Biology 0610/41 October/November 2020: question paper and mark scheme

Question

Water is an essential molecule for life. (a) Complete the statements. Water moves into and out of cells by …… . Water is known as a …… because it can dissolve solutes. [2] (b) A leaf cell was put into a solution. The water potential of the solution was lower than the water potential of the contents of the cell. Fig. 1.1 is a sketch of the cell after three hours in the solution. nucleus Fig. 1.1 The leaf cell was transferred into pure water. Sketch the expected appearance of the cell after it had been in the pure water for three hours. Draw one arrow on your sketch to show the direction of water movement. [3] (c) A plant was not watered for one week. Fig. 1.2 shows a series of photographs of the plant during the week. day 0 day 3 day 7 Fig. 1.2 Explain how the lack of water has affected the support of the leaves of the plant shown in Fig. 1.2. Use the term turgor pressure in your answer. …… [3] [Total: 8]

Question

Pathogens cause disease. (a) Fig. 2.1 shows some cells that are part of the human immune system. These cells are responding to one type of pathogen. Q R T S Fig. 2.1 Explain how the immune system responds to an invasion of pathogens. Use the letters in Fig. 2.1 in your answer. …… [6] (b) A vaccine was introduced in 1942 for a particular disease. Fig. 2.2 shows the effect of introducing the vaccine on the number of cases of the disease in one country. 250 vaccine introduced 200 150 number of cases of disease per million people 100 50 0 1920 1930 1940 1950 1960 1970 1980 year Fig. 2.2 In 1946 the government of the country concluded that the vaccine was successful. Discuss the evidence, shown in Fig. 2.2, for and against this conclusion. …… [4] [Total: 10]

Question

All living organisms excrete waste products. (a) Fig. 3.1 is a photomicrograph of Naegleria fowleri, a single-celled protoctist that lives in watery environments. A magnification ×4000 Fig. 3.1 (i) State a feature of N. fowleri, visible in Fig. 3.1, that distinguishes it from prokaryotes. …… [1] (ii) State the name and function of structure A. structure …… function …… [2] (iii) Suggest how N. fowleri excretes carbon dioxide. …… [1] (b) Urea is a toxin that is excreted by the kidneys in humans. Describe how and where in the body urea is formed. …… [3] (c) Fig. 3.2 shows part of the human excretory system and associated blood vessels. The arrows indicate the direction of blood flow. D E F G H not to scale Fig. 3.2 (i) Draw a label line and the letter X on Fig. 3.2 to show the location of the cortex in one of the kidneys. [1] (ii) Table 3.1 contains statements about the labelled structures in Fig. 3.2. Complete the table by: • stating the name of the structure • identifying the letter that labels that structure. Table 3.1 description name of structure letter from Fig. 3.2 organ that stores urine tube that carries urine out of the kidney blood vessel with the lowest concentration of urea blood vessel with the lowest concentration of carbon dioxide tube that carries urine out of the body [5] (d) Doctors wanted to investigate the effect of exercise on the excretion of salts. They collected urine from people before and after running a long distance on a hot day. The results of their investigation are shown in Table 3.2. Table 3.2 before running after running average volume of urine / cm3 1156.0 569.0 average concentration of sodium in 85.6 78.2 urine / mmol per dm3 (i) Suggest why there is a difference in the volume of urine produced before running compared with after running. Use the information in Table 3.2 in your answer. …… [2] (ii) Calculate the percentage decrease in the average sodium concentration after running compared with before running. Give your answer to one significant figure. Space for working. …… % [3] (iii) Describe how the kidney tubules enable the excretion of salts. …… [3] (e) Large plasma proteins are usually prevented from entering the urine. State the name of one protein found in blood plasma. …… [1] [Total: 22]

Question

(a) Fig. 4.1 shows a bee with pollen on its legs. Fig. 4.1 Bees are insects that pollinate some flowering plants. They are attracted to the flowers by their colour, scent and nectar. (i) Describe other ways in which flowers and pollen grains are adapted for insect pollination. …… [3] (ii) State where pollen is produced in a flower. …… [1] (iii) State the name of the process that produces haploid pollen nuclei. …… [1] (iv) Explain why it is important that the pollen nuclei are haploid. …… [1] (b) (i) Describe how the pollen that is carried by an insect to another flower results in the formation of a plant embryo. …… [5] (ii) Describe the advantages of cross-pollination. …… [2] (c) Some people are concerned that genetically modified plants might cross-pollinate with wild varieties of plants. (i) Suggest how farmers could prevent cross-pollination between genetically modified plants and wild varieties of plants. …… [1] (ii) State two advantages of genetically modified crops. 1 …… 2 …… [2] [Total: 16]

Question

Milk is a source of some of the nutrients that are part of a balanced diet. (a) Calcium and protein are two nutrients found in milk. Describe the importance of calcium and protein in the diet. calcium …… protein …… [4] (b) Lactose is found in cows’ milk. Some people do not have the enzyme to digest lactose. State the names of two organs, associated with the alimentary canal, that produce enzymes. 1 …… 2 …… [2] (c) Fig. 5.1 shows a flow diagram for the production of lactose-free milk. Step 1 collect cows’ milk from farm diagram of Step 4 Step 2 heat milk to a high temperature for 15 seconds milk Step 3 allow milk to cool to 20°C beads containing Step 4 pour milk into a container of enzyme beads containing enzymes Step 5 collect lactose-free milk lactose-free milk Step 6 store lactose-free milk at 2°C in sterile bottles Fig. 5.1 (i) Explain how heating the milk in step 2 in Fig. 5.1 ensures the hygienic preparation of lactose-free milk. …… [1] (ii) Explain why the milk must be cooled in step 3 before it makes contact with the enzymes. …… [2] (iii) State the name of the enzyme used to make lactose-free milk in step 4. …… [1] (iv) Suggest why the enzymes are kept in the beads in step 4 rather than mixed as an enzyme solution with the milk. …… [1] (d) Milk is produced by mammals. (i) Explain the advantages to newborn mammals of breast milk. …… [4] (ii) Explain why breast-feeding mothers are advised to drink plenty of water and avoid excessive alcohol consumption. …… [2] [Total: 17]

Question

Sensitivity is one of the characteristics of all living organisms. (a) Define the term sensitivity. …… [2] (b) The eye is an example of a sense organ. (i) Define the term sense organ. …… [2] (ii) Adrenaline is a hormone that is released in ‘fight or flight’ situations. It causes a change in the eye. Complete Table 6.1 by stating the parts of the eye that change when adrenaline is released into the blood. Table 6.1 action part of the eye muscle that relaxes muscle that contracts widens [3] [Total: 7]