Unit 1 Cell Biology Practice 1 [72 marks]

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1 Unit 1 Cell Biology Practice 1 [72 marks] 1. Which structure found in eukaryotes has a single membrane? A. Nucleus B. Lysosome C. Chloroplast D. Mitochondrion 2. The following electron micrograph shows part of a palisade mesophyll cell. Which of the labelled structures controls the exchange of substances to and from the cell?

2 3. Cladograms can be created by comparing DNA or protein sequences. The cladogram on the left is based on DNA sequences and the cladogram on the right is based on comparing protein sequences. What is the reason that cladograms based on DNA sequences are more reliable predictors of the phylogenetic relationship of species than cladograms based on protein sequences? A. Amino acids are not as chemically stable as DNA nucleotides. B. DNA mutates but amino acids do not. C. Several different triplets of bases can code for the same amino acid. D. There are 20 different amino acids but only 4 nucleotides. 4. Which organism has DNA located in three organelles? A. A sponge B. A fern C. A flatworm D. A bacterium 5. Which organelle is involved in generating vesicles destined for the cell membrane? A. Golgi apparatus B. Smooth endoplasmic reticulum C. Rough endoplasmic reticulum D. Lysosome

3 6. When during the cell cycle does DNA replication take place? 7. The giant alga Acetabularia has a feature that suggests it is an exception to the cell theory. What feature is this? A. It lacks a nucleus. B. It lacks a cell wall. C. It has only one mitochondrion. D. It lacks subdivision into separate cells. 8. The image shows an electron micrograph of mesophyll cells. What is the name of the structure labelled X? A. Cytoplasm B. Mitochondrion C. Nucleus D. Chloroplast

4 9. The bacterium Neisseria gonorrhoeae causes infections related to the human reproductive system. The graph shows the percentage of samples in which this bacterium showed resistance to six antibiotics over a period of ten years. What is a possible explanation for the total percentage resistance being larger than 100% in 2010? A. People do not take the antibiotics as prescribed. B. More people have been sampled in that year. C. There was an epidemic of Neisseria gonorrhoeae in that year. D. Some bacteria are resistant to more than one antibiotic. 10. What is a role of cholesterol in animal cells? A. It increases body fat. B. It controls membrane fluidity. C. It lines the inner wall of capillaries. D. It is a constituent of bile. 11. What is evidence for the endosymbiotic theory? 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.

5 12. The graph shows the survival probabilities for current smokers and for those who never smoked among women 30 to 80 years of age. What can be deduced from this graph? A. There is a correlation between smoking and cancer. B. Smoking reduces life expectancy. C. Smoking causes cancer. D. 70 % of smokers survive to 80 years old. 13. Which evidence falsifies the Davson Danielli model? I. The presence of globular proteins within the phospholipid bilayer II. Non-polar amino acids cause proteins to remain embedded in membranes III. Membrane proteins remain in a fixed position inside a membrane A. I only B. I and II only C. II and III only D. I, II and III 14. The diagram shows the concentration of four cyclins during the cell cycle. Which curve represents the cyclin that promotes the assembly of the mitotic spindle?

6 15. The image shows an electron micrograph of pancreatic exocrine cells. What is the role of the vesicles shown in the micrograph? A. To transport hormones between the rough endoplasmic reticulum and the Golgi apparatus B. To store glycogen when blood glucose levels are high C. To move enzymes out of the cell by exocytosis D. To digest cellulose 16. What is evidence for the endosymbiotic theory? 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. 17. Which feature of striated muscle cells allows them to be considered as a possible exception to the cell theory? 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. 18. Which characteristic of stem cells makes them useful for treating Stargardt s disease? 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. 19. The cell membrane model proposed by Davson Danielli was a phospholipid bilayer sandwiched between two layers of globular protein. Which evidence led to the acceptance of the Singer Nicolson model? A. The orientation of the hydrophilic phospholipid heads towards the proteins B. The formation of a hydrophobic region on the surface of the membrane C. The placement of integral and peripheral proteins in the membrane D. The interactions due to amphipathic properties of phospholipids

7 20. What provides evidence for the endosymbiotic theory? A. Mitochondrial DNA in eukaryotic cells B. 70S ribosomes in prokaryotic cells C. Gene transfer from prokaryotic cells to eukaryotic cells using plasmids D. Prokaryotic cells (Escherichia coli) in the large intestine digest proteins Native oyster populations are decreasing where rivers meet the ocean along the northwest coast of North America. These oyster populations are being attacked by a gastropod. It is known that oysters and gastropods have hard parts composed of calcium carbonate and that ocean acidification is increasing. Studies were carried out using juvenile oysters and gastropods to investigate the effects of acidification on the decrease in the population of oysters. The first step was to raise oysters in two different mesocosms. One had seawater at a normal concentration of CO 2 and the other had sea water with a high concentration of CO 2. Gastropods were raised in two further mesocosms with normal and high CO2 concentrations respectively. Outline how acidified sea water could affect the shells of the oyster. 21a.

8 A juvenile gastropod will attack a juvenile oyster by using its tongue-like structure (radula) to drill a hole through the oyster shell. Once the hole has been drilled, the gastropod sucks out the soft flesh. Researchers investigated the shell thickness at the site of the drill hole in relation to the size of the oyster. The results are seen in this graph. 21b. Outline the trends shown in the data in the graph. [2 marks]

9 Equal numbers of oysters raised in seawater with a normal CO 2 concentration and in seawater with a high CO 2 concentration were then presented together to the gastropod predators in seawater with a normal CO 2 concentration. The same numbers of oysters from the two groups were also presented together to the gastropods in seawater with a high CO 2 concentration. The bar charts show how many of the oysters were drilled by the gastropods and the mean size of drilled oysters. 21c. Estimate how much smaller drilled oysters raised in seawater at a high CO 2 concentration were than drilled oysters raised in seawater at a normal CO 2 concentration.

10 Deduce from the data in the bar charts which factors were and were not correlated significantly with the number of oysters drilled 21d. by the gastropods. [2 marks] 21e. Suggest reasons for the differences in the numbers of oysters drilled, as shown in the bar charts. [2 marks] 21f. The radula in a gastropod is hard but not made of calcium carbonate. Outline how this statement is supported by the drilling success of the gastropods in seawater with normal or high CO 2 concentrations. [2 marks]

11 21g. Using all the data, evaluate how CO concentrations affect the development of oysters and their predation by gastropods. 2 [2 marks] 22a. Pictured below are Louis Pasteur s original drawings of swan-necked flasks. [3 marks] Describe how Pasteur s experiments provided convincing evidence to falsify the concept of spontaneous generation.

12 22b. State the function of life in Paramecium that is carried out by: cilia. State the function of life in Paramecium that is carried out by: 22c. the contractile vacuole. 22d. Discuss the advantages and disadvantages of the use of adult stem cells. [3 marks]

13 22e. Explain the role of decomposers in an ecosystem. [2 marks] Oxygen is needed to complete aerobic cell respiration. Explain how chemical energy for use in the cell is generated by electron transport and chemiosmosis. 23a. [8 marks]

14 Outline four different functions of membrane proteins. 23b. [4 marks]

15 Distinguish between anabolism, catabolism and metabolism. 23c. [3 marks]

16 24a. Cells go through a repeating cycle of events in growth regions such as plant root tips and animal embryos. Outline this cell cycle. [4 marks] Draw a labelled diagram of the formation of a chiasma by crossing over. 24b. [3 marks]

17 Explain the control of gene expression in eukaryotes. 24c. [8 marks] International Baccalaureate Organization 2017 International Baccalaureate - Baccalauréat International - Bachillerato Internacional Printed for St Andrews International School, Bangkok