plz!! asnswer this questions.....

[darknight_007]

DETAILED ANSWE... PLZZ!!!! HELP... :ugeek:

1) xplain wy smokin izz no longer regarded as
i) advisable 4 maintainance of gud health [8]
ii) socially acceptable [2] (M/J/07)

2) describe the played by artifical selection in the production of a named economically important plant or animal. [6] (O/N/06)

 

[Zohaib Sherazi]

i)Cigarette smoke contains harmful chemicals such as tar, nicotine, carbon monoxide, irritant particles, and other carcinogens like acroline.

Nicotine makes the blood platelets sticky and increases the probability of a blood clot occurring. If this takes place in the coronary artery heart failure can occur as oxygen supply to the heart is cut off. Moreover, nicotine mimics a natural neuorotransmitter that causes vasoconstriction of the areteries during cold weather. This results in narrowing of the arteries even in normal conditions hence making the blood pressure, heart rate increase.

Tar can cause uncontrolled mitosis in the lungs which can spread to other parts of the body as well. Irritant particles stimulate the goblet cells to secret excess mucus and paralyze cilia on the other hand. The breathing pathway is blocked and a person has to breath deeper and harder. This can destroy the alveoli and reduce the surface area for the absorption of oxygen.

ii)Smoking is no longer socially acceptable as it also causes a negative externality apart from harming the smoker which is "passive smoking". As those who do not want to smoke also get affected by the chemicals prevailing within cigarette smoke, therefore, smoking is 'no longer' socially acceptable.

2- Artificial selection involves human selection of the best traits of organisms and then their breeding. For example a plant that gives a high yield of a crop can be interbred with a wild variety of the same plant that although is not high yielding but is pest resistant. Over the passage of time the useful alleles are passed on into the plant therefore increasing the allele frequency and resulting in a new species that possesses both the useful traits of being high yielding and pest resistance.

As the selection pressure applied was human induced and not natural therefore this is an example of 'artificial' selection.

 

[hassam]

gr8 anser .
CO can combine with oxygen to form carboxyhaemoglobin which is a quite stable compound.hence when haemoglobin molecules are occupied, oxygen can no longer bind and thus the oxygen carrying capaacity of blood is reduced.so in severe case this can lead to anaemia (breathlessness)

 

[hassam]

zohaib bhai question
suggest why an injury that cuts open an artery is more dangerous than an injury to vein?[2]

 

[book worm]

Good one Zohaib Brother..

Just wanted to add that in the second part regarding the smoking being socially unacceptable, you can also mention

1) The cigarette smoke contains CO,CO2 and other pollutants which can lead to environmental problems such as air pollution,global warming etc.
2) Smoking during pregnancy is harmful for the fetus and the baby and a mother has no right to bring harm to the baby therefore, it is unacceptable.

Hassam: An injury to artery will result in more blood loss than the vein because blood flows at higher pressure in artery. Moreover the repair of artery will also take more time as compared to vein because it has thick muscular walls.

 

[Zohaib Sherazi]

^Correct.