Topic 1 1819 [50 Marks] - IB Biology Resources

Topic 1 1819 [50 marks]1.Which feature of striated muscle cells allows them to be considered as a possible exception to the cell theory?[1 mark]A. They are found in multicellular organisms.B. They contain more than one nucleus.C. They are specialized for movement.D. They do not carry out mitosis.MarkschemeB2.Which characteristic of stem cells makes them useful for treating Stargardt’s disease?[1 mark]A. They can differentiate into retinal cells.B. They are readily available from especially created embryos.C. They transport white blood cells to the eyes.D. They divide by binary fission so provide sufficient cells.MarkschemeAThe following electron micrograph which shows part of two adjacent liver cells.3.What is the structure labelled Y?A. NucleusB. Starch grainC. LysosomeD. Mitochondrion[1 mark]

MarkschemeD4.Where can 70S ribosomes be found?[1 mark]A. On membranes of the Golgi apparatusB. In prokaryotic cellsC. On membranes of the rough endoplasmic reticulumD. In nucleiMarkschemeB5.Which are functions of membrane proteins?A. Hormone binding sites and DNA replicationB. Cell adhesion and translationC. Cell to cell communication and protein pumpsD. Passive transport and glycosis[1 mark]MarkschemeC6.What feature of cell membranes allows endocytosis to occur?[1 mark]A. Fluidity of phospholipid bilayerB. Presence of protein pumpsC. Presence of carrier proteinsD. Glycoprotein binding sitesMarkschemeA7.The salt concentration inside an animal cell is 1.8 %. The salt concentration in the surrounding medium becomes 5 %. What will be[1 mark]the likely response?A. The cell will gain water from the medium.B. The cell will lose salt to the medium.C. The cell will remain unchanged.D. The cell will shrink from loss of water.MarkschemeD

8.The diagram is a model of one type of movement across a membrane.[1 mark]What is this type of movement?A. Simple diffusionB. Facilitated diffusionC. OsmosisD. Active transportMarkschemeB9.Why do crop plants dry out when a field is irrigated with water contaminated by sea water?[1 mark]A. The plants lose water by active transport.B. The plants gain salt by osmosis.C. The plants gain salt by diffusion.D. The plants lose water by osmosis.MarkschemeD10. Cells in the adrenal gland produce the hormone epinephrine and store it in vesicles. To release epinephrine these vesicles arecarried to the plasma membrane and fuse with it. What process is occurring?A. ExpulsionB. ExchangeC. ExcretionD. ExocytosisMarkschemeD[1 mark]

11.The statement relates to Pasteur’s experiments.[1 mark]What did this statement suggest?A. Mold evolved by endosymbiosis.B. Oxygen is required for anaerobic respiration.C. Cells can only be formed by division of pre-existing cells.D. Nutrients are a requirement for mold growth.MarkschemeC12. Which mitotic phase is labelled X in the micrograph of an onion (Allium cepa) root tip?[1 mark]A. ProphaseB. MetaphaseC. AnaphaseD. TelophaseMarkschemeB13.What is the process shown in this image?A. Binary fission of a prokaryotic cellB. Telophase II in a eukaryotic cellC. End of mitosis in a prokaryotic cellD. Cytokinesis of a eukaryotic cell[1 mark]

MarkschemeA14.During which stage does the cell surface area to volume ratio decrease?[1 mark]A. InterphaseB. MetaphaseC. TelophaseD. CytokinesisMarkschemeA15.During which stage of the cell cycle are the numbers of mitochondria increased in a cell?A. CytokinesisB. InterphaseC. MeiosisD. Mitosis[1 mark]MarkschemeB16.What is evidence for the endosymbiotic theory?[1 mark]A. RNA can catalyse metabolic reactions.B. Meteorites contain organic molecules.C. Amino acids can be synthesized from inorganic compounds.D. Mitochondria possess their own DNA.MarkschemeD17.Which of the following will contribute to the cell theory?I. Living organisms are composed of cells.II. All cells come from pre-existing cells by mitosis.III. Cells are the smallest units of life.A. I onlyB. II onlyC. I and III onlyD. I, II and IIIMarkschemeC[1 mark]

18. Which functions of life are carried out by all unicellular organisms?[1 mark]MarkschemeB19.What is a difference between a cell in the G 1 phase and a cell in the G 2 phase of the cell cycle?[1 mark]A. A cell in the G2 phase would be smaller than a cell in the G 1 phase.B. A cell in the G2 phase would have more mitochondria than a cell in the G 1 phase.C. A cell in the G1 phase would have more DNA in its chromosomes than a cell in the G 2 phase.D. DNA replication occurs in the G 1 phase but not in the G2 phase.MarkschemeB20.A botanist measures a leaf and finds it is 24 cm long and 8 cm wide. His drawing of the leaf is 4 cm wide. Which was themagnification and length of his drawing, assuming that the proportions of the drawing were correct?[1 mark]MarkschemeD21. (i) State the process that divides one nucleus into two genetically identical nuclei.(ii) Explain how the cell cycle is controlled.[5 marks]

Markscheme(i) mitosis(ii)a. cell cycle is a sequence of stages / cell cycle is G 1, S, G2 and mitosisb. (control of the cell cycle) by cyclins/cyclinc. levels of cyclins rise (and fall)/fluctuate during the cell cycle/surge at different times/have to reach a certain concentrationd. conditions inside as well as outside the cell affect regulatione. four cyclins/different cyclins to enter different stages of/events in the cell cycle / cyclins regulate the sequence/timing of the cell cycle /cyclins trigger the next stagesThe idea of different cyclins acting at different phases must be clear .f. cyclin-dependent kinases / cyclins bind to kinases and activate themg. kinases phosphorylate other proteinsh. phosphorylated proteins perform specific functions in the cell cycle22. Draw a labelled diagram of a eukaryotic plant cell as seen in an electron micrograph.[4 marks]MarkschemeCell wall shown with two continuous lines to indicate the thicknessPlasma membrane/cell membrane shown as a single continuous lineAccept inner line of wall as membrane if clearly labelled.Nuclear membrane/nucleus shown with double membrane and nuclear poresVacuole «membrane»/tonoplast shown as a single continuous lineChloroplast/plastid shown with a double line to indicate the envelope and thylakoids/granaMitochondrion shown with double membrane/cristae23a. Draw a labelled diagram to show the structure of membranes.[6 marks]MarkschemeAward [1] for each structure clearly drawn and correctly labelled.phospholipid bilayer – with head and tails;hydrophilic / phosphate / polar heads and hydrophobic / hydrocarbon / fatty acid / non-polar tails labelled;integral/intrinsic protein – embedded in the phospholipid bilayer;protein channel – integral protein showing clear channel/pore;peripheral/extrinsic protein – on the surface;glycoprotein with carbohydrate attached; (carbohydrate should project outwardly from membrane protein )cholesterol – shown embedded in bilayer; (must appear in hydrophobic region)thickness indicated (10 nm); (allow answers in the range of 7 nm to 13 nm )23b. Explain passive transport and active transport across membranes.[8 marks]

Markschemediffusion/facilitated diffusion and osmosis are passive;do not require energy/ATP;diffusion is movement from high to low concentration/down a (concentration) gradient;facilitated diffusion uses (protein) channels/carrier proteins;osmosis is water movement from lower to higher solute concentration / from higher to lower water potential/concentration;across a partially permeable membrane;active transport/formation of vesicles require energy;in the form of ATP;active transport moves materials up/against the (concentration) gradient/from low to high concentration;protein pumps required;endocytosis into cells / exocytosis out of cells;example of active or passive transport; (e.g. sodium potassium pump for active transport / oxygen exchange in alveoli for passivetransport)The micrograph shows a cell from the root of an onion ( Allium cepa) during mitosis.24a. Calculate the magnification of the image.[1 mark]Markscheme136 (accept answers in the range of 132 to 140)24b. Deduce the stage of mitosis shown in the micrograph.[1 mark]Markschemeanaphase25a.State the property of stem cells that makes them useful in medical treatment.[1 mark]Markschemehas the ability to differentiate (into specialized tissue)25b. Explain how multicellular organisms develop specialized tissues.[2 marks]

Markschemeonly some genes are expressed in each cell type/tissue;tissues therefore develop differently/become differentiated;example of differentiated cell and the function of tissues;This image shows a normal red blood cell.These images show two red blood cells that have been placed in solutions with different concentrations of solutes.26a.Deduce, with a reason, which red blood cell has been placed in a hypertonic solution.[1 mark]Markschemecell 2 because it has plasmolized/lost water/volume has decreased26b. State what change there has been in the cell surface area to volume ratio in red blood cell 1.[1 mark]Markschemedecreased International Baccalaureate Organization 2018International Baccalaureate - Baccalauréat International - Bachillerato Internacional Printed for Dubai American Academy

The micrograph shows a cell from the root of an onion (Allium cepa) during mitosis. Calculate the magnification of the image. Markscheme 136 (accept answers in the range of 132 to 140) 24b.Deduce the stage of mitosis shown in the micrograph. Markscheme anaphase 25a. State the property of stem cells that makes them useful in medical treatment .