Long-distance transport in mammals and plants requires a transport system and a transport medium. The double circulatory system of mammals, which is summarised in Figure 5.1, includes the heart and blood vessels.

Figure 5.1, a schematic double circulatory system diagram: boxes for the head and upper limbs, the lungs, the kidneys, the liver, the intestines and the lower limbs are linked by paired vessel loops to a four-chambered heart drawn as a central box, its two atria above two ventricles separated by a dashed valve line either side of a central septum. Ten points are labelled: A, B and C sit on the vessel loop between the heart and the lungs and head, with C at the point where that loop crosses beneath the lungs; K sits further round the same outer loop on the left, between the lungs and the kidneys/liver/intestines/lower limbs; H and G label the left-hand heart chambers, H at the atrium (valve) level and G below it at the ventricle level; D and E label the corresponding right-hand chambers; J labels the vessel entering the heart box beside H; F labels the vessel between the liver and the intestines.

Select the letter, or letters, from Figure 5.1 that match each description below. Where more than one letter is correct, select all of them.

The chamber of the heart that receives blood from the vena cava.

The chamber of the heart that pumps blood directly into the pulmonary artery.

An artery with a large quantity of elastic fibres and proportionately very little smooth muscle in the tunica media.

A vein transporting oxygenated blood.

5(b)(i)Water Inorganic IonsMedium2 marks

Water is the main component of the transport medium in mammals and in plants. Describe how a high specific heat capacity makes water suitable as the main component of blood.

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5(b)(ii)Plant Structure TransportMedium3 marks

Explain the importance of water in the mass flow of substances in phloem sap.

Answer

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