G Transport Plants 1. The following diagram is of a section through a leaf.

(pic) (a) Identify cells A to D.

(b) Describe the methods by which water moves from structure B through D. [4] ! " #

2. (a) Explain how water enters a plant root from the soil and travels through to the endodermis. [4] $ %

(b) From the root, water is transported upwards through the stem. Explain how evaporation from the leaves can cause the water to move upwards. [2] &'

(c) State four structural features of the xylem vessel that are related to water transport. [4]

(d) In daylight, most of the water evaporates from the leaves but some is used by the plant. Describe the ways in which this water could be used by the plant. [2]

3. The diagram shows the pathway taken by water passing through a plant.

(a) Name (i) the process by which water enters root hairs from the soil. [1] (ii) the pathway through the cell walls of the root cortex. [1]

(b) All water passes through the endodermis by the same pathway. Explain what causes this. [2] ( )

(c) Describe and explain how water moves through the trunk of a tree to the leaves. [3] '

4. (table) (a) The table shows the transpiration rate of a group of plants exposed to different humidities at a

temperature of 25C. Describe and explain the relationship between humidity and transpiration rate. [3]

The diagrams show a section through a typical leaf and a section through a leaf from a xerophytic plant. The xerophytic leaf has a lower transpiration rate than the typical leaf.

(pic)

(b) Describe two features shown in the diagram of the xerophytic leaf which reduce transpiration rate. Explain how each of these features contributes to a lower transpiration rate. [4] ' ' *

5. Translocation involves the accumulation of sucrose in phloem sieve tube elements. Explain, in terms of water potential, how an increase in concentration of sucrose in phloem sieve tube elements causes (a) water to enter. [2]

(b) translocation to occur. [2] '

6. The diagram shows some cells from phloem tissue. (pic) (a) Name the main carbohydrate transported by phloem tissue. [1]

(b) Describe and explain two ways in which the sieve tubes are adapted for their

transport function. [4]

(c) (i) Carbohydrate enters the sieve tubes in the leaves. What effect does the entry of the carbohydrate have on the water potential in the sieve tubes? [1] (ii) Explain how this effect may result in mass flow of substances in the phloem. [2]

G Transport Animals 1. (pic) (a) The figure beside this is a simplified plan of the mammalian circulatory system. The

system is described as a closed double circulation. (i) Use the information in the figure to state what is meant by the term closed double circulation. [2] (ii) Suggest an advantage of the closed double circulation shown in the figure. [2] )

2. The figure below shows two blood vessels, X and Y, in transverse section. (pic) (a) State which of the blood vessels, X or Y, is a vein. [1]

+ (b) Give two reasons for your choice. [2]

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(c) Explain briefly how blood in the veins is returned to the heart. [3] ' ,

3. (a) Describe the route taken by a red blood cell from leaving the right ventricle of the heart to entering the left atrium. [2] * - '.,-, '

(b) The drawing shows a red blood cell. (pic) (i) The centre of this cell appears light in colour when seen with an

optical microscope. Explain why. [1] (ii) Draw diagrams in the space below to show the appearance of this cell along Section X-X Section Y-Y

(c) There are no nuclei or other cell organelles in the cytoplasm of red blood cells. Describe one way in which the structure of a red blood cell (i) is similar to the structure of a lymphocyte [1]

(ii) is different from the structure of a prokaryotic cell such as a bacterium. [1] / 0 "

4. Figure 1 shows a molecule of human haemoglobin.

(pic) (a) Explain why the -chains always have the same tertiary structure. [2]

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(b) Give the evidence from the diagram that a human haemoglobin molecule has a quaternary structure. [1] 2

5. The diagram shows some aspects of the exchange of carbon dioxide and oxygen between a red blood cell and muscle tissue.

(pic) (a) Increased muscle activity increases the amount of oxygen released from a red blood cell during

exercise. Using information in the diagram, explain how. [3] ( ( 34 .

(b) The blood in a vein leaving a muscle has a pH only slightly lower than that in the artery entering it. This is partly due to haemoglobin in the red cells acting as a buffer. Explain why the pH in the vein is lower than that in the artery. [2] ( ( 34

6. The diagram shows a human heart seen from the front. (pic) (a) (i) Which one or more of vessels A to D contains oxygenated blood? [1]

(ii) During a cardiac cycle, the pressure of the blood in vessel C is higher than the pressure of the blood in vessel B. Explain what causes this difference in pressure. [1] '

(b) What does the diagram suggest about the pressure in the atria compared to the pressure in the ventricles at the stage in the cardiac cycle represented in the diagram? Explain your answer. [2]

(c) Parts X and Y are involved in coordinating the heart beat. Name X and Y. [2] -" 5 0 -

(d) The wave of electrical activity which coordinates the heart beat is delayed slightly at part X. It then passes along part Y to the base of the ventricles. Explain the importance of (i) the slight delay at part X. [2] (ii) the electrical activity being passed to the base of the ventricles. [2] 6 (7