CBSE Class 12 English Unseen Passage N

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CBSE Class 12 English Unseen Passage N. Students should do unseen passages for class 12 English which will help them to get better marks in English class tests and exams. Unseen passages are really scoring and practicing them on regular basis will be very useful. Refer to the unseen passage below with answers.

Read the passage below:         

Smoking is the major cause of mortality with bronchogenic carcinoma of the lung and is one of the factors causing death due to malignancies of larynx, oral cavity, oesophagus, bladder, kidney, pancreas, stomach and uterine cervix and coronary heart diseases.

Nicotine is the major substance present in the smoke that causes physical dependence. The additives do produce damage to the body- for example; ammonia can result in a 100-fold increase in the ability of nicotine to enter into the smoke.

Levulinic acid, added to cigarettes to mask the harsh taste of the nicotine, can increase the binding of nicotine to brain receptors, which increases the 'kick' of nicotine.

Smoke from the burning end of a cigarette contains over 4000 chemicals and 40 carcinogens. It has long been known that tobacco smoke is carcinogenic or cancer-causing.

The lungs of smokers collect an annual deposit of 1 to 1.5 pounds of the gooey black material. Invisible gas phase of cigarette smoke contains nitrogen, oxygen and toxic gases like carbon monoxide, formaldehyde, acrolein, hydrogen cyanide and nitrogen oxides. These gases are poisonous and in many cases interfere with the body's ability to transport oxygen.

Like many carcinogenic compounds, they can act as tumour promoters or tumour initiators by acting directly on the genetic make-up of cells of the body leading to development of cancer

During smoking within the first 8 - 10 seconds, nicotine is absorbed through the lungs and quickly 'moved' into the bloodstream and circulated throughout the brain. Nicotine can also enter the bloodstream through the mucous membranes that line the mouth (if tobacco is chewed) or nose (if snuff is used) and even through the skin. Our brain is made of billions of nerve cells. They communicate with each other by chemical messengers called neurotransmitters.

Nicotine is one of the most powerful nerve poisons and binds stereo-selectively to nicotinic receptors located in the brain, autonomic ganglia, the medulla, neuro-muscular junctions. Located throughout the brain, they play a critical role in cognitive processes and memory.

The nicotine molecule is shaped like neurotransmitters called acetylcholine which are involved in many functions include muscle movement, breathing, heart-rate, learning and memory. Nicotine, because of the similar structure with acetylcholine when it gets into the brain, attached itself to acetylcholine sites and produces toxic effect.  

In high concentrations, nicotine is more deadly. In fact one drop of purified nicotine on the tongue will kill a person. It has been used as a pesticide for centuries.

Recent research studies suggest that acute nicotine administration would result in increased dopamine release from the brain, producing perceptions of pleasure and happiness, increased energy and motivation, increased alertness, increased feeling of vigour during the early phase of smoking.

However notwithstanding these superficial effects, research shows that the relationship between smoking and memory loss is strongest in people who smoke more than 20 cigarettes each day and this is not specific to the socio-economic status, gender and a range of associated medical conditions. Smoking may speed up age related memory loss and the details are not yet clear. Some studies suggest that repeated exposure to high nicotinic smoke related to the Brain-wiring' is nothing but neuro-biochemistry that deals with complex interaction among genetic experience and bio-chemistry of brain cells.

‘NO' is a unique molecule which plays a role in a number of beneficial and some of the harmful brain and body mechanisms, for example, synapse formation, drug tolerance and local regulation of cerebral blood flow, Parkinson's disease etc. It is also found that people who smoke more cigarettes a day have poorer memories in middle age than non-smokers.

Some experts say that smoking is linked to memory problems because it contributes to narrowed arteries that restrict blood-flow to the brain. One of the causes of memory decline in relation to the brain function could be the nerve cell death or decreased density of interconnected neuronal network due to loss of dendrites, the tiny filaments which connect one nerve cell to another. Abstinence from smoking is essential, not only to avoid this system effect but also to reduce the ill-effects on the environment.

I. Read the passage carefully and choose the most appropriate option from those which are given below: 

1. Which is the major substance that is present in smoke that causes physical dependence:

a) Methanol

b) Nicotine

c) nEthanol

d) Boro 

2.Smoke from burning end of cigarette contains over:

a) 4000 chemicals and 40 carcinogens

b) 400 chemicals and 40 carcinogens

c) 400 chemicals and 4 carcinogens

d) 40 chemicals and 40 carcinogens 

3.In high concentration, nicotine is more:

a) Lively

b) Active

c) Deadly

d) Inactive 

II.(a) Answer the following questions briefly: 

1.Which acid is added to cigarette and why?

2.Does smoking is linked to memory?

3.Smoking is major___________ .

4.Nicotine molecule is shaped like neurotransmitters called____________. 

(b) Fill in the blanks with one word only: 

‘NO' is a unique (a) _____which plays a role in a number of beneficial and some of the (b) _____ brain and body mechanisms, for example, (c) _______, drug tolerance and local regulation of blood flow, Parkinson's disease etc. 

III.Pick out the words from the passage which mean the same as the following: 

a.Poisonous (para 9)

b.Causes sleep (para 11)

Suggested Answers for the above mentioned question:

I.(b) Nicotine

(a) 4000 chemicals and 40 carcinogens

(c) Deadly 

II.(a) 1. Levulinic acid, added to cigarettes to mask the harsh taste of the nicotine, can increase the binding of nicotine to brain receptors, which increases the ‘kick’ of nicotine. 

2.Smoking is linked to memory problems because it contributes to narrowed arteries that restrict blood-flow to the brain.

3.cause of mortality. 


(b) (a) molecule

(b) harmful

(c) synapse formation

(d) cerebral 

III.(a) Toxic

(b) Dopamine

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