F4 Biology 2nd Term WS 07 ans: 8 Transport in humans III

8    Transport in humans III

2^nd Term WS 07

Textbook exercise (P. 28 - 32)

M.C.

1	2	3	4	5	6	7	8	9
D	A	D	B	C	C	D	D	C

Q. 15      

(a)   (i)    (Heart) à B à D à E à C à A                                                                                      1

       (ii)   Blood flows from a high pressure region to a low pressure region.                                      1

(b)   When the ventricle of the heart contracts, blood is forced into the artery B,

       resulting in the increase of blood pressure.                                                                                  1

       Blood in the artery flows forward along the blood vessels while

       the ventricle of the heart relaxes, as a result the blood pressure drops.                                       1

(c)   White blood cells (lymphocyte / phagocyte)                                                                                1

       Antibodies                                                                                                                                    1

       (accept other alternatives)

16    (a)    Plasma                                                                                                                                 1

(b)    More proteins / glucose / amino acids / fatty acids / oxygen /

        Higher pressure /

        Less urea / carbon dioxide                                                                                                          1

(c)    (i)     The left ventricle contracts.                                                                                                 1

        (ii)    Loss of fluid / volume /

                 Friction / resistance of capillary wall                                                                                  1

(d)   The water potential in the capillary is not as low / is higher / less negative.

        / The water potential gradient is reduced.                                                                                   1

        More tissue fluid is formed at the arteriole end.                                                                         1

        Less is absorbed into the capillary by osmosis.                                                                           1

Q.17

Arteries carry blood leaving the heart.                                                                                                1

They have thick walls to withstand the high pressure.                                                                       1

Capillaries are the site of material exchange.                                                                                      1

Capillaries have a single layer of cells so diffusion distance is short.                                                 1

Veins return blood to the heart.                                                                                                          1

Veins have larger lumen to reduce resistance to flow.                                                                        1

Veins do not support high pressure.                                                                                                    1

Veins have valves to avoid backflow of blood.                                                                                  1

P. 37 Reading to learn

1      Due to the blocking of the lymph vessels, tissue fluid in the legs cannot return to the blood circulation.    1

        On the other hand, tissue fluid forms continuously.                                                            1

        Tissue fluid accumulates in the legs and leads to swelling.                                                 1

2      Kill mosquitoes using pesticides. / Wear long-sleeved clothes to avoid mosquito bites. / Use insect repellant. (any 2 or other reasonable answers)                                                             1 x 2