Short Notes On Biology

Here we are providing the short notes on Biology which will be help to crack science part in may examinations like SSC, Railway and other competitive exams.

Important Facts About Human Body:

Largest and strongest Bone in the body: Femur (thigh bone)
Smallest Bone in the body: Stapes in ear
Volume of Blood in the body: 6 litres (in 70 kg body)
Number of Red Blood Cells(R.B.C.): 1. In male: 5 to 6 million/cubic mm
2. In female: 4 to 5 million/cubic mm
Life span of Red Blood Cells(R.B.C.): 100 to 120 days
Life span of White Blood Cell(W.B.C.): 3-4 days
Time taken by R.B.C. to complete

one cycle of circulation:

20 seconds
Other name of Red Blood Cell (R.B.C.): Erythrocytes
Largest White Blood Cells: Monocytes
Smallest White Blood Cells: Lymphocyte
Who discovered Blood Group: Karl Landsteiner
Blood Platelets count: 150,000 – 400,000 platelets per micro litre
Haemoglobin (Hb): 1. In male: 14-15 gm/100 c.c. of blood
2. In female: 11-14 gm/100 c.c. of blood
Hb content in body: 500-700 gm
pH of Urine: 6.5-8
pH of Blood: 7.36-7.41
Volume of Semen: 2-5 ml/ejaculation
Normal Sperm Count: 250-400 million/ejaculation
Menstrual cycle: 28 days
Menopause age: 45-50 years
Blood clotting time: 3-5 minutes
Weight of Brain: 1300-1400 gm in human adult
Normal Blood Pressure (B.P.): 120/80 mm Hg
Universal blood donor: O
Universal blood recipient: AB
Average body weight: 70 kg
Normal body temperature: 37 degree Celsius
Breathing Rate at rest: 12-16/minute
Number of Spinal Nerves: 31 pairs
Largest Endocrine Gland: Thyroid gland
Normal Heart Beat at rest: 72 beats per minute
Largest Gland: Liver
Largest Muscle in the body: Gluteus Maximus or Buttock Muscle
Smallest Muscle in the body: Stapedius
Largest Artery: Aorta
Largest Vein: Inferior Vena Cava
Largest and longest Nerve: Sciatic Nerve
Longest Cell: Neurons (nerve cells)
Minimum distance for proper vision: 25 cm
Pulse rate: 72 per minute
Thinnest Skin: Eyelids
Weight of Heart: 200-300 gm

Common Drugs and Their Usage:

Drugs/Medicine Use
Anaesthetics It is a drug that induces insensitivity to pain.
Antiflatulent It is a drug that reduces intestinal gas
Antipyretics It is a drug used to lower body temperature.
Analgesics It is a drug that is used to prevent or relieve pain. Eg. Aspirin.
Antibiotics It is a drug that inhibits the growth of or destroys micro-organisms. Eg. Penicillin.
Antihistamines It is a drug used to relieve symptoms of cold and allergies.
Antispasmodic It is a drug used to relieve spasm of involuntary muscle usually in stomach.
Antacid It is a drug used for preventing or correcting acidity, especially in the stomach.
Diuretics It is a drug that promotes the production of urine.
Laxative It is a drug used to provide relief in constitpation.



List of Diseases caused by Virus, Bacteria, Protozoa and Worm:


Disease caused by Viruses:

1. Chicken pox – It is caused by Varicella-zoster virus.
2. Small Pox – It is caused by Variola virus.
3. Common Cold –It is caused by Rhinovirus.
4. AIDS (Acquired Immunono Deficiency Syndrome) – It is caused by Human

Immunodeficiency Virus (HIV).

5. Measles –It is caused by Measles virus.
6. Mumps –It is caused by Mumps virus.
7. Rabies – It is caused by Rabies virus (Rhabdoviridae family).
8. Dengue fever –It is caused by Dengue virus.
9. Viral encephalitis – It is an inflammation of the brain. It is caused by rabies virus, Herpessimplex, polio virus, measles virus, and JC virus.


Disease caused by Bacteria:

1. Whooping Cough – It is caused by a bacterium called Bordetella pertussis.
2.Diphtheria – It is caused by Corynebacteriumdiphtheriae.
3. Cholera – It is caused by Vibrio cholerae.
4. Leprosy – It is caused by Mycobacterium leprae.
5. Pneumonia-It is caused by Streptococcus pneumoniae.
6. Tetanus –It is caused by Clostridium tetani.
7. Typhoid – It is caused by Salmonella typhi.
8. Tuberculosis –It is caused by Mycobacterium tuberculosis.
9. Plague – It is caused by Yersinia pestis.



1. Malaria It is spread by Anopheles mosquitoes. The Plasmodium parasite that causes malaria is neither a virus nor a bacteria it is a single celled parasite that multiplies in red blood cells of humans.
2.Amoebic dysentery It is caused by Entamoebahistolytica.
3.Sleeping sickness It is caused by Trypanosomabrucei.
4. Kala azar It is caused by Leishmaniadonovani.



1. Tapeworn They are intestinal parasites. It cannot live on its own. It survives within the intestine of an animal including human.
2. Filariasis It is caused by thread like filarial nematode worms. Most cases of filaria are caused by the parasite known as Wuchereriabancrofti.
3. Pinworm It is caused by small, thin, white roundworm called Enterobiusvermicularis.



1. Anaemia It is caused due to deficiency of mineral Iron.
2. Ariboflavinosis It is caused due to deficiency of Vitamin B2.
3. BeriBeri It is caused due to deficiency of Vitamin B.
4. Goitre It is caused due to deficiency of Iodine.
5. Impaired clotting of the blood It is caused due to deficiency of Vitamin K.
6. Kwashiorkor It is caused due to deficiency of Protein.
7. Night Blindness It is caused due to deficiency of Vitamin A.
8. Osteoporosis It is caused due to deficiency of mineral Calcium.
9. Rickets It is caused due to deficiency of Vitamin D.
10. Scurvy It is caused due to deficiency of Vitamin C.



Disease Affected Body Part
AIDS Immune system of the body
Arthritis Joints
Asthma Bronchial muscles
Bronchitis Lungs
Carditis Heart
Cataract Eye
Cystitis Bladder
Colitis Intestine
Conjunctivitis Eye
Dermatitis Skin
Diabetes Pancreas and blood
Diphtheria Throat
Eczema Skin
Goitre Thyroid gland
Glossitis Tongue
Glaucoma Eye
Gastritis Stomach
Hepatitis Liver
Jaundice Liver
Malaria Spleen
Meningitis Brain and spinal cord
Myelitis Spinal cord
Neuritis Nerves
Otitis Ear
Osteomyelitis Bones
Paralysis Nerves and limb
Pyorrhoea Teeth
Peritonitis Abdomen
Pneumonia Lungs
Rhinitis Nose
Rheumatism Joints
Tuberculosis Lungs
Tonsillitis Tonsils
Trachoma Eye



K.Landsteiner : Classified human beings (1900) in four groups on the basis of the reaction of their blood:A,B,AB and O.

Blood group Carries antigen Carries antibody Can donate blood to Can receive blood from
AB A,B None Only AB Universal Accepter
O None A,B Universal donor Only O

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