CAIE Biology (9700)

Fig. 1.1 is a diagram of part of the inner membrane of a mitochondrion. inner membrane intermembrane space carriers matrix

(i) The coenzymes NAD and F AD deliver hydrogen atoms to the electron transport chain (ETC). With reference to Fig. 1.1, state which of the four carriers receives hydrogen atoms from reduced F AD.

Hydrogen atoms that are delivered to the ETC by reduced NAD and reduced F AD split into protons and electrons. Energy is released as electrons pass along the ETC. Describe the events that occur as a result of this release of energy.

Describe how structure 5 in Fig. 1.1 is involved in oxidative phosphorylation.

Cyanide ions (CN ) are highly toxic. Cyanide ions bind to carrier 4 in Fig. 1.1 and inactivate the carrier . Suggest and explain how the binding of cyanide ions to carrier 4 can have an ef fect on respiration. [Total: 10] * 0000800000003 *

When organisms reproduce, they pass on their alleles to the next generation. There are many factors that can affect how allele frequencies change over time in a population. Explain how genetic drift and the founder ef fect may affect allele frequencies in populations. [Total: 6] * 0000800000004 *

Rice, Oryza sativa, is an important grain crop. A rice grain is a seed and can have a structure known as an awn, which projects from the tip of the grain. Fig. 3.1 shows a rice grain with an awn present and a rice grain with no awn present.awn grain no awn present

(i) The development of awns is controlled by two genes: gene A/a and gene B/b. The genes are present on dif ferent autosomes. The presence of either dominant allele A or dominant allele B results in rice plants producing grains with awns. A cross was carried out between a rice plant that is homozygous dominant for the two genes (double homozygous dominant) and a rice plant that is homozygous recessive for the two genes (double homozygous recessive). All F1 of fspring plants produced grains with awns. Construct a genetic diagram, including a Punnett square, to show the cross that produces the F2 generation, including phenotypes. State the ratio of the offspring phenotypes produced. [5] * 0000800000005 *

Deduce the type of inheritance shown by the ratio of the of fspring phenotypes stated in 3(a)(i).

It is common for wild rice plants to have grains with awns present. Suggest a selective advantage to wild rice of having awns present on their grains.

One of the changes that occurred during the domestication of wild rice to cultivated rice was the loss of the awns from rice grains. Farmers found that long awns made storing and processing rice grains more dif ficult. It was also observed that rice plants that have grains with no awns have an increased grain yield.

Explain the principles used by farmers to produce rice plant grains with no awns. development and in the number of grains of rice produced. When the transcription factor is present there is: (positive regulation) (negative regulation). with no awns and an increased grain yield. [Total: 14] * 0000800000007 *

Sexual reproduction in plants and animals involves:

In most species of plants and animals, the cell that is formed as a result of fertilisation is diploid and contains homologous chromosomes. Explain why the cell that is formed as a result of fertilisation is a diploid cell and contains homologous chromosomes.

State the name of the stage in meiosis when reduction division occurs and ex plain a reason for your choice. stage in meiosis reason [2] * 0000800000008 *

Microscope slides can be prepared for viewing with a light microscope to show the dif ferent stages of meiosis in plant cells. In the male reproductive organ of plants, meiosis takes place in cells known as pollen mother cells. Fig. 4.1 and Fig. 4.2 show photomicrographs of two dif ferent stages of meiosis in pollen mother cells from a lily plant, Lilium.

Identify the stages of meiosis shown in Fig. 4.1 and Fig. 4.2. Fig. 4.1 Fig. 4.2

The cells formed at the end of meiosis in a Lilium pollen mother cell each have 12 chromosomes. State the number of sister chromatids found in a Lilium pollen mother cell at the start of meiosis. [Total: 8] * 0000800000009 *

A number of diseases in humans can be treated using recombinant human proteins. These are produced by recombinant DNA technology.

To produce a human protein for treatment of a disease, recombinant DNA technology needs a gene coding for the particular human protein. Outline the dif ferent ways that can be used to obtain a gene that codes for a human protein.

Diabetes mellitus is a disease in which the blood glucose concentration cannot be controlled. Many people with diabetes mellitus use recombinant human insulin to help control their blood glucose concentration. Before recombinant human insulin became available, animals were the main source of insulin. Explain the advantages of using recombinant human insulin to treat diabetes.

Explain why the DNA involved in the production of recombinant human insulin is termed recombinant DNA.

Recombinant human insulin analogues are insulin proteins that have slightly altered amino acid sequences compared with recombinant human insulin. These analogues can be more effective than human insulin. Synthetic genes coding for insulin analogues have been developed. The bacterium Escherichia coli can be used as a host for a synthetic gene for the large-scale manufacture of an analogue. When scientists have determined the changes that are needed to produce an insulin analogue, they can obtain a synthetic gene coding for the analogue by making changes to a length of DNA using genetic engineering. Suggest how scientists genetically engineer a synthetic gene coding for the insulin analogue and explain how the changes they make allow the correct analogue to be produced. [Total: 12] * 0000800000011 *

Guard cells are located in the epidermis of the leaves of most plants. When environmental conditions change, this causes changes in guard cells that control the opening and closing of stomata.

Describe the structure of guard cells.

Stomata have daily rhythms of opening and closing. Fig. 6.1 shows the percentage of stomata open at dif ferent times of the day , over a period of three days, in the thale cress plant, Arabidopsis thaliana. 24:00 12:00 24:00 12:00 time of day 24:00 24:0012:00 percentage of stomata openKey 12:00= midday 24:00= midnight = darkness Fig. 6.1 * 0000800000012 *

With reference to Fig. 6.1, describe the rhythm of stomatal opening and closing.

Suggest other environmental factors, apart from the time of day , that can contribute to stomatal closure.

Table 6.1 shows some of the events occurring during the closure of a stoma. The events are not listed in the correct order . Table 6.1 event description of event A water leaves the guard cells by osmosis B active transport of hydrogen ions out of the guard cells stops C stoma closes D plant is subjected to a change in environmental conditions E plant releases abscisic acid F calcium ions move into the cytoplasm of the guard cells G abscisic acid binds to receptors on the cell surface membrane of guard cells H guard cells become flaccid I water potential of the guard cells increases J potassium ions leave the guard cells Complete Table 6.2 to show the correct order of the events shown in Table 6.1. Three of the events have been completed for you. Table 6.2 correct order letter of event 1 D 5 F 10 C [4] [Total: 12] * 0000800000014 *

An axon membrane is described as being at its resting potential when an action potential is not occurring. Describe and explain how a resting potential of an ax on membrane is maintained.

Hypokalaemia is a condition in which there is a low concentration of potassium ions (K ) in the body. This can affect nervous coordination. Fig. 7.1 shows a normal action potential and Fig. 7.2 shows an action potential of a person with hypokalaemia. 0 1 2 3 time / ms 4 5 -120 -100-80-60-40-20+20+40 membrane potential / mV 0 1 2 3 time / ms 4 5 -120 -100-80-60-40-20+20+40 membrane potential / mV Fig. 7.2 * 0000800000016 *

With reference to Fig. 7.1 and Fig. 7.2, describe the dif ferences between a normal action potential and an action potential of a person with hypokalaemia.

Suggest how hypokalaemia may affect nervous coordination. [Total: 11] * 0000800000017 *

A lichen describes a mutually beneficial association of a fungus with an organism termed a photobiont. An example of a photobiont is the green alga, T rebouxia sp., which is a photosynthetic protoctist. Fig. 8.1 shows lichen attached to a tree.

Outline the characteristic features of the kingdom Fungi.

Suggest how a fungus and a green alga benefit from the relationship shown by a lichen.

A suspension of T rebouxia in water was used to investigate the ef fect of the intensity of light on the rate of photosynthesis. The volume of oxygen released over a set period of time was used as a measure of the rate of photosynthesis at each different light intensity. All other conditions were kept constant. Fig. 8.2 shows how light intensity affected the volume of oxygen released by T rebouxia. light intensity volume of oxygen released

State which photosystem is involved in the release of oxygen.

With reference to Fig. 8.2: [Total: 11] * 0000800000019 *

The biodiversity of an area can be assessed using a variety of sampling methods. Outline how a frame quadrat could be used to assess the biodiversity of plants in a field.

A student investigated whether the height of the soft rush plant, Juncus effusus, decreases with an increase in altitude on a hillside in the United Kingdom. Spearman' s rank correlation was used to assess the relationship between the height of the plants and altitude. The equation for Spearman' s rank correlation (r ) is: = 1 - ( 6 × ΣD - n ) Key to symbols: D = difference in rank between each pair of measurements n = number of pairs of items in the sample was calculated to be 550.

Calculate the Spearman's rank correlation for these data. Give your answer to three decimal places. answer [3] * 0000800000020 *

The null hypothesis for this investigation is: there is no correlation between the altitude and the height of the soft rush plants. Table 9.1 shows the critical values for Spearman's rank correlation. Table 9.1 n p = 0.05 10 0.564 12 0.504 14 0.459 Use your value of Spearman' s rank correlation and Table 9.1 to state and explain if the null hypothesis is correct. [Total: 9] * 0000800000021 *

The grey seal, Halichoerus grypus, is an aquatic mammal that lives in the North Atlantic Ocean. It feeds on fish, which it hunts at depths of up to 70 metres. Fig. 10.1 shows a grey seal. Diving to hunt for fish has an effect on the respiration of the grey seal. A study was carried out to measure the blood lactate concentration of a grey seal before, during and after a dive in deep water. * 0000800000022 * Fig. 10.2 shows the results of this study. 0 20 40 60 time / min dive blood lactate concentration / mmol dm With reference to Fig. 10.2, suggest reasons for the change in blood lactate concentration of the seal: [Turn over * 0000800000023 *

Some seal species are classified as endangered on the IUCN Red List of Threatened Species Suggest ways in which seal species may be conserved. [Total: 7] The boundaries and names shown, the designations used and the presentation of material on any maps contained in this question paper/insert do not imply official endorsement or acceptance by Cambridge Assessment International Education concerning the legal status of any country , territory, or area or any of its authorities, or of the delimitation of its frontiers or boundaries. Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable ef fort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cambridgeinternational.org after the live examination series. Local Examinations Syndicate (UCLES), which is a department of the University of Cambridge. * 0000800000024 *