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Innate immunity is defined as the resistance to infections that an individual possesses due to his or her genetic make-up and thus it is inborn defence mechanism present naturally in the body.

Correct answer is (c) T-lymphocytes

Following are the unique features of acquired immunity:

1. Specificity : Production of specific antibody or T-lymphocyte against a particular antigen/ pathogen is called specificity. 

2. Diversity : Ability to recognize vast variety of diverse pathogens or foreign molecules by immunity is called diversity. 

3. Discrimination between self and nonself : Acquired immunity can differentiate between own body cells (self) and foreign (non-self) molecules. 

4. Memory : The first immune response upon encounter of a specific foreign agent and its elimination is retained as a memory. This results in quicker and stronger immune response when the same pathogen is encountered again.

1. Skin and mucous covering, when intact protects the body against the invasion by pathogens. The healthy skin has bactericidal activity due to the salts present in drying sweat. 

2. Sebaceous glands in the skin produce secretions and long chain of fatty acids. These are bactericidal and fungicidal. 

3. Respiratory tract is provided with mucosa which prevents entry of microorganisms to a large extent. 

4. The inhaled particles are arrested through hair in the nasal passage. The particles that pass beyond nasal passage are caught by mucus lining the epithelium. They are swept back to pharynx. Then they are either swallowed or coughed out. 

5. The cough reflex is an important defence mechanism of respiratory tract. 

6. There is saliva in the mouth which has inhibitory effect on microorganisms. Gastric secretions has acidity and hence microorganisms are destroyed in stomach. 

7. The flushing action of urine eliminates bacteria from the urethra. Semen too has antibacterial substances, e.g. Spermine and zinc.

1. Phagocytic cells ingest and destroy the pathogens. 

2. This is natural defence against the invasion of pathogenic microorganisms and other foreign particles in blood and tissues. 

3. Phagocytic cells are of two types, viz. microphages and macrophages. They can remove foreign particles that enter the body. 

4. Natural killer (NK) cells is a class of lymphocytes which carry out important and non-specific defence against viral infections and tumours.

I. Cancer : Cancer is a disease caused by uncontrolled cell division due to disturbed cell cycle.

II. Difference between benign tumour and malignant tumour:

III. The main five types of cancer:

Types of Cancer : According to the tissue affected, the cancers are classified into five main types. These are as follows:

1. Carcinoma : Cancer of epithelial tissue covering or lining the body organs is known as carcinoma. E.g. breast cancer, lung cancer, cancer of stomach, skin cancer, etc. 

2. Sarcoma : Cancer of connective tissue is called sarcoma. Following are the types of sarcoma osteosarcoma (bone cancer), myosarcoma (muscle cancer), chondrosarcoma (cancer of cartilage) and liposarcoma (cancer of adipose tissue). 

3. Lymphoma : Cancer of lymphatic tissue is called lymphoma. Lymphatic nodes, spleen and tissues of immune system are affected due to lymphoma. 

4. Leukaemia : Leukaemia is blood cancer. In this condition, excessive formation of leucocytes take place in the bone marrow. There are millions of abnormal immature leucocytes which cannot fight infections. Monocytic leukaemia,lymphoblastic leukaemia, etc. are the types of leukaemia. 

5. Adenocarcinoma : Cancer of glandular tissues such as thyroid, pituitary, adrenal, etc. is called adenocarcinoma.

There are two basic types of immunity, viz. innate immunity and acquired immunity.

(A) Innate immunity:

1. Innate immunity is natural, inborn immunity, which helps the body to fight against the invasion of microorganisms. 

2. Innate immunity is non-specific because it does not depend on previous exposure to foreign substances.

3. Innate immunity mechanisms consist of various types of barriers such as anatomical barriers, physiological barriers, phagocytic barriers and inflammatory barriers. They prevent entry of foreign agents into the body.

(B) Acquired immunity:

1. The immunity that an individual acquires during his life is called acquired immunity or adaptive immunity or specific immunity. It helps the body to adapt by fighting against specific antigens hence it is called adaptive immunity. Since it is produced specifically against an antigen, it is called specific immunity. 

2. Acquired immunity takes long time for its activation. 

3. This type of immunity is seen only in vertebrates.

4. Due to acquired immunity, the body is able to defend against any invading foreign agent.

I. Taking drugs or alcohol:

1. Youngsters are at the vulnerable age, where they lack the planning about their future.

2. If they fall into bad company or are facing parental neglect, they get hooked on to alcohol or drugs. 

3. Some common causes for addiction among youngsters are insufficient parental supervision and monitoring or excessive pressure and expectations from them. Lack of communication between an adolescent and parents. 

4. Poorly defined rules for the family. Continuous family conflicts. 

5. Favourable parental attitudes towards alcohol and drug uses. Many a times, at home children are exposed to such habits. 

6. Inability to cope up with present and hence switching to the addictions. Risk taking behaviour which is common among youngsters.

II. Methods/measures to avoid drug abuse:

1. There should be complete acceptance for the child, because the adolescent phase is the most crucial phase when the children should be treated with love, care and respect. 

2. Many physical, hormonal and psychological transformations are taking place in this phase. Therefore child suffers from stressful situation. 

3. Wrong company and bad influence of peer group can trap the child in bad addictive habits. Thus, family should be supportive and communicative to help such children. 

4. The sexual thoughts should be sublimed by channelizing energy into healthy pursuits like sports, reading, music, yoga and other extracurricular activities. 

5. Ill-effects of drugs or alcohol should be told to youngsters. 

6. Education and counselling can control the children from getting hooked on to the addictions.

Taplow feels if his grades are good, he would opt for science. He feels science is more interesting than the study of classics.

Taplow had been asked to do some extra work by Mr Crocker-Harris. He was waiting for the master In the school. Frank also caine there and met Taplow.

Mr Harris is a teacher who would not compromise on the rules and regulations to suffice the sentiments of students. He believes in fair assessment of his students and is not swayed by emotions, as the man is hardly human. He is not a sadist, but strict in performance of his duties. Even on his last day at school, when he is over busy in own affairs he does not neglect his duty towards students.

Frank encourages Taplow to comment on Mr Crocker-Harris by cleverly asking Taplow several questions. He appreciated Taplow’s imitation of Mr Crocker-Harris and also asks him to repeat it.

Crocker-Harris is Taplow’s teacher. According to Taplow and me also; Mr Crocker- Harris is a strict disciplinarian. He was a hardworking teacher and fully devoted to his duty as he called Taplow even on the last day of school to make up for his missed class. No student in his entire career has a courage to ‘cut’ Mr Crocker-Harris.

He is neither partial nor biased; he will give Taplow whatever he deserves. He tries to maintain an appropriate distance from his students. He never responds the feelings shown by his students and remains shrivel. He is a man of principals and keeps the rules of the school. His students like him even after his strict behaviour. His colleagues, even Frank, envy him for the effect he has on the students. He is strict but not a sadist that he seems to be.

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During their manufacture, vaccines are rigorously tested. Many rounds of study, examination and research are carried out before they are used for general public. Extensive research and evidences are gathered to check their safety. Sometimes, some vaccines produce side effects but these are rare and mild. Hence vaccines are considered to be safe.

Correct answer is (a) cadmium oxide

1. Alcohol in any form is toxic for the body. Hence as soon as alcohol is consumed, the liver tries to detoxify it. 

2. In low doses it acts as a stimulant but in high dose, it acts on central nervous system, especially the cerebrum and cerebellum. Still higher dose can induce a comatose condition. 

3. Alcohol affect the gastrointestinal tract by causing inflammation and damage to gastric 

4 mucosa. Ulceration and painful condition arises in alcoholics. 4. Excessive doses of alcohol induce vomiting.

5. The worst effect of alcohol is on liver causing diseases like cirrhosis. 

6. Alcohol induces hypertension and cardiac problems. 

7. Apart from physical effect, it causes deterioration of mental health and emotional well-being. 

8. Alcoholic person cannot think due to numbness in his/her cerebrum. 

9. The social health is greatly affected as the alcoholic can cause problems to his family, friends and society in general.

Marijuana, Ganja, Hashish and Charas.

Correct answer is (d) incubation period

Correct answer is (b) State of complete physical, mental and social well-being

1. Opioids:

• Opioids bind to specific opioid receptors present in the central nervous system and in gastrointestinal tract. 
• They are depressants and slow down the body functions.

2. Cannabinoids:

• Cannabinoids interact with receptors in the brain. 
• They affect cardiovascular system of the body.

3. Morphine:

• Morphine is an effective sedative and pain killer when used for medicinal purpose. 
• When abused it affects physical, physiological and psychological functions.

1. Opioids bind to specific opioid receptors which are present in central nervous system and gastrointestinal tract. Some opioids e.g. heroin act like depressants and slow down all the body functions. 

2. Cannabinoids have the capacity to interact with receptors present in the brain. Inhalation or ingestion of cannabinoids such as marijuana, hashish, charas and ganja have adverse effect on cardiovascular system. 

3. Cannabinoid like LSD causes hallucinations. 

4. All these substances are addictive and hence cause adverse effects on the body and health.

1. Balanced diet 

2. Personal hygiene 

3. Regular exercise 

4. Right attitude of mind 

5. Good habits.

c. health is a state of complete physical, mental and social well-being

Correct option is (b) Oparin and Haldane

Assumptions of theory of chemical evolution are: 

1. The Earth’s surface and atmosphere during the first billion years of its existence, were radically different from those of to days conditions. 

2. The primitive earth’s atmosphere did not have oxygen. 

3. The first life arose from a series of chemical reactions. 

4. Solar radiation, ultra violet rays and lightning, must have been the chief sources of energy for these chemical reactions.

Theory of chemical evolution was proposed by oparin and Handane independently.

The famous swan necked flask experiment was conducted by Louis Pasteur.

(d) Lower jaw bone

1. As water in a river flows down a slope, it plucks sediment from the land. Other streams join it forming a broad river basin. 

2. The water carries soil, sand and sediments down stream. 

3. As the river reaches flatter ground, it slows down and drops the sediments there. This is called deposition. 

4. The sediments build up a flood plain. 

5. At the river’s mouth, the water loses its force, drops all its sediments and thus deltas are formed. 

6. Flood plains and deltas make fertile farm land. 

7. The sediments deposited in flood plains and deltas are called silt.

8. Silt is rich in nutrients. 

9. Many ancient civilisations flourished in flood plains and deltas. 

Thus the deposition of rivers are useful to man.

There are six major plates on the earth. They are African, North American, South American, Indo Australian, Antarctic, Eurasian and Pacific plates.

The massive base of rocks on which all the continents and even the oceans are actually situated are called plates.

There are four natural realms of the earth.

They are 

1. Lithosphere 

2. Hydrosphere 

3. Atmosphere and 

4. Biosphere.

• Landforms continuously keep on changing due to denudation activities. 
• But these changes occur very slowly. 
• The structure of mountains, plateaus and plains keep on changing through process known as ‘erosion cycle’ or ‘geomorphic cycle’.

• Trees, plants and grass constitute vegetation. 
• Vegetation contribute to the weathering of rocks by driving roots into fine cracks or holes in the rocks.
• They also enable water and moisture to enter into rocks which further enable weathering. 
• On the other hand plant or grass cover on soils prevent easy denudation or transportation of soil by wind or water.

• Lithosphere is the solid crust or the hard top part of the earth. 
• When it heats due to sunrays or cools down, it influences air and water too. 
• We and most other living beings live on this realm. 
• We use the rocks and soils and other things found in this hard crust in many ways.

• When volcano erupts, the molten material (also accompanied by steam, smoke and various gases) comes out from the depths of the earth.
• The molten materials cool on the earth and form hard rocks called “Igneous rocks”.

There are two kinds of changes taking place in the lithosphere. 

They are : 

a. The slow movement 

b. The sudden movement. 

3) The slow movement leads to the formation of the crust. 

4) The sudden movements (eruption of volcanoes and earthquakes) can be destructive and cause much damage.

• The region where the two plates meet and push each other, a lot of pressure is exerted. 
• One plate is pushed under into the mantle while the other plate is pushed up, to form a chain of mountains. 
• This movement of plates is called ‘Plate tectonics’.

The Barren islands, and Narcondam are volcanoes situated in India.

“Atmosphere” is derived from two greek words “atmos” means vapour and “sphaira” means sphere or ball.