General Knowledge & General Awareness Notes: General Science - Biology

BIOLOGY

BRANCHES OF BIOLOGY 
(a) Anthropology: Deals with the scientific study of man and the mankind. 
(b) Agronomy: Deals with the management of farms and science of crop production.
(c) Apiculture: Deals with the process of bee keeping for commercial purposes. 
(d) Entomology: Deals with the structure, habits and classification of insects. 
(e) Eugenics: Deals with improving the human race. 
(f) Pathology: Deals with the nature of disease, their causes, symptoms, effects, their cure and control. 
(g) Physiotherapy: Deals with the treatment of diseases, body weakness or defects with the help of massage and exercise etc. 
(h) Sericulture: Deals with the production of raw silk from silkworm. 
(i) Pharmacology: Deals with the knowledge and manufacture of drugs. 
(j) Occupational therapy: Deals with treating the physically handicapped or injured persons through exercise etc. 
(k) Psychology: Deals with the study of human mind, its behaviour and mental qualities. 
(l) DNA finger printing: Technique to help identify a person on the basis of genes.

ANIMALS/PLANTS
- The organisms that closely resemble one another are placed in one group, the groups which have similarities are combined together into larger groups, and these into still larger ones. The most inclusive category is kingdom.

Other major categories, in descending order are: phylum, class, order, family, genus, and species. Man belongs to Animal kingdom, chordata division or phylum, Mammalia class, Primates order, Hominidae family, Homo genus and Sapiens species.

- Carbohydrates: For a normal person, 400 to 500 gms of carbohydrates are required daily but for sportspersons, growing children and nursing mothers, it is on higher side.
- Proteins: They are complex organic compounds made up of carbon, hydrogen, oxygen and nitrogen. The building blocks of Protein are Amino acids and there are large number of amino acids.
- Proteins are essential for the growth of children and teenagers, and for maintenance and making good the wear and tear of the body tissues in adults.
- An adult needs about 1 gm of protein per kg of body weight.
- Fats: They are esters of long chain fatty acids and an alcohol called glycerol. Fats also contain atoms of carbon, hydrogen and oxygen.
- The main function of fats in the body is to provide a steady source of energy and for this purpose, they are deposited within the body.
- One gm of fat gives 37 kilojoules of energy which is more than double of that given by carbohydrates.
- Fats, the richest source of energy to our body, can be stored in the body for subsequent use. Fats, soluble in organic solvents and insoluble in water, also supply fatsoluble vitamins to our body.
- Minerals: Some of the important minerals needed by our body are — iron, iodine, calcium, phosphorus, sodium, potassium, zinc, copper, magnesium, chloride, fluoride and sulphur.
- We get most of the minerals in combined form from plant sources. Deficiency of these minerals causes many diseases.
- Energy Requirements: The energy requirement of a body varies according to age, sex, lifestyle, occupation, climate and special situations like pregnancy and lactation.

Age Energy requirements

5 years 6000 kJ per day
11 years 9000 kJ per day
18 years 11000 kJ per day
Adult (normal work) 9600 kJ per day
Adult (heavy work) 12000 kJ per day
Adult (very heavy work) 16000 kJ per day

- Vitamins: They act as catalysts in certain chemical reactions of metabolism in our body.
- They don't provide energy to our body nor form body tissues.
- More than 15 types of vitamins are known and only 2 vitamins — D and K can be formed in our body.

Vitamin - Necessity - Source
Vitamin A For maintaining healthy eyesight, Cod liver oil, fish, eggs, milk, normal skin and hair carrot, leafy vegetables.
Vitamin B1 For growth, carbohydrate metabolism, Milk, soya-food, meat, whole functioning of heart, nerves and muscles. cereals, green vegetables.
Vitamin C For keeping teeth, gums and joints healthy, for Citrus fruits, guava, tomatoes. increasing resistance of body to infection
Vitamin D For normal growth of bones and teeth Milk, eggs, butter, cod liver oil, sun light.
Vitamin E For normal reproduction, functioning of Green leafy vegetables, milk, muscles and protection of liver butter, tomato.
Vitamin K For normal clotting of blood and normal functioning of liver Green leafy vegetables, soyabean, tomato.

- Roughage: Though it does not provide any energy to the body, yet keeps the digestive system in order, by helping in retaining water in the body and preserving constitution.
- The main source of roughage are salads, cabbage, corn cob, porridge, vegetables and fruits with stems.

CELL THEORY
- Cell is the basic unit of structure of all living organisms. According to the cell theory, all organism are composed of cells and cell products and growth and development results from the division and differentiation of cells.
- Cells membrane surrounds all living cells.
- Nucleus is the most important cell organelle which controls and coordinates all cell activities and also concerned with the transmission of heredity characters.
- Mitochondria, ribosomes, lysosomes and dictyosomes are present in plant and animal cells.
- Only plant cells have cell wall, chloroplast and vacuole.
- Viruses constitute a difficulty since in many ways they are intermediate between living and dead matter.
- The cell is said to be made up of a substance called Protoplasm which has two main constituents cytoplasm and nucleus, and is bounded by a cell membrane on outside.
- Cells take up the raw materials for metabolism through the cell membrane from extracellular fluid surrounding them.
- Cytoplasm inside is responsible for maintaining the internal distribution of organelles and also for free cell movements.
- Mitochondria inside provides energy for reactions inside the cell. Ribosomes are responsible for the synthesis of proteins.
- The Endoplasmic Reticulum helps in addition of other sugar units to proteins and their transportation to other parts of the cell.

DISEASES
COMMUNICABLE DISEASES
- They are the diseases which can be transmitted from reservoirs of infection or infected person to the healthy but susceptible persons.
- The disease causing agent or the pathogen can be transmitted directly or indirectly.

DEFICIENCY DISEASES
- These occur due to deficiency of some nutrients in the diet or some hormone due to hypo activity or damage to endocrine glands.

Diet - Deficiency Disease
Protein Kwashiorkor
Protein-energy Marasmus malnutrition
Vitamin A Night-blindness, Xerophthalmia
Vitamin B1 Beri-Beri
Vitamin B2 Cheilosis
Vitamin B5 Pellagra
Vitamin C Scurvy
Vitamin D Rickets (in children), (in adult) Osteomalacia
Vitamin K Hypothrombinemia
Iron Anaemia
Iodine Goitre
Fluoride Dental caries 
Calcium and Affects formation phosphorus of bones and teeth

Hormone Deficiency - Disease
Insulin Diabetes
Thyroxine Cretinism (child), Goitre
STH Dwarfism, Gigantism

ALLERGIC DISEASE
- In these diseases, body becomes hypersensitive to some foreign agents, allergens, which cause inflammation when come in contact with the body or enter inside the body.
- Foreign agents can be dust, pollens, certain-foods, serum, certain drugs or fabrics.
- The unfavourable response of the body to allergens is called allergic reaction. Asthma and hay fever are allergic diseases.

BACTERIAL DISEASES
- Bacteria are minute organisms which are known to cause a number of diseases:
 

Disease - Incubation period - Spread through

Tuberculosis 2-10 weeks Air-borne,droplet infection
Diptheria 2-6 days Air-borne droplet infection
Cholera 6 hours to Contaminated food and 2-3 days water. House flies are the vectors
Leprosy Upto 5 years Prolonged and intimate contact
Whopping 7-14 days Droplet infection cough
Tetanus 3-21 days Entry of cysts through any wound made by sharp object, dog bite or fall on the road
Typhoid 1-3 weeks Directed and Contact
Plague 2-6 days Rats and bed-bugs transmit the germs
Pneumonia 1-3 days Air-borne

VIRAL DISEASES
Disease  - Incubation - Spread period through
Chicken-pox 12-20 days Direct contact with infected persons or infected objects
Smallpox 12 days Droplet infection
Poliomyalitis 7-14 days Direct and oral
Measles 10 days Droplet infection
Mumps 12-26 days Droplet infection
Rabies 1-3 months Bite of rabied animal like dogs, monkeys, cats
Influenza 24-28 hours Air-borne

DISEASES CAUSED BY PROTOZOA
- Amoebiasis (Amoebic dysentery), Malaria, Kala-azar, Trypanosomiasis and Giardiasis are main diseases caused by Protozoans.
- Malaria is a parasitic infection.

SYSTEM OF HUMAN BODY

DIGESTIVE SYSTEM
- The digestive system consists of alimentary canal and digestive glands. Alimentary canal is about 8-10 meters long tube of varying diameter. Food is taken in through mouth.
- The tongue helps in ingestion, chewing, tasting and swallowing of food and mixing of food and saliva.
- Salivary glands secret saliva which helps in digestion of starch. Gastric glands present in the mucosa of the stomach, provide acidic medium for the food digestion.
- Liver, the largest sized, reddish brown gland of body, secrets bile. Liver is present in the right upper part of the abdomen. The bile secreted by the liver is stored in gall bladder. It helps in the emulsification and digestion of fats.
- Pancreas is the second largest gland in human body and secretes pancreatic juices. Intestine also secret juices.

RESPIRATORY SYSTEM
- Oxygen is needed for the oxidation and expelling of carbon dioxide is necessary to avoid its-accumulation.
This process of exchange of gases between the environment and the body, is called respiration.
- In some unicellular organisms like aerobic bacteria, amoeba, hydra, etc. there is direct exchange of gases between the carbon dioxide of the body and oxygen of water.
- There is no blood for transport of gases. However, in larger and complex form of animals, specialised respiratory organs are developed.
- Amphibians respire through skin, fishes through gills and mammals, birds and reptiles through lungs.
- A normal adult inspires or expires about 500 ml of gas with each breath and about 72 breathes per minutes.

CIRCULATORY SYSTEM
- Main components of the circulatory system are heart, blood vessels and blood.
- Heart is a thick, muscular, contractile and automatic pumping organ. In birds and mammals, heart is divided into four chambers.
- Arteries are thick walled blood vessels which always carry the blood away from the heart to various body parts.
- Veins are thin walled blood vessels which always carry the blood from various parts generally to the heart.
- In an adult healthy person, the normal rate of heart beat at rest is about 70-72 times per minute.

BLOOD
- It is red, opaque, somewhat sticky and viscous fluid in the body of animals.
- It is slightly alkaline (pH = 7.4), heavier than water (sp gr = 1.05) and five times more viscous than distilled water.
- Blood forms 6 to 10% of the body weight.
- An adult, on average, has about 6.8 litres of blood.
- Blood contains plasma and blood corpuscles with the former occupying 55-60% of the volume.
- Plasma transports food components, metabolic wastes and hormones; keeps constant level of pH of blood, maintains body temperature and helps in blood clotting.
- Erythrocytes or red blood corpuscles (RBCs), leukocytes or white blood corpuscles (WBCs) and blood platelets are other parts of the blood.
- Due to the presence of iron containing pigm ent haemoglobin, RBCs are red in colour. The RBCs are crucial for ex-change of oxygen and carbon dioxide. WBCs are nucleated and non-pigmented cells. They are larger in size than RBCs but far less in number (1 : 600).
- WBCs play an important role in immune system of the body. Blood platelets cause the coagulation of blood and clot formation to prevent excessive bleeding.
- Human blood is divided into four main Groups—A, B, A. and O.
- The plasma of Group A blood contains an anti-B factor and vice-versa, so that people of Groups A and B cannot accept each other's blood.
- Group AB contains neither anti-A nor anti-B factor and people with this group can receive transfusions from both but can give to neither.
- Group O contains both anti-A and anti-B and can receive blood only from Group O but can donate blood to all Groups. Group O is called universal donor because they can donate to all the Groups.
- Group AB is called universal acceptor because they can accept blood from all Groups.

SKELETON SYSTEM
- The frame or the hard structure of the human body is composed from the bones and the organs of making such frame are called skeleton system.

Bones
- Bone is the hardest tissue of the body and form the largest section of the body weight.
- Bones contain organic as well as inorganic matters. With advancing age, the inorganic matter's share increases, causing the bones to become more brittle.
- Long bones such as humerus and femur are hollow while small bones are solid.

EXCRETORY SYSTEM
- In men, excretory system is formed of one pair of kidneys, one pair of ureters, a urinary bladder and a urethra. Kidney is about 10 cm long, bean shaped, dark-red and slightly flattened structure.
- Sweet glands, oil glands, lungs and liver also act as additional excretory organ.
- In case of kidney failure, a man can treated by hemodialysis or transplantation of a kidney from a donor's body.

NERVOUS SYSTEM
- The system which controls and coordinates the body functions, retains memory and receives and sends signals, is called the nervous system.
- The nervous system comprises brain, spinal cord, nerves and nerve fibres.
- Human brain weighs about 1200 to 1400 gm. Main parts of the brain are cerebrum, cerebellum and medulla oblongata.
- Cerebrum controls voluntary function and is site of intelligence, will power, emotions, etc.
- Cerebellum controls involuntary functions like heart beat, respiration, etc.
- Spinal cord is about 45 cm long and about 35 gm in weight. It conducts impulses to and from the brain and controls reflex actions of the body.
- Various cranial (arising from ending into brain) and spinal nerves (arising from spinal cord) control smell, vision, movements of body parts, taste and hearing.

REPRODUCTION SYSTEM
- In this type of reproduction, there is formation and fusion of sex cells, called gametes.
- Organism develops from the zygote through embryo formation.
- It generally involves two parents — male and female.
- The offsprings are different from the parent as variations appear due to new combinations of genes. So, it plays an important role in evolution.
- All higher plants and animals reproduce sexually.

CHROMOSOMES
- Plants and animals have fixed number of chromosomes per cell.
- Genes are located on chromosomes and are responsible for transfer of characteristics from one cell to the next either in the same organism or from parents to offspring.
- Man has 23 pairs of chromosomes, of which one pair is sex chromosomes.
- Males child inherits X chromosomes from the female parent and Y from the male parent.
- Female child receives a X chromosome each from either of its parents.
- Mendel was the first scientist to explain transmission of units from reproductive cells of the parents to the offsprings.

CLONING
- It is the process of producing genetically identical copies of a biological material, starting from a single cell. The original genes are transplanted and thus one can produce organisms of known and desirable characteristics.

GENETIC ENGINEERING
- It is the method of artificial synthesis of new genes and their subsequent transplantation or methods of correcting the defective genes.
- It has helped in producing plants and animals with specific characters.
- So, crippling hereditary diseases can also be cured like hemophilia etc.

DNA FINGERPRINTING
- It consists of examining repetitive DNA in the genome for variations in the length of restriction fragments.
- Every individual has his own pattern, so that fingerprinting can match blood to a particular person, and patterns are inherited from parent to child, allowing the method to identify relationships between individuals.

IN-VITRO FERTILIZATION
- When a sperm and an egg are made to fertilize outside a living body (usually a test tube), it is called in-vitro fertilization.
- This process has been used to impregnate several females who could not do so through natural means.

Diseases and the Parts of Body they Affect

AIDS—Immune system of body
Arthritis—Inflammation of joints
Asthma—Lungs
Cataract—Eyes
Conjunctivitis—Eyes
Diabetes—Pancreas
Diphtheria—Throat
Glaucoma—Eyes
Eczema—Skin
Goitre—Front of the neck (due to enlargement of thyroid gland)
Gout—Joints of bone
Jaundice—Liver
Meningitis—Brain or spinal cord
Pleurisy—Pleura (inflammation of)
Polio—motor neurons
Pneumonia—Lungs
Pyorrhoea—Sockets of teeth
Tuberculosis—Lungs
Typhoid—Intestine
Malaria—Spleen
Leukaemia—Blood
Rickets—Bones