SPM Biology 2016


8 . (a) Diagram 8 shows the transport system of plant. Based on the diagram, describe the mechanism of water transport from the soil to the leaves.

Rajah 8 menunjukkan system pengangkutan bagi tumbuhan. Berdasarkan rajah, huraikan mekanisme pengangkutan air dari tanah ke daun.

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(b) Cardiovascular disease is one of the main causes of death in our country. The following are the factors that can lead to the disease:

Penyakit kardiovaskular adalah satu daripada penyebab utama kematian dalam negara kita. Berikut adalah factor-faktor yang boleh menyebabkan penyakit itu:

  • Smoking


  • Unbalanced diet

Diet yang tidak seimbang

  • Unhealthy lifestyle

Gaya hidup yang tidak sihat

Explain the factors given which contribution to the cardiovascular disease.

Terangkan factor-faktor yang diberi yang menyumbang kepada penyakit kardiovascular.

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Answer ( 1 )


    8. a) -Water is transported from roots up to the shoots and leaves.

    -Root hair cell sap is hypertonic to soil water, water diffuses into root hair cells via osmosis.

    -Now in the cortex, it will have a higher osmotic pressure than the root hair cells. water then enters the cortex cells via osmosis.

    -The adjacent cortex cells would be hypertonic in concentration. Thus, water moves into adjacent cortex cells and eventually into the xylem tissue.

    -There is a water concentration gradient across the cortex, creating a pushing force causing water to enter the xylem tissue.

    -There is also active secretion of ions from the soil into the xylem tissue, resulting in an increase in osmotic pressure.

    -Root pressure is created as water now enters the xylem.

    -Upward pull of water through xylem vessels due to root pressure.

    -In the stem, water is transported up the plant with the help of capillary action and then up to the leaves by transpirational pull.

    -The adhesive and coadhesive properties of water molecules also help with the continuous transportation of water up the stem through the xylem tissue.


    b)  Smoking

    -Cigarette smoke contains nicotine and tar.

    -Nicotine acts as a stimulant which causes heart rate to increase.

    -Nicotine also causes blood vessels to constrict.

    -To overcome the small lumen of blood vessels, the heart pumps harder causing blood pressure to increase.

    -Tar causes blood to become sticky and this increases the chances of a clot occurring.  A clot can lead to heart attacks as blood flow is blocked.

    Unbalanced diet

    -Diet rich in fats and high in cholesterol may lead to cardiovascular diseases.

    -Cholesterol deposits within arteries as plaques (atherosclerosis).

    -Narrowing of the lumen of blood vessels increases the risk of high blood pressure as the heart has to pump with a larger force to get oxygenated blood all around the body and overcome the reduction in blood flow. High blood pressure may cause arteries to burst.

    -If not enough blood gets to the heart, this could lead to angina pectoris or a myocardial infarction. 

    -High sodium intake may lead to high blood pressure.

    Unhealthy lifestyle

    -Sedentary lifestyle and minimal amount of exercise results in slow blood circulation.

    -Higher risk of getting a heart attack.

    -Excessive consumption of alcohol may cause an increase in blood pressure.

    -Heavy drinking may lead to heart diseases like heart failure.

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