Biology 0610/41 October/November 2021: question paper and mark scheme

Question

(a) Fish, mammals and birds are all groups of vertebrates. (i) State the names of the two other main groups of vertebrates. …… and …… [1] (ii) Complete Table 1.1 to compare the features of fish, mammals and birds. Table 1.1 feature fish mammals birds organ involved in gas gills lungs exchange circulatory system double body covering fur presence of external ears no (pinnae) [3] (b) Fig. 1.1 is a micrograph of part of some fish gills. magnification ×110 Fig. 1.1 Fish gills are adapted for gas exchange by diffusion. (i) Define the term diffusion. …… [2] (ii) Suggest one adaptation, visible in Fig. 1.1, that shows that fish gills are efficient structures for gas exchange by diffusion. …… [1] (c) Some pollutants decrease the concentration of dissolved oxygen in rivers. This can result in the death of fish. (i) State one type of pollutant that can result in a decrease in the concentration of dissolved oxygen in rivers. …… [1] (ii) Researchers investigated the effect of the concentration of dissolved oxygen in water on gas diffusion distance in tissues. The thickness of fish gills was used to determine the gas diffusion distance. The researchers changed the concentration of dissolved oxygen by bubbling different concentrations of oxygen into water. The temperature of the water was kept constant at 15 °C. Their results are shown in Fig. 1.2. 3.5 3.0 2.5 gas diffusion 2.0 distance / μm 1.5 1.0 0.5 0.0 6 7 8 9 10 11 12 dissolved oxygen concentration / mg per dm3 Fig. 1.2 Fig. 1.3 shows the relationship between the concentration of dissolved oxygen and water temperature. 12 11 10 dissolved oxygen 9 concentration / mg per dm3 8 7 6 0 5 10 15 20 25 30 35 temperature / °C Fig. 1.3 Complete steps 1 to 3 to determine the effect on gas diffusion distance of increasing the temperature of the water from 15 °C to 25 °C. Step 1 Find the concentration of dissolved oxygen from Fig. 1.3 at: 15 °C: …… mg per dm3 25 °C: …… mg per dm3 Step 2 Use the values from step 1 to find the gas diffusion distances from Fig. 1.2: …… µm …… µm Step 3 Calculate the difference in the values from step 2. …… µm [3] [Total: 11]

Question

(a) Two tomato plants that produce red fruit were bred together. This cross produced 71 offspring plants with red fruit and 26 offspring plants with yellow fruit. Complete the genetic diagram to show this cross. Select a suitable letter to represent the alleles and decide which allele will need a capital letter and which allele will need a lower case letter. letter representing the allele for red fruit …… letter representing the allele for yellow fruit …… parental phenotypes red fruit × red fruit parental genotypes …… × …… gametes , × , offspring genotypes …… expected phenotype ratio …… red fruit : …… yellow fruit actual phenotype ratio 71 red fruit : 26 yellow fruit [6] (b) Researchers carried out some experiments on tomato plants that were homozygous for fruit colour. State how the researchers could be sure that the fruit came from homozygous plants. …… [1] (c) The researchers analysed two pigments, chlorophyll and lycopene, in homozygous red tomato fruit and homozygous yellow tomato fruit. Chlorophyll is found in unripe tomato fruit. (i) Describe the function of chlorophyll. …… [2] (ii) State the name of one mineral required for the synthesis of chlorophyll. …… [1] (iii) The researchers analysed the concentration of the pigments in tomato fruits: • before they were ready to eat (unripe) • when they were ready to eat (ripe). The results of the analysis are shown in Table 2.1. Table 2.1 chlorophyll concentration lycopene concentration / mg per g of tomato fruit / mg per g of tomato fruit unripe red fruit 10.0 0.0 ripe red fruit 1.2 105.7 unripe yellow fruit 6.2 0.0 ripe yellow fruit 0.4 0.7 Use the information in Table 2.1 to compare the changes in pigments in red fruit and yellow fruit as they ripen. …… [3] (d) A gene is responsible for the production of lycopene in fruits. Geneticists have recently produced genetically modified pink pineapples using the gene associated with the production of lycopene. (i) Genes are found at specific locations on an important biological molecule. State the name of this biological molecule. …… [1] (ii) Describe the disadvantages of genetically modifying crops. …… [2] [Total: 16]

Question

Some washing powders contain enzymes. (a) Fig. 3.1 shows a box of biological washing powder containing enzymes. Wonder washing powder Biological washing powder removes stains made from oil, egg, juice, grass and many more. Directions: • add 1–2 scoops to main wash • works best at 30 °C but do not use above 50 °C Ingredients: • soap • enzymes Fig. 3.1 (i) Eggs contain protein. Describe how the biological washing powder removes egg stains. …… [3] (ii) Explain why the manufacturer states that the washing powder works best at 30 °C and should not be used above 50 °C. …… [4] (b) Scientists used enzymes and bile in the early development of biological washing powders. Outline the roles of bile in the body. …… [4] [Total: 11]

Question

Cholera is a transmissible disease. (a) State the name of the type of pathogen that causes cholera. …… [1] (b) A study was designed to test the effectiveness of a cholera vaccine in an area where outbreaks of cholera occur frequently. The doctors gave some people in this area the new vaccine. (i) Suggest what the cholera vaccine must contain to be effective. …… [1] (ii) Explain why the people were not protected from cholera immediately after receiving the vaccine. …… [3] (iii) The doctors ensured that the people who received the new vaccine had not had cholera before. Suggest why. …… [1] (iv) There was an outbreak of cholera in the area two months after the new vaccine was given. The people who had symptoms of cholera were monitored in hospital for two days. Some of the infected people had received the new vaccine and others had not received the vaccine. The results are shown in Fig. 4.1. 100 90 80 Key: vaccinated 70 not vaccinated 60 percentage of people in hospital with 50 the symptom 40 30 20 10 0 pathogen present diarrhoea high body in faeces temperature factors monitored in hospital Fig. 4.1 Using the information in Fig. 4.1, discuss how effective the vaccine was at preventing the symptoms of cholera. …… [2] (c) (i) Explain how cholera causes diarrhoea. …… [4] (ii) Describe how diarrhoea is treated. …… [2] [Total: 14]

Question

The circulatory system is comprised of the heart, blood vessels and the blood. (a) Explain how the structures of the heart ensure that blood flows in one direction. Include the names of these structures in your answer. …… [4] (b) Fig. 5.1 shows a diagram of some blood vessels associated with the skin. J Key: indicates the direction of blood flow P K L N M not to scale Fig. 5.1 Table 5.1 shows the functions of some blood vessels. Complete Table 5.1 by: • naming the type of blood vessel • stating the letter of the type of blood vessel from Fig. 5.1. Table 5.1 function type of blood vessel letter on Fig. 5.1 regulates blood flow by constricting and dilating collects blood from a network of the narrowest blood vessels withstands the highest blood pressure allows the transfer of substances to and from tissue fluid transports blood towards the heart redirects blood flow deeper under the surface of the skin [6] (c) State the name of the blood vessels that deliver blood to the: kidneys …… heart muscle …… [2] (d) Describe how blockages in the vessels that deliver blood to the heart muscle can be treated. …… [4] [Total: 16]

Question

Many crop plants are grown as monocultures. Fig. 6.1 shows the destruction of a monoculture of maize as a result of drought. Fig. 6.1 (a) Describe the negative impacts to an ecosystem of large-scale monocultures, such as the one shown in Fig. 6.1. …… [3] (b) The fruits of maize are produced on structures called cobs. Each cob has many fruits. Fig. 6.2 shows how the maize cobs have changed over thousands of years as a result of selective breeding. fruit length of maize cob maize cob time Fig. 6.2 State two desirable features, visible in Fig. 6.2, that have been selected from the more ancient varieties of maize. 1 …… 2 …… [2] (c) The process of selective breeding involves a series of steps, as shown in Fig. 6.3. Step 1 select two plants with desirable features Step 2 transfer pollen from the flower of one plant to a flower on the second plant Step 3 use bags to cover the flowers that are pollinated Step 4 collect the seeds, germinate them and wait for the plants to grow Step 5 select the plants from step 4 that have the desirable features Step 6 continue step 2 to step 5 for many generations Fig. 6.3 (i) Explain why the flowers are covered with bags in step 3. …… [1] (ii) Explain why the seeds in step 4 need oxygen to germinate. …… [2] (iii) Explain why some of the plants in step 5 may show features not visible in the parent plants. …… [1] (iv) Suggest why selective breeding should continue for many generations (step 6). …… [2] (v) State how new features, which did not exist in ancient varieties of a crop plant, could appear. …… [1] [Total: 12]