9700_s23_qp_21
A paper of Biology, 9700
Questions:
6
Year:
2023
Paper:
2
Variant:
1
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1
is a transmission electron micrograph of a cell from the stem of sago pondweed, Stuckenia pectinata. cell wall magnification ×2500 air space G A B C D E F State the evidence from that shows that the cell is from the stem of S. pectinata and not from the mesophyll of a leaf. Complete each row in Table 1.1 to identify a cell structure shown in that carries out the function listed. Table 1.1 function name of cell structure letter on gas exchange production of subunits of ribosomes active transport of ions aerobic respiration Plant vacuoles develop when vesicles fuse together. The vacuoles increase in size as more vesicles fuse. shows the movement of vesicles within a plant cell during the development of a vacuole. Key Golgi body cell surface membrane rough endoplasmic reticulum protein folded correctly protein not folded correctly vacuole multi-vesicular body X Name the process that is occurring at X. Some of the vesicles formed by the Golgi body pass to the vacuole. These vesicles contain proteins that have been folded correctly and some that have not folded into their correct shapes. The proteins that have not folded correctly pass to the vacuole where they are broken down. Explain how proteins that have not folded correctly are broken down in the vacuole. Small vacuoles in S. pectinata may have roles similar to lysosomes in animal cells. Describe the role of lysosomes in animal cells in defence against pathogens.
1. Cell structure  →  1.2. Cells as the basic units of living organisms
4. Cell membranes and transport  →  4.2. Movement into and out of cells
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2
Glycogen and cellulose are polymers. shows small, representative regions of a glycogen molecule and a cellulose molecule. CH2OH CH2OH CH2OH H O H H OH CH2 O H OH H H O H H OH O H OH H H O O H H OH O H H O H H OH O H OH H OH H O glycogen cellulose OH H H CH2OH H O H H OH O H OH H O H OH CH2OH O H H O H OH H H CH2OH H O H H OH O OH H OH CH2OH O H H Describe three ways, visible in , in which the molecule of glycogen differs from the molecule of cellulose. Glycogen is found in the form of granules in mammalian liver and muscle cells. is a diagram of part of a molecule of glycogen isolated from a glycogen granule. Explain how the structure of glycogen is related to its function in cells. Explain how the arrangement of cellulose molecules in plant cell walls is related to their function.
2. Biological molecules  →  2.2. Carbohydrates and lipids
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3
shows some fruits of the grapevine, Vitis vinifera. Sucrose is transported in the phloem of the grapevine to the fruits. In the fruits, sucrose is hydrolysed by the enzyme sucrase, which is found in cell walls. The glucose and fructose produced by the hydrolysis of sucrose pass through membrane proteins, known as hexose transporters, into the cytoplasm of the fruit cells. State why membrane proteins are required for the movement of molecules, such as glucose, across cell surface membranes into cells. Researchers investigated one type of hexose transporter, known as VvHT1, which is found in the fruit cells of V. vinifera. They used a mutant strain of yeast that has very few hexose transporters in its cell surface membranes to investigate the properties of VvHT1. The researchers inserted molecules of VvHT1 into the cell surface membranes of the mutant strain of yeast. • Equal volumes of mutant yeast cells with VvHT1 were kept in eight different concentrations of glucose solution. • The rate of uptake of glucose by the yeast cells in each solution was determined. • All the solutions were kept at the same temperature and pH. The results are shown in . concentration of glucose / μmol dm–3 rate of uptake of glucose / μmol min–1 g–1 The researchers concluded that VvHT1 is responsible for the facilitated diffusion of glucose into the cells. Explain how the results in provide evidence to support this conclusion. The researchers thought that grapevines could be modified to have more hexose transporters to increase the size and quality of grapes. Explain why increasing the number of hexose transporters could be commercially important to growers of grapevines. is a diagram of a protein in the cell surface membrane of a macrophage from a mouse. Macrophages use these proteins in antigen presentation. Non-self antigens bind to the proteins and are involved in the activation of specific T-lymphocytes during the immune response. antigen-binding region cytoplasm State what is meant by a non-self antigen. Some pathogens enter human cells. Macrophages partially digest these pathogens and present antigens to T-lymphocytes during immune responses. With reference to , explain how T-lymphocytes respond to infection by a specific type of pathogen.
2. Biological molecules  →  2.2. Carbohydrates and lipids
7. Transport in plants  →  7.2. Transport mechanisms
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4
The gene for the enzyme catalase is on chromosome 11 in humans. Explain the meaning of the term gene. Two enzymes, DNA polymerase and DNA ligase, are involved in the replication of DNA. shows the replication of part of human chromosome 11 by DNA polymerase. The arrows show the direction of synthesis of the new polynucleotides by DNA polymerase. G G C A G A T T T G C C T G C T G A G G A A A C G G A C G A C T C C C C G T G A T T T G C C T G C T G A C T A A A C G G A C G A C C C T A A C A T T G T 5' 5' 3' 3' A T T A A G A C C C T G C C DNA polymerase DNA polymerase Describe the roles of DNA polymerase and DNA ligase in the replication of DNA. State the name of the stage of interphase in the cell cycle when DNA replication occurs. is a diagram of chromosome 11 at metaphase of mitosis. A B State the names and functions of structures A and B. structure A function structure B function Complete to show what happens to chromosome 11 in anaphase, so that the daughter nuclei are genetically identical. cell surface membrane
6. Nucleic acids and protein synthesis  →  6.1. Structure of nucleic acids and replication of DNA
19. Genetic technology  →  19.1. Principles of genetic technology
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5
is a longitudinal section of a capillary in muscle tissue as viewed with a transmission electron microscope. magnification ×2000 State the evidence, visible in , that identifies the cells inside the capillary as red blood cells. Explain how the structure of the capillary wall is related to its functions. is a diagram showing some of the events that occur as blood flows through a capillary in a respiring tissue. CO2 CO2 CO2 CO2 CO2 O2 O2 CO2 + H2O H2O red blood cell O2 O2 O2 O2 O2 carbonic anhydrase H2CO3 HCO3 – HCO3 – H+ cells of respiring tissue An increase in respiration results in an increase in the carbon dioxide concentration in the blood and the release of more oxygen from red blood cells to tissues. Explain how an increase in carbon dioxide in the blood leads to the release of more oxygen from red blood cells. Chloride ions are a constituent of blood plasma. The concentration of chloride ions in the plasma of deoxygenated blood is between 2–4 mmol dm–3 lower than in the plasma of oxygenated blood. Explain why the concentration of chloride ions in the blood plasma of deoxygenated blood is lower than in the plasma of oxygenated blood.
8. Transport in mammals  →  8.2. Transport of oxygen and carbon dioxide
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6
is a diagram showing the passage of water through the tissues of a flowering plant from the soil to the atmosphere. The arrows show the direction of water movement. xylem in stem root leaf soil particles X Y The structure labelled X is part of the symplast pathway. State the name of structure X. The structure labelled Y in the cell wall is a barrier to the apoplast pathway. State the name of structure Y. With reference to , complete the statements about the movement of water in the flowering plant. Water moves from the soil solution to the cytoplasm of root hair cells by Water moves from the xylem in the root to the leaf by Water moves from mesophyll cell walls to intercellular air spaces by Water vapour moves from intercellular air spaces to the atmosphere outside the leaf by
4. Cell membranes and transport  →  4.2. Movement into and out of cells
7. Transport in plants  →  7.2. Transport mechanisms
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