9700 Biology November 2025 Question Paper 11

In a photomicrograph of magnification 5000, a chloroplast measures 25 mm in diameter. What is the actual diameter of the chloroplast?

m

A cell in the human body is specialised for synthesis and secretion of lipids. Which row shows the organelles required by the cell for synthesis and secretion of lipids? mitochondria smooth endoplasmic reticulum vesicles

The photomicrograph shows part of a cell. Which row is correct? this cell will contain 70S ribosomes this could be part of a plant cell the organelles shown could be used to make antibodies

Which statement about viruses is correct?

Solution X was tested for the presence of non-reducing sugars. It did not contain reducing sugars. Some steps that can be used to test for the presence of biological molecules are listed. Add Benedict’s solution to the test-tube. Add dilute hydrochloric acid to the test-tube. Add sodium hydrogencarbonate to the test-tube. Heat the test-tube in a water-bath. Which order of steps to identify the presence of non-reducing sugars in solution X is correct?

The diagram shows the structure of part of a biological molecule. OH OH HO OH OH CH2 O CH2OH HOH2C O O HO OH O CH2 HOH2C HOH2C O HO OH O CH2 CH2 O HO OH O CH2OH CH2 O HO OH O CH2 HOH2C O HO OH O CH2 HOH2C O HO OH O CH2OH O Which statements about this biological molecule are correct? It has monomers joined by ester bonds. It is a macromolecule. It is a polysaccharide.

Which diagram has a covalent bond that joins monomers together to form a biological polymer in eukaryotes? O P O R O– O R R NH3 + –O R O O R

Which feature of storage polysaccharides means they do not change the water potential of cells?

Which molecules contain at least four double bonds? saturated triglyceride collagen haemoglobin

In some people a mutation can affect the beta chains in their haemoglobin molecules. As a result polar amino acids on the outer surfaces of the chains are replaced by non-polar amino acids. What will be the effect on haemoglobin?

The graph shows the effect of substrate concentration on an enzyme-catalysed reaction with and without a competitive inhibitor. rate of reaction substrate concentration key with inhibitor without inhibitor What is the effect of the competitive inhibitor on Vmax and Km?

The graph shows energy changes in a chemical reaction. energy progress of reaction What is the activation energy when an enzyme is added?

The diagram shows an enzyme, its substrate and an enzyme–substrate complex. enzyme substrate enzyme–substrate complex Which statement explains how this substrate is able to enter the active site of this enzyme?

What are the main roles of glycolipids in cell surface membranes? to help cells to attach to each other to form tissues to act as antigens for cell-to-cell recognition to increase fluidity for the cell surface membrane

A sample of healthy plant cells taken from the same tissue is placed in a beaker containing distilled water. The cells change in size. What would explain this change in size?

A student studying surface area to volume ratio and diffusion made a cuboid, S1, using agar stained blue with a pH indicator. The dimensions of S1 are shown in the diagram. The student made a second agar cuboid, S2. Each dimension of S2, (the length, the width and the height), was half that of S1. 8 mm 5 mm 30 mm 4 mm S1 S2 2.5 mm 15 mm not to scale The student placed each cuboid in a test-tube and covered it in acid. The time taken for each cuboid to completely change colour was recorded. All variables other than the size of the cuboids were standardised. Which row shows the surface area to volume ratio of S1 and the time taken for S1 to change colour completely in acid compared to the time taken for S2 to change colour completely? surface area to volume ratio of S1 time taken for S1 to change colour completely in acid compared to S2

Two test-tubes, labelled X and Y, were set up containing equal volumes of solution X or solution Y respectively. A large number of type P cells and a large number of type Q cells were added into test-tube X and also into test-tube Y. After a few minutes, samples of the solutions were taken and the cells were observed with a microscope. ● In solution X, all of cell type P had burst and cell type Q had not burst. ● In solution Y, no cells had burst. Which row correctly identifies cell type Q and solutions X and Y? cell type Q solution X solution Y

A human muscle cell contains 46 chromosomes. How many centromeres will be present in a cell during the stages of the mitotic cell cycle? early prophase metaphase anaphase

Telomeres become shorter during each cell cycle of a specialised cell. In which phase of the cell cycle do telomeres shorten?

The photomicrographs show stages of mitosis. What is the correct order for the stages of mitosis?

The gene that codes for protein R is 130 kb long. Protein R is 220 kDa in mass. The typical mass of an amino acid is 110 Da. (1000 base pairs = 1 kb, 1000 Da = 1 kDa) Which row is correct? approximate length of introns in this gene / base pairs approximate length of mRNA for this gene / base pairs

The diagram shows a section of DNA. Two of the bases in this section are labelled 1 and 2. O O O O O O Which row correctly identifies the bases 1 and 2? base 1 base 2

Which row describes the role of the enzymes DNA polymerase and DNA ligase? DNA polymerase DNA ligase

The table shows some of the DNA triplet codes for some amino acids. amino acid DNA triplet code amino acid DNA triplet code arginine GCA glycine CCA arginine GCC glycine CCG arginine GCG glycine CCT asparagine TTA lysine TTC asparagine TTG lysine TTT cysteine ACA proline GGA cysteine ACG proline GGC STOP ATC valine CAC The base sequence on the template DNA strand coding for part of a polypeptide is shown. CCA TTC ACG GCG TTA GCA Two mutations occur in this sequence during DNA replication. Which mutated DNA would result in two different amino acids?

The diagram shows a vertical section through part of the stem of a dicotyledonous plant. Three types of structures are labelled. W U V What are the structures U, V and W? companion cells phloem sieve tube elements xylem vessel elements

Which features of xylem vessels help to reduce the resistance to water flow? Lignin forms an incomplete secondary wall. There are no cross walls between the vessel elements. The xylem vessels form narrow tubes.

What causes water to move from the root hair cells to the endodermis?

Which changes occur as carbohydrate is moved into a sink? water potential of the sieve tube element becomes volume of liquid of the sieve tube element

Which statement correctly compares blood plasma and tissue fluid in a healthy person?

The body maintains an average normal blood pH of 7.4. Which row describes the conditions that would increase the dissociation rate of haemoglobin the most during periods of intense exercise? blood pH blood CO2 partial pressure / kPa

The graph shows changes in blood pressure during one cardiac cycle. 0.75 time / s blood pressure / kPa X key aorta ventricle atrium What is happening at time X? aortic semilunar valve atrium

How many times must a carbon dioxide molecule pass through a cell surface membrane to travel from the tissue fluid into the blood plasma? (Assume there are no pores between the cells the carbon dioxide molecule must pass through.)

Two types of epithelial cells, 1 and 2, occur in the mammalian gas exchange system in a healthy human. Which row shows the function and distribution of these types of epithelial cells? cell type 1 cell type 2

Which tissues would be seen in a photomicrograph of the wall of the trachea? elastic fibres smooth muscle

The graph shows the decrease in cases of tuberculosis (TB) in a country between 1910 and 2000. 1910 1920 1940 1960 year 1980 2000 90 000 80 000 70 000 60 000 50 000 40 000 30 000 20 000 10 000 number of cases per year Which factors could have contributed to the fall over this period? pasteurisation of milk the provision of new housing to reduce overcrowding removing large pools of stagnant water identification of contacts of people infected with TB

The pathogens for some diseases are transmitted by vectors. Which disease is transmitted with the help of a vector that could be controlled by the removal of pools of water?

How does penicillin affect bacteria?

The hybridoma method is used for the production of monoclonal antibodies. Which two types of cell are used in this method?

What describes a non-specific immune response?