : is zero-referenced against a perfect vacuum, so it is equal to gauge pressure plus atmospheric pressure. Gauge pressure : is zero-referenced against ambient air pressure, so it is equal to absolute pressure minusatmospheric pressure. Negative signs are usually omitted.

Friction is required for us to move.we cannot move if there is no friction.we cannot move in a frictionles surface. When we move forward , there is a force which opposes it an it is called friction.

Friction is a necessary evil . It is needed for the motion of any object over the other . 

Friction is essential for movement of vehicles, locomotion in our body and a number of other actitivies.

When both the rods are suspended using a thread, the bar magnet always setttle in north- south direction as as itself  acts as huge magnet having north pole towards geographical south. the soft iron bar may settle in any direction,

The nucleus is a double membrane organelle separate from the cytoplasm that contains the majority of the genetic material in a eukaryotic cell. This genetic material is in the form of deoxyribonucleic acid (DNA), and this along with any other DNA present in a cell (e.g. in the mitochondria) make up the genome (completely set of genetic material in a cell) of an organism.

The DNA in the nucleus is double stranded and consists of genes (a specific length of DNA consisting of mononucleitides joined together by phosphodiester bonds) consisting of non coding DNA (introns, which contain short tandem repeats at specific loci) and coding DNA (exons). This coding DNA is really important as it is transcribed to produce mRNA which is complementary to the antisense strand of DNA and therefore consists of particular codons (triplets of bases). This mRNA detaches from the DNA and leaves the nucleus through a nuclear pore, entering the cytoplasm where it binds to a ribosone and is translated to produce a primary structured protein (polypeptide chain/sequence of amino acids). This process is called protein synthesis and it allows a cell to produce particular proteins depending on which genes are switched on (therefore expressed) or off which depends on the epigenetic markers on the DNA contained in the nucleus, which have been established due to the environment or developmental cues.

The function of nucleus in the cell are :

1. It carries genes and helps in inheritance of of character from parents to progeny.
2. It also the metabolic activity of the cells
3. it is refered as the brain of the cell

The nucleus is a membrane-enclosed organelle found in eukaryotic cells.

The function of a nucleus is to control all activities of a cell. It controls gene expression and mediate the replication of DNA during the cell cycle.